android客户端通过socket与服务器进行通信可以分为以下几步：

应用程序与服务器通信可以采用两种模式：TCP可靠通信 和UDP不可靠通信。

（1）通过IP地址和端口实例化Socket，请求连接服务器：

     socket = new Socket(HOST, PORT);   //host:为服务器的IP地址  port：为服务器的端口号

（2）获取Socket流以进行读写，并把流包装进BufferWriter或者PrintWriter：

   PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);  

   这里涉及了三个类：socket.getOutputStream得到socket的输出字节流，OutputStreamWriter是字节流向字符流转换的桥梁，BufferWriter是字符流，然后再包装进PrintWriter。

（3）对Socket进行读写

     if (socket.isConnected()) {
                    if (!socket.isOutputShutdown()) {
                        out.println(msg);
                    }
                }

（4）关闭打开的流

      out.close();

 在写代码的过程中一定要注意对socket  输入流  输出流的关闭

下面是一个简单的例子：

main.xml

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    1. xml version="1.0" encoding="utf-8"?>   
      2. 
      
      
      
      
    2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     
      3. 
      
      
      
      
    3.     android:orientation="vertical"    
      4. 
      
      
      
      
    4.     android:layout_width="fill_parent"     
      5. 
      
      
      
      
    5.     android:layout_height="fill_parent">     
      6. 
      
      
      
      
    6.     <TextView    
      7. 
      
      
      
      
    7.         android:id="@+id/TextView"    
      8. 
      
      
      
      
    8.         android:singleLine="false"     
      9. 
      
      
      
      
    9.         android:layout_width="fill_parent"     
      10. 
      
      
      
      
    10.         android:layout_height="wrap_content" />     
      11. 
      
      
      
      
    11.     <EditText android:hint="content"    
      12. 
      
      
      
      
    12.         android:id="@+id/EditText01"     
      13. 
      
      
      
      
    13.         android:layout_width="fill_parent"     
      14. 
      
      
      
      
    14.         android:layout_height="wrap_content">     
      15. 
      
      
      
      
    15.     EditText>     
      16. 
      
      
      
      
    16.     <Button    
      17. 
      
      
      
      
    17.         android:text="send"    
      18. 
      
      
      
      
    18.         android:id="@+id/Button02"     
      19. 
      
      
      
      
    19.         android:layout_width="fill_parent"     
      20. 
      
      
      
      
    20.         android:layout_height="wrap_content">     
      21. 
      
      
      
      
    21.     Button>     
      22. 
      
      
      
      
    22. LinearLayout>    
      23.

下面是android客户端的源代码：

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    1. package com.android.SocketDemo;   
      2. 
      
      
      
      
    2.    
      3. 
      
      
      
      
    3. import java.io.BufferedReader;   
      4. 
      
      
      
      
    4. import java.io.BufferedWriter;   
      5. 
      
      
      
      
    5. import java.io.IOException;   
      6. 
      
      
      
      
    6. import java.io.InputStreamReader;   
      7. 
      
      
      
      
    7. import java.io.OutputStreamWriter;   
      8. 
      
      
      
      
    8. import java.io.PrintWriter;   
      9. 
      
      
      
      
    9. import java.net.Socket;   
      10. 
      
      
      
      
    10.    
      11. 
      
      
      
      
    11. import android.app.Activity;   
      12. 
      
      
      
      
    12. import android.app.AlertDialog;   
      13. 
      
      
      
      
    13. import android.content.DialogInterface;   
      14. 
      
      
      
      
    14. import android.os.Bundle;   
      15. 
      
      
      
      
    15. import android.os.Handler;   
      16. 
      
      
      
      
    16. import android.os.Message;   
      17. 
      
      
      
      
    17. import android.view.View;   
      18. 
      
      
      
      
    18. import android.widget.Button;   
      19. 
      
      
      
      
    19. import android.widget.EditText;   
      20. 
      
      
      
      
    20. import android.widget.TextView;   
      21. 
      
      
      
      
    21.    
      22. 
      
      
      
      
    22. public class SocketDemo extends Activity implements Runnable {   
      23. 
      
      
      
      
    23.     private TextView tv_msg = null;   
      24. 
      
      
      
      
    24.     private EditText ed_msg = null;   
      25. 
      
