<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical" >
  <ScrollView
    android:id="@+id/scrollview3"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" >
    <TextView
      android:id="@+id/chattxt2"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:background="#98F5FF" />
  </ScrollView>
  <EditText
    android:id="@+id/chattxt"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />
  <Button
    android:id="@+id/chatOk"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="发送" >
  </Button>
</LinearLayout>

package com.pku.net;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.net.UnknownHostException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.*;
public class SocketClientActivity extends Activity {
  SocketServerThread yaochatserver;
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.socketclient);
    try {
      yaochatserver = new SocketServerThread();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    if (yaochatserver != null) {
      yaochatserver.start();
    }
    findviews();
    setonclick();
  }
  private EditText chattxt;
  private TextView chattxt2;
  private Button chatok;
  public void findviews() {
    chattxt = (EditText) this.findViewById(R.id.chattxt);
    chattxt2 = (TextView) this.findViewById(R.id.chattxt2);
    chatok = (Button) this.findViewById(R.id.chatOk);
  }
  private void setonclick() {
    chatok.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        try {
          connecttoserver(chattxt.getText().toString());
        } catch (UnknownHostException e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
        } catch (IOException e) {
          // TODO Auto-generated catch block
          e.printStackTrace();
        }
      }
    });
  }
  public void connecttoserver(String socketData) throws UnknownHostException,
      IOException {
    Socket socket = RequestSocket("127.0.0.1", 5000);
    SendMsg(socket, socketData);
    String txt = ReceiveMsg(socket);
    this.chattxt2.setText(txt);
  }
  private Socket RequestSocket(String host, int port)
      throws UnknownHostException, IOException {
    Socket socket = new Socket(host, port);
    return socket;
  }
  private void SendMsg(Socket socket, String msg) throws IOException {
    BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(
        socket.getOutputStream()));
    writer.write(msg.replace("\n", " ") + "\n");
    writer.flush();
  }
  private String ReceiveMsg(Socket socket) throws IOException {
    BufferedReader reader = new BufferedReader(new InputStreamReader(
        socket.getInputStream()));
    String txt = reader.readLine();
    return txt;
  }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.pku.net"
  android:versionCode="1"
  android:versionName="1.0" >
  <uses-sdk android:minSdkVersion="8" />
  <uses-permission android:name="android.permission.INTERNET"/>
  <application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name" >
    <activity
      android:name=".HttpURLActivity"
      android:label="@string/app_name" >
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    <activity android:name="GetNetImage"></activity>
    <activity android:name="HttpClientActivity"></activity>
    <activity android:name="SocketClientActivity"></activity>
  </application>
</manifest>

package com.pku.net;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class SocketServerThread extends Thread {
  public SocketServerThread() throws IOException {
    CreateSocket();
    // 创建Socket服务器
  }
  public void run() {
    Socket client;
    String txt;
    try {
      while (true)
      // 线程无限循环，实时监听socket端口
      {
        client = ResponseSocket();
        // 响应客户端链接请求。。
        while (true) {
          txt = ReceiveMsg(client);
          System.out.println(txt);
          // 链接获得客户端发来消息，并将其显示在Server端的屏幕上
          SendMsg(client, txt);
          // 向客户端返回消息
          if (true)
            break;
          // 中断，继续等待链接请求
        }
        CloseSocket(client);
        // 关闭此次链接
      }
    } catch (IOException e) {
      System.out.println(e);
    }
  }
  private ServerSocket server = null;
  private static final int PORT = 5000;
  private BufferedWriter writer;
  private BufferedReader reader;
  private void CreateSocket() throws IOException {
    server = new ServerSocket(PORT, 100);
    System.out.println("Server starting..");
  }
  private Socket ResponseSocket() throws IOException {
    Socket client = server.accept();
    System.out.println("client connected..");
    return client;
  }
  private void CloseSocket(Socket socket) throws IOException {
    reader.close();
    writer.close();
    socket.close();
    System.out.println("client closed..");
  }
  private void SendMsg(Socket socket, String Msg) throws IOException {
    writer = new BufferedWriter(new OutputStreamWriter(
        socket.getOutputStream()));
    writer.write(Msg + "\n");
    writer.flush();
  }
  private String ReceiveMsg(Socket socket) throws IOException {
    reader = new BufferedReader(new InputStreamReader(
        socket.getInputStream()));
    System.out.println("server get input from client socket..");
    String txt = "Sever send:" + reader.readLine();
    return txt;
  }
 /*
  public static void main(final String args[]) throws IOException {
    SocketServerThread yaochatserver = new SocketServerThread();
    if (yaochatserver != null) {
      yaochatserver.start();
    }
  }  */
}