Java-网络编程
2022/4/9 22:19:38
本文主要是介绍Java-网络编程，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！
1.网络编程有两个主要的问题：
- 如何准确的定位到网络上的一台或多台主机
- 找到主机后如何进行通信
2.网络编程的要素
- IP和端口号
- 网络通信协议
1.IP
cmd->ipconfig:查看本机IP地址
1 package com.KingJ.lesson1;
2
3 import java.net.Inet4Address;
4 import java.net.InetAddress;
5 import java.net.UnknownHostException;
6
7 public class TestInetAddress {
8 public static void main(String[] args) {
9 try {
10 //查询本机地址
11 InetAddress inetaddress1 = InetAddress.getByName("127.0.0.1");
12 System.out.println(inetaddress1);
13 InetAddress inetaddress2 = InetAddress.getByName("localhost");
14 System.out.println(inetaddress2);
15 InetAddress inetaddress3 = InetAddress.getLocalHost();
16 System.out.println(inetaddress3);
17
18 //查询网站地址
19 InetAddress inetaddress4 = InetAddress.getByName("www.baidu.com");
20 System.out.println(inetaddress4);
21
22 //常用方法
23 System.out.println(inetaddress4.getAddress());
24 System.out.println(inetaddress4.getCanonicalHostName());//获取规范的名字
25 System.out.println(inetaddress4.getHostAddress());//IP
26 System.out.println(inetaddress4.getHostName());//域名，或自己电脑的名字
27
28
29 } catch (UnknownHostException e) {
30 e.printStackTrace();
31 }
32 }
33 }
2.端口
常见DOS命令：
1 package com.KingJ.lesson1;
2
3 import java.net.InetSocketAddress;
4
5 public class TestInetSocketAddress {
6 public static void main(String[] args) {
7 InetSocketAddress inetSocketAddress1 = new InetSocketAddress("127.168.0.1", 8080);
8 System.out.println(inetSocketAddress1);
9 InetSocketAddress inetSocketAddress2 = new InetSocketAddress("localhost", 8080);
10 System.out.println(inetSocketAddress2);
11
12 System.out.println(inetSocketAddress1.getAddress());
13 System.out.println(inetSocketAddress1.getHostName());//地址
14 System.out.println(inetSocketAddress1.getPort());//端口
15 }
16 }
3.TCP
3.1TCP实现聊天
客户端：
1 package com.KingJ.lesson2;
2
3 import java.io.IOException;
4 import java.io.OutputStream;
5 import java.net.InetAddress;
6 import java.net.Socket;
7 import java.net.UnknownHostException;
8 import java.nio.charset.StandardCharsets;
9
10 public class TestClientdemo01 {
11 public static void main(String[] args) {
12 Socket socket = null;
13 OutputStream os = null;
14 //1.要知道服务器的地址，端口号
15 try {
16 //1.要知道服务器的地址，端口号
17 InetAddress serverIP = InetAddress.getByName("127.0.0.1");
18 int port = 9999;
19 //2.创建一个socket连接
20 socket = new Socket(serverIP, port);
21 //3.发送消息 I/O流
22 os = socket.getOutputStream();
23 os.write("你好，请滚出去".getBytes());
24 } catch (Exception e) {
25 e.printStackTrace();
26 } finally {
27 if (os != null) {
28 try {
29 os.close();
30 } catch (IOException e) {
31 e.printStackTrace();
32 }
33 }
34 if (socket != null) {
35 try {
36 socket.close();
37 } catch (IOException e) {
38 e.printStackTrace();
39 }
40 }
41
42 }
43 }
44
45 }
服务器端：
1 package com.KingJ.lesson2;
2
3 import java.io.ByteArrayOutputStream;
4 import java.io.IOException;
5 import java.io.InputStream;
6 import java.net.ServerSocket;
7 import java.net.Socket;
8
9 public class TestServerdemo02 {
10
11 public static void main(String[] args) {
12 ServerSocket serverSocket = null;
13 Socket socket = null;
14 InputStream is = null;
15 ByteArrayOutputStream baos = null;
16
17 try {
18 //1.我得有一个地址
19 serverSocket = new ServerSocket(9999);
20 //2.等待客户端连接过来
21 socket = serverSocket.accept();
22 //3.读取客户端发来的消息