      
      
      
    25.     private Button btn_send = null;   
      26. 
      
      
      
      
    26. //    private Button btn_login = null;   
      27. 
      
      
      
      
    27.     private static final String HOST = "192.168.1.223";   
      28. 
      
      
      
      
    28.     private static final int PORT = 9999;   
      29. 
      
      
      
      
    29.     private Socket socket = null;   
      30. 
      
      
      
      
    30.     private BufferedReader in = null;   
      31. 
      
      
      
      
    31.     private PrintWriter out = null;   
      32. 
      
      
      
      
    32.     private String content = "";   
      33. 
      
      
      
      
    33.    
      34. 
      
      
      
      
    34.     /** Called when the activity is first created. */   
      35. 
      
      
      
      
    35.     @Override   
      36. 
      
      
      
      
    36.     public void onCreate(Bundle savedInstanceState) {   
      37. 
      
      
      
      
    37.         super.onCreate(savedInstanceState);   
      38. 
      
      
      
      
    38.         setContentView(R.layout.main);   
      39. 
      
      
      
      
    39.    
      40. 
      
      
      
      
    40.         tv_msg = (TextView) findViewById(R.id.TextView);   
      41. 
      
      
      
      
    41.         ed_msg = (EditText) findViewById(R.id.EditText01);   
      42. 
      
      
      
      
    42. //        btn_login = (Button) findViewById(R.id.Button01);   
      43. 
      
      
      
      
    43.         btn_send = (Button) findViewById(R.id.Button02);   
      44. 
      
      
      
      
    44.    
      45. 
      
      
      
      
    45.         try {   
      46. 
      
      
      
      
    46.             socket = new Socket(HOST, PORT);   
      47. 
      
      
      
      
    47.             in = new BufferedReader(new InputStreamReader(socket.getInputStream()));   
      48. 
      
      
      
      
    48.             out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(   
      49. 
      
      
      
      
    49.                     socket.getOutputStream())), true);   
      50. 
      
      
      
      
    50.         } catch (IOException ex) {   
      51. 
      
      
      
      
    51.             ex.printStackTrace();   
      52. 
      
      
      
      
    52.             ShowDialog("login exception" + ex.getMessage());   
      53. 
      
      
      
      
    53.         }   
      54. 
      
      
      
      
    54.         btn_send.setOnClickListener(new Button.OnClickListener() {   
      55. 
      
      
      
      
    55.    
      56. 
      
      
      
      
    56.             @Override   
      57. 
      
      
      
      
    57.             public void onClick(View v) {   
      58. 
      
      
      
      
    58.                 // TODO Auto-generated method stub   
      59. 
      
      
      
      
    59.                 String msg = ed_msg.getText().toString();   
      60. 
      
      
      
      
    60.                 if (socket.isConnected()) {   
      61. 
      
      
      
      
    61.                     if (!socket.isOutputShutdown()) {   
      62. 
      
      
      
      
    62.                         out.println(msg);   
      63. 
      
      
      
      
    63.                     }   
      64. 
      
      
      
      
    64.                 }   
      65. 
      
      
      
      
    65.             }   
      66. 
      
      
      
      
    66.         });   
      67. 
      
      
      
      
    67.         new Thread(SocketDemo.this).start();   
      68. 
      
      
      
      
    68.     }   
      69. 
      
      
      
      
    69.    
      70. 
      
      
      
      
    70.     public void ShowDialog(String msg) {   
      71. 
      
      
      
      
    71.         new AlertDialog.Builder(this).setTitle("notification").setMessage(msg)   
      72. 
      
      
      
      
    72.                 .setPositiveButton("ok", new DialogInterface.OnClickListener() {   
      73. 
      
      
      
      
    73.    
      74. 
      
      
      
      
    74.                     @Override   
      75. 
      
      
      
      
    75.                     public void onClick(DialogInterface dialog, int which) {   
      76. 
      
      
      
      
    76.                         // TODO Auto-generated method stub   
      77. 
      
      
      
      
    77.    
      78. 
      
      
      
      
    78.                     }   
      79. 
      
      
      
      
    79.                 }).show();   
      80. 
      
      
      
      
    80.     }   
      81. 
      
      
      
      
    81.    
      82. 
      
      
      
      
    82.     public void run() {   
      83. 
      
      
      
      
    83.         try {   
      84. 
      
