java基础知识总结(五)

1.网络编程基础
一些基础概念：
ip地址：标识网络上的一台主机 ，逻辑地址 可变
mac地址：标识网络上的一台主机，物理地址 不可变
端口：标识主机中的一个进程 0--65535 1024以下的为预留端口
协议：通信双方之间的约定和标准
URL:统一资源定位符
协议名：//主机名：端口号/相对路径
OSI七层模型：从下至上依次是 物理-->数据链路-->网络-->传输-->会话-->表示-->应用
下层为上层提供服务。

传输层:
tcp:传输控制协议，面向连接，可靠
udp：用户数据报协议，非面向连接，不可靠

tcp简单测试 客服端服务器请求数据：
客户端eg:

package test;

import java.io.*;
import java.net.*;

public class TCPClient {

    /**
     * @param args
     * @throws IOException 
     * @throws UnknownHostException 
     */
    public static void main(String[] args) throws UnknownHostException, IOException {
        // TODO Auto-generated method stub
//向服务器发起连接
        Socket s = new Socket("192.168.1.101",9000);
    
        InputStream is = s.getInputStream();
        BufferedReader in = new BufferedReader(new InputStreamReader(is));
        for (int i = 0; i < 30; i++)
        {
            String string = in.readLine();
            System.out.println(string);
        }
        in.close();
    }
}

服务器端代码：
eg:

package test;

import java.io.*;
import java.net.*;

public class TCPServer
{

    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException 
    {
        // TODO Auto-generated method stub
        
        //服务器进程绑定9000端口
        ServerSocket ss = new ServerSocket(9000);
        while(true)
        {
            //阻塞方法，等待客户端的连接请求
            Socket socket = ss.accept();
            System.out.println(socket.getInetAddress());
            TcpServerThread threads = new TcpServerThread(socket);
            threads.start();
        }
        
        

    }

}
class  TcpServerThread extends Thread
{ 
    Socket socket;
    public void run() 
    {
        OutputStream os;
        try {
            os = socket.getOutputStream();
            PrintWriter out = new PrintWriter(os);
            for (int i = 0; i < 30; i++)
            {
                out.println("Hello +"+i);
                out.flush();
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        
    }
    TcpServerThread(Socket socket)
    {
        this.socket = socket;
    }
}

udp简单测试 客服端服务器请求数据：
客户端代码：

package test;

import java.io.IOException;
import java.net.*;

public class UDPClient {

    /**
     * @param args
     * @throws IOException 
     */
    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
DatagramSocket ds = new DatagramSocket();
//发一封信给服务器
String string= "i am here";
byte[] bs1 = string.getBytes();
DatagramPacket sendLetter = new DatagramPacket(bs1, bs1.length,InetAddress.getLocalHost(),7000);
ds.send(sendLetter);

//从服务器收30封信
for (int i = 0; i < 30; i++) 
{
    DatagramPacket receiveLetter = new DatagramPacket(new byte[100], 100);
    ds.receive(receiveLetter);
    byte[] bs = receiveLetter.getData();
    int offset = receiveLetter.getOffset();
    int length = receiveLetter.getLength();
    String s = new String(bs,offset,length);
    System.out.println(s);
}
ds.close();

    }

}

服务器代码：

package test;

import java.io.*;
import java.net.*;
import java.security.interfaces.DSAKey;

public class UDPServer {

    /**
     * @param args
     * @throws IOException 
     * @throws InterruptedException 
     */
    public static void main(String[] args) throws IOException, InterruptedException {
        // TODO Auto-generated method stub

        DatagramSocket ds = new DatagramSocket(7000);
        //从客户端收信
        DatagramPacket receiveLetter = new DatagramPacket(new byte[100], 100);
        ds.receive(receiveLetter);
        InetAddress address = receiveLetter.getAddress();
        int port = receiveLetter.getPort();
        System.out.println("收到了情求");
        
        //给客服端发送30封信
        for (int i = 0; i < 30; i++)
        {
            //显示信的内容
            String str = "hello"+i;
            byte[] bs = str.getBytes();
            DatagramPacket sendLetter = new DatagramPacket(bs, 0,bs.length,address,port);
            ds.send(sendLetter);
            Thread.sleep(1000);
        }
        ds.close();
    }
}