标签：
1. InetAddress类
2. Socket： IP地址和端口号的结合，socket允许程序把网络连接当成一个流，数据在两个socket间通过IO传输， 通信的两端都要有socket. 主动发起通信请求的是客户端，等待通信请求的是服务端
3. DatagramSocket 和 DatagramPacket实现了UDP协议网络程序， 使用DatagramSocket发送和接收，系统不保证UDP数据报一定能够安全送到目的地，也不能确定什么时候可以抵达
DatagramPacket对象封装了UDP数据报，在数据报中包含了发送端的IP地址和端口号以及接收端的IP地址和端口号，给出了完整的地址信息，因此无须建立发送方和接收方的连接
4. URL类
URL u = new URL("http://www.baidu.com");
InputStream in = u.openStream();
URLConnection uc = u.openConnection();
uc.getInputStream();
uc.getOutputSteam();
1 package learn.JavaBasics.Class; 2 3 import java.io.*; 4 import java.net.InetAddress; 5 import java.net.ServerSocket; 6 import java.net.Socket; 7 import java.net.UnknownHostException; 8 9 public class SocketDemo { 10 public void server() { 11 ServerSocket ss = null; 12 Socket s = null; 13 InputStream in = null; 14 OutputStream out = null; 15 16 try { 17 //开始在端口监听 18 ss = new ServerSocket(9999); 19 20 //当有连接进来时，会新建一个socket 21 s = ss.accept(); 22 23 //获取输入流 24 in = s.getInputStream(); 25 26 //对输入流进行处理 27 byte[] b = new byte[1024]; 28 int len; 29 String msg = ""; 30 31 while((len=in.read(b)) != -1) { 32 msg = new String(b, 0, len); 33 } 34 35 System.out.println("The message from "+ s.getInetAddress().getHostName()+ 36 "(ip:"+ s.getInetAddress().getHostAddress()+") is: \""+msg+"\""); 37 38 39 //获取输出流，反馈信息 40 out = s.getOutputStream(); 41 out.write("The msg from client has been received".getBytes()); 42 } catch (IOException e) { 43 // TODO Auto-generated catch block 44 e.printStackTrace(); 45 } finally { 46 if (in != null) { 47 try { 48 in.close(); 49 } catch (IOException e) { 50 // TODO Auto-generated catch block 51 e.printStackTrace(); 52 } 53 } 54 55 if (s != null) { 56 try { 57 s.close(); 58 } catch (IOException e) { 59 // TODO Auto-generated catch block 60 e.printStackTrace(); 61 } 62 } 63 64 if (ss != null) { 65 try { 66 ss.close(); 67 } catch (IOException e) { 68 // TODO Auto-generated catch block 69 e.printStackTrace(); 70 } 71 } 72 73 if (out != null) { 74 try { 75 out.close(); 76 } catch (IOException e) { 77 // TODO Auto-generated catch block 78 e.printStackTrace(); 79 } 80 } 81 } 82 } 83 84 public void client() { 85 Socket s = null; 86 OutputStream out = null; 87 InputStream in = null; 88 89 try { 90 //新建一个Socket 91 s = new Socket(InetAddress.getLocalHost(), 9999); 92 93 //获取输出流 94 out = s.getOutputStream(); 95 96 //发送信息， 并提示 97 out.write("This is client".getBytes()); 98 System.out.println("client message has sent"); 99 100 //这句话存在的原因是，Server端的getInputSream流的read方法是阻塞， 它在接收信息，但不知道信息是否接收完全，所以一直在等待， 101 //所以Server端的反馈信息无发发送过来，程序死掉， 102 //这里显式的通知Server，发送结束 103 //FileInputSteam里的read方法与这个一样，但BufferInputSteam里的read方法是非阻塞的 104 s.shutdownOutput(); 105 106 //获取输入流，接收服务端的反馈信息 107 in = s.getInputStream(); 108 109 byte[] b = new byte[1024]; 110 int len; 111 String msg = ""; 112 113 while((len=in.read(b)) != -1) { 114 msg = new String(b, 0, len); 115 } 116 System.out.println("Response from Server: "+msg); 117 System.out.println("connection over"); 118 