      
      
      
    84.             while (true) {   
      85. 
      
      
      
      
    85.                 if (socket.isConnected()) {   
      86. 
      
      
      
      
    86.                     if (!socket.isInputShutdown()) {   
      87. 
      
      
      
      
    87.                         if ((content = in.readLine()) != null) {   
      88. 
      
      
      
      
    88.                             content += "\n";   
      89. 
      
      
      
      
    89.                             mHandler.sendMessage(mHandler.obtainMessage());   
      90. 
      
      
      
      
    90.                         } else {   
      91. 
      
      
      
      
    91.    
      92. 
      
      
      
      
    92.                         }   
      93. 
      
      
      
      
    93.                     }   
      94. 
      
      
      
      
    94.                 }   
      95. 
      
      
      
      
    95.             }   
      96. 
      
      
      
      
    96.         } catch (Exception e) {   
      97. 
      
      
      
      
    97.             e.printStackTrace();   
      98. 
      
      
      
      
    98.         }   
      99. 
      
      
      
      
    99.     }   
      100. 
      
      
      
      
    100.    
      101. 
      
      
      
      
    101.     public Handler mHandler = new Handler() {   
      102. 
      
      
      
      
    102.         public void handleMessage(Message msg) {   
      103. 
      
      
      
      
    103.             super.handleMessage(msg);   
      104. 
      
      
      
      
    104.             tv_msg.setText(tv_msg.getText().toString() + content);   
      105. 
      
      
      
      
    105.         }   
      106. 
      
      
      
      
    106.     };   
      107. 
      
      
      
      
    107. }   
      108.


下面是服务器端得java代码：

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    1. import java.io.BufferedReader;   
      2. 
      
      
      
      
    2. import java.io.BufferedWriter;   
      3. 
      
      
      
      
    3. import java.io.IOException;   
      4. 
      
      
      
      
    4. import java.io.InputStreamReader;   
      5. 
      
      
      
      
    5. import java.io.OutputStreamWriter;   
      6. 
      
      
      
      
    6. import java.io.PrintWriter;   
      7. 
      
      
      
      
    7. import java.net.ServerSocket;   
      8. 
      
      
      
      
    8. import java.net.Socket;   
      9. 
      
      
      
      
    9. import java.util.ArrayList;   
      10. 
      
      
      
      
    10. import java.util.List;   
      11. 
      
      
      
      
    11. import java.util.concurrent.ExecutorService;   
      12. 
      
      
      
      
    12. import java.util.concurrent.Executors;   
      13. 
      
      
      
      
    13.    
      14. 
      
      
      
      
    14.    
      15. 
      
      
      
      
    15. public class Main {   
      16. 
      
      
      
      
    16.     private static final int PORT = 9999;   
      17. 
      
      
      
      
    17.     private List<Socket> mList = new ArrayList<Socket>();   
      18. 
      
      
      
      
    18.     private ServerSocket server = null;   
      19. 
      
      
      
      
    19.     private ExecutorService mExecutorService = null; //thread pool   
      20. 
      
      
      
      
    20.        
      21. 
      
      
      
      
    21.     public static void main(String[] args) {   
      22. 
      
      
      
      
    22.         new Main();   
      23. 
      
      
      
      
    23.     }   
      24. 
      
      
      
      
    24.     public Main() {   
      25. 
      
      
      
      
    25.         try {   
      26. 
      
      
      
      
    26.             server = new ServerSocket(PORT);   
      27. 
      
      
      
      
    27.             mExecutorService = Executors.newCachedThreadPool();  //create a thread pool   
      28. 
      
      
      
      
    28.             System.out.print("server start ...");   
      29. 
      
      
      
      
    29.             Socket client = null;   
      30. 
      
      
      
      
    30.             while(true) {   
      31. 
      
      
      
      
    31.                 client = server.accept();   
      32. 
      
      
      
      
    32.                 mList.add(client);   
      33. 
      
      
      
      
    33.                 mExecutorService.execute(new Service(client)); //start a new thread to handle the connection   
      34. 
      
      
      
      
    34.             }   
      35. 
      
      
      
      
    35.         }catch (Exception e) {   
      36. 
      
      
      
      
    36.             e.printStackTrace();   
      37. 
      
      
      
      
    37.         }   
      38. 
      