23 is = socket.getInputStream();
24
25 //管道流
26 baos = new ByteArrayOutputStream();
27 byte[] buffer = new byte[1024];
28 int len;
29 while ((len = is.read(buffer)) != -1) {
30 baos.write(buffer, 0, len);
31 }
32 System.out.println(baos.toString());
33
34
35 } catch (IOException e) {
36 e.printStackTrace();
37 } finally {
38 //关闭资源
39 if (baos != null) {
40 try {
41 baos.close();
42 } catch (IOException e) {
43 e.printStackTrace();
44 }
45 }
46 if (is != null) {
47 try {
48 is.close();
49 } catch (IOException e) {
50 e.printStackTrace();
51 }
52 }
53 if (socket != null) {
54 try {
55 socket.close();
56 } catch (IOException e) {
57 e.printStackTrace();
58 }
59 }
60 if (serverSocket != null) {
61 try {
62 serverSocket.close();
63 } catch (IOException e) {
64 e.printStackTrace();
65 }
66 }
67
68
69 }
70 }
71 }
3.2 文件上传
服务器端：
1 package com.KingJ.lesson2.TestFile;
2
3 import java.io.FileOutputStream;
4 import java.io.InputStream;
5 import java.io.OutputStream;
6 import java.net.ServerSocket;
7 import java.net.Socket;
8
9 public class TestServer1 {
10 public static void main(String[] args) throws Exception {
11 //1.创建服务
12 ServerSocket serverSocket = new ServerSocket(9999);
13 //2.监听客户端的连接
14 Socket socket = serverSocket.accept();
15 //3.获取输入流
16 InputStream is = socket.getInputStream();
17
18 //4.文件输出
19 FileOutputStream fos = new FileOutputStream("receive.PNG");
20 byte[] buffer = new byte[1024];
21 int len;
22 while ((len = is.read(buffer)) != -1) {
23 fos.write(buffer, 0, len);
24 }
25
26 //通知客户端接收完毕
27 OutputStream os = socket.getOutputStream();
28 os.write("接收完毕".getBytes());
29
30 //关闭资源
31 os.close();
32 fos.close();
33 is.close();
34 socket.close();
35 serverSocket.close();
36 }
37 }
客户端
1 package com.KingJ.lesson2.TestFile;
2
3 import java.io.*;
4 import java.net.InetAddress;
5 import java.net.Socket;
6
7 public class TestClient1 {
8 public static void main(String[] args) throws Exception {
9 //1.创建一个socket连接
10 Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9999);
11 //2.创建一个输出流
12 OutputStream os = socket.getOutputStream();
13 //3.读取文件
14 FileInputStream fis = new FileInputStream(new File("HTML.PNG"));
15 //4.写出文件
16 byte[] buffer = new byte[1024];
17 int len;
18 while ((len = fis.read(buffer)) != -1) {
19 os.write(buffer, 0, len);
20 }
21 //通知服务器我已经发送完了
22 socket.shutdownOutput();
23 //确定服务器接收完毕
24 InputStream inputStream = socket.getInputStream();
25 ByteArrayOutputStream baos = new ByteArrayOutputStream();
26 byte[] buffer2 = new byte[1024];
27 int len2;
28 while ((len = inputStream.read(buffer2)) != -1) {
29 baos.write(buffer, 0, len);
30 }
31 System.out.println(baos.toString());
32
33
34 //5.关闭资源
35 baos.close();
36 inputStream.close();
37 fis.close();
38 os.close();
39 socket.close();
40
41
42 }
43 }
4.UDP
发送方：
1 package com.KingJ.lesson1.lesson4;
2
3 import java.net.DatagramPacket;
4 import java.net.DatagramSocket;
5 import java.net.InetAddress;
6 import java.net.SocketException;
7
8 public class UdpClient1 {
9 public static void main(String[] args) throws Exception {
10 //1.建立一个socket
11 DatagramSocket socket = new DatagramSocket();
12 //要发送的消息
13 String msg = "你好，请滚出去!";
14 //发送给谁
15 InetAddress localhost = InetAddress.getByName("localhost");
16 int port = 9999;
17 //2.建个包
18 DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);
