网络编程

代码分享：
1.多个用户访问一个服务器

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;

public class ClientTest {
    public static void main(String[] args) {
        Socket socket2 = null;
        //键盘输入流
        InputStreamReader isr = null;
        BufferedReader bfr = null;
        //网络输出流
        OutputStreamWriter osw = null;
        BufferedWriter bfw = null;
        try {
            socket2 = new Socket("127.0.0.1", 9999);
            isr = new InputStreamReader(System.in);
            bfr = new BufferedReader(isr);

            osw = new OutputStreamWriter(socket2.getOutputStream());
            bfw = new BufferedWriter(osw);
            String string = bfr.readLine();
            while (string != null) {
                bfw.write(string);
                bfw.newLine();
                bfw.flush();
                string = bfr.readLine();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bfw.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                bfr.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                socket2.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
    }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;

class ServerThread implements Runnable {

    private Socket socket;

    public ServerThread(Socket socket) {
        this.socket = socket;
    }
    InputStreamReader isr = null;   //网络输入流
    BufferedReader bfr = null;
    @Override
    public void run() {
        try {
            isr = new InputStreamReader(socket.getInputStream());
            bfr = new BufferedReader(isr);
            String string = bfr.readLine();
            while (string != null) {
                System.out.println(string);
                string = bfr.readLine();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bfr.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                socket.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
    }
}
public class ServerTest {
    public static void main(String[] args) {
        ServerSocket server = null;
        Socket socket = null;
        while (true) {
            try {
                server  = new ServerSocket(9999);
                System.out.println("我是服务器，正在监视.....");
                socket = server.accept();
                Runnable r = new ServerThread(socket);
                Thread t = new Thread(r);
                t.start();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    server.close();
                } catch (Exception e2) {
                    e2.printStackTrace();
                }
            }
        }
    }
}

2.服务器给用户传文件

import java.io.BufferedInputStream;
import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.net.Socket;

public class ClientTest2 {
    public static void main(String[] args) {
        Socket socket = null;

        BufferedInputStream bis = null; //网络输入流
        FileOutputStream fos = null; //文件输出流
        BufferedWriter bfw = null; //网络输出流

        try {
            socket = new Socket("localhost", 8888);
            bis = new BufferedInputStream(socket.getInputStream());
            fos = new FileOutputStream("机器猫2.png");
            bfw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            byte[] buf = new byte[8192];
            int realCount = bis.read(buf);
            while(realCount != -1) {
                fos.write(buf, 0, realCount);
                fos.flush();                //每次写完一定要flush不然文件可能差些东西
                realCount = bis.read(buf);
            }
            bfw.write("接收成功，并保存");
            bfw.flush();

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                fos.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                bis.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                bfw.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                socket.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }

        }
    }
}

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;

public class ServerTest2 {
    public static void main(String[] args) {
        ServerSocket server = null;
        Socket socket = null;

        FileInputStream fis = null;     //文件输入流
        BufferedOutputStream bos = null; //网络输出流
        BufferedReader isr = null; //网络输入流

        try {
            server = new ServerSocket(8888);
            socket = server.accept();

            fis = new FileInputStream("机器猫.png");
            bos = new BufferedOutputStream(socket.getOutputStream());
            isr = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            byte[] buf = new byte[8192];
            int realCount = fis.read(buf);
            while (realCount != -1) {
                bos.write(buf, 0, realCount);
                bos.flush();                //每次写完一定要flush，不然东西差点，还有两边都要flush
                realCount = fis.read(buf);
            }
            socket.shutdownOutput();
            String string  = isr.readLine();
            System.out.println(string);

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bos.close();
            } catch (Exception e2) {
            }
            try {
                fis.close();
            } catch (Exception e2) {
            }
            try {
                isr.close();
            } catch (Exception e2) {
            }
            try {
                socket.close();
            } catch (Exception e2) {
            }
            try {
                server.close();
            } catch (Exception e2) {
            }
        }
    }
}

3.简单的用户/服务器

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;

import org.junit.Test;

public class NetTest {

    @Test
    public void Server() {

        ServerSocket server = null;
        Socket socket1 = null;
        //输出流
        OutputStream os = null;
        OutputStreamWriter osw = null;
        BufferedWriter bfw = null;
        //输入流
        InputStream is = null;
        InputStreamReader isr = null;
        BufferedReader bfr = null;

        try {
            server = new ServerSocket(7878);
            socket1 = server.accept();

            os = socket1.getOutputStream();
            osw = new OutputStreamWriter(os, "UTF8");
            bfw = new BufferedWriter(osw);
            bfw.write("abcde");
            bfw.newLine();
            bfw.flush();

            is = socket1.getInputStream();
            isr = new InputStreamReader(is, "UTF8");
            bfr = new BufferedReader(isr);
            String string = bfr.readLine();
            System.out.println(string);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bfr.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                bfw.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                socket1.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                server.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
    }

    @Test
    public void Client() {

        Socket socket2 = null;
        //输出流
        OutputStream os = null;
        OutputStreamWriter osw = null;
        BufferedWriter bfw = null;
        //输入流
        InputStream is = null;
        InputStreamReader isr = null;
        BufferedReader bfr = null;

        try {
            socket2 = new Socket("127.0.0.1", 7878);

            is = socket2.getInputStream();
            isr = new InputStreamReader(is, "UTF8");
            bfr = new BufferedReader(isr);
            String string = bfr.readLine();
            System.out.println(string);

            os = socket2.getOutputStream();
            osw = new OutputStreamWriter(os, "UTF8");
            bfw = new BufferedWriter(osw);
            StringBuilder sb = new StringBuilder(string);
            sb.reverse();
            bfw.write(new String(sb));
            bfw.newLine();
            bfw.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bfr.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                bfw.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
            try {
                socket2.close();
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
    }
}