      
      
      
    38.     }   
      39. 
      
      
      
      
    39.     class Service implements Runnable {   
      40. 
      
      
      
      
    40.             private Socket socket;   
      41. 
      
      
      
      
    41.             private BufferedReader in = null;   
      42. 
      
      
      
      
    42.             private String msg = "";   
      43. 
      
      
      
      
    43.                
      44. 
      
      
      
      
    44.             public Service(Socket socket) {   
      45. 
      
      
      
      
    45.                 this.socket = socket;   
      46. 
      
      
      
      
    46.                 try {   
      47. 
      
      
      
      
    47.                     in = new BufferedReader(new InputStreamReader(socket.getInputStream()));   
      48. 
      
      
      
      
    48.                     msg = "user" +this.socket.getInetAddress() + "come toal:"   
      49. 
      
      
      
      
    49.                         +mList.size();   
      50. 
      
      
      
      
    50.                     this.sendmsg();   
      51. 
      
      
      
      
    51.                 } catch (IOException e) {   
      52. 
      
      
      
      
    52.                     e.printStackTrace();   
      53. 
      
      
      
      
    53.                 }   
      54. 
      
      
      
      
    54.                    
      55. 
      
      
      
      
    55.             }   
      56. 
      
      
      
      
    56.    
      57. 
      
      
      
      
    57.             @Override   
      58. 
      
      
      
      
    58.             public void run() {   
      59. 
      
      
      
      
    59.                 // TODO Auto-generated method stub   
      60. 
      
      
      
      
    60.                 try {   
      61. 
      
      
      
      
    61.                     while(true) {   
      62. 
      
      
      
      
    62.                         if((msg = in.readLine())!= null) {   
      63. 
      
      
      
      
    63.                             if(msg.equals("exit")) {   
      64. 
      
      
      
      
    64.                                 System.out.println("ssssssss");   
      65. 
      
      
      
      
    65.                                 mList.remove(socket);   
      66. 
      
      
      
      
    66.                                 in.close();   
      67. 
      
      
      
      
    67.                                 msg = "user:" + socket.getInetAddress()   
      68. 
      
      
      
      
    68.                                     + "exit total:" + mList.size();   
      69. 
      
      
      
      
    69.                                 socket.close();   
      70. 
      
      
      
      
    70.                                 this.sendmsg();   
      71. 
      
      
      
      
    71.                                 break;   
      72. 
      
      
      
      
    72.                             } else {   
      73. 
      
      
      
      
    73.                                 msg = socket.getInetAddress() + ":" + msg;   
      74. 
      
      
      
      
    74.                                 this.sendmsg();   
      75. 
      
      
      
      
    75.                             }   
      76. 
      
      
      
      
    76.                         }   
      77. 
      
      
      
      
    77.                     }   
      78. 
      
      
      
      
    78.                 } catch (Exception e) {   
      79. 
      
      
      
      
    79.                     e.printStackTrace();   
      80. 
      
      
      
      
    80.                 }   
      81. 
      
      
      
      
    81.             }   
      82. 
      
      
      
      
    82.              
      83. 
      
      
      
      
    83.            public void sendmsg() {   
      84. 
      
      
      
      
    84.                System.out.println(msg);   
      85. 
      
      
      
      
    85.                int num =mList.size();   
      86. 
      
      
      
      
    86.                for (int index = 0; index < num; index ++) {   
      87. 
      
      
      
      
    87.                    Socket mSocket = mList.get(index);   
      88. 
      
      
      
      
    88.                    PrintWriter pout = null;   
      89. 
      
      
      
      
    89.                    try {   
      90. 
      
      
      
      
    90.                        pout = new PrintWriter(new BufferedWriter(   
      91. 
      
      
      
      
    91.                                new OutputStreamWriter(mSocket.getOutputStream())),true);   
      92. 
      
      
      
      
    92.                        pout.println(msg);   
      93. 
      
      
      
      
    93.                    }catch (IOException e) {   
      94. 
      
      
      
      
    94.                        e.printStackTrace();   
      95. 
      
      
      
      
    95.                    }   
      96. 
      
      
      
      
    96.                }   
      97. 
      
      
      
      
    97.            }   
      98. 
      
      
      
      
    98.         }       
      99. 
      
      
      
      
    99. }   
      100.