关于UDP编程的问题 - 黑马程序员技术交流社区

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import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
/**
* 示例：应用UDP协议的Socket接收端示例
* @author lt
*/
public class UDPReceiveDemo {
public void receiveData() throws SocketException,UnknownHostException,IOException{
//创建一个指定端口和IP的UDP码头,不写在while中防止出现bindException
DatagramSocket ds = new DatagramSocket(50000,InetAddress.getLocalHost());
while(true){
//创建一个数据包对象用于接收数据包
byte[] bt = new byte[1024];
DatagramPacket dp = new DatagramPacket(bt,bt.length);
//通过receive方法接收数据包
ds.receive(dp);
//获取数据包中的信息,发送的时候封装了InetAddress对象，端口号，字符串
int port = dp.getPort();//发送端的端口号
InetAddress ia = dp.getAddress();//发送端的IP地址
byte[] getByte = dp.getData();
int length = dp.getLength();
String getByteStr = new String(getByte,0,length);
System.out.println(port + " " + ia.getHostAddress() + " " +
length + " " + getByteStr);
}
}
public static void main(String[] args) {
try {
new UDPReceiveDemo().receiveData();
} catch (SocketException e) {
System.out.println("创建DatagramSocket出现异常。");
} catch (UnknownHostException e) {
System.out.println("未知主机异常。");
} catch (IOException e) {
System.out.println("接收数据包时发生异常。");
}
}
}

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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
/**
* 示例：键盘输入的方式向服务器发送信息
* @author lt
*/
public class UDPSendKeyboardDemo {
public void sendDataByKeyboard() throws SocketException,UnknownHostException,IOException{
//可以制定一个发送端的端口
DatagramSocket ds = new DatagramSocket();
InputStream is = System.in;
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String str = null;
while((str = br.readLine())!=null){
if("88".equals(str)){
break;
}
DatagramPacket dp = new DatagramPacket(str.getBytes(),str.length(),
InetAddress.getLocalHost(),50000);
ds.send(dp);
}
if(ds != null){
ds.close();
}
}
public static void main(String[] args) {
try {
new UDPSendKeyboardDemo().sendDataByKeyboard();
} catch (SocketException e) {
System.out.println("数据报Socket创建时发生异常。");
} catch (UnknownHostException e) {
System.out.println("未知主机异常。");
} catch (IOException e) {
System.out.println("发送数据包异常。");
}
}
}

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