黑马程序员——Java网络编程

黑马程序员——Java网络编程

---------------------- android培训、java培训、期待与您交流！ ----------------------

一、TCP和UDP

●  UDP

■  将数据的源和目的封装在数据包中，不需要建立连接

■  第个数据报的大小限制在64K内

■  因无连接，是不可靠的协议，速度快

●  TCP

■  建立连接，开成传输数据的通道；

■  在连接中进行大数据量传输；

■  通过三次握手完成连接，是可靠协议；

■  必须建立连接，效率会稍低

二、Socket

●  Socket就是为网络服务提供的一种机制

●  通信的两端都有Socket

●  网络通信其实就是Socket间的通信

●  数据在两个Socket间通过IO传输

三、UDP传输

●  UDP通信流程：

1、建立UDPSocket服务通过DatagramSocket对象
2、提供数据，并将数据封装到数据包中（DatagramPacket(byte[] buf，int length，InetAddress address，int port)）
3、通过Socket服务的发送功能，将数据发送出去通过send()方法
4、关闭资源，close()方法。

●  实例：UDP简单通信实例

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
 
// 接收端
public class UdpReceive {
    public static void main(String[] args) throws IOException {
        DatagramSocket s = new DatagramSocket(9999);
 
        byte[] buf = new byte[1024];
        DatagramPacket p = new DatagramPacket(buf, buf.length);
 
        s.receive(p);
 
        String ip = p.getAddress().getHostAddress();
        String data = new String(p.getData(), 0, p.getLength());
        int port = p.getPort();
 
        System.out.println("ip: " + ip + " port: " + port);
        System.out.println("data:" + data);
 
        s.close();
    }
}

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 
// 发送端
public class UdpSend {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket();
 
        byte[] data = "Helloworld".getBytes();
        DatagramPacket packet = new DatagramPacket(data, data.length,
                InetAddress.getByName("localhost"), 9999);
 
        socket.send(packet);
 
        socket.close();
    }
}

●  实例：UDP简单通信实例（方式二）

发送端

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 
public class UdpSend2 {
    public static void main(String[] args) throws Exception {
        DatagramSocket s = new DatagramSocket();
 
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line = null;
 
        while ((line = br.readLine()) != null) {
            byte[] b = line.getBytes();
 
            DatagramPacket p = new DatagramPacket(b, 0, b.length,
                    InetAddress.getByName("localhost"), 8989);
           
            s.send(p);
           
            if ("88".equals(line))
                break;
        }
 
        br.close();
        s.close();
    }
}

接收端

import java.net.DatagramPacket;
import java.net.DatagramSocket;
 
public class UdpReceive2 {
    public static void main(String[] args) throws Exception {
        DatagramSocket s = new DatagramSocket(8989);
 
        byte[] b = new byte[1024 * 64];
        DatagramPacket p = new DatagramPacket(b, b.length);
 
        while (true) {
            s.receive(p);
 
            String ip = p.getAddress().getHostAddress();
            String data = new String(p.getData(), 0, p.getLength());
 
            System.out.println(ip + "说: " + data);
           
            if("88".equals(data))
                break;
        }
       
        s.close();
    }
}

● 实例：简单UDP聊天实例

// Send.java
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 
public class Send extends Thread {
    private DatagramSocket s;
 
    @Override
    public void run() {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 
        String line = null;
 
        try {
            while ((line = br.readLine()) != null) {
                byte[] buf = line.getBytes();
 
                DatagramPacket p = new DatagramPacket(buf, buf.length,
                        InetAddress.getByName("10.11.24.255"), 10000);
 
                s.send(p);
 
                if ("88".equals(line))
                    break;
            }
 
            br.close();
        } catch (IOException e) {
            throw new RuntimeException("发送失败");
        }
    }
 
    public Send(DatagramSocket s) {
        super();
        this.s = s;
    }
}

// Receive.java
import java.net.DatagramPacket;
import java.net.DatagramSocket;
 
public class Receive extends Thread {
    private DatagramSocket s;
 
    @Override
    public void run() {
        try {
            byte[] buf = new byte[1024 * 64];
            DatagramPacket p = new DatagramPacket(buf, buf.length);
 
            while (true) {
                s.receive(p);
 
                String ip = p.getAddress().getHostAddress();
                String data = new String(p.getData(), 0, p.getLength());
 
