Java 网络编程 - 总结概述

IP地址

IP地址IntAddress

• 唯一定位一台网络上的计算机
• 127.0.0.1：本地localhost
• IP地址的分类
  • ipV4/ipV6
    • ipV4:127.0.0.1,4个字节组成；0~255，42亿~；30亿都在北美，亚洲4亿；2011年就用完了
    • ipV6:128位。8个无符号整数
  • 公网（互联网）-私网（局域网）
    • ABCD类地址
    • 192.168 .xx.xx，专门给组织内部使用的
• 域名：方面记忆，免去了记录IP的问题

 1 //测试IP
 2 public class TestInetAddress {
 3     public static void main(String[] args) {
 4         try {
 5             //查询本机地址
 6             InetAddress inetAddress = InetAddress.getByName("127.0.0.1");
 7             System.out.println(inetAddress);
 8             InetAddress localhost = InetAddress.getByName("localhost");
 9             System.out.println(localhost);
10             InetAddress localHost = InetAddress.getLocalHost();
11             System.out.println(localHost);
12
13             //查询网站ip地址
14             InetAddress inetAddress1 = InetAddress.getByName("www.baidu.com");
15             System.out.println(inetAddress1);
16
17             //常用方法
18             System.out.println(inetAddress1.getHostAddress());//ip
19             System.out.println(inetAddress1.getHostName());//域名，或者自己的名字
20         } catch (UnknownHostException e) {
21             e.printStackTrace();
22         }
23     }
24 }

端口

ip相当于省/市/区/街/楼,端口就是门牌号；端口表示计算机上的一个程序的进程

• 不同的进程有不同的端口号！用来区分软件！
• 被规定0~65535
• TCP，UDP：65535*2；tcp：80；udp：80
• 端口分类
  • 公有端口0~1023
    • HTTP:80
    • HTTPS:443
    • FTP:21
    • Telent:23
  • 程序注册端口：1024~49151，分配用户或者程序
    • Tomcat：8080
    • MySQL：3306
    • Orcal：1521
  • 动态、私有：49152~65535

//CMD
netstat -ano #查看所有的端口
netstat -ano|findstr "5900" #查看指定的端口
tasklist|findstr "8696" #查看指定端口的进程

 1 //端口
 2 public class TestInetSocketAddress {
 3     public static void main(String[] args) {
 4         InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
 5         System.out.println(socketAddress);
 6
 7         System.out.println(socketAddress.getAddress());
 8         System.out.println(socketAddress.getHostName());//地址
 9         System.out.println(socketAddress.getPort());//端口
10     }
11 }

通信协议

协议：约定，共同遵守，都能理解

网络通信协议：速率，传输码率，代码结构，传输控制....

TCP/IP协议簇：实际上是一组协议

重要

• TCP：用户传输协议
• UDP：用户数据报协议

TCP UDP对比

TCP：打电话

• 连接，稳定
• 三次握手，四次挥手
• 客户端、服务端
• 传输完成，释放连接，效率低

UDP：发短信

• 不连接，不稳定
• 客户端、服务端：没有明确的界限
• 不管有没有准备好，都可以发给你

TCP实现聊天

 1 //服务端
 2 public class TcpServerDemo01 {
 3     public static void main(String[] args) {
 4         ServerSocket serverSocket = null;
 5         Socket accept=null;
 6         InputStream is=null;
 7         ByteArrayOutputStream baos=null;
 8         try {
 9             //1.得有一个地址
10             serverSocket = new ServerSocket(9999);
11
12             while (true){
13                 //2.等待客户端连接过来
14                 accept = serverSocket.accept();
15                 //3.读取客户端得消息
16                 is = accept.getInputStream();
17
18                 //管道流
19                 baos = new ByteArrayOutputStream();
20                 byte[] bytes = new byte[1024];
21                 int len;
22                 while ((len=is.read(bytes))!=-1){
23                     baos.write(bytes,0,len);
24                 }
25                 System.out.println(baos.toString());
26             }
27
28         } catch (IOException e) {
29             e.printStackTrace();
30         }finally {
31             //关闭流
32             try {
33                 baos.close();
34             } catch (IOException e) {
35                 e.printStackTrace();
36             }
37             try {
38                 is.close();
39             } catch (IOException e) {
40                 e.printStackTrace();
41             }
42             try {
43                 accept.close();
44             } catch (IOException e) {
45                 e.printStackTrace();
46             }
47             try {
48                 serverSocket.close();
49             } catch (IOException e) {
50                 e.printStackTrace();
51             }
52
53         }
54     }
55 }

 1 //客户端
 2 public class TcpClientDemo01 {
 3     public static void main(String[] args) {
 4         Socket socket=null;
 5         OutputStream os=null;
 6
 7         try {
 8             //1.要直到服务器得地址
 9             InetAddress serverIP= InetAddress.getByName("127.0.0.1");
10             int port=9999;
11             //2.创建一个socker连接
12             try {
13                 socket = new Socket(serverIP,port);
14                 //3.发送消息 IO流
15                 os = socket.getOutputStream();
16                 os.write("Hello".getBytes());
17             } catch (IOException e) {
18                 e.printStackTrace();
19             }
20
21
22         } catch (UnknownHostException e) {
23             e.printStackTrace();
24         }finally {
25             try {
26                 os.close();
27             } catch (IOException e) {
28                 e.printStackTrace();
29             }
30             try {
31                 socket.close();
32             } catch (IOException e) {
33                 e.printStackTrace();
34             }
35         }
36     }
37 }

