Android客户端与服务器端的Socket通讯：

socket通讯依赖IP地址和端口号，每种服务都打开一个Socket，并绑定到一个端口上，不同的端口对应于不同的服务。

服务器端代码：

实例化主类，定义端口号的主方法：

package com.example.socketdemoclient;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;public class Main {private static final int PORT = 9999;private List<Socket> mList = new ArrayList<Socket>();private ServerSocket server = null;private ExecutorService mExecutorService = null; //thread poolpublic static void main(String[] args) {new Main();}public Main() {try {//实例化一个Socket服务server = new ServerSocket(PORT);//启动一个线程池mExecutorService = Executors.newCachedThreadPool();  //create a thread poolSystem.out.println("服务器已启动...");Socket client = null;while(true) {client = server.accept();//把客户端放入客户端集合中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()));//客户端只要一连到服务器，便向客户端发送下面的信息。msg = "服务器地址：" +this.socket.getInetAddress() + "come toal:"+mList.size()+"（服务器发送）";this.sendmsg();} catch (IOException e) {e.printStackTrace();}}@Overridepublic void run() {try {while(true) {if((msg = in.readLine())!= null) {//当客户端发送的信息为：exit时，关闭连接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;//接收客户端发过来的信息msg，然后发送给客户端。} else {msg = socket.getInetAddress() + ":" + msg+"（服务器发送）";this.sendmsg();}}}} catch (Exception e) {e.printStackTrace();}}/*** 循环遍历客户端集合，给每个客户端都发送信息。*/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())),true);pout.println(msg);}catch (IOException e) {e.printStackTrace();}}}}
}

socket服务Server类：

package com.test.socket.message;import java.io.*;
import java.net.*;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.*;
import javax.swing.JOptionPane;public class Server {ServerSocket ss = null;private String getnameString=null;boolean started = false;List<Client> clients = new ArrayList<Client>();List<Info> infos = new ArrayList<Info>();public static void main(String[] args) {//弹出框，出入端口号String inputport = JOptionPane.showInputDialog("請輸入該服務器使用的端口:");int port = Integer.parseInt(inputport);new Server().start(port);}public void start(int port) {try {ss = new ServerSocket(port);System.out.println("服務器啟動");started = true;} catch (BindException e) {System.out.println(" 端口已经被占用");System.exit(0);}catch (IOException e) {e.printStackTrace();}try {while (started) {Socket s = ss.accept();Client c = new Client (s);System.out.println("a client is connected");new Thread(c).start();clients.add(c);}} catch (IOException e) {e.printStackTrace();}finally {try {ss.close();} catch (IOException e) {e.printStackTrace();}}}public List<Client> getClient(){return clients;}class Client implements Runnable {private String chatKey="SLEEKNETGEOCK4stsjeS";private Socket s = null;private DataInputStream dis = null;private DataOutputStream dos = null;private boolean bConnected = false;private String sendmsg=null;Client (Socket s) {this.s = s;try {dis = new DataInputStream (s.getInputStream());dos = new DataOutputStream (s.getOutputStream());bConnected = true;} catch(IOException e) {e.printStackTrace();}}public void send (String str) {try {//System.out.println(s);dos.writeUTF(str+"");dos.flush();} catch(IOException e) {clients.remove(this);System.out.println("对方已经退出了");}}public void run() {try {while (bConnected) {String str = dis.readUTF();DateFormat df = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");String date = "  ["+df.format(new Date())+"]";if(str.startsWith(chatKey+"online:")){Info info = new Info();getnameString = str.substring(27);info.setName(getnameString);infos.add(info);for (int i=0; i<clients.size(); i++) {Client c = clients.get(i);c.send(getnameString+" on line."+date);}System.out.println(getnameString+" on line."+date);}else if(str.startsWith(chatKey+"offline:")){getnameString = str.substring(28);clients.remove(this);for (int i=0; i<clients.size(); i++) {Client c = clients.get(i);c.send(getnameString+" off line."+date);}System.out.println(getnameString+" off line."+date);}else{int charend = str.indexOf("end;");String chatString = str.substring(charend+4);String chatName = str.substring(25, charend);sendmsg=chatName+date+"\n"+chatString; for (int i=0; i<clients.size(); i++) {Client c = clients.get(i);c.send(sendmsg);}System.out.println(sendmsg);}}} catch (SocketException e) {System.out.println("client is closed!");clients.remove(this);} catch (EOFException e) {System.out.println("client is closed!");clients.remove(this);}catch (IOException e) {e.printStackTrace();}finally {try {if (dis != null) dis.close();if (dos != null) dos.close();if (s != null) s.close();} catch (IOException e) {e.printStackTrace();}}}}class Info{private String info_name = null;public Info(){}public void setName(String name){info_name = name;}public String getName(){return info_name;}}
}

服务器端代码：

Android客户端：

package com.example.socketdemoclient;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.Socket;
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.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;public class MainActivity 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 = "10.0.2.2";private static final int PORT = 9999;private Socket socket = null;private BufferedReader in = null;private PrintWriter out = null;private String content = "";// 接收线程发送过来信息，并用TextView显示public Handler mHandler = new Handler() {public void handleMessage(Message msg) {super.handleMessage(msg);tv_msg.setText(content);}};@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);tv_msg = (TextView) findViewById(R.id.TextView);ed_msg = (EditText) findViewById(R.id.EditText01);btn_send = (Button) findViewById(R.id.Button02);try {socket = new Socket(HOST, PORT);in = new BufferedReader(new InputStreamReader(socket.getInputStream()));out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())), true);} catch (IOException ex) {ex.printStackTrace();ShowDialog("login exception" + ex.getMessage());}btn_send.setOnClickListener(new Button.OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubString msg = ed_msg.getText().toString();if (socket.isConnected()) {if (!socket.isOutputShutdown()) {out.println(msg);}}}});// 启动线程，接收服务器发送过来的数据new Thread(MainActivity.this).start();}/*** 如果连接出现异常，弹出AlertDialog！*/public void ShowDialog(String msg) {new AlertDialog.Builder(this).setTitle("notification").setMessage(msg).setPositiveButton("ok", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {}}).show();}/*** 读取服务器发来的信息，并通过Handler发给UI线程*/public void run() {try {while (true) {if (!socket.isClosed()) {if (socket.isConnected()) {if (!socket.isInputShutdown()) {if ((content = in.readLine()) != null) {content += "\n";mHandler.sendMessage(mHandler.obtainMessage());} else {}}}}}} catch (Exception e) {e.printStackTrace();}}
}

权限：

<uses-permission android:name="android.permission.INTERNET" />