网络编程—UDP与URL
网络编程—UDP
发消息:不用连接;需要知道对方的地址!
发送消息
客户端
package com.deng.lesson03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
//不需要连接服务器
public class UdpClientDemo01 {
public static void main(String[] args) throws Exception{
//1.建立一个Socket
DatagramSocket socket = new DatagramSocket();
//2.建个包
String msg = "你好,欢迎光临";
//发送给谁
InetAddress localhost = InetAddress.getByName("localhost");
int port = 9090;
//数据 数据的长度起始 要发送给谁
DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length,localhost,port);
//3.发送包
socket.send(packet);
//4.关闭流
socket.close();
}
}
服务端
package com.deng.lesson03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class UdpServerDemo01 {
public static void main(String[] args) throws Exception{
//开放端口
DatagramSocket socket= new DatagramSocket(9090);
//接受数据包
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
socket.receive(packet);//阻塞接受
System.out.println(packet.getAddress().getHostAddress());
System.out.println(new String(packet.getData(),0,packet.getLength()));
//关闭连接
socket.close();
}
}
咨询
循环发送消息
package com.deng.chat;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
//发送方
public class UdpSenderDemo01 {
public static void main(String[] args) throws Exception{
DatagramSocket socket = new DatagramSocket(8888);
//准备数据 控制台System.in
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while (true){
String data = reader.readLine();
byte[] datas = data.getBytes();
DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress("localhost",6666));
socket.send(packet);
if (data.equals("bye")){
break;
}
}
socket.close();
}
}
循环接收消息
package com.deng.chat;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
//接收方
public class UdpReceiveDemo01 {
public static void main(String[] args) throws Exception{
DatagramSocket socket = new DatagramSocket(6666);
while (true){
//准备接受包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0, container.length);
socket.receive(packet);//阻塞式接受包裹
//断开连接 bye
byte[] data = packet.getData();
String receiveData = new String(data, 0, data.length);
System.out.println(receiveData);
if (receiveData.equals("bye")){
break;
}
}
socket.close();
}
}
在线咨询: 两个人都可以是发送方 都可以是接收方
建一个TalkReceive
package com.deng.chat;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class TalkReceive implements Runnable{
DatagramSocket socket = null;
private int port;
private String msgFrom;
public TalkReceive(int port,String msgFrom) {
this.port = port;
this.msgFrom =msgFrom;
try {
socket = new DatagramSocket(port);
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true){
try {
//准备接受包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0, container.length);
socket.receive(packet);//阻塞式接受包裹
//断开连接 bye
byte[] data = packet.getData();
String receiveData = new String(data, 0, data.length);
System.out.println(msgFrom +":"+receiveData);
if (receiveData.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
建一个TalkSend
package com.deng.chat;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
public class TalkSend implements Runnable{
DatagramSocket socket = null;
BufferedReader reader = null;
private int fromPort;
private String toIP;
private int toPort;
public TalkSend(int fromPor,String toIP,int toPort) {
this.fromPort = fromPort;
this.toIP = toIP;
this.toPort = toPort;
try {
socket = new DatagramSocket(fromPort);
reader = new BufferedReader(new InputStreamReader(System.in));
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
try {
while (true){
String data = reader.readLine();
byte[] datas = data.getBytes();
DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress(this.toIP,this.toPort));
socket.send(packet);
if (data.equals("bye")){
break;
}
}
} catch (IOException e) {
e.printStackTrace();
}
socket.close();
}
}
建一个TalkSend
package com.deng.chat;
public class TalkSend {
public static void main(String[] args) {
//开启两个线程
new Thread(new TalkSend(7777,"localhost",9999)).start();
new Thread(new TalkReceive(8888,"老师")).start();
}
}
建一个TalkTeacher
package com.deng.chat;
public class TalkTeacher {
public static void main(String[] args) {
new Thread(new TalkSend(5555,"localhost",8888)).start();
new Thread(new TalkReceive(9999,"学生")).start();
}
}
URL
统一资源定位符:定位资源的,定位互联网上的某一个资源
DNS 域名解析 xxx.x..x..x
1.协议: //ip地址:端口/项目名/资源
例题:下载网络资源
package com.deng.lesson04;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
//下载网络资源
public class urlDown {
public static void main(String[] args) throws Exception{
//1.下载地址
URL url = new URL("https://s4.music.126.net/style/web2/img/default/default_avatar_40.jpg");
//2.连接到这个资源 HTTP
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
InputStream inputStream = urlConnection.getInputStream();
FileOutputStream fos = new FileOutputStream("40.jpg");
byte[] buffer = new byte[1024];
int len;
while ((len=inputStream.read(buffer))!=-1){
fos.write(buffer,0,len);//写出数据
}
fos.close();
inputStream.close();
urlConnection.disconnect();//断开连接
}
}
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