以C#编写的Socket服务器的Android手机聊天室Demo

 

   内容摘要

   1.程序架构

   2.通信协议

   3.服务器源代码

   4.客户端源代码

   5.运行效果

  一、程序架构

  在开发一个聊天室程序时，我们可以使用Socket、Remoting、WCF这些具有双向通信的协议或框架。而现在，我正要实现一个C#语言作为服务器端、Android作为客户端的聊天室。由于服务器端和客户端不是同一语言(C#和java)，所有我选择了Socket作为通信协议。

  图1.1所示，我们可以看出：android手机客户端A向服务器端发送消息，服务器端收到消息后，又把消息推送到android手机客户端B。

 图1.1

  二、通信协议

我们知道，在C#语言中使用Socket技术需要“四部曲”，即“Bind”，“Listen”，“Accept”，“Receive”。然而Socket编程不像WCF那样面向对象。而且对应每个请求都用同一种方式处理。作为习惯面向对象编程的我来说，编写一个传统的Socket程序很不爽。绞尽脑汁，我们将数据传输的格式改为json(JavaScript Object Notation 是一种轻量级的数据交换格式)，面对对象的问题就解决了。

   假设程序的服务契约有两个方法：“登陆”和“发送消息”。调用登陆的方法，就传送方法名(Method Name)为“Logon”的json数据；调用发送消息的方法，就传送方法名为“Send”的json数据。返回的数据中也使用json格式，这样在android客户端中也能知道是哪个方法的返回值了。

  三、服务器源代码

 首先需要编写一个处理客户端消息的接口：IResponseManager。

    public interface IResponseManager
    {
        void Write(Socket sender, IList<Socket> cliens, IDictionary<string, object> param);
    }

其次，我们知道，换了是WCF编程的话，就需要在服务契约中写两个方法：“登陆”和“发送消息”。由于这里是Socket编程，我们实现之前写的IResponseManager接口，一个实现作为“登陆”的方法，另一个实现作为“发送消息”的方法。

public class LogonResponseManager : IResponseManager
    {
        public void Write(System.Net.Sockets.Socket sender, IList<System.Net.Sockets.Socket> cliens, IDictionary<string, object> param)
        {
            Console.WriteLine("客户端({0})登陆", sender.Handle);
            var response = new SocketResponse
            {
                Method = "Logon",
                DateTime = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"),
                Result = new { UserName = param["UserName"].ToString() }
            };

            JavaScriptSerializer jss = new JavaScriptSerializer();
            string context = jss.Serialize(response);
            Console.WriteLine("登陆发送的数据为:{0}", context);
            sender.Send(Encoding.UTF8.GetBytes(context + "\n"));
        }
    }

public class SendResponseManager : IResponseManager
    {
        public void Write(System.Net.Sockets.Socket sender, IList<System.Net.Sockets.Socket> cliens, IDictionary<string, object> param)
        {
            Console.WriteLine("客户端({0})发送消息", sender.Handle);
            var msgList = param["Message"] as IEnumerable<object>;
            if (msgList == null)
            {
                return;
            }

            var response = new SocketResponse
            {
                Method = "Send",
                DateTime = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"),
                Result = new
                { 
                    UserName = param["UserName"].ToString(),
                    Message = msgList.Select(s => s.ToString()).ToArray() 
                }
            };

            JavaScriptSerializer jss = new JavaScriptSerializer();
            string context = jss.Serialize(response);
            Console.WriteLine("消息发送的数据为:{0}", context);

            Parallel.ForEach(cliens, (item) =>
            {
                try
                {
                    item.Send(Encoding.UTF8.GetBytes(context + "\n"));
                }
                catch { };
            });
        }
    }

最后在Socket程序中使用反射加“策略模式”调用这两个接口实现类。

            var typeName = "SocketServer." + request.Method + "ResponseManager, SocketServer";
            Console.WriteLine("反射类名为：" + typeName);

            Type type = Type.GetType(typeName);
            if (type == null)
            {
                return;
            }

            var manager = Activator.CreateInstance(type) as IResponseManager;
            manager.Write(sender, this.socketClientSesson.Select(s => s.Key).ToList(),
                request.Param as IDictionary<string, object>);

