javaSocket編程

2019-11-14 14:59:18

字體：大中小

來源：轉載

供稿：網(wǎng)友

一.網(wǎng)絡通信，常見的結構是C/S模式。客戶端在需要服務時向服務器請求連接，服務端被動接收連接，建立連接后，雙方開始通信。服務器進程一般作為守護進程，一直運行，不斷監(jiān)聽網(wǎng)絡端口，被動接收客戶端的請求，當接收到客戶的請求時，會啟動一個服務進程來處理客戶的請求，并繼續(xù)監(jiān)聽網(wǎng)絡端口。

（上圖轉自：http://tutorials.jenkov.com/java-networking/index.html）

二.網(wǎng)絡上進程之間通過雙向的通信連接來實現(xiàn)信息的交換。這樣連接的一端稱為一個Socket。Socket由ip號和端口號確定。在java中使用Socket來實現(xiàn)基于TCP/IP協(xié)議的網(wǎng)絡程序，主要涉及到下面幾步：

客戶端：

1.根據(jù)服務器的IP和端口號，建立Socket

2.打開輸入、輸出流

3.對Socket進行讀寫

4.關閉輸入、輸出流，關閉套接字

服務器端：

1.根據(jù)端口號建立ServerSocket

2.被動監(jiān)聽客戶端請求

3.當監(jiān)聽到客戶端請求時，接收請求，啟動工作線程，處理請求。若不再接收請求時，進入4；否則，繼續(xù)監(jiān)聽，轉2

4.關閉ServerSocket

下面以例子來說明：

客戶端代碼：

package com.net.examples;import java.io.DataInputStream;import java.io.DataOutputStream;import java.io.IOException;import java.io.OutputStream;import java.net.Socket;import java.net.UnknownHostException;public class Client {    /**     * @param args     * @throws IOException      * @throws UnknownHostException      * @throws InterruptedException      */    public static void main(String[] args) throws UnknownHostException,         IOException, InterruptedException {        //這里假設有三個client，每個client分別發(fā)送一次請求        int clientCount = 3;        MyRunable run = new MyRunable();        while(clientCount > 0){            //每個線程模擬一個client,三個線程名分別為1，2，3            new Thread(run,clientCount+"").start();            clientCount--;        }    }}//定義MyRunable，重寫run方法實現(xiàn)client線程class MyRunable implements Runnable{    public void run() {        int messCount = 2;        Socket socket = null;        DataOutputStream o = null;        DataInputStream in = null;        try {            //1.創(chuàng)建Socket，建立連接            socket = new Socket("127.0.0.1",8080);            //2.打開輸入輸出流            o = new DataOutputStream(socket.getOutputStream());            in = new DataInputStream(socket.getInputStream());            System.out.);                //每個client對Socket寫兩次            while(messCount > 0 ){                try {                    //3.對Socket進行寫                    o.writeUTF("" + messCount);                    o.flush();                } catch (IOException e) {                    e.printStackTrace();                }                System.out.println("I am client:"+Thread.currentThread().getName() +",I send message:" + messCount);                messCount--;            }            //對Socket進行讀            System.out.println("I am client:" + Thread.currentThread().getName() + ",and server "+ in.readUTF() + "(me!)");        } catch (IOException e2) {            e2.printStackTrace();        } finally{            try {                //4.關閉輸入輸出流，關閉socket，釋放資源                o.close();                in.close();                socket.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }}

服務端代碼：

package com.net.examples;import java.io.DataInputStream;import java.io.DataOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.ServerSocket;import java.net.Socket;//Serverpublic class Server {    private static int clientCount = 3;    //Server線程結束運行條件，這里是假設知道一共會收到三次客戶端請求    private static boolean isStop(){        return clientCount == 0 ? true:false;    }    public static void main(String[] args) throws IOException, InterruptedException {        //1.建立ServerSocket        ServerSocket serverSocket = new ServerSocket(8080);        //2.監(jiān)聽客戶端請求        while(!isStop()){            //3.接收到客戶端請求，并啟動一個線程處理            Socket client = serverSocket.accept();            new MyThread(client,clientCount).start();            clientCount--;        }        //4.關閉ServerSocket        serverSocket.close();    }}//客戶端請求處理線程class MyThread extends Thread{    private Socket clientSocket;    private int id;    private DataInputStream input;    private DataOutputStream output ;    public MyThread (){    }    public MyThread(Socket soc,int i){        this.clientSocket = soc;        this.id = i;    }    public void run(){        try {            //獲得輸入輸出流            input = new DataInputStream((clientSocket.getInputStream()));            output = new DataOutputStream(clientSocket.getOutputStream());            int count = 2;            //讀取Socket            while(count > 0){                System.out.println("I am server.I have received message:" + input.readUTF() + ",from" + id);                count --;            }            //寫Socket            output.writeUTF("respose to client" + id);            output.flush();;        } catch (IOException e) {            e.printStackTrace();        }finally {            try {                //釋放資源，關閉連接                input.close();                output.close();                clientSocket.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }}