最近新的系统开发用的是Cookie存储用户信息，使用des加密

工具类如下所示:

  1. /**
  2.  * Copyright (c) 2013-Now http://jeesite.com All rights reserved.
  3.  */
  4. package com.lms.common.utils;
  5.  
  6. import java.io.UnsupportedEncodingException;
  7. import java.util.ArrayList;
  8. import java.util.List;
  9.  
  10. /**
  11.  * DES加密解密工具
  12.  * 加密：DesUtils.encode("admin","1,2,3");
  13.  * 解密：DesUtils.decode("012C2C9BA925FAF8045B2FD9B02A2664","1,2,3");
  14.  * @author ThinkGem
  15.  */
  16. public class DesUtils {
  17.  
  18.     private static DesCore desCore = new DesCore();
  19.  
  20.     /**
  21.      * DES加密（secretKey代表3个key，用逗号分隔）
  22.      */
  23.     public static String encode(String data, String secretKey) {
  24.         if (StringUtils.isBlank(data)){
  25.             return "";
  26.         }
  27.         String[] ks = StringUtils.split(secretKey, ",");
  28.         if (ks.length >= 3){
  29.             return desCore.strEnc(data, ks[0], ks[1], ks[2]);
  30.         }
  31.         return desCore.strEnc(data, secretKey, "", "");
  32.     }
  33.  
  34.     /**
  35.      * DES解密（secretKey代表3个key，用逗号分隔）
  36.      */
  37.     public static String decode(String data, String secretKey) {
  38.         if (StringUtils.isBlank(data)){
  39.             return "";
  40.         }
  41.         String[] ks = StringUtils.split(secretKey, ",");
  42.         if (ks.length >= 3){
  43.             return desCore.strDec(data, ks[0], ks[1], ks[2]);
  44.         }
  45.         return desCore.strDec(data, secretKey, "", "");
  46.     }
  47.  
  48.     /**
  49.      * DES加密/解密
  50.      * @Copyright Copyright (c) 2006
  51.      * @author Guapo
  52.      */
  53.     @SuppressWarnings({"rawtypes","unused","unchecked"})
  54.     static class DesCore {
  55.  
  56.         /*
  57.          * encrypt the string to string made up of hex return the encrypted string
  58.          */
  59.         public String strEnc(String data, String firstKey, String secondKey, String thirdKey) {
  60.  
  61.             int leng = data.length();
  62.             String encData = "";
  63.             List firstKeyBt = null, secondKeyBt = null, thirdKeyBt = null;
  64.             int firstLength = 0, secondLength = 0, thirdLength = 0;
  65.             if (firstKey != null && firstKey != "") {
  66.                 firstKeyBt = getKeyBytes(firstKey);
  67.                 firstLength = firstKeyBt.size();
  68.             }
  69.             if (secondKey != null && secondKey != "") {
  70.                 secondKeyBt = getKeyBytes(secondKey);
  71.                 secondLength = secondKeyBt.size();
  72.             }
  73.             if (thirdKey != null && thirdKey != "") {
  74.                 thirdKeyBt = getKeyBytes(thirdKey);
  75.                 thirdLength = thirdKeyBt.size();
  76.             }
  77.  
  78.             if (leng > 0) {
  79.                 if (leng < 4) {
  80.                     int[] bt = strToBt(data);
  81.                     int[] encByte = null;
  82.                     if (firstKey != null && firstKey != "" && secondKey != null && secondKey != "" && thirdKey != null && thirdKey != "") {
  83.                         int[] tempBt;
  84.                         int x, y, z;
  85.                         tempBt = bt;
  86.                         for (x = 0; x < firstLength; x++) {
  87.                             tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  88.                         }
  89.                         for (y = 0; y < secondLength; y++) {
  90.                             tempBt = enc(tempBt, (int[]) secondKeyBt.get(y));
  91.                         }
  92.                         for (z = 0; z < thirdLength; z++) {
  93.                             tempBt = enc(tempBt, (int[]) thirdKeyBt.get(z));
  94.                         }
  95.                         encByte = tempBt;
  96.                     } else {
  97.                         if (firstKey != null && firstKey != "" && secondKey != null && secondKey != "") {
  98.                             int[] tempBt;
  99.                             int x, y;
  100.                             tempBt = bt;
  101.                             for (x = 0; x < firstLength; x++) {
  102.                                 tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  103.                             }
  104.                             for (y = 0; y < secondLength; y++) {
  105.                                 tempBt = enc(tempBt, (int[]) secondKeyBt.get(y));
  106.                             }
  107.                             encByte = tempBt;
  108.                         } else {
  109.                             if (firstKey != null && firstKey != "") {
  110.                                 int[] tempBt;
  111.                                 int x = 0;
  112.                                 tempBt = bt;
  113.                                 for (x = 0; x < firstLength; x++) {
  114.                                     tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  115.                                 }
  116.                                 encByte = tempBt;
  117.                             }
  118.                         }
  119.                     }
  120.                     encData = bt64ToHex(encByte);
  121.                 } else {
  122.                     int iterator = (leng / 4);
  123.                     int remainder = leng % 4;
  124.                     int i = 0;
  125.                     for (i = 0; i < iterator; i++) {
  126.                         String tempData = data.substring(i * 4 + 0, i * 4 + 4);
  127.                         int[] tempByte = strToBt(tempData);
  128.                         int[] encByte = null;
  129.                         if (firstKey != null && firstKey != "" && secondKey != null && secondKey != "" && thirdKey != null && thirdKey != "") {
  130.                             int[] tempBt;
  131.                             int x, y, z;
  132.                             tempBt = tempByte;
  133.                             for (x = 0; x < firstLength; x++) {
  134.                                 tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  135.                             }
  136.                             for (y = 0; y < secondLength; y++) {
  137.                                 tempBt = enc(tempBt, (int[]) secondKeyBt.get(y));
  138.                             }
  139.                             for (z = 0; z < thirdLength; z++) {
  140.                                 tempBt = enc(tempBt, (int[]) thirdKeyBt.get(z));
  141.                             }
  142.                             encByte = tempBt;
  143.                         } else {
  144.                             if (firstKey != null && firstKey != "" && secondKey != null && secondKey != "") {