完整的Socket服务器代码如下：

public class SocketHost
    {
        private IDictionary<Socket, byte[]> socketClientSesson = new Dictionary<Socket, byte[]>();

        public int Port { get; set; }

        public void Start()
        {
            var socketThread = new Thread(() =>
            {
                Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                IPEndPoint iep = new IPEndPoint(IPAddress.Any, this.Port);

                //绑定到通道上
                socket.Bind(iep);

                //侦听
                socket.Listen(6);

                //通过异步来处理
                socket.BeginAccept(new AsyncCallback(Accept), socket);

            });

            socketThread.Start();

            Console.WriteLine("服务器已启动");
        }

        private void Accept(IAsyncResult ia)
        {
            Socket socket = ia.AsyncState as Socket;
            var client = socket.EndAccept(ia);

            socket.BeginAccept(new AsyncCallback(Accept), socket);

            byte[] buf = new byte[1024];
            this.socketClientSesson.Add(client, buf);

            try
            {
                client.BeginReceive(buf, 0, buf.Length, SocketFlags.None, new AsyncCallback(Receive), client);
                string sessionId = client.Handle.ToString();
                Console.WriteLine("客户端({0})已连接", sessionId);
            }
            catch (Exception ex)
            {
                Console.WriteLine("监听请求时出错：\r\n" + ex.ToString());
            }
        }

        private void Receive(IAsyncResult ia)
        {
            var client = ia.AsyncState as Socket;

            if (client == null || !this.socketClientSesson.ContainsKey(client))
            {
                return;
            }

            int count = client.EndReceive(ia);

            byte[] buf = this.socketClientSesson[client];

            if (count > 0)
            {
                try
                {
                    client.BeginReceive(buf, 0, buf.Length, SocketFlags.None, new AsyncCallback(Receive), client);
                    string context = Encoding.UTF8.GetString(buf, 0, count);
                    Console.WriteLine("接收的数据为:", context);

                    this.Response(client, context);
                }
                catch (Exception ex)
                {
                    Console.WriteLine("接收的数据出错:\r\n{0}", ex.ToString());
                }
            }
            else
            {
                try
                {
                    string sessionId = client.Handle.ToString();
                    client.Disconnect(true);
                    this.socketClientSesson.Remove(client);
                    Console.WriteLine("客户端({0})已断开", sessionId);
                }
                catch (Exception ex)
                {
                    Console.WriteLine("客户端已断开出错" + ex.ToString());
                }
            }
        }

        private void Response(Socket sender, string context)
        {
            SocketRequest request = null;
            JavaScriptSerializer jss = new JavaScriptSerializer();
            request = jss.Deserialize(context, typeof(SocketRequest)) as SocketRequest;

            if (request == null)
            {
                return;
            }

            var typeName = "SocketServer." + request.Method + "ResponseManager, SocketServer";
            Console.WriteLine("反射类名为：" + typeName);

            Type type = Type.GetType(typeName);
            if (type == null)
            {
                return;
            }

            var manager = Activator.CreateInstance(type) as IResponseManager;
            manager.Write(sender, this.socketClientSesson.Select(s => s.Key).ToList(),
                request.Param as IDictionary<string, object>);
        }
    }

最后，json数据传输的实体对象为：

   [Serializable]
    public class SocketRequest
    {
        public string Method { get; set; }

        public string DateTime { get; set; }

        public object Param { get; set; }
    }

    [Serializable]
    public class SocketResponse
    {
        public string Method { get; set; }

        public string DateTime { get; set; }

        public object Result { get; set; }
    }

 四、客户端源代码

1.布局文件

logon.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent" android:background="@drawable/background">

    <LinearLayout android:orientation="vertical"
        android:layout_width="fill_parent" android:layout_height="60dip"
        android:background="@drawable/logon" />

    <LinearLayout android:orientation="vertical"
        android:layout_width="fill_parent" android:layout_height="fill_parent"
        android:paddingLeft="10dp" android:paddingRight="10dp">

        <View android:layout_width="fill_parent" android:layout_height="20dip" />

        <TextView android:id="@+id/feedback_title" android:textColor="#FFFFFF"
            android:layout_width="fill_parent" android:layout_height="wrap_content"
            android:text="用户名：" />
        <EditText android:id="@+id/edtUserName" android:layout_width="fill_parent"
            android:layout_height="wrap_content" />

