标签：13 java socket 编程网络 import new net public

1.IP 地址

IP地址：InetAddress

import java.net.InetAddress;
import java.net.UnknownHostException;

//测试IP
public class TestInetAddress {
    public static void main(String[] args) {
        try {
            //获取本机地址
            InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress1);
            InetAddress inetAddress3 = InetAddress.getByName("localhost");
            System.out.println(inetAddress3);
            InetAddress inetAddress4 = InetAddress.getLocalHost();
            System.out.println(inetAddress4);
            //查询网站 IP 地址
            InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress2);
            //常用方法
            //System.out.println(inetAddress2.getAddress());
            System.out.println(inetAddress2.getCanonicalHostName());//规范的名字
            System.out.println(inetAddress2.getHostAddress());//IP
            System.out.println(inetAddress2.getHostName());//域名，或自己电脑的名字
        } catch (UnknownHostException e) {
            throw new RuntimeException(e);
        }
    }
}

2.端口

import java.net.InetSocketAddress;

public class TestSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
        System.out.println(socketAddress);
        System.out.println(socketAddress.getAddress());
        System.out.println(socketAddress.getHostName());
        System.out.println(socketAddress.getPort());
    }
}

3.通信协议

4.TCP

客户端

连接服务器 Socket
发送消息

服务器

建立服务器的端口 ServerSocket
等待用户的连接 accept
接收用户的消息

例子：

客户端

import java.io.*;
import java.net.InetAddress;
import java.net.Socket;

//客户端
public class TcpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1.创建一个 socket 连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);
        //2.创建一个输出流
        OutputStream os = socket.getOutputStream();
        //3.读取文件
        FileInputStream fis = new FileInputStream(new File("1.jpg"));
        //4.写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len = fis.read(buffer)) != -1){
            os.write(buffer, 0, len);
        }
        //通知服务器，我已经结束了
        socket.shutdownOutput();//我已经传输完了
        //确定服务器接收完毕，才能断开连接
        InputStream inputStream = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[1024];
        int len2;
        while ((len2 = inputStream.read(buffer2)) != -1){
            baos.write(buffer2, 0, len2);
        }
        //5.关闭连接
        baos.close();
        inputStream.close();
        fis.close();
        os.close();
        socket.close();
    }
}

服务器端

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

//服务端
public class TcpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //1.创建服务
        ServerSocket serverSocket = new ServerSocket(9000);
        //2.监听客户端的连接
        Socket socket = serverSocket.accept();//阻塞式监听，会一直等待客户端连接
        //3.获取输入流
        InputStream is = socket.getInputStream();
        //4.文件输出
        FileOutputStream fos = new FileOutputStream(new File("receive.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len = is.read(buffer)) != -1){
            fos.write(buffer, 0, len);
        }
        //通知客户端我接收完毕了
        OutputStream os = socket.getOutputStream();
        os.write("我接收完毕了，你可以断开了".getBytes());
        //5.关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();

    }
}

5.UDP

不用连接，但需要直到对方的地址：Datagram

例1：消息发送

发送端

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，服务器";
        //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();
    }
}

接收端

import java.net.DatagramPacket;
import java.net.DatagramSocket;
//还是要等待客户端的连接
public class UdpServerDemo02 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
        socket.receive(packet);//阻塞接收
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(), 0, packet.getLength()));
        //关闭连接
        socket.close();
    }
}

例2：聊天实现

发送端

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class UdpSenderDemo01 {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket(8888);
        //准备数据：控制台读取 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();
    }
}

接收端

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class UdpReceiveDemo02 {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket(6666);
        while (true){
            //准备接收包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container, 0, container.length);
            socket.receive(packet);//阻塞式接收包裹
            //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();
    }
}

例3：UDP 多线程在线咨询

发送端

import java.io.BufferedReader;
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 fromPort, 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) {
            throw new RuntimeException(e);
        }
    }

    public TalkSend(DatagramSocket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        while (true){
            try {
                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 (Exception e){
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

接收端

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) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void run() {
        while (true){
            try {
                //准备接收包裹
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);
                socket.receive(packet);//阻塞式接收包裹
                //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) {
                throw new RuntimeException(e);
            }
        }
        socket.close();
    }
}

学生端：

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(777, "localhost", 9999)).start();
        new Thread(new TalkReceive(8888, "老师")).start();
    }
}

老师端：

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();
    }
}

6.URL 下载网络资源

url 使用：

import java.net.MalformedURLException;
import java.net.URL;

public class URLDemo {
    public static void main(String[] args) throws MalformedURLException {
        URL url = new URL("http://localhost:8080/helloworld/index.jsp?user=test&password=123");
        System.out.println(url.getProtocol());//协议
        System.out.println(url.getHost());//主机IP
        System.out.println(url.getPort());//端口
        System.out.println(url.getPath());//文件
        System.out.println(url.getFile());//全路径
        System.out.println(url.getQuery());//参数
    }
}

下载网络资源：

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class URLDown {
    public static void main(String[] args) throws IOException {
        //1.下载地址
        URL url = new URL("https://t7.baidu.com/it/u=1951548898,3927145&fm=193&f=GIF");
        //2.连接到这个资源 HTTP
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        InputStream inputStream = urlConnection.getInputStream();
        FileOutputStream fos = new FileOutputStream("1.jpg");
        byte[] buffer = new byte[1024];
        int len;
        while ((len = inputStream.read(buffer)) != -1) fos.write(buffer, 0, len);//写出这个数据

        fos.close();
        inputStream.close();
        urlConnection.disconnect();//断开连接
    }
}

标签：13,java,socket,编程,网络,import,new,net,public
From： https://www.cnblogs.com/luoluostudy/p/18178198

13.网络编程