Java网络编程

TCP

客户端

• 连接服务器 Socket

• 发送消息

• package com.guanxing.lesson02;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.net.InetAddress;
  import java.net.Socket;
  import java.net.UnknownHostException;
  
  //客户端
  public class TcpClientDemo01 {
      public static void main(String[] args) throws IOException {
  
          Socket socket = null;
          OutputStream os = null;
          try {
              //1.要知道服务器的地址，端口
              InetAddress serverIP = InetAddress.getByName("127.0.0.1");
              int port = 9999;
              //2.创建一个socket连接
              socket = new Socket(serverIP, port);
              //3.发送信息 IO流
              os = socket.getOutputStream();
              os.write("你好，欢迎离开TCP聊天".getBytes());
  
          } catch (UnknownHostException e) {
              e.printStackTrace();
          } finally {
              //关闭资源
              if (os != null) {
                  try {
                      os.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              if (socket != null) {
                  try {
                      socket.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
          }
      }
  }
  

服务端

• 建立服务的端口 ServerSocket

• 等到用户的连接 accept

• 接收用户的消息

• package com.guanxing.lesson02;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.ServerSocket;
  import java.net.Socket;
  
  //服务端
  public class TcpServerDemo01 {
      public static void main(String[] args) {
          //提升作用域
          ServerSocket serverSocket = null;
          Socket socket = null;
          InputStream is = null;
          ByteArrayOutputStream baos = null;
          try {
              //1.我得有一个地址
              serverSocket = new ServerSocket(9999);
              //循环持续接收
              while (true) {
                  //2.等待客户端连接过来
                  socket = serverSocket.accept();
                  //3.读取客户端的消息
                  is = socket.getInputStream();
                  //管道流（防止乱码超过规定的字节数）
                  baos = new ByteArrayOutputStream();
                  byte[] buffer = new byte[1024];
                  int len;
                  while ((len=is.read(buffer)) != -1) {
                      baos.write(buffer, 0, len);
                  }
                  System.out.println(baos.toString());
              }
          } catch (IOException e) {
              e.printStackTrace();
          } finally {
              //关闭资源
              if (baos != null) {
                  try {
                      baos.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              if (is != null) {
                  try {
                      is.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              if (socket != null) {
                  try {
                      socket.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              if (serverSocket != null) {
                  try {
                      serverSocket.close();
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
          }
      }
  }
  

文件上传

客户端

package com.guanxing.lesson02;

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

public class TcpClientDemo02 {
    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("heibao.jpg"));
        //4.写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len=fis.read(buffer))!=-1) {
            os.write(buffer, 0, len);
        }

        //通知服务器已经传输完了
        socket.shutdownOutput();

        //确定服务端接收完毕
        InputStream is = socket.getInputStream();
        //字符串的管道流
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        byte[] buffer2 = new byte[2014];
        int len2;
        while ((len2=is.read(buffer2))!=-1) {
            baos.write(buffer2, 0, len2);
        }
        System.out.println(baos.toString());

        //5.关闭资源
        baos.close();
        is.close();
        fis.close();
        os.close();
        socket.close();
    }
}

服务端

package com.guanxing.lesson02;

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

public class TcpServerDemo02 {
    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(文件的管道流)
        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);
        }

        //通知客户端接收完毕
        OutputStream os = socket.getOutputStream();
        os.write("我接收完毕了,你可以爬了".getBytes());

        //5.关闭资源
        os.close();
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

Udp

udp没有明确的客户端和服务端 !

发送方

package com.guanxing.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

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(5个参数: 数据 数据长度 接收者 端口)
        String msg = "你好啊, 服务器!";
            //发送给谁
        InetAddress localhost = InetAddress.getByName("127.0.0.1");
        int port = 9090;
        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();
    }
}

接收方

package com.guanxing.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

//还是要等待客户端的连接!
public class UdpServerDemo01 {
    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);
        //处理数据
        System.out.println(packet.getAddress().getHostAddress());  //127.0.0.1
        System.out.println(new String(packet.getData()));  //你好啊, 服务器!

        //关闭连接
        socket.close();
    }
}

Udp聊天基础版

发送方

package com.guanxing.lesson04Chat;

import java.io.BufferedReader;
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 Exception {
        //1.建立连接
        DatagramSocket socket = new DatagramSocket(8888);

        //2.创建包
        //创建包里的数据 : 控制台读取
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        while (true) {
            String msg = reader.readLine();
            //字符串要转化为字节
            byte[] msgs = msg.getBytes();
            //接收者和端口
            DatagramPacket packet = new DatagramPacket(msgs, 0, msgs.length, new InetSocketAddress("localhost", 6666));
            //3.发送包
            socket.send(packet);

            //如果输入为 bye,则停止
            if (msg.equals("bye")) {
                break;
            }
        }
        //4.关闭流
        socket.close();
    }
}

接收方

package com.guanxing.lesson04Chat;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        //1.开放端口
        DatagramSocket socket = new DatagramSocket(6666);

        //2.死循环接收数据
        while (true) {
            //准备接收数据的容器
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container, 0, container.length);
            socket.receive(packet); //阻塞式接收

            //断开连接 bye
            byte[] data = packet.getData();
            String msg = new String(data, 0, packet.getLength());  //这里避免接收多余的空字节
            //打印接收到的信息
            System.out.println(msg);

            if (msg.equals("bye")) {
                break;
            }
        }
        socket.close();
    }
}