        <View android:layout_width="fill_parent" android:layout_height="2dip"
            android:background="#FF909090" />

        <TextView android:layout_width="fill_parent"
            android:textColor="#FFFFFF" android:layout_height="wrap_content"
            android:text="IP地址：" />
        <EditText android:id="@+id/edtIp" android:layout_width="fill_parent"
            android:layout_height="wrap_content" android:digits="1234567890." 
            android:text="192.168.1.101"/>

        <View android:layout_width="fill_parent" android:layout_height="2dip"
            android:background="#FF909090" />

        <TextView android:layout_width="fill_parent"
            android:textColor="#FFFFFF" android:layout_height="wrap_content"
            android:text="端口号：" />
        <EditText android:id="@+id/edtPort" android:layout_width="fill_parent"
            android:layout_height="wrap_content" android:inputType="number"
            android:numeric="integer" android:text="1234"/>

        <LinearLayout android:orientation="horizontal"
            android:layout_width="fill_parent" android:layout_height="wrap_content"
            android:layout_marginTop="10dp">
        </LinearLayout>
        <RelativeLayout android:layout_width="fill_parent"
            android:layout_height="fill_parent">
            <View android:id="@+id/feedback_content" android:layout_width="fill_parent"
                android:layout_height="fill_parent" android:maxEms="10"
                android:minEms="10" android:gravity="top"
                android:layout_marginBottom="50dip" />
            <Button android:id="@+id/btnLogon" android:layout_width="fill_parent"
                android:layout_height="50dp" android:text="登陆" android:textSize="19dp"
                android:layout_gravity="center_horizontal"
                android:layout_alignParentBottom="true" />
        </RelativeLayout>
    </LinearLayout>
</LinearLayout>

main.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="fill_parent"
    android:layout_height="fill_parent" android:background="@drawable/background">

    <ListView android:layout_width="fill_parent"
        android:layout_height="wrap_content" android:id="@+id/ltvMessage">
    </ListView>

    <RelativeLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content">

        <EditText android:layout_width="fill_parent"
            android:layout_height="wrap_content" android:id="@+id/edtMessage"
            android:hint="请输入消息" android:layout_alignTop="@+id/btnSend"
            android:layout_toLeftOf="@+id/btnSend" />

        <Button android:text="SEND" android:id="@+id/btnSend"
            android:layout_height="wrap_content" android:layout_width="wrap_content"
            android:layout_alignParentRight="true" />
    </RelativeLayout>

</LinearLayout>

listview_item.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="wrap_content"
    android:orientation="vertical" android:paddingBottom="3dip"
    android:paddingLeft="10dip">

    <TextView android:layout_height="wrap_content"
        android:layout_width="fill_parent" android:id="@+id/itmMessage"
        android:textSize="20dip">
    </TextView>

    <LinearLayout android:layout_width="fill_parent"
        android:orientation="horizontal" android:layout_height="20dip">
        <TextView android:layout_height="fill_parent"
            android:layout_width="100dip" android:id="@+id/itmUserName" >
        </TextView>

        <TextView android:layout_height="fill_parent"
            android:layout_width="200dip" android:id="@+id/itmTime" >
        </TextView>

    </LinearLayout>

</LinearLayout>

SocketClient：

package ld.socket;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.UnknownHostException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.os.Handler;
import android.os.Message;
import android.util.Log;

public class SocketClient {

    private static Socket client;

    private static SocketClient instance = null;

    public static SocketClient getInstance() {
        if (instance == null) {

            synchronized (ChartInfo.class) {
                if (instance == null) {
                    try {
                        ChartInfo chartInfo = ChartInfo.getInstance();
                        client = new Socket(chartInfo.getIp(), chartInfo
                                .getPort());
                        instance = new SocketClient();
                    } catch (UnknownHostException e) {
                        // TODO Auto-generated catch block
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                    }
                }
            }
        }
        return instance;
    }

    private SocketClient() {
        this.initMap();
        this.startThread();
    }

    private void initMap() {
        this.handlerMap = new HashMap<String, Handler>();
    }

    public void close() {
        try {
            client.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            //e.printStackTrace();
        }
        instance = null;
    }
    
    private void startThread() {
        Thread thread = new Thread() {
            @Override
            public void run() {

                while (true) {
                    if (client == null || !client.isConnected()) {
                        continue;
                    }