  145.                                 int[] tempBt;
  146.                                 int x, y;
  147.                                 tempBt = tempByte;
  148.                                 for (x = 0; x < firstLength; x++) {
  149.                                     tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  150.                                 }
  151.                                 for (y = 0; y < secondLength; y++) {
  152.                                     tempBt = enc(tempBt, (int[]) secondKeyBt.get(y));
  153.                                 }
  154.                                 encByte = tempBt;
  155.                             } else {
  156.                                 if (firstKey != null && firstKey != "") {
  157.                                     int[] tempBt;
  158.                                     int x;
  159.                                     tempBt = tempByte;
  160.                                     for (x = 0; x < firstLength; x++) {
  161.                                         tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  162.                                     }
  163.                                     encByte = tempBt;
  164.                                 }
  165.                             }
  166.                         }
  167.                         encData += bt64ToHex(encByte);
  168.                     }
  169.                     if (remainder > 0) {
  170.                         String remainderData = data.substring(iterator * 4 + 0, leng);
  171.                         int[] tempByte = strToBt(remainderData);
  172.                         int[] encByte = null;
  173.                         if (firstKey != null && firstKey != "" && secondKey != null && secondKey != "" && thirdKey != null && thirdKey != "") {
  174.                             int[] tempBt;
  175.                             int x, y, z;
  176.                             tempBt = tempByte;
  177.                             for (x = 0; x < firstLength; x++) {
  178.                                 tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  179.                             }
  180.                             for (y = 0; y < secondLength; y++) {
  181.                                 tempBt = enc(tempBt, (int[]) secondKeyBt.get(y));
  182.                             }
  183.                             for (z = 0; z < thirdLength; z++) {
  184.                                 tempBt = enc(tempBt, (int[]) thirdKeyBt.get(z));
  185.                             }
  186.                             encByte = tempBt;
  187.                         } else {
  188.                             if (firstKey != null && firstKey != "" && secondKey != null && secondKey != "") {
  189.                                 int[] tempBt;
  190.                                 int x, y;
  191.                                 tempBt = tempByte;
  192.                                 for (x = 0; x < firstLength; x++) {
  193.                                     tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  194.                                 }
  195.                                 for (y = 0; y < secondLength; y++) {
  196.                                     tempBt = enc(tempBt, (int[]) secondKeyBt.get(y));
  197.                                 }
  198.                                 encByte = tempBt;
  199.                             } else {
  200.                                 if (firstKey != null && firstKey != "") {
  201.                                     int[] tempBt;
  202.                                     int x;
  203.                                     tempBt = tempByte;
  204.                                     for (x = 0; x < firstLength; x++) {
  205.                                         tempBt = enc(tempBt, (int[]) firstKeyBt.get(x));
  206.                                     }
  207.                                     encByte = tempBt;
  208.                                 }
  209.                             }
  210.                         }
  211.                         encData += bt64ToHex(encByte);
  212.                     }
  213.                 }
  214.             }
  215.             return encData;
  216.         }
  217.  
  218.         /*
  219.          * decrypt the encrypted string to the original string
  220.          *
  221.          * return the original string
  222.          */
  223.         public String strDec(String data, String firstKey, String secondKey, String thirdKey) {
  224.             int leng = data.length();
  225.             String decStr = "";
  226.             List firstKeyBt = null, secondKeyBt = null, thirdKeyBt = null;
  227.             int firstLength = 0, secondLength = 0, thirdLength = 0;
  228.             if (firstKey != null && firstKey != "") {
  229.                 firstKeyBt = getKeyBytes(firstKey);
  230.                 firstLength = firstKeyBt.size();
  231.             }
  232.             if (secondKey != null && secondKey != "") {
  233.                 secondKeyBt = getKeyBytes(secondKey);
  234.                 secondLength = secondKeyBt.size();
  235.             }
  236.             if (thirdKey != null && thirdKey != "") {
  237.                 thirdKeyBt = getKeyBytes(thirdKey);
  238.                 thirdLength = thirdKeyBt.size();
  239.             }
  240.  
  241.             int iterator = leng / 16;
  242.             int i = 0;
  243.             for (i = 0; i < iterator; i++) {
  244.                 String tempData = data.substring(i * 16 + 0, i * 16 + 16);
  245.                 String strByte = hexToBt64(tempData);
  246.                 int[] intByte = new int[64];
  247.                 int j = 0;
  248.                 for (j = 0; j < 64; j++) {
  249.                     intByte[j] = Integer.parseInt(strByte.substring(j, j + 1));
  250.                 }
  251.                 int[] decByte = null;
  252.                 if (firstKey != null && firstKey != "" && secondKey != null && secondKey != "" && thirdKey != null && thirdKey != "") {
  253.                     int[] tempBt;
  254.                     int x, y, z;
  255.                     tempBt = intByte;
  256.                     for (x = thirdLength - 1; x >= 0; x--) {
  257.                         tempBt = dec(tempBt, (int[]) thirdKeyBt.get(x));
  258.                     }
  259.                     for (y = secondLength - 1; y >= 0; y--) {
  260.                         tempBt = dec(tempBt, (int[]) secondKeyBt.get(y));
  261.                     }
  262.                     for (z = firstLength - 1; z >= 0; z--) {
  263.                         tempBt = dec(tempBt, (int[]) firstKeyBt.get(z));
  264.                     }
  265.                     decByte = tempBt;
  266.                 } else {
