socket是网络上的两个程序通过一个双向的通信连接实现数据的交换，这个连接的一端称为一个socket。socket通常也称作"套接字"，用于描述IP地址和端口，是一个通信链的句柄，可以用来实现不同虚拟机或不同计算机之间的通信。在Internet上的主机一般运行了多个服务软件，同时提供几种服务。

客户软件将插头插到不同编号的插座，就可以得到不同的服务最重要的是，Socket是面向客户/服务器模型而设计的，针对客户和服务器程序提供不同的Socket系统调用。客户随机申请一个Socket，系统为之分配一个Socket号;服务器拥有全局公认的Socket，任何客户都可以向它发出连接请求和信息请求。Socket利用客户/服务器模式巧妙地解决了进程之间建立通信连接的问题。服务器Socket半相关为全局所公认非常重要。

目前想让手机客户端和服务器保持长连接故选择socket进行通信

首先是新建一个socket服务器端

package com.wpndemo.socket;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.io.PrintWriter;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.ArrayList;

import java.util.List;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

/**

* TODO

* @author cuiran

* @version TODO

*/

public class Main {

private static final int PORT = 8090;

private List mList = new ArrayList();

private ServerSocket server = null;

private ExecutorService mExecutorService = null; //thread pool

public static final String bm="utf-8"; //全局定义，以适应系统其他部分

public static void main(String[] args) {

new Main();

}

public Main() {

try {

server = new ServerSocket(PORT);

mExecutorService = Executors.newCachedThreadPool(); //create a thread pool

System.out.print("server start ...");

Socket client = null;

while(true) {

client = server.accept();

mList.add(client);

mExecutorService.execute(new Service(client)); //start a new thread to handle the connection

}

}catch (Exception e) {

e.printStackTrace();

}

}

class Service implements Runnable {

private Socket socket;

private BufferedReader in = null;

private String msg = "";

public Service(Socket socket) {

this.socket = socket;

try {

in = new BufferedReader(new InputStreamReader(socket.getInputStream(),bm));

msg = "user" +this.socket.getInetAddress() + "come toal:"

+mList.size();

this.sendmsg();

} catch (IOException e) {

e.printStackTrace();

}

}

@Override

public void run() {

// TODO Auto-generated method stub

try {

while(true) {

if((msg = in.readLine())!= null) {

if(msg.equals("exit")) {

System.out.println("ssssssss");

mList.remove(socket);

in.close();

msg = "user:" + socket.getInetAddress()

+ "exit total:" + mList.size();

socket.close();

this.sendmsg();

break;

} else {

System.out.println("msg="+msg);

msg = socket.getInetAddress() + ":" + msg;

this.sendmsg();

}

}

}

} catch (Exception e) {

e.printStackTrace();

}

}

public void sendmsg() {

System.out.println(msg);

int num =mList.size();

for (int index = 0; index < num; index ++) {

Socket mSocket = mList.get(index);

PrintWriter pout = null;

try {

pout = new PrintWriter(new BufferedWriter(

new OutputStreamWriter(mSocket.getOutputStream(),bm)),true);

pout.println(msg);

}catch (IOException e) {

e.printStackTrace();

}

}

}

}

}

然后是新建一个Android工程：

在文件【AndroidManifest.XML】添加内容：

然后是创建类：

package com.cayden.socket;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

import java.io.PrintWriter;

import java.io.UnsupportedEncodingException;

import java.net.Socket;

import com.cayden.util.Conf;

import android.app.Activity;

import android.app.AlertDialog;

import android.content.DialogInterface;

import android.os.Bundle;

import android.os.Handler;

import android.os.Message;

import android.util.Log;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

public class SocketActivity extends Activity implements Runnable {

private TextView tv_msg = null;

private EditText ed_msg = null;

private Button btn_send = null;

// private Button btn_login = null;

private static final String HOST = "219.143.49.189";

private static final int PORT = 8403;

private Socket socket = null;

private BufferedReader in = null;

private PrintWriter out = null;

private String content = "";

public static final String bm="utf-8"; //全局定义，以适应系统其他部分

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

tv_msg = (TextView) findViewById(R.id.TextView);

ed_msg = (EditText) findViewById(R.id.EditText01);

// btn_login = (Button) findViewById(R.id.Button01);

btn_send = (Button) findViewById(R.id.sendBtn);

try {

socket = new Socket(HOST, PORT);

in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(

socket.getOutputStream(),bm)), true);

Log.i(Conf.TAG, "连接成功");

} catch (IOException ex) {

ex.printStackTrace();

Log.i(Conf.TAG, "出现异常："+ex.getMessage());

ShowDialog("login exception" + ex.getMessage());

}

btn_send.setOnClickListener(new Button.OnClickListener() {

@Override

public void onClick(View v) {

// TODO Auto-generated method stub

String msg = ed_msg.getText().toString();

if (socket.isConnected()) {

if (!socket.isOutputShutdown()) {

try {

out.println(msg);

} catch (Exception e) {

e.printStackTrace();

}

}

}

}

});

new Thread(SocketActivity.this).start();

}

public void ShowDialog(String msg) {

new AlertDialog.Builder(this).setTitle("notification").setMessage(msg)

.setPositiveButton("ok", new DialogInterface.OnClickListener() {

@Override

public void onClick(DialogInterface dialog, int which) {

}

}).show();

}

@Override

public void run() {

// TODO Auto-generated method stub

try {

while (true) {

if (socket.isConnected()) {

if (!socket.isInputShutdown()) {

if ((content = in.readLine()) != null) {

content += "\n";

mHandler.sendMessage(mHandler.obtainMessage());

} else {

}

}

}

}

} catch (Exception e) {

e.printStackTrace();

}

}

public Handler mHandler = new Handler() {

public void handleMessage(Message msg) {

super.handleMessage(msg);

tv_msg.setText(tv_msg.getText().toString() + content);

}

};

}

通过上文可以知道要实现手机客户端和服务器保持长连接需要选择socket通信，整个流程下来首先要做的是新建一个socket服务器端，再新建一个android工程，最后创建一个类。在后续中会增加采用mina框架来实现通信。