                    BufferedReader reader;
                    try {
                        reader = new BufferedReader(new InputStreamReader(
                                client.getInputStream()));
                        String line = reader.readLine();
                        Log.d("initSocket", "line:" + line);
                        if (line.equals("")) {
                            continue;
                        }

                        JSONObject json = new JSONObject(line);
                        String method = json.getString("Method");
                        Log.d("initSocket", "method:" + method);
                        if (method.equals("")
                                || !handlerMap.containsKey(method)) {
                            Log.d("initSocket", "handlerMap not method");
                            continue;
                        }

                        Handler handler = handlerMap.get(method);
                        if (handler == null) {
                            Log.d("initSocket", "handler is null");
                            continue;
                        }
                        Log.d("initSocket", "handler:" + method);
                        Object obj = json.getJSONObject("Result");
                        Log.d("initSocket", "Result:" + obj);
                        Message msg = new Message();
                        msg.obj = obj;
                        handler.sendMessage(msg);

                    } catch (IOException e) {

                    } catch (JSONException e) {

                    }
                }
            }
        };
        thread.start();
    }

    private Map<String, Handler> handlerMap;

    public void putHandler(String methodnName, Handler handler) {
        this.removeHandler(methodnName);
        this.handlerMap.put(methodnName, handler);
    }

    public void removeHandler(String methodnName) {
        if (this.handlerMap.containsKey(methodnName)) {
            this.handlerMap.remove(methodnName);
        }
    }

    public void logon(String userName) {
        Log.d("initSocket", "logon");
        try {
            OutputStreamWriter osw = new OutputStreamWriter(client
                    .getOutputStream());

            BufferedWriter writer = new BufferedWriter(osw);

            JSONObject param = new JSONObject();
            param.put("UserName", userName.replace("\n", " "));

            JSONObject json = this.getJSONData("Logon", param);

            writer.write(json.toString());
            writer.flush();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public void sendMessage(String message) {
        Log.d("initSocket", "Send");
        try {
            OutputStreamWriter osw = new OutputStreamWriter(client
                    .getOutputStream());

            BufferedWriter writer = new BufferedWriter(osw);

            JSONArray array = new JSONArray();
            for (String item : message.split("\n")) {
                array.put(item);
            }

            JSONObject param = new JSONObject();
            param.put("Message", array);

            param.put("UserName", ChartInfo.getInstance().getUserName());

            JSONObject json = this.getJSONData("Send", param);

            writer.write(json.toString());
            writer.flush();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    private JSONObject getJSONData(String methodName, JSONObject param) {
        JSONObject json = new JSONObject();
        try {
            json.put("Method", methodName);
            SimpleDateFormat format = new SimpleDateFormat(
                    "yyyy-MM-dd HH:mm:ss");
            json.put("DateTime", format.format(new Date()));
            json.put("Param", param);
            return json;
        } catch (JSONException e) {
            return null;
        }
    }
}

LogonActivity：

package ld.socket;

import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.ComponentName;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class LogonActivity extends Activity {

    private EditText edtUserName;
    private EditText edtIp;
    private EditText edtPort;

    private Button btnLogon;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        setContentView(R.layout.logon);

        this.initViews();
    }

    private void initViews() {
        this.edtUserName = (EditText) this.findViewById(R.id.edtUserName);
        this.edtIp = (EditText) this.findViewById(R.id.edtIp);
        this.edtPort = (EditText) this.findViewById(R.id.edtPort);

        this.btnLogon = (Button) this.findViewById(R.id.btnLogon);
        this.btnLogon.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                // showAlert(edtUserName.getText().toString());
                if (edtUserName.getText().toString().equals("")) {
                    showDialog("请输入用户名");
                    return;
                }

                if (edtIp.getText().toString().equals("")) {
                    showDialog("请输入IP地址");
                    return;
                }

                if (edtPort.getText().toString().equals("")) {
                    showDialog("请输入端口号");
                    return;
                }

                int port = Integer.parseInt(edtPort.getText().toString());
                ChartInfo chartInfo = ChartInfo.getInstance();
                chartInfo.setIp(edtIp.getText().toString());
                chartInfo.setPort(port);
                SocketClient proxy = SocketClient.getInstance();

                if (proxy == null) {
                    showDialog("未接入互联网");
                    setWireless();
                    return;
                }

                proxy.putHandler("Logon", new Handler() {
                    @Override
                    public void handleMessage(Message msg) {