  267.                     if (firstKey != null && firstKey != "" && secondKey != null && secondKey != "") {
  268.                         int[] tempBt;
  269.                         int x, y, z;
  270.                         tempBt = intByte;
  271.                         for (x = secondLength - 1; x >= 0; x--) {
  272.                             tempBt = dec(tempBt, (int[]) secondKeyBt.get(x));
  273.                         }
  274.                         for (y = firstLength - 1; y >= 0; y--) {
  275.                             tempBt = dec(tempBt, (int[]) firstKeyBt.get(y));
  276.                         }
  277.                         decByte = tempBt;
  278.                     } else {
  279.                         if (firstKey != null && firstKey != "") {
  280.                             int[] tempBt;
  281.                             int x, y, z;
  282.                             tempBt = intByte;
  283.                             for (x = firstLength - 1; x >= 0; x--) {
  284.                                 tempBt = dec(tempBt, (int[]) firstKeyBt.get(x));
  285.                             }
  286.                             decByte = tempBt;
  287.                         }
  288.                     }
  289.                 }
  290.                 decStr += byteToString(decByte);
  291.             }
  292.             return decStr;
  293.         }
  294.  
  295.         /*
  296.          * chang the string into the bit array
  297.          *
  298.          * return bit array(it's length % 64 = 0)
  299.          */
  300.         public List getKeyBytes(String key) {
  301.             List keyBytes = new ArrayList();
  302.             int leng = key.length();
  303.             int iterator = (leng / 4);
  304.             int remainder = leng % 4;
  305.             int i = 0;
  306.             for (i = 0; i < iterator; i++) {
  307.                 keyBytes.add(i, strToBt(key.substring(i * 4 + 0, i * 4 + 4)));
  308.             }
  309.             if (remainder > 0) {
  310.                 // keyBytes[i] = strToBt(key.substring(i*4+0,leng));
  311.                 keyBytes.add(i, strToBt(key.substring(i * 4 + 0, leng)));
  312.             }
  313.             return keyBytes;
  314.         }
  315.  
  316.         /*
  317.          * chang the string(it's length <= 4) into the bit array
  318.          *
  319.          * return bit array(it's length = 64)
  320.          */
  321.         public int[] strToBt(String str) {
  322.             int leng = str.length();
  323.             int[] bt = new int[64];
  324.             if (leng < 4) {
  325.                 int i = 0, j = 0, p = 0, q = 0;
  326.                 for (i = 0; i < leng; i++) {
  327.                     int k = str.charAt(i);
  328.                     for (j = 0; j < 16; j++) {
  329.                         int pow = 1, m = 0;
  330.                         for (m = 15; m > j; m--) {
  331.                             pow *= 2;
  332.                         }
  333.                         // bt.set(16*i+j,""+(k/pow)%2));
  334.                         bt[16 * i + j] = (k / pow) % 2;
  335.                     }
  336.                 }
  337.                 for (p = leng; p < 4; p++) {
  338.                     int k = 0;
  339.                     for (q = 0; q < 16; q++) {
  340.                         int pow = 1, m = 0;
  341.                         for (m = 15; m > q; m--) {
  342.                             pow *= 2;
  343.                         }
  344.                         // bt[16*p+q]=parseInt(k/pow)%2;
  345.                         // bt.add(16*p+q,""+((k/pow)%2));
  346.                         bt[16 * p + q] = (k / pow) % 2;
  347.                     }
  348.                 }
  349.             } else {
  350.                 for (int i = 0; i < 4; i++) {
  351.                     int k = str.charAt(i);
  352.                     for (int j = 0; j < 16; j++) {
  353.                         int pow = 1;
  354.                         for (int m = 15; m > j; m--) {
  355.                             pow *= 2;
  356.                         }
  357.                         // bt[16*i+j]=parseInt(k/pow)%2;
  358.                         // bt.add(16*i+j,""+((k/pow)%2));
  359.                         bt[16 * i + j] = (k / pow) % 2;
  360.                     }
  361.                 }
  362.             }
  363.             return bt;
  364.         }
  365.  
  366.         /*
  367.          * chang the bit(it's length = 4) into the hex
  368.          *
  369.          * return hex
  370.          */
  371.         public String bt4ToHex(String binary) {
  372.             String hex = "";
  373.             if (binary.equalsIgnoreCase("0000")) {
  374.                 hex = "0";
  375.             } else if (binary.equalsIgnoreCase("0001")) {
  376.                 hex = "1";
  377.             } else if (binary.equalsIgnoreCase("0010")) {
  378.                 hex = "2";
  379.             } else if (binary.equalsIgnoreCase("0011")) {
  380.                 hex = "3";
  381.             } else if (binary.equalsIgnoreCase("0100")) {
  382.                 hex = "4";
  383.             } else if (binary.equalsIgnoreCase("0101")) {
  384.                 hex = "5";
  385.             } else if (binary.equalsIgnoreCase("0110")) {
  386.                 hex = "6";
  387.             } else if (binary.equalsIgnoreCase("0111")) {
  388.                 hex = "7";
  389.             } else if (binary.equalsIgnoreCase("1000")) {
  390.                 hex = "8";
  391.             } else if (binary.equalsIgnoreCase("1001")) {
  392.                 hex = "9";
  393.             } else if (binary.equalsIgnoreCase("1010")) {
  394.                 hex = "A";
  395.             } else if (binary.equalsIgnoreCase("1011")) {
  396.                 hex = "B";
  397.             } else if (binary.equalsIgnoreCase("1100")) {
  398.                 hex = "C";
  399.             } else if (binary.equalsIgnoreCase("1101")) {
  400.                 hex = "D";
  401.             } else if (binary.equalsIgnoreCase("1110")) {
  402.                 hex = "E";
  403.             } else if (binary.equalsIgnoreCase("1111")) {
  404.                 hex = "F";
  405.             }
  406.  
  407.             return hex;
  408.         }
  409.  
  410.         /*
  411.          * chang the hex into the bit(it's length = 4)
  412.          *
  413.          * return the bit(it's length = 4)
  414.          */
  415.         public String hexToBt4(String hex) {
  416.             String binary = "";
  417.             if (hex.equalsIgnoreCase("0")) {
  418.                 binary = "0000";
  419.             } else if (hex.equalsIgnoreCase("1")) {
  420.                 binary = "0001";
  421.             }