19
20 //3.发送包
21 socket.send(packet);
22
23 //关闭流
24 socket.close();
25
26 }
27 }
接收方：
1 package com.KingJ.lesson1.lesson4;
2
3 import java.net.DatagramPacket;
4 import java.net.DatagramSocket;
5 import java.net.SocketException;
6
7 public class UdpServer1 {
8 public static void main(String[] args) throws Exception {
9 //开放端口
10 DatagramSocket socket = new DatagramSocket(9999);
11 //接收数据包
12 byte[] buffer = new byte[1024];
13 DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
14
15 socket.receive(packet);
16 System.out.println(new String(packet.getData(), 0, packet.getData().length));
17
18 //关闭连接
19 socket.close();
20
21 }
22 }
在线咨询实现：
1 package com.KingJ.chat;
2
3 import java.io.BufferedReader;
4 import java.io.InputStreamReader;
5 import java.net.DatagramPacket;
6 import java.net.DatagramSocket;
7 import java.net.InetSocketAddress;
8
9 public class TalkSend implements Runnable {
10 DatagramSocket socket = null;
11 BufferedReader reader = null;
12
13 private int fromPort;//自己的端口
14 private String toIP;//对方的IP
15 private int toPort;//对方的端口号
16
17
18 public TalkSend(int fromPort, String toIP, int toPort) {
19 this.fromPort = fromPort;
20 this.toIP = toIP;
21 this.toPort = toPort;
22 try {
23 socket = new DatagramSocket(fromPort);
24 reader = new BufferedReader(new InputStreamReader(System.in));
25 } catch (Exception e) {
26 e.printStackTrace();
27 }
28
29 }
30
31 @Override
32 public void run() {
33
34 while (true) {
35 try {
36 String data = reader.readLine();
37 byte[] datas = data.getBytes();//数据转换为字节
38 DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, this.toPort));
39 socket.send(packet);
40 if (data.equals("bye")) {
41 break;
42 }
43
44 } catch (Exception e) {
45 e.printStackTrace();
46 }
47
48 }
49
50 socket.close();
51 }
52 }
1 package com.KingJ.chat;
2
3 import java.io.IOException;
4 import java.net.DatagramPacket;
5 import java.net.DatagramSocket;
6 import java.net.SocketException;
7
8 public class TalkReceive implements Runnable {
9 DatagramSocket socket = null;
10 private int port;
11 private String msgFrom;
12
13 public TalkReceive(int port, String msgFrom) {
14 this.port = port;
15 this.msgFrom = msgFrom;
16 try {
17 socket = new DatagramSocket(port);
18 } catch (SocketException e) {
19 e.printStackTrace();
20 }
21
22 }
23
24 @Override
25 public void run() {
26 //准备接收包裹
27 byte[] container = new byte[1024];
28 while (true) {
29
30 try {
31 DatagramPacket packet = new DatagramPacket(container, 0, container.length);
32 socket.receive(packet);
33
34 byte[] data = packet.getData();
35 String receiveDatas = new String(data, 0, packet.getLength());
36 System.out.println(msgFrom + ":" + receiveDatas);
37
38 if (receiveDatas.equals(("bye"))) {
39 break;
40 }
41 } catch (IOException e) {
42 e.printStackTrace();
43 }
44
45
46 }
47 socket.close();
48
49 }
50 }
1 package com.KingJ.chat;
2
3 public class TalkStudent {
4 public static void main(String[] args) {
5 new Thread(new TalkSend(7777, "localhost", 9999)).start();
6 new Thread(new TalkReceive(8888, "老师")).start();
7 }
8 }
1 package com.KingJ.chat;
2
3 public class TalkTeacher {
4 public static void main(String[] args) {
5 new Thread(new TalkSend(5555, "localhost", 8888)).start();
6 new Thread(new TalkReceive(9999, "老师")).start();
7 }
8 }
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