tcp（网络编程）

import java.net.*; import java.io.*; class Test //发送端 { public static void main(String[] args) throws SocketException,IOException { Socket s=new Socket("172.16.99.99",12000); OutputStream out=s.getOutputStream();// 返回此套接字的输出流。 BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(out)); bw.write("hello!!"); bw.flush(); //bw.close(); 若这个关闭了，则关闭了Socket() InputStream in=s.getInputStream(); byte[] b=new byte[1024]; int len=in.read(b); System.out.println(new String(b,0,len)); s.close(); } } import java.io.*; import java.net.*; class Rec //接收端 { public static void main(String[] args)throws Exception { ServerSocket ss=new ServerSocket(12000); Socket s=ss.accept(); InputStream in=s.getInputStream(); BufferedInputStream bf=new BufferedInputStream(in); byte[] b=new byte[1024]; int len=bf.read(b); System.out.println(new String(b,0,len)); OutputStream out=s.getOutputStream(); out.write("how are you!".getBytes()); //ss.close(); } }

import java.net.*; import java.io.*; class Test //发送端 { public static void main(String[] args) throws SocketException,IOException { Socket s=new Socket("172.16.99.99",12000); BufferedReader bufr=new BufferedReader(new InputStreamReader(System.in)); PrintWriter out=new PrintWriter(s.getOutputStream(),true); BufferedReader bufn=new BufferedReader(new InputStreamReader(s.getInputStream())); for(int i=0;i<3;i++) { String line=bufr.readLine(); if(line==null) break; out.println(line); String info=bufn.readLine();System.out.println("info:"+info); if(info.contains("欢迎")) break; } bufr.close(); s.close(); } } import java.io.*; import java.net.*; class UserThread implements Runnable { private Socket s; UserThread(Socket s) { this.s=s; } public void run() { String ip=s.getInetAddress().getHostAddress(); System.out.println(ip+"...connected"); try{ for(int x=0;x<3;x++) { BufferedReader bufn=new BufferedReader(new InputStreamReader(s.getInputStream())); String name=bufn.readLine(); BufferedReader bufr=new BufferedReader(new FileReader("user.txt")); PrintWriter out=new PrintWriter(s.getOutputStream(),true); String line=null; boolean flag=false; while((line=bufr.readLine())!=null) { if(line.equals(name)) { flag=true; break; } } if(flag) { System.out.println(name+"已登录"); out.println(name+",欢迎光临"); break; } else { System.out.println(name+"尝试登录"); out.println(name+".用户名不存在"); } } s.close(); } catch(Exception e){e.toString();} } } class Rec //接收端 { public static void main(String[] args)throws Exception { ServerSocket ss=new ServerSocket(12000); while(true) { Socket s=ss.accept(); new Thread(new UserThread(s)).start(); } } }