  422.             if (hex.equalsIgnoreCase("2")) {
  423.                 binary = "0010";
  424.             }
  425.             if (hex.equalsIgnoreCase("3")) {
  426.                 binary = "0011";
  427.             }
  428.             if (hex.equalsIgnoreCase("4")) {
  429.                 binary = "0100";
  430.             }
  431.             if (hex.equalsIgnoreCase("5")) {
  432.                 binary = "0101";
  433.             }
  434.             if (hex.equalsIgnoreCase("6")) {
  435.                 binary = "0110";
  436.             }
  437.             if (hex.equalsIgnoreCase("7")) {
  438.                 binary = "0111";
  439.             }
  440.             if (hex.equalsIgnoreCase("8")) {
  441.                 binary = "1000";
  442.             }
  443.             if (hex.equalsIgnoreCase("9")) {
  444.                 binary = "1001";
  445.             }
  446.             if (hex.equalsIgnoreCase("A")) {
  447.                 binary = "1010";
  448.             }
  449.             if (hex.equalsIgnoreCase("B")) {
  450.                 binary = "1011";
  451.             }
  452.             if (hex.equalsIgnoreCase("C")) {
  453.                 binary = "1100";
  454.             }
  455.             if (hex.equalsIgnoreCase("D")) {
  456.                 binary = "1101";
  457.             }
  458.             if (hex.equalsIgnoreCase("E")) {
  459.                 binary = "1110";
  460.             }
  461.             if (hex.equalsIgnoreCase("F")) {
  462.                 binary = "1111";
  463.             }
  464.             return binary;
  465.         }
  466.  
  467.         /*
  468.          * chang the bit(it's length = 64) into the string
  469.          *
  470.          * return string
  471.          */
  472.         public String byteToString(int[] byteData) {
  473.             String str = "";
  474.             for (int i = 0; i < 4; i++) {
  475.                 int count = 0;
  476.                 for (int j = 0; j < 16; j++) {
  477.                     int pow = 1;
  478.                     for (int m = 15; m > j; m--) {
  479.                         pow *= 2;
  480.                     }
  481.                     count += byteData[16 * i + j] * pow;
  482.                 }
  483.                 if (count != 0) {
  484.                     str += "" + (char) (count);
  485.                 }
  486.             }
  487.             return str;
  488.         }
  489.  
  490.         public String bt64ToHex(int[] byteData) {
  491.             String hex = "";
  492.             for (int i = 0; i < 16; i++) {
  493.                 String bt = "";
  494.                 for (int j = 0; j < 4; j++) {
  495.                     bt += byteData[i * 4 + j];
  496.                 }
  497.                 hex += bt4ToHex(bt);
  498.             }
  499.             return hex;
  500.         }
  501.  
  502.         public String hexToBt64(String hex) {
  503.             String binary = "";
  504.             for (int i = 0; i < 16; i++) {
  505.                 binary += hexToBt4(hex.substring(i, i + 1));
  506.             }
  507.             return binary;
  508.         }
  509.  
  510.         /*
  511.          * the 64 bit des core arithmetic
  512.          */
  513.  
  514.         public int[] enc(int[] dataByte, int[] keyByte) {
  515.             int[][] keys = generateKeys(keyByte);
  516.             int[] ipByte = initPermute(dataByte);
  517.             int[] ipLeft = new int[32];
  518.             int[] ipRight = new int[32];
  519.             int[] tempLeft = new int[32];
  520.             int i = 0, j = 0, k = 0, m = 0, n = 0;
  521.             for (k = 0; k < 32; k++) {
  522.                 ipLeft[k] = ipByte[k];
  523.                 ipRight[k] = ipByte[32 + k];
  524.             }
  525.             for (i = 0; i < 16; i++) {
  526.                 for (j = 0; j < 32; j++) {
  527.                     tempLeft[j] = ipLeft[j];
  528.                     ipLeft[j] = ipRight[j];
  529.                 }
  530.                 int[] key = new int[48];
  531.                 for (m = 0; m < 48; m++) {
  532.                     key[m] = keys[i][m];
  533.                 }
  534.                 int[] tempRight = xor(pPermute(sBoxPermute(xor(expandPermute(ipRight), key))), tempLeft);
  535.                 for (n = 0; n < 32; n++) {
  536.                     ipRight[n] = tempRight[n];
  537.                 }
  538.  
  539.             }
  540.  
  541.             int[] finalData = new int[64];
  542.             for (i = 0; i < 32; i++) {
  543.                 finalData[i] = ipRight[i];
  544.                 finalData[32 + i] = ipLeft[i];
  545.             }
  546.             return finallyPermute(finalData);
  547.         }
  548.  
  549.         public int[] dec(int[] dataByte, int[] keyByte) {
  550.             int[][] keys = generateKeys(keyByte);
  551.             int[] ipByte = initPermute(dataByte);
  552.             int[] ipLeft = new int[32];
  553.             int[] ipRight = new int[32];
  554.             int[] tempLeft = new int[32];
  555.             int i = 0, j = 0, k = 0, m = 0, n = 0;
  556.             for (k = 0; k < 32; k++) {
  557.                 ipLeft[k] = ipByte[k];
  558.                 ipRight[k] = ipByte[32 + k];
  559.             }
  560.             for (i = 15; i >= 0; i--) {
  561.                 for (j = 0; j < 32; j++) {
  562.                     tempLeft[j] = ipLeft[j];
  563.                     ipLeft[j] = ipRight[j];
  564.                 }
  565.                 int[] key = new int[48];
  566.                 for (m = 0; m < 48; m++) {
  567.                     key[m] = keys[i][m];
  568.                 }
  569.  
  570.                 int[] tempRight = xor(pPermute(sBoxPermute(xor(expandPermute(ipRight), key))), tempLeft);
  571.                 for (n = 0; n < 32; n++) {
  572.                     ipRight[n] = tempRight[n];
  573.                 }
  574.             }
  575.  
  576.             int[] finalData = new int[64];
  577.             for (i = 0; i < 32; i++) {
  578.                 finalData[i] = ipRight[i];
  579.                 finalData[32 + i] = ipLeft[i];
  580.             }
  581.             return finallyPermute(finalData);
  582.         }
  583.  
  584.         public int[] initPermute(int[] originalData) {
  585.             int[] ipByte = new int[64];
  586.             int i = 0, m = 1, n = 0, j, k;
  587.             for (i = 0, m = 1, n = 0; i < 4; i++, m += 2, n += 2) {
  588.                 for (j = 7, k = 0; j >= 0; j--, k++) {
  589.                     ipByte[i * 8 + k] = originalData[j * 8 + m];
  590.                     ipByte[i * 8 + k + 32] = originalData[j * 8 + n];
  591.                 }
  592.             }
  593.             return ipByte;
  594.         }
