Java--UDP通信（双向）
新建两个工程，一个Send,一个Receive，先启动Receive,再启动Send，至此就可以双向通信
Send工程：
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;import java.net.SocketException;public class Send {//接收消息的端口private static final int PORT_RECEIVE = 8080;public static void main(String[] args) {handler();}private static void handler() {DatagramSocket sendSocket = null;DatagramSocket receiveSocket = null;try {//实例化两个套接字，一个用于接收消息，一个用于发送消息sendSocket = new DatagramSocket();receiveSocket = new DatagramSocket(PORT_RECEIVE);//实例化线程并启动，一个用于接收消息，一个用于发送消息new Thread(new SendThread(sendSocket)).start();new Thread(new ReceiveThread(receiveSocket)).start();} catch (SocketException e) {System.out.println("handler:异常！");}}}/* * 发送消息的线程类 */class SendThread implements Runnable{//将消息发送到指定端口和地址private static final int PORT_SEND = 9090;private static final String IP_SEND = "localhost";private DatagramSocket sendSocket;public SendThread(DatagramSocket sendSocket) {this.sendSocket = sendSocket;}@Overridepublic void run() {BufferedReader br = null;try {while(true){//键盘录入br = new BufferedReader(new InputStreamReader(System.in));String line = null;while((line = br.readLine()) != null){//将键盘录入的内容转换成字节数组byte[] buf = line.getBytes();//实例化一个数据包，指定发送的内容，内容长度，发送的地址和端口DatagramPacket dp = new DatagramPacket(buf, buf.length, InetAddress.getByName(IP_SEND), PORT_SEND);//发送数据包sendSocket.send(dp);//打印发送的内容System.out.println("I:" + line);}}} catch (IOException e) {System.out.println("send fail！");}finally{if(sendSocket != null){sendSocket.close();}if(br != null){try {br.close();} catch (IOException e) {e.printStackTrace();}}}}}/* * 接收消息的线程类 */class ReceiveThread implements Runnable{private DatagramSocket receiveSocket;public ReceiveThread(DatagramSocket receiveSocket) {this.receiveSocket = receiveSocket;}@Overridepublic void run() {try {while(true){//一次接收的内容的最大容量byte[] buf = new byte[1024];DatagramPacket dp = new DatagramPacket(buf, buf.length);//接收数据包receiveSocket.receive(dp);//取得数据包里的内容 String data = new String(dp.getData(), 0, dp.getLength());//打印接收到的数据System.out.println("Other:" + data);}} catch (IOException e) {System.out.println("receive fail");}finally{if(receiveSocket != null){receiveSocket.close();}}}}
Receive工程：
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;import java.net.SocketException;public class Receive {//接收消息的端口private static final int PORT_RECEIVE = 9090;public static void main(String[] args) {handler();}private static void handler() {DatagramSocket sendSocket = null;DatagramSocket receiveSocket = null;try {//实例化两个套接字，一个用于接收消息，一个用于发送消息sendSocket = new DatagramSocket();receiveSocket = new DatagramSocket(PORT_RECEIVE);//实例化线程并启动，一个用于接收消息，一个用于发送消息new Thread(new SendThread(sendSocket)).start();new Thread(new ReceiveThread(receiveSocket)).start();} catch (SocketException e) {System.out.println("handler:异常！");}}}/* * 发送消息的线程类 */class SendThread implements Runnable{//将消息发送到指定端口和地址private static final int PORT_SEND = 8080;private static final String IP_SEND = "localhost";private DatagramSocket sendSocket;public SendThread(DatagramSocket sendSocket) {this.sendSocket = sendSocket;}@Overridepublic void run() {BufferedReader br = null;try {while(true){//键盘录入br = new BufferedReader(new InputStreamReader(System.in));String line = null;while((line = br.readLine()) != null){//将键盘录入的内容转换成字节数组byte[] buf = line.getBytes();//实例化一个数据包，指定发送的内容，内容长度，发送的地址和端口DatagramPacket dp = new DatagramPacket(buf, buf.length, InetAddress.getByName(IP_SEND), PORT_SEND);//发送数据包sendSocket.send(dp);//打印发送的内容System.out.println("I:" + line);}}} catch (IOException e) {System.out.println("send fail");}finally{if(sendSocket != null){sendSocket.close();}if(br != null){try {br.close();} catch (IOException e) {e.printStackTrace();}}}}}/* * 接收消息的线程类 */class ReceiveThread implements Runnable{private DatagramSocket receiveSocket;public ReceiveThread(DatagramSocket receiveSocket) {this.receiveSocket = receiveSocket;}@Overridepublic void run() {try {while(true){//一次接收的内容的最大容量byte[] buf = new byte[1024];DatagramPacket dp = new DatagramPacket(buf, buf.length);//接收数据包receiveSocket.receive(dp);String data = new String(dp.getData(), 0, dp.getLength());//取得数据包里的内容 System.out.println("Other:" + data);}} catch (IOException e) {System.out.println("receive fail");}finally{if(receiveSocket != null){receiveSocket.close();}}}}