图片通过Base64Coder编码、解码

通过这个编码类我们可以将图片转换为这个编码的字符串，上传到服务器。

这个编码是来自小马的一个范例，我看了下挺有用的。所以就放上来以备不时之需。

先说下用法:

            /**
             * 下面注释的方法是将裁剪之后的图片以Base64Coder的字符方式上
             * 传到服务器，QQ头像上传采用的方法跟这个类似
             */

            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            photo.compress(Bitmap.CompressFormat.JPEG, 60, stream);
            byte[] b = stream.toByteArray();
            // 将图片流以字符串形式存储下来

            String tp = new String(Base64Coder.encodeLines(b));
            /*这个地方大家可以写下给服务器上传图片的实现，直接把字符串tp直接上传就可以了，
            服务器处理的方法是服务器那边的事了

            如果下载到的服务器的数据还是以Base64Coder的形式的话，可以用以下方式转换
            为我们可以用的图片类型就OK啦*/
            Bitmap dBitmap = BitmapFactory.decodeFile(tp);
            Drawable drawable = new BitmapDrawable(dBitmap);

工具类Base64Coder.java：

package com.xiaoma.piccut.demo;

/**
 * 下面这些注释是下载这个类的时候本来就有的，本来要删除的，但看了下竟然是license
 * 好东西，留在注释里，以备不时之用，大家有需要加license的可以到下面的网址找哦
 */

//EPL, Eclipse Public License, V1.0 or later, http://www.eclipse.org/legal
//LGPL, GNU Lesser General Public License, V2.1 or later, http://www.gnu.org/licenses/lgpl.html
//GPL, GNU General Public License, V2 or later, http://www.gnu.org/licenses/gpl.html
//AL, Apache License, V2.0 or later, http://www.apache.org/licenses
//BSD, BSD License, http://www.opensource.org/licenses/bsd-license.php
/**
* A Base64 encoder/decoder.
*
* <p>
* This class is used to encode and decode data in Base64 format as described in RFC 1521.
*
* <p>
* Project home page: <a href="http://www.source-code.biz/base64coder/java/">www.source-code.biz/base64coder/java</a><br>
* Author: Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland<br>
* Multi-licensed: EPL / LGPL / GPL / AL / BSD.
*/

/**
 * 这个类在上面注释的网址中有，大家可以自行下载下，也可以直接用这个，
 * 公开的Base64Coder类（不用深究它是怎么实现的，
 * 还是那句话，有轮子直接用轮子），好用的要死人了...
 * 小马也很无耻的引用了这个网址下的东东，吼吼...
* @Title: Base64Coder.java
* @Package com.xiaoma.piccut.demo
* @Description: TODO
* @author XiaoMa
 */

public class Base64Coder {

//The line separator string of the operating system.
private static final String systemLineSeparator = System.getProperty("line.separator");

//Mapping table from 6-bit nibbles to Base64 characters.
private static char[]    map1 = new char[64];
static {
   int i=0;
   for (char c='A'; c<='Z'; c++) map1[i++] = c;
   for (char c='a'; c<='z'; c++) map1[i++] = c;
   for (char c='0'; c<='9'; c++) map1[i++] = c;
   map1[i++] = '+'; map1[i++] = '/'; }

//Mapping table from Base64 characters to 6-bit nibbles.
private static byte[]    map2 = new byte[128];
static {
   for (int i=0; i<map2.length; i++) map2[i] = -1;
   for (int i=0; i<64; i++) map2[map1[i]] = (byte)i; }

/**
* Encodes a string into Base64 format.
* No blanks or line breaks are inserted.
* @param s  A String to be encoded.
* @return   A String containing the Base64 encoded data.
*/
public static String encodeString (String s) {
return new String(encode(s.getBytes())); }

/**
* Encodes a byte array into Base 64 format and breaks the output into lines of 76 characters.
* This method is compatible with <code>sun.misc.BASE64Encoder.encodeBuffer(byte[])</code>.
* @param in  An array containing the data bytes to be encoded.
* @return    A String containing the Base64 encoded data, broken into lines.
*/
public static String encodeLines (byte[] in) {
return encodeLines(in, 0, in.length, 76, systemLineSeparator); }

/**
* Encodes a byte array into Base 64 format and breaks the output into lines.
* @param in            An array containing the data bytes to be encoded.
* @param iOff          Offset of the first byte in <code>in</code> to be processed.
* @param iLen          Number of bytes to be processed in <code>in</code>, starting at <code>iOff</code>.
* @param lineLen       Line length for the output data. Should be a multiple of 4.
* @param lineSeparator The line separator to be used to separate the output lines.
* @return              A String containing the Base64 encoded data, broken into lines.
*/
public static String encodeLines (byte[] in, int iOff, int iLen, int lineLen, String lineSeparator) {
int blockLen = (lineLen*3) / 4;
if (blockLen <= 0) throw new IllegalArgumentException();
int lines = (iLen+blockLen-1) / blockLen;
int bufLen = ((iLen+2)/3)*4 + lines*lineSeparator.length();
StringBuilder buf = new StringBuilder(bufLen);
int ip = 0;
while (ip < iLen) {
   int l = Math.min(iLen-ip, blockLen);
   buf.append (encode(in, iOff+ip, l));
   buf.append (lineSeparator);
   ip += l; }
return buf.toString(); }