  595.  
  596.         public int[] expandPermute(int[] rightData) {
  597.             int[] epByte = new int[48];
  598.             int i, j;
  599.             for (i = 0; i < 8; i++) {
  600.                 if (i == 0) {
  601.                     epByte[i * 6 + 0] = rightData[31];
  602.                 } else {
  603.                     epByte[i * 6 + 0] = rightData[i * 4 - 1];
  604.                 }
  605.                 epByte[i * 6 + 1] = rightData[i * 4 + 0];
  606.                 epByte[i * 6 + 2] = rightData[i * 4 + 1];
  607.                 epByte[i * 6 + 3] = rightData[i * 4 + 2];
  608.                 epByte[i * 6 + 4] = rightData[i * 4 + 3];
  609.                 if (i == 7) {
  610.                     epByte[i * 6 + 5] = rightData[0];
  611.                 } else {
  612.                     epByte[i * 6 + 5] = rightData[i * 4 + 4];
  613.                 }
  614.             }
  615.             return epByte;
  616.         }
  617.  
  618.         public int[] xor(int[] byteOne, int[] byteTwo) {
  619.             // var xorByte = new Array(byteOne.length);
  620.             // for(int i = 0;i < byteOne.length; i ++){
  621.             // xorByte[i] = byteOne[i] ^ byteTwo[i];
  622.             // }
  623.             // return xorByte;
  624.             int[] xorByte = new int[byteOne.length];
  625.             for (int i = 0; i < byteOne.length; i++) {
  626.                 xorByte[i] = byteOne[i] ^ byteTwo[i];
  627.             }
  628.             return xorByte;
  629.         }
  630.  
  631.         public int[] sBoxPermute(int[] expandByte) {
  632.  
  633.             // var sBoxByte = new Array(32);
  634.             int[] sBoxByte = new int[32];
  635.             String binary = "";
  636.             int[][] s1 = { { 14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7 }, { 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8 },
  637.                     { 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0 }, { 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13 } };
  638.  
  639.             /* Table - s2 */
  640.             int[][] s2 = { { 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10 }, { 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5 },
  641.                     { 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15 }, { 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 } };
  642.  
  643.             /* Table - s3 */
  644.             int[][] s3 = { { 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8 }, { 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1 },
  645.                     { 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7 }, { 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 } };
  646.             /* Table - s4 */
  647.             int[][] s4 = { { 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15 }, { 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9 },
  648.                     { 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4 }, { 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14 } };
  649.  
  650.             /* Table - s5 */
  651.             int[][] s5 = { { 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9 }, { 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6 },
  652.                     { 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14 }, { 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3 } };
  653.  
  654.             /* Table - s6 */
  655.             int[][] s6 = { { 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11 }, { 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8 },
  656.                     { 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6 }, { 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 } };
  657.  
  658.             /* Table - s7 */
  659.             int[][] s7 = { { 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1 }, { 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6 },
  660.                     { 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2 }, { 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12 } };
  661.  
  662.             /* Table - s8 */
  663.             int[][] s8 = { { 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7 }, { 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2 },
  664.                     { 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8 }, { 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11 } };
  665.  
  666.             for (int m = 0; m < 8; m++) {
  667.                 int i = 0, j = 0;
  668.                 i = expandByte[m * 6 + 0] * 2 + expandByte[m * 6 + 5];
  669.                 j = expandByte[m * 6 + 1] * 2 * 2 * 2 + expandByte[m * 6 + 2] * 2 * 2 + expandByte[m * 6 + 3] * 2 + expandByte[m * 6 + 4];
  670.                 switch (m) {
  671.                 case 0:
  672.                     binary = getBoxBinary(s1[i][j]);
  673.                     break;
  674.                 case 1:
  675.                     binary = getBoxBinary(s2[i][j]);
  676.                     break;
  677.                 case 2:
  678.                     binary = getBoxBinary(s3[i][j]);
  679.                     break;
  680.                 case 3:
  681.                     binary = getBoxBinary(s4[i][j]);
  682.                     break;
  683.                 case 4:
  684.                     binary = getBoxBinary(s5[i][j]);
  685.                     break;
  686.                 case 5:
  687.                     binary = getBoxBinary(s6[i][j]);
  688.                     break;
  689.                 case 6:
  690.                     binary = getBoxBinary(s7[i][j]);
  691.                     break;
  692.                 case 7:
  693.                     binary = getBoxBinary(s8[i][j]);
  694.                     break;
  695.                 }
  696.                 sBoxByte[m * 4 + 0] = Integer.parseInt(binary.substring(0, 1));
  697.                 sBoxByte[m * 4 + 1] = Integer.parseInt(binary.substring(1, 2));
  698.                 sBoxByte[m * 4 + 2] = Integer.parseInt(binary.substring(2, 3));
  699.                 sBoxByte[m * 4 + 3] = Integer.parseInt(binary.substring(3, 4));
  700.             }
  701.             return sBoxByte;
  702.         }
  703.  
  704.         public int[] pPermute(int[] sBoxByte) {
  705.             int[] pBoxPermute = new int[32];
  706.             pBoxPermute[0] = sBoxByte[15];
  707.             pBoxPermute[1] = sBoxByte[6];
  708.             pBoxPermute[2] = sBoxByte[19];
  709.             pBoxPermute[3] = sBoxByte[20];
  710.             pBoxPermute[4] = sBoxByte[28];
  711.             pBoxPermute[5] = sBoxByte[11];
  712.             pBoxPermute[6] = sBoxByte[27];
  713.             pBoxPermute[7] = sBoxByte[16];
  714.             pBoxPermute[8] = sBoxByte[0];
