java的网络编程

一：基础的网络编程

1.InetAddress

import java.net.InetAddress;
public class Test128 {
    public static void main(String[] args) throws Exception {
        //inetMethod();
        inetMethod2();
    }
    public static void inetMethod()throws Exception{
        //local的问题
        InetAddress i=InetAddress.getLocalHost();
        String address=i.getHostAddress();
        String name=i.getHostName();
        System.out.println("address="+address);
        System.out.println("name="+name);
    }
    public static void inetMethod2()throws Exception{
        //根据域名来处理        
        InetAddress ia=InetAddress.getByName("www.baidu.com");
        String address=ia.getHostAddress();
        String name=ia.getHostName();
        System.out.println("address="+address);
        System.out.println("name="+name);
    }

}

二：UDP

1.接收端

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

public class Test130 {

    public static void main(String[] args) throws Exception {
        reviceShow();

    }
    public static void reviceShow()throws Exception{
        DatagramSocket ds=new DatagramSocket(10004);
        byte[] buf=new byte[1024];
        DatagramPacket dp=new DatagramPacket(buf,buf.length);
        ds.receive(dp);
        String ip=dp.getAddress().getHostAddress();
        String data=new String(dp.getData(),0,dp.getLength());
        int port=dp.getPort();
        System.out.println("ip="+ip);
        System.out.println("data="+data);
        System.out.println("port="+port);
    }

}

2.发送端

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

/**
 * 发送端
 * @author Administrator
 *
 */
public class Test129 {
    public static void main(String[] args) throws Exception {
        sendShow();        
    }
    public static void sendShow()throws Exception{
        DatagramSocket ds=new DatagramSocket();
        byte[] buf="info send".getBytes();
        DatagramPacket dp=new DatagramPacket(buf,buf.length,
                InetAddress.getByName("10.66.130.139"),10004);
        ds.send(dp);
        ds.close();
    }
}

三：TCP

1.通信，交换图片（但是一次）

先是服务端：

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * 服务端
 * @author Administrator
 *
 */
public class Test123 {

    public static void main(String[] args) throws Exception {
        ServerSocket ss=new ServerSocket(10009);
        Socket s=ss.accept();
        InputStream in=s.getInputStream();
        FileOutputStream fos=new FileOutputStream("shsj.jpg");
        byte[] buf=new byte[1024];
        int len=0;
        while((len=in.read(buf))!=-1){
            fos.write(buf, 0, len);
        }
        OutputStream out=s.getOutputStream();
        out.write("成功".getBytes());
        fos.close();
        s.close();
        ss.close();
    }

}

再是客户端：

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;

/**
 * 发送端
 * @author Administrator
 *
 */
public class Test122 {
    public static void main(String[] args) throws Exception {
        Socket s=new Socket("10.66.113.25",10009);
        FileInputStream fis=new FileInputStream("u.jpg");
        OutputStream out=s.getOutputStream();
        byte[] buf=new byte[1024];
        int len=0;
        while((len=fis.read(buf))!=-1){
            out.write(buf, 0, len);
        }
        //important
        s.shutdownOutput();
        InputStream ins=s.getInputStream();
        byte[] bufin=new byte[1024];
        int num=ins.read(bufin);
        System.out.println(new String(bufin,0,num));
        fis.close();
        ins.close();
        s.close();
    }

}

2.多线程服务端

先写客户端

注意添加一些限制条件，同时，这里是添加的参数是文件路径

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;

public class Test124 {

    public static void main(String[] args) throws Exception {
        if(args.length!=1){
            System.out.println("choose a pic");
            return;
        }
        File file=new File(args[0]);
        if(!(file.exists()&&file.isFile())){
            System.out.println("file have problem");
            return;
        }
        if(!file.getName().endsWith(".jpg")){
            System.out.println("file type is error");
            return;
        }
        if(file.length()>1024*1024*5){
            System.out.println("file > 5M");
            return;
        }
        Socket s=new Socket("10.66.113.25",10019);
        FileInputStream fis=new FileInputStream(file);
        OutputStream out=s.getOutputStream();
        byte[] buf=new byte[1024];
        int len=0;
        while((len=fis.read(buf))!=-1){
            out.write(buf, 0, len);
        }
        s.shutdownOutput();
        InputStream in=s.getInputStream();
        byte[] bufin=new byte[1024];
        int num=in.read(bufin);
        String str=new String(bufin,0,num);
        fis.close();
        s.close();        
    }
}

