Java学习笔记53（网络编程：TCP协议案例）

简易的案例

客户端：

package demo;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.Socket;public class TCPClient {    public static void main(String[] args) throws IOException {        Socket socket = new Socket("127.0.0.1", 7000);        OutputStream out = socket.getOutputStream();        out.write("hello".getBytes());        InputStream in = socket.getInputStream();        byte[] data = new byte[1024];        int len = in.read(data);        System.out.println(new String(data, 0, len));        socket.close();    }}

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服务器端：

package demo;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.ServerSocket;import java.net.Socket;public class TCPServer {    public static void main(String[] args) throws IOException {        ServerSocket server = new ServerSocket(7000);        Socket socket = server.accept();        InputStream in = socket.getInputStream();        byte[] data = new byte[1024];        int len = in.read(data);        System.out.println(new String(data, 0, len));        OutputStream out = socket.getOutputStream();        out.write("收到".getBytes());        socket.close();        server.close();    }}

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先启动服务器端，再启动客户端，服务器端打印:hello，然后客户端打印:收到

注意区分这里的流对象

接下来在这个案例基础上做一个图片上传案例

图片上传的本质就是文件复制

客户端：

package demo1;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.Socket;public class TCPClient {    public static void main(String[] args) throws IOException {        Socket socket = new Socket("127.0.0.1", 7000);        OutputStream out = socket.getOutputStream();        FileInputStream fis = new FileInputStream("d:\\666.jpeg");        int len = 0;        byte[] bytes = new byte[1024];        while ((len = fis.read(bytes)) != -1) {            out.write(bytes, 0, len);        }        socket.shutdownOutput();        // 服务器端读不到-1，不会终止，调用这个方法可以终止        InputStream in = socket.getInputStream();        len = in.read(bytes);        System.out.println(new String(bytes, 0, len));        fis.close();        socket.close();    }}

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服务器端：

package demo1;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.ServerSocket;import java.net.Socket;import java.util.Random;public class TCPServer {    public static void main(String[] args) throws IOException {        ServerSocket server = new ServerSocket(7000);        Socket socket = server.accept();        InputStream in = socket.getInputStream();        File upload = new File("d:\\upload");        if (!upload.exists()) {            upload.mkdirs();        }        String filename = System.currentTimeMillis() + new Random().nextInt(999999) + ".jpeg";        FileOutputStream fos = new FileOutputStream(upload + File.separator + filename);        // 这里是处理图片重名的问题        byte[] bytes = new byte[1024];        int len = 0;        while ((len = in.read(bytes)) != -1) {            fos.write(bytes, 0, len);        }        socket.getOutputStream().write("上传成功".getBytes());        fos.close();        socket.close();        server.close();    }}

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如果多个客户端一起上传，就需要多线程的技术，每个客户端占一个线程

客户端不需要修改

服务器端：

package demo1;import java.io.IOException;import java.net.ServerSocket;import java.net.Socket;public class TCPServer {    public static void main(String[] args) throws IOException {        ServerSocket server = new ServerSocket(7000);        while (true) {            Socket socket = server.accept();            new Thread(new Upload(socket)).start();        }    }}

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package demo1;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.ServerSocket;import java.net.Socket;import java.util.Random;public class Upload implements Runnable {    private Socket socket;    public Upload(Socket socket) {        this.socket = socket;    }    public void run() {        try {            InputStream in = socket.getInputStream();            File upload = new File("d:\\upload");            if (!upload.exists()) {                upload.mkdirs();            }            String filename = System.currentTimeMillis() + new Random().nextInt(999999) + ".jpeg";            FileOutputStream fos = new FileOutputStream(upload + File.separator + filename);            // 这里是处理图片重名的问题            byte[] bytes = new byte[1024];            int len = 0;            while ((len = in.read(bytes)) != -1) {                fos.write(bytes, 0, len);            }            socket.getOutputStream().write("上传成功".getBytes());            fos.close();            socket.close();        } catch (IOException ex) {            System.out.println(ex);        }    }}

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放弃等于又一次可以选择的机会。