  715.             pBoxPermute[9] = sBoxByte[14];
  716.             pBoxPermute[10] = sBoxByte[22];
  717.             pBoxPermute[11] = sBoxByte[25];
  718.             pBoxPermute[12] = sBoxByte[4];
  719.             pBoxPermute[13] = sBoxByte[17];
  720.             pBoxPermute[14] = sBoxByte[30];
  721.             pBoxPermute[15] = sBoxByte[9];
  722.             pBoxPermute[16] = sBoxByte[1];
  723.             pBoxPermute[17] = sBoxByte[7];
  724.             pBoxPermute[18] = sBoxByte[23];
  725.             pBoxPermute[19] = sBoxByte[13];
  726.             pBoxPermute[20] = sBoxByte[31];
  727.             pBoxPermute[21] = sBoxByte[26];
  728.             pBoxPermute[22] = sBoxByte[2];
  729.             pBoxPermute[23] = sBoxByte[8];
  730.             pBoxPermute[24] = sBoxByte[18];
  731.             pBoxPermute[25] = sBoxByte[12];
  732.             pBoxPermute[26] = sBoxByte[29];
  733.             pBoxPermute[27] = sBoxByte[5];
  734.             pBoxPermute[28] = sBoxByte[21];
  735.             pBoxPermute[29] = sBoxByte[10];
  736.             pBoxPermute[30] = sBoxByte[3];
  737.             pBoxPermute[31] = sBoxByte[24];
  738.             return pBoxPermute;
  739.         }
  740.  
  741.         public int[] finallyPermute(int[] endByte) {
  742.             int[] fpByte = new int[64];
  743.             fpByte[0] = endByte[39];
  744.             fpByte[1] = endByte[7];
  745.             fpByte[2] = endByte[47];
  746.             fpByte[3] = endByte[15];
  747.             fpByte[4] = endByte[55];
  748.             fpByte[5] = endByte[23];
  749.             fpByte[6] = endByte[63];
  750.             fpByte[7] = endByte[31];
  751.             fpByte[8] = endByte[38];
  752.             fpByte[9] = endByte[6];
  753.             fpByte[10] = endByte[46];
  754.             fpByte[11] = endByte[14];
  755.             fpByte[12] = endByte[54];
  756.             fpByte[13] = endByte[22];
  757.             fpByte[14] = endByte[62];
  758.             fpByte[15] = endByte[30];
  759.             fpByte[16] = endByte[37];
  760.             fpByte[17] = endByte[5];
  761.             fpByte[18] = endByte[45];
  762.             fpByte[19] = endByte[13];
  763.             fpByte[20] = endByte[53];
  764.             fpByte[21] = endByte[21];
  765.             fpByte[22] = endByte[61];
  766.             fpByte[23] = endByte[29];
  767.             fpByte[24] = endByte[36];
  768.             fpByte[25] = endByte[4];
  769.             fpByte[26] = endByte[44];
  770.             fpByte[27] = endByte[12];
  771.             fpByte[28] = endByte[52];
  772.             fpByte[29] = endByte[20];
  773.             fpByte[30] = endByte[60];
  774.             fpByte[31] = endByte[28];
  775.             fpByte[32] = endByte[35];
  776.             fpByte[33] = endByte[3];
  777.             fpByte[34] = endByte[43];
  778.             fpByte[35] = endByte[11];
  779.             fpByte[36] = endByte[51];
  780.             fpByte[37] = endByte[19];
  781.             fpByte[38] = endByte[59];
  782.             fpByte[39] = endByte[27];
  783.             fpByte[40] = endByte[34];
  784.             fpByte[41] = endByte[2];
  785.             fpByte[42] = endByte[42];
  786.             fpByte[43] = endByte[10];
  787.             fpByte[44] = endByte[50];
  788.             fpByte[45] = endByte[18];
  789.             fpByte[46] = endByte[58];
  790.             fpByte[47] = endByte[26];
  791.             fpByte[48] = endByte[33];
  792.             fpByte[49] = endByte[1];
  793.             fpByte[50] = endByte[41];
  794.             fpByte[51] = endByte[9];
  795.             fpByte[52] = endByte[49];
  796.             fpByte[53] = endByte[17];
  797.             fpByte[54] = endByte[57];
  798.             fpByte[55] = endByte[25];
  799.             fpByte[56] = endByte[32];
  800.             fpByte[57] = endByte[0];
  801.             fpByte[58] = endByte[40];
  802.             fpByte[59] = endByte[8];
  803.             fpByte[60] = endByte[48];
  804.             fpByte[61] = endByte[16];
  805.             fpByte[62] = endByte[56];
  806.             fpByte[63] = endByte[24];
  807.             return fpByte;
  808.         }
  809.  
  810.         public String getBoxBinary(int i) {
  811.             String binary = "";
  812.             switch (i) {
  813.             case 0:
  814.                 binary = "0000";
  815.                 break;
  816.             case 1:
  817.                 binary = "0001";
  818.                 break;
  819.             case 2:
  820.                 binary = "0010";
  821.                 break;
  822.             case 3:
  823.                 binary = "0011";
  824.                 break;
  825.             case 4:
  826.                 binary = "0100";
  827.                 break;
  828.             case 5:
  829.                 binary = "0101";
  830.                 break;
  831.             case 6:
  832.                 binary = "0110";
  833.                 break;
  834.             case 7:
  835.                 binary = "0111";
  836.                 break;
  837.             case 8:
  838.                 binary = "1000";
  839.                 break;
  840.             case 9:
  841.                 binary = "1001";
  842.                 break;
  843.             case 10:
  844.                 binary = "1010";
  845.                 break;
  846.             case 11:
  847.                 binary = "1011";
  848.                 break;
  849.             case 12:
  850.                 binary = "1100";
  851.                 break;
  852.             case 13:
  853.                 binary = "1101";
  854.                 break;
  855.             case 14:
  856.                 binary = "1110";
  857.                 break;
  858.             case 15:
  859.                 binary = "1111";
  860.                 break;
  861.             }
  862.             return binary;
  863.         }
  864.  
  865.         /*
  866.          * generate 16 keys for xor
  867.          */
  868.         public int[][] generateKeys(int[] keyByte) {
  869.             int[] key = new int[56];
  870.             int[][] keys = new int[16][48];
  871.  
  872.             // keys[ 0] = new Array();
  873.             // keys[ 1] = new Array();
  874.             // keys[ 2] = new Array();
  875.             // keys[ 3] = new Array();
  876.             // keys[ 4] = new Array();
  877.             // keys[ 5] = new Array();
  878.             // keys[ 6] = new Array();
  879.             // keys[ 7] = new Array();
  880.             // keys[ 8] = new Array();
  881.             // keys[ 9] = new Array();
  882.             // keys[10] = new Array();
  883.             // keys[11] = new Array();
  884.             // keys[12] = new Array();
  885.             // keys[13] = new Array();