                System.out.println("【" + ip + "】说: " + data);
            }
        } catch (Exception e) {
            throw new RuntimeException("接收失败");
        }
    }
 
    public Receive(DatagramSocket s) {
        super();
        this.s = s;
    }
}

// ChatDemo.java
import java.net.DatagramSocket;
 
public class ChatDemo {
    public static void main(String[] args) throws Exception {
        DatagramSocket sendSocket=new DatagramSocket();
        DatagramSocket receSocket=new DatagramSocket(10000);
       
        new Send(sendSocket).start();
        new Receive(receSocket).start();
    }
}

三、TCP传输

TCP分客户端和服务端，客户端对应的对象是Socket，服务端对应的对象是ServerSocket。

●  实例：演示Tcp传输的客户端与服务端的互访

服务端

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
 
public class TcpServer2 {
    public static void main(String[] args) throws IOException {
        ServerSocket ss = new ServerSocket(10000);
 
        Socket s = ss.accept();
 
        String ip = s.getInetAddress().getHostAddress();
        System.out.println(ip + "connected...  says: ");
 
        InputStream in = s.getInputStream();
        byte[] buf = new byte[1024];
        int len = in.read(buf);
        System.out.println(new String(buf, 0, len));
       
        OutputStream out=s.getOutputStream();
        out.write("哥们收到， 你也好".getBytes());
       
        s.close();
        ss.close();
    }
}

客户端

import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
 
public class TcpClient2 {
    public static void main(String[] args) throws Exception {
        Socket s = new Socket(InetAddress.getByName("localhost"), 10000);
 
        OutputStream out = s.getOutputStream();
        out.write("服务端，你好！".getBytes());
 
        InputStream in = s.getInputStream();
        byte[] buf = new byte[1024];
        int len = in.read(buf);
        System.out.println(new String(buf, 0, len));
       
        s.close();
    }
}

●   实例：TCP文件传输

服务端

import java.io.*;
import java.net.*;
 
public class FileUploadServer {
    public static void main(String[] args) throws IOException {
        ServerSocket ss = new ServerSocket(10002);
 
        Socket s = ss.accept();
        String ip = s.getInetAddress().getHostAddress();
        System.out.println(ip + "connected success...");
 
        BufferedReader br = new BufferedReader(new InputStreamReader(
                s.getInputStream()));
        String filename = br.readLine(); // 接收文件名
        System.out.println("文件名：" + filename);
 
        BufferedInputStream bis = new BufferedInputStream(s.getInputStream());
        BufferedOutputStream bos = new BufferedOutputStream(
                new FileOutputStream("d:\\upload\\" + filename));
 
        byte[] b = new byte[1024 * 64];
        int len = 0;
 
        while ((len = bis.read(b)) != -1) {
            bos.write(b, 0, len);
            bos.flush();
        }
 
        PrintWriter out = new PrintWriter(s.getOutputStream(), true);
        out.println("文件【" + filename + "】传输成功！");
 
        s.close();
        ss.close();
    }
}

客户端

import java.io.*;
import java.net.*;
 
public class FileUploadClient {
    public static void main(String[] args) throws Exception {
        Socket s = new Socket(InetAddress.getByName("10.11.24.235"), 10002);
 
        // 要发送的文件
        File file = new File("d:\\卷面成绩查询.exe");
       
        if (!file.exists()) {
            System.err.println("文件不存在！");
            s.close();
            return;
        }
 
        // 发送文件名到服务器
        PrintWriter pw = new PrintWriter(s.getOutputStream(), true);
        pw.println(file.getName());
 
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(
                file));
        BufferedOutputStream bos = new BufferedOutputStream(s.getOutputStream());
        byte[] b = new byte[1024 * 64];
        int len = 0;
 
        while ((len = bis.read(b)) != -1) {
            bos.write(b, 0, len);
            bos.flush();
        }
 
        s.shutdownOutput(); // 关闭客户输出流，相当于给流中加入一个结束标记
 
        BufferedReader br = new BufferedReader(new InputStreamReader(
                s.getInputStream()));
        String str = br.readLine();
        System.out.println(str);
 
        s.close();
    }
}

---------------------- android培训、java培训、期待与您交流！ ----------------------

详细请查看：http://edu.csdn.net/heima