再写服务端

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * 服务端
 * @author Administrator
 *
 */
public class Test125 {

    public static void main(String[] args) throws Exception {
        ServerSocket ss=new ServerSocket(10019);
        while(true){
            Socket s=ss.accept();
            new Thread(new ServerThread(s)).start();
        }
    }
}
/**
 * 需要一个多线程的类
 * 下面类是用在服务端的类
 */
class ServerThread implements Runnable{
    private Socket s;
    public ServerThread(Socket s){
        this.s=s;
    }
    public void run(){
        int count=1;
        String ip=s.getInetAddress().getHostAddress();
        try{
            System.out.println(ip+"connect");
            InputStream ins=s.getInputStream();
            File dir=new File("d:\pic");
            File file=new File(dir,ip+"("+count+").jpg");
            while(file.exists()){
                file=new File(dir,ip+"("+(count++)+").jpg");
            }
            FileOutputStream fos=new FileOutputStream(file);
            byte[] buf=new byte[1024];
            int len=0;
            while((len=ins.read(buf))!=-1){
                fos.write(buf, 0, len);
            }
            OutputStream out=s.getOutputStream();
            out.write("success".getBytes());
            fos.close();
            s.close();
            
        }catch(Exception e){
            new RuntimeException();
        }
    }
}

3.客户端并发登录

服务端

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Test127 {

    public static void main(String[] args) throws Exception{
        ServerSocket ss=new ServerSocket(10089);
        while(true){
            Socket s=ss.accept();
            new Thread(new LoginThread(s)).start();
        }
    }
}
class LoginThread implements Runnable{
    private Socket s;
    LoginThread(Socket s){
        this.s=s;
    }
    public void run(){
        String ip=s.getInetAddress().getHostAddress();
        System.out.println("ip="+ip+" connect");
        try{
            for(int i=0;i<3;i++){
                BufferedReader bufin=new BufferedReader(new InputStreamReader(
                        s.getInputStream()));
                String str=bufin.readLine();
                if(str==null)
                    break;
                BufferedReader buf=new BufferedReader(new FileReader("user.txt"));
                PrintWriter out=new PrintWriter(s.getOutputStream(),true);
                String line=null;
                boolean flag=false;
                while((line=buf.readLine())!=null){
                    if(line.equals(str)){
                        flag=true;
                        break;
                    }
                }
                if(flag){
                    System.out.println(str+"已登录");
                    out.println(str+"欢迎登录");
                    break;
                }else{
                    System.out.println(str+"尝试登录");
                    out.println(str+"用户不存在");
                }
            }
        }catch(Exception e){
            throw new RuntimeException(ip+"failed");
        }
    }
}

客户端

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

/**
 * client
 * @author Administrator
 *
 */
public class Test126 {

    public static void main(String[] args) throws Exception {
        Socket s=new Socket("10.66.113.25",10089);
        //键盘录入
        BufferedReader bufr=new BufferedReader(new InputStreamReader(System.in));
        //输出到服务端
        PrintWriter out=new PrintWriter(s.getOutputStream(),true);
        //读取返回内容
        BufferedReader bufin=new BufferedReader(
                new InputStreamReader(s.getInputStream()));
        //次数
        for(int x=0;x<3;x++){
            String line=bufr.readLine();
            if(line==null)
                break;
            out.println(line);
            String info=bufin.readLine();
            System.out.println("info="+info);
            if("info".contains("欢迎"))
                break;
        }
        bufr.close();
        s.close();

    }


}