  886.             // keys[14] = new Array();
  887.             // keys[15] = new Array();
  888.             int[] loop = new int[] { 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };
  889.  
  890.             for (int i = 0; i < 7; i++) {
  891.                 for (int j = 0, k = 7; j < 8; j++, k--) {
  892.                     key[i * 8 + j] = keyByte[8 * k + i];
  893.                 }
  894.             }
  895.  
  896.             int i = 0;
  897.             for (i = 0; i < 16; i++) {
  898.                 int tempLeft = 0;
  899.                 int tempRight = 0;
  900.                 for (int j = 0; j < loop[i]; j++) {
  901.                     tempLeft = key[0];
  902.                     tempRight = key[28];
  903.                     for (int k = 0; k < 27; k++) {
  904.                         key[k] = key[k + 1];
  905.                         key[28 + k] = key[29 + k];
  906.                     }
  907.                     key[27] = tempLeft;
  908.                     key[55] = tempRight;
  909.                 }
  910.                 // var tempKey = new Array(48);
  911.                 int[] tempKey = new int[48];
  912.                 tempKey[0] = key[13];
  913.                 tempKey[1] = key[16];
  914.                 tempKey[2] = key[10];
  915.                 tempKey[3] = key[23];
  916.                 tempKey[4] = key[0];
  917.                 tempKey[5] = key[4];
  918.                 tempKey[6] = key[2];
  919.                 tempKey[7] = key[27];
  920.                 tempKey[8] = key[14];
  921.                 tempKey[9] = key[5];
  922.                 tempKey[10] = key[20];
  923.                 tempKey[11] = key[9];
  924.                 tempKey[12] = key[22];
  925.                 tempKey[13] = key[18];
  926.                 tempKey[14] = key[11];
  927.                 tempKey[15] = key[3];
  928.                 tempKey[16] = key[25];
  929.                 tempKey[17] = key[7];
  930.                 tempKey[18] = key[15];
  931.                 tempKey[19] = key[6];
  932.                 tempKey[20] = key[26];
  933.                 tempKey[21] = key[19];
  934.                 tempKey[22] = key[12];
  935.                 tempKey[23] = key[1];
  936.                 tempKey[24] = key[40];
  937.                 tempKey[25] = key[51];
  938.                 tempKey[26] = key[30];
  939.                 tempKey[27] = key[36];
  940.                 tempKey[28] = key[46];
  941.                 tempKey[29] = key[54];
  942.                 tempKey[30] = key[29];
  943.                 tempKey[31] = key[39];
  944.                 tempKey[32] = key[50];
  945.                 tempKey[33] = key[44];
  946.                 tempKey[34] = key[32];
  947.                 tempKey[35] = key[47];
  948.                 tempKey[36] = key[43];
  949.                 tempKey[37] = key[48];
  950.                 tempKey[38] = key[38];
  951.                 tempKey[39] = key[55];
  952.                 tempKey[40] = key[33];
  953.                 tempKey[41] = key[52];
  954.                 tempKey[42] = key[45];
  955.                 tempKey[43] = key[41];
  956.                 tempKey[44] = key[49];
  957.                 tempKey[45] = key[35];
  958.                 tempKey[46] = key[28];
  959.                 tempKey[47] = key[31];
  960.                 int m;
  961.                 switch (i) {
  962.                 case 0:
  963.                     for (m = 0; m < 48; m++) {
  964.                         keys[0][m] = tempKey[m];
  965.                     }
  966.                     break;
  967.                 case 1:
  968.                     for (m = 0; m < 48; m++) {
  969.                         keys[1][m] = tempKey[m];
  970.                     }
  971.                     break;
  972.                 case 2:
  973.                     for (m = 0; m < 48; m++) {
  974.                         keys[2][m] = tempKey[m];
  975.                     }
  976.                     break;
  977.                 case 3:
  978.                     for (m = 0; m < 48; m++) {
  979.                         keys[3][m] = tempKey[m];
  980.                     }
  981.                     break;
  982.                 case 4:
  983.                     for (m = 0; m < 48; m++) {
  984.                         keys[4][m] = tempKey[m];
  985.                     }
  986.                     break;
  987.                 case 5:
  988.                     for (m = 0; m < 48; m++) {
  989.                         keys[5][m] = tempKey[m];
  990.                     }
  991.                     break;
  992.                 case 6:
  993.                     for (m = 0; m < 48; m++) {
  994.                         keys[6][m] = tempKey[m];
  995.                     }
  996.                     break;
  997.                 case 7:
  998.                     for (m = 0; m < 48; m++) {
  999.                         keys[7][m] = tempKey[m];
  1000.                     }
  1001.                     break;
  1002.                 case 8:
  1003.                     for (m = 0; m < 48; m++) {
  1004.                         keys[8][m] = tempKey[m];
  1005.                     }
  1006.                     break;
  1007.                 case 9:
  1008.                     for (m = 0; m < 48; m++) {
  1009.                         keys[9][m] = tempKey[m];
  1010.                     }
  1011.                     break;
  1012.                 case 10:
  1013.                     for (m = 0; m < 48; m++) {
  1014.                         keys[10][m] = tempKey[m];
  1015.                     }
  1016.                     break;
  1017.                 case 11:
  1018.                     for (m = 0; m < 48; m++) {
  1019.                         keys[11][m] = tempKey[m];
  1020.                     }
  1021.                     break;
  1022.                 case 12:
  1023.                     for (m = 0; m < 48; m++) {
  1024.                         keys[12][m] = tempKey[m];
  1025.                     }
  1026.                     break;
  1027.                 case 13:
  1028.                     for (m = 0; m < 48; m++) {
  1029.                         keys[13][m] = tempKey[m];
  1030.                     }
  1031.                     break;
  1032.                 case 14:
  1033.                     for (m = 0; m < 48; m++) {
  1034.                         keys[14][m] = tempKey[m];
  1035.                     }
  1036.                     break;
  1037.                 case 15:
  1038.                     for (m = 0; m < 48; m++) {
  1039.                         keys[15][m] = tempKey[m];
  1040.                     }
  1041.                     break;
  1042.                 }
  1043.             }
  1044.             return keys;
  1045.         }
  1046.     }
  1047.  
  1048. }