TCP文件上传

 1 //服务端
 2 public class TcpServerDemo02 {
 3     public static void main(String[] args) throws Exception{
 4         //1.创建服务
 5         ServerSocket serverSocket = new ServerSocket(9000);
 6         //2.监听客户端得连接
 7         Socket accept = serverSocket.accept();//阻塞式监听，会一直等待客户端得连接
 8         //3.获取输入流
 9         InputStream is = accept.getInputStream();
10
11         //4.文件输出
12         FileOutputStream fos = new FileOutputStream("receive.jpg");
13         byte[] by = new byte[1024];
14         int len;
15         while ((len=is.read(by))!=-1){
16             fos.write(by,0,len);
17         }
18
19         //通知客户端我接收完毕了
20         OutputStream os = accept.getOutputStream();
21         os.write("接收完毕".getBytes());
22
23         os.close();
24         fos.close();
25         is.close();
26         accept.close();
27         serverSocket.close();
28     }
29 }

 1 //客户端
 2 public class TcpClientDemo02 {
 3     public static void main(String[] args) throws Exception{
 4         //1.创建一个socket连接
 5         Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9000);
 6         //2.创建一个输出流
 7         OutputStream os = socket.getOutputStream();
 8
 9         //3.读取文件
10         FileInputStream fis = new FileInputStream("D:\\WorkSpace\\JavaSE\\基础语法\\111.png");
11         //4.写出文件
12         byte[] by = new byte[1024];
13         int len;
14         while ((len=fis.read(by))!=-1){
15             os.write(by,0,len);
16         }
17
18         //通知服务器，我已经传输结束了
19         socket.shutdownOutput();
20
21         //确认服务器接收完毕，才能断开连接
22         InputStream is = socket.getInputStream();
23         ByteArrayOutputStream baos = new ByteArrayOutputStream();
24
25         byte[] bytes = new byte[1024];
26         int leng;
27         while ((leng=is.read(bytes))!=-1){
28             baos.write(bytes,0,leng);
29         }
30         System.out.println(baos.toString());
31
32         baos.close();
33         is.close();
34         os.close();
35         fis.close();
36         socket.close();
37     }
38 }

UDP消息发送

 1 //发送方
 2 public class UdpClientDemo01 {
 3     public static void main(String[] args) throws Exception{
 4         //1.建立一个Socket
 5         DatagramSocket datagramSocket = new DatagramSocket();
 6
 7         //2.建个包
 8         String msg="你好啊，服务器！";
 9         InetAddress localhost = InetAddress.getByName("localhost");
10         int port = 9090;
11
12         //数据、数据的长度起始、要发给谁
13         DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);
14
15         //发送包
16         datagramSocket.send(datagramPacket);
17
18         //4.关闭流
19         datagramSocket.close();
20     }
21 }

 1 //接收方
 2 public class UdpServerDemo01 {
 3     public static void main(String[] args) throws Exception{
 4         //开放端口
 5         DatagramSocket datagramSocket = new DatagramSocket(9090);
 6         //接收数据
 7         byte[] bytes = new byte[1024];
 8         DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length);
 9
10         datagramSocket.receive(datagramPacket);//阻塞接收
11
12         System.out.println(datagramPacket.getAddress());
13         System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));
14     }
15 }

UDP聊天实现

 1 //发送方
 2 public class UdpSenderDemo01 {
 3     public static void main(String[] args) throws Exception{
 4
 5         DatagramSocket datagramSocket = new DatagramSocket(8888);
 6
 7         //准备数据：控制台读取System.in
 8         BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
 9
10         while (true){
11             String data=reader.readLine();
12             byte[] bytes = data.getBytes();
13             DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length,new InetSocketAddress("localhost",6666));
14             datagramSocket.send(datagramPacket);
15             if(bytes.equals("byebye")){
16                 break;
17             }
18         }
19         datagramSocket.close();
20     }
21 }

 1 //接收方
 2 public class UdpReceiveDemo01 {
 3     public static void main(String[] args) throws Exception{
 4         DatagramSocket datagramSocket = new DatagramSocket(6666);
 5
 6         while (true){
 7             //准备接收包裹
 8             byte[] bytes = new byte[1024];
 9             DatagramPacket datagramPacket = new DatagramPacket(bytes,0,bytes.length);
10
11             //断开连接 byebye
12             byte[] data = datagramPacket.getData();
13             String string = new String(data, 0, data.length);
14             System.out.println(string);
15             if(string.equals("byebye")){
16                 break;
17             }
18         }
19
20         datagramSocket.close();
21
22     }
23 }