Android实现TCP与UDP传输

 

关于TCP和UDP协议的描述，可参考http://zhoujianghai.iteye.com/blog/1052970

 

下面是android与PC端使用TCP和UDP协议通信的例子：

以PC端作为服务器，android端使用TCP协议与服务器建立连接，使用UDP协议接受和发送数据。

服务器端代码：

ThunderServer.java

 

package com.zhoujh.thunder.server;

import java.io.DataOutputStream;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.ArrayList;

/**
 * 服务器端
 * @author 
 * zhoujianghai
 * 2011-5-15
 * 下午05:10:50
 */
public class ThunderServer{
	private static int ID = 1;
	
	/**TCP端口 */
	private static final int TCP_PORT = 8000;
	/**UDP端口 */
	private static final int UDP_PORT = 9999;
	
	
	/**与服务器已经建立链接的客户端数量 */
	private ArrayList<Client> clients = new ArrayList<Client>();
	
	public static void main(String args[]) {
		new ThunderServer().start();
	}

	private void start() {
		new UDPThread().start();
		ServerSocket serverSocket = null;

		try {
			serverSocket = new ServerSocket(TCP_PORT);
		} catch (IOException e) {
			e.printStackTrace();
		}
		while (true) {
			Socket socket = null;
			try {
				socket = serverSocket.accept();
				System.out.println("socket="+socket);
				
			
				String IP = socket.getInetAddress().getHostAddress();
				Client c = new Client(IP);	
				clients.add(c);
				
				DataOutputStream out = new DataOutputStream(socket.getOutputStream());
				out.writeInt(ID++);
				
				System.out.println("一个新的客户端已连接，IP:"+IP+";port="+socket.getPort()+"; ID="+(ID-1));
			} catch (IOException e) {
				e.printStackTrace();
			}finally{
				if(socket != null) {
					try {
						socket.close();
						socket = null;
					} catch (IOException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
				}
			}
		}
		
	}
	
	/**
	 * 客户端：ip地址和udp端口
	 * @author 
	 * zhoujianghai
	 * 2011-5-15
	 * 下午04:41:09
	 */
	private class Client {
		String IP;
		int udpPort;

		public Client(String IP) {
			this.IP = IP;
		}
		public void setUdpPort(int udpPort) {
			this.udpPort = udpPort;
		}
	}
	
	/**
	 * 接收客户端发送的数据，并把接收到的数据发送给所有客户端,使用UDP协议
	 * @author 
	 * zhoujianghai
	 * 2011-5-15
	 * 下午04:54:03
	 */
	private class UDPThread extends Thread {
		//服务器每次收发数据的缓冲区，大小是1024个字节
		byte[] buf = new byte[1024];
		
		public void run() {
			DatagramSocket ds = null;
			try {
				ds = new DatagramSocket(UDP_PORT);
			} catch (SocketException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
			while(ds != null) {
				DatagramPacket packet = new DatagramPacket(buf, buf.length);

				try {
					//接收数据包
					ds.receive(packet);
					System.out.println("地址:"+packet.getAddress()+"  端口:"+packet.getPort()+"数据："+new String(packet.getData()));
					String clientIp =  (packet.getAddress().toString().split("/")[1]);
					for(Client c:clients) {
						
						if(clientIp.trim().equals(c.IP) && c.udpPort == 0) {
							c.setUdpPort(packet.getPort());
						}
					}
					//把接收到的数据包发送给所有已连接的客户端
					System.out.println("clients.size="+clients.size());
					for(Client c:clients) {
						System.out.println("server send:IP="+c.IP+"; udpPort="+c.udpPort);
						//设置数据包要发送的客户端地址
						packet.setSocketAddress(new InetSocketAddress(c.IP, c.udpPort));
						ds.send(packet);
					}
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}
	
}

 

客户端的核心代码：

 

public void connectServer(String IP,int port) {

		this.IP = IP;
		
		try {
			socket = new DatagramSocket(udpPort);
		} catch (SocketException e) {
			e.printStackTrace();
		}
		
		Socket s = null;
		try {
			s = new Socket(IP,port);
			System.out.println("s="+s);
			
			DataInputStream dis = new DataInputStream(s.getInputStream());
			int id = dis.readInt();
			System.out.println("id="+id);
	
		} catch (UnknownHostException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}finally {
			if(s != null) {
				try {
					s.close();
					s = null;
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	
	}

 

 

客户端代码绑定的UDP端口”udpPort“跟服务器端接收到的不一样，为了避免了使用UDP通信时，android客户端接收不到server发送的数据的问题，server端根据接收到的数据得出发送数据包的客户端的ip地址和端口，不需要进行端口的转发，真机和模拟器一样。代码：

 

String clientIp =  (packet.getAddress().toString().split("/")[1]);
					for(Client c:clients) {
						
						if(clientIp.trim().equals(c.IP) && c.udpPort == 0) {
							c.setUdpPort(packet.getPort());
						}
					}