把信息存储到浏览器中还是加密的要好，虽然现在有不少在线解密工具，但是还是推荐加密

下面进入正题，如何清除Cookie？

在谈谈这个问题前，我们是如何使用js获取Cookie呢？

    function getMyCookie(name){

        var arr,reg=new RegExp("(^| )"+name+"=([^;]*)(;|$)");

        if(arr=document.cookie.match(reg))

            return unescape(arr[2]);

        else

            return null;

    }

<!-- 例如cookie的名字叫name 可通过getMyCookie("name")获得Cookie-->

Cookie通常是加密的，假如存储的Cookie是一个字符串，如何将其解密呢？

比如我使用的是DES加密和解密，我通过ajax获取它并将其解析出来？

代码如下:

js代码:

 //自动加载获取Cookie

    function autoLoad(){

        var str ="获取Cookie";

        $.ajax({

            url:"getCookie",

            type:"POST",

            data : {"str":str},

            dataType : 'json',

            success:function(data){

            var json = eval("("+data+")");

            if(json.returnCode=="200"){

                $("#userId").val(json.userId);

            }else if(json.returnCode=="500"){

                window.location.href='view/Login.html';

            }else{

                alert("有问题，请联系管理员");

            }

            },error:function(){

                alert("失败");

            }

        });

    }

Java代码:

/**

	 * 获取Cookie信息

	 * @param str

	 * @param request

	 * @return

	 */

	@RequestMapping(value="/getCookie",method=RequestMethod.POST,produces="application/json;charset=utf-8")

	@ResponseBody

	public String getCookie(String str,HttpServletRequest request) {

		logger.info("获取Cookie信息");

		logger.info("str:"+str);

		Map<String,Object> map = new HashMap<String,Object>();

		//获取Cookie

		String cookie = CookieUtils.getCookie(request, "userId");

		if(cookie!=""||cookie!=null) {

        logger.info("Cookie:"+cookie);

        //将Cookie解密

        String userId =  DesUtils.decode(cookie, "userId");

        //打印Cookie解密

        logger.info("userId:"+userId);

        map.put("userId", userId);

		map.put("returnMsg", "可获取Cookie");

		map.put("returnCode", "200");

		}else {

		map.put("returnMsg", "不能获取Cookie");

		map.put("returnCode", "500");

		}

        return JSON.toJSONString(map);

	}

　　

如何清除Cookie?

代码如下所示:

我的存储用户信息是用Cookie，自然注销功能也是用清除Cookie的做法

/**

 * 退出功能

 */

function getMyCookie(name){

    var arr,reg=new RegExp("(^| )"+name+"=([^;]*)(;|$)");

    if(arr=document.cookie.match(reg))

        return unescape(arr[2]);

    else

        return null;

}

function delCookie(name){

    var exp = new Date();

    exp.setTime(exp.getTime() - 1);

    var cval=getMyCookie(name);

    if(cval!=null)

        document.cookie= name + "="+cval+";expires="+exp.toGMTString()+";path=/";

}

//退出功能

$(function(){

    $("#exit").click(function(){

        delCookie("userId");

        location.href="http://localhost:8080/blog-web/";

    });

});

首先Cookie有如下优缺点:

优点:

(1)可配置到期规则 Cookie 可以在浏览器会话结束时到期，或者可以在客户端计算机上无限期存在，这取决于客户端的到期规则。

(2)不需要任何服务器资源 Cookie 存储在客户端并在发送后由服务器读取。

(3)简单性 Cookie 是一种基于文本的轻量结构，包含简单的键值对。

　　 (4)数据持久性 虽然客户端计算机上 Cookie 的持续时间取决于客户端上的 Cookie 过期处理和用户干预，Cookie 通常是客户端上持续时间最长的数据保留形式。

缺点:

　　(1) 大小受到限制 大多数浏览器对 Cookie 的大小有 4096 字节的限制，尽管在当今新的浏览器和客户端设备版本中，支持 8192 字节的 Cookie 大小已愈发常见。

　　 (2)用户配置为禁用 有些用户禁用了浏览器或客户端设备接收 Cookie 的能力，因此限制了这一功能。

　　 (3) 潜在的安全风险 Cookie 可能会被篡改。用户可能会操纵其计算机上的 Cookie，这意味着会对安全性造成潜在风险或者导致依赖于 Cookie 的应用程序失败。另外，虽然 Cookie 只能被将它们发送到客户端的域访问，历史上黑客已经发现从用户计算机上的其他域访问 Cookie 的方法。您可以手动加密和解密 Cookie，但这需要额外的编码，并且因为加密和解密需要耗费一定的时间而影响应用程序的性能。

　　

具体为什么要用Cookie结合业务需要。

对于我为什么用Cookie?而不用session，session存储服务器端，并不是全局的，而且随着用户越来越多，每个用户都有与之对应的session,对于服务器而言，无形之间形成了不小的并发。

而使用cookie，cookie虽然有安全方面的风险，但是是全局的，全局唯一一个cookie，只需将用户关键信息，例如id或用户名之类的存储其中，这样我每个页面都可以获取的到。这样实现拦截非法登录的效果也是很好的，而且无形之间减少了很多并发。当然就目前而言，对我来说，使用cookie不再向之前为了获取session，搞个拦截器过滤器，真的有种白了少年头，空悲切的感觉啊！

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