119 //这里的后边没有了，所以服务端可以不显式的提示，不影响功能 120 } catch (IOException e) { 121 // TODO Auto-generated catch block 122 e.printStackTrace(); 123 } finally { 124 if (out != null) { 125 try { 126 out.close(); 127 } catch (IOException e) { 128 // TODO Auto-generated catch block 129 e.printStackTrace(); 130 } 131 } 132 if (s != null) { 133 try { 134 s.close(); 135 } catch (IOException e) { 136 // TODO Auto-generated catch block 137 e.printStackTrace(); 138 } 139 } 140 141 if (in != null) { 142 try { 143 in.close(); 144 } catch (IOException e) { 145 // TODO Auto-generated catch block 146 e.printStackTrace(); 147 } 148 } 149 } 150 } 151 152 public static void main(String[] args) { 153 new Thread(new Runnable(){ 154 @Override 155 public void run() { 156 // TODO Auto-generated method stub 157 new SocketDemo().server(); 158 } 159 }).start(); 160 161 new Thread(new Runnable() { 162 @Override 163 public void run() { 164 // TODO Auto-generated method stub 165 new SocketDemo().client(); 166 } 167 }).start(); 168 } 169 170 }
1 package learn.JavaBasics.Class; 2 3 import java.io.IOException; 4 import java.net.DatagramPacket; 5 import java.net.DatagramSocket; 6 import java.net.InetAddress; 7 import java.net.SocketException; 8 import java.net.UnknownHostException; 9 10 public class TestUDP { 11 public void receive(){ 12 DatagramSocket ds = null; 13 14 try { 15 //定义接收的数据报大小 16 byte[] b = new byte[1024]; 17 DatagramPacket packet = new DatagramPacket(b, 0, b.length); 18 19 //定义一个接收的Socket，用于在特定的端口接收指定大小的数据报 20 ds = new DatagramSocket(9999); 21 ds.receive(packet); 22 23 String str = new String(packet.getData(), 0, packet.getLength()); 24 25 System.out.println(str); 26 } catch (SocketException e) { 27 // TODO Auto-generated catch block 28 e.printStackTrace(); 29 } catch (IOException e) { 30 // TODO Auto-generated catch block 31 e.printStackTrace(); 32 } finally { 33 if (ds != null) { 34 ds.close(); 35 } 36 } 37 } 38 39 public void send() { 40 DatagramSocket ds = null; 41 42 try { 43 //新建一个用于发送的Socket 44 ds = new DatagramSocket(); 45 46 //数据 47 byte[] b = "你好， 这里是发送端的数据, UDP sender".getBytes(); 48 49 //封装数据到数据报中， 一个数据报不能大于64K, 记录着数据信息， 两端的IP和端口号 50 DatagramPacket packet = new DatagramPacket(b, 0, b.length, InetAddress.getLocalHost(), 9999); 51 52 //使用Socket把数据报发走 53 ds.send(packet); 54 } catch (SocketException e) { 55 // TODO Auto-generated catch block 56 e.printStackTrace(); 57 } catch (UnknownHostException e) { 58 // TODO Auto-generated catch block 59 e.printStackTrace(); 60 } catch (IOException e) { 61 // TODO Auto-generated catch block 62 e.printStackTrace(); 63 } finally { 64 if (ds != null) { 65 ds.close(); 66 } 67 } 68 } 69 70 public static void main(String[] args) { 71 new Thread(new Runnable(){ 72 @Override 73 public void run() { 74 new TestUDP().receive(); 75 } 76 }).start(); 77 78 new Thread(new Runnable(){ 79 @Override 80 public void run() { 81 new TestUDP().send(); 82 } 83 }).start(); 84 } 85 }
标签：
原文地址：http://www.cnblogs.com/hangtt/p/4855290.html