/**
* Encodes a byte array into Base64 format.
* No blanks or line breaks are inserted in the output.
* @param in  An array containing the data bytes to be encoded.
* @return    A character array containing the Base64 encoded data.
*/
public static char[] encode (byte[] in) {
return encode(in, 0, in.length); }

/**
* Encodes a byte array into Base64 format.
* No blanks or line breaks are inserted in the output.
* @param in    An array containing the data bytes to be encoded.
* @param iLen  Number of bytes to process in <code>in</code>.
* @return      A character array containing the Base64 encoded data.
*/
public static char[] encode (byte[] in, int iLen) {
return encode(in, 0, iLen); }

/**
* Encodes a byte array into Base64 format.
* No blanks or line breaks are inserted in the output.
* @param in    An array containing the data bytes to be encoded.
* @param iOff  Offset of the first byte in <code>in</code> to be processed.
* @param iLen  Number of bytes to process in <code>in</code>, starting at <code>iOff</code>.
* @return      A character array containing the Base64 encoded data.
*/
public static char[] encode (byte[] in, int iOff, int iLen) {
int oDataLen = (iLen*4+2)/3;       // output length without padding
int oLen = ((iLen+2)/3)*4;         // output length including padding
char[] out = new char[oLen];
int ip = iOff;
int iEnd = iOff + iLen;
int op = 0;
while (ip < iEnd) {
   int i0 = in[ip++] & 0xff;
   int i1 = ip < iEnd ? in[ip++] & 0xff : 0;
   int i2 = ip < iEnd ? in[ip++] & 0xff : 0;
   int o0 = i0 >>> 2;
   int o1 = ((i0 &   3) << 4) | (i1 >>> 4);
   int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
   int o3 = i2 & 0x3F;
   out[op++] = map1[o0];
   out[op++] = map1[o1];
   out[op] = op < oDataLen ? map1[o2] : '='; op++;
   out[op] = op < oDataLen ? map1[o3] : '='; op++; }
return out; }

/**
* Decodes a string from Base64 format.
* No blanks or line breaks are allowed within the Base64 encoded input data.
* @param s  A Base64 String to be decoded.
* @return   A String containing the decoded data.
* @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
*/
public static String decodeString (String s) {
return new String(decode(s)); }

/**
* Decodes a byte array from Base64 format and ignores line separators, tabs and blanks.
* CR, LF, Tab and Space characters are ignored in the input data.
* This method is compatible with <code>sun.misc.BASE64Decoder.decodeBuffer(String)</code>.
* @param s  A Base64 String to be decoded.
* @return   An array containing the decoded data bytes.
* @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
*/
public static byte[] decodeLines (String s) {
char[] buf = new char[s.length()+3];
int p = 0;
for (int ip = 0; ip < s.length(); ip++) {
   char c = s.charAt(ip);
   if (c != ' ' && c != '\r' && c != '\n' && c != '\t')
      buf[p++] = c; }
   while ((p % 4) != 0)
       buf[p++] = '0';

return decode(buf, 0, p); }

/**
* Decodes a byte array from Base64 format.
* No blanks or line breaks are allowed within the Base64 encoded input data.
* @param s  A Base64 String to be decoded.
* @return   An array containing the decoded data bytes.
* @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
*/
public static byte[] decode (String s) {
return decode(s.toCharArray()); }

/**
* Decodes a byte array from Base64 format.
* No blanks or line breaks are allowed within the Base64 encoded input data.
* @param in  A character array containing the Base64 encoded data.
* @return    An array containing the decoded data bytes.
* @throws    IllegalArgumentException If the input is not valid Base64 encoded data.
*/
public static byte[] decode (char[] in) {
return decode(in, 0, in.length); }

/**
* Decodes a byte array from Base64 format.
* No blanks or line breaks are allowed within the Base64 encoded input data.
* @param in    A character array containing the Base64 encoded data.
* @param iOff  Offset of the first character in <code>in</code> to be processed.
* @param iLen  Number of characters to process in <code>in</code>, starting at <code>iOff</code>.
* @return      An array containing the decoded data bytes.
* @throws      IllegalArgumentException If the input is not valid Base64 encoded data.
*/
public static byte[] decode (char[] in, int iOff, int iLen) {
if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4.");
while (iLen > 0 && in[iOff+iLen-1] == '=') iLen--;
int oLen = (iLen*3) / 4;
byte[] out = new byte[oLen];
int ip = iOff;
int iEnd = iOff + iLen;
int op = 0;
while (ip < iEnd) {
   int i0 = in[ip++];
   int i1 = in[ip++];
   int i2 = ip < iEnd ? in[ip++] : 'A';
   int i3 = ip < iEnd ? in[ip++] : 'A';
   if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
      throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
   int b0 = map2[i0];
   int b1 = map2[i1];
   int b2 = map2[i2];
   int b3 = map2[i3];
   if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
      throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
   int o0 = ( b0       <<2) | (b1>>>4);
   int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
   int o2 = ((b2 &   3)<<6) |  b3;
   out[op++] = (byte)o0;
   if (op<oLen) out[op++] = (byte)o1;
   if (op<oLen) out[op++] = (byte)o2; }
return out; }

//Dummy constructor.
private Base64Coder() {}

} // end class Base64Coder