                        SocketClient proxy = SocketClient.getInstance();
                        proxy.removeHandler("Logon");
                        Log.d("initSocket", "handleMessage");
                        if (msg == null || msg.obj == null) {
                            return;
                        }

                        JSONObject json = (JSONObject) msg.obj;
                        try {
                            String userName = json.getString("UserName");
                            Log.d("initSocket", "userName:" + userName);
                            ChartInfo.getInstance().setUserName(userName);
                            Intent itt = new Intent();
                            itt
                                    .setClass(LogonActivity.this,
                                            MainActivity.class);
                            LogonActivity.this.startActivity(itt);
                        } catch (JSONException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                });
                proxy.logon(edtUserName.getText().toString());
            }
        });
    }

    private void setWireless() {
        Intent mIntent = new Intent("/");
        ComponentName comp = new ComponentName("com.android.settings",
                "com.android.settings.WirelessSettings");
        mIntent.setComponent(comp);
        mIntent.setAction("android.intent.action.VIEW");
        startActivityForResult(mIntent, 0);
    }

    private void showDialog(String mess) {
        new AlertDialog.Builder(this).setTitle("信息").setMessage(mess)
                .setNegativeButton("确定", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                    }
                }).show();
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {

        if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {

            AlertDialog alertDialog = new AlertDialog.Builder(
                    LogonActivity.this).setTitle("退出程序").setMessage("是否退出程序")
                    .setPositiveButton("确定",
                            new DialogInterface.OnClickListener() {

                                public void onClick(DialogInterface dialog,
                                        int which) {
                                    LogonActivity.this.finish();
                                }

                            }).setNegativeButton("取消",

                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            return;
                        }
                    }).create(); // 创建对话框

            alertDialog.show(); // 显示对话框

            return false;

        }

        return false;
    }

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        SocketClient proxy = SocketClient.getInstance();
        if (proxy != null) {
            proxy.close();
        }
    }

}

MainActivity：

package ld.socket;

import org.json.JSONException;
import org.json.JSONObject;

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.KeyEvent;
import android.view.View;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;

public class MainActivity extends Activity {

    private EditText edtMessage;

    private Button btnSend;

    private ListView ltvMessage;

    private MessageAdapter adapter;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // 隐藏键盘
        this.getWindow().setSoftInputMode(
                WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);

        Log.d("initSocket", "MessageAdapter");
        this.adapter = new MessageAdapter(this);
        Log.d("initSocket", "adapter is ok");

        this.findThisViews();
        this.initHandler();

        this.serOnClick();

        Log.d("initSocket", "onCreate");
    }

    private void findThisViews() {
        this.edtMessage = (EditText) this.findViewById(R.id.edtMessage);
        this.btnSend = (Button) this.findViewById(R.id.btnSend);

        this.ltvMessage = (ListView) this.findViewById(R.id.ltvMessage);
        // this.ltvMessage.setEnabled(false);
        this.ltvMessage.setAdapter(this.adapter);
    }

    private void initHandler() {

        Handler handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                if (msg.obj == null) {
                    Log.d("initSocket", "handleMessage is null");
                    return;
                }

                Log.d("initSocket", "handleMessage");
                try {
                    JSONObject json = (JSONObject) msg.obj;
                    String userName = json.getString("UserName");

                    StringBuilder sb = new StringBuilder();
                    int length = json.getJSONArray("Message").length();
                    for (int i = 0; i < length; i++) {
                        String item = json.getJSONArray("Message").getString(i);
                        if (item.equals("")) {
                            continue;
                        }
                        if (length > i + 1) {
                            Log.d("initSocket", "length:" + length);
                            Log.d("initSocket", "i:" + i);
                            Log.d("initSocket", "item:" + item);
                            item += "\n";
                        }
                        sb.append(item);
                    }

                    MessageRecord record = new MessageRecord();
                    record.setUserName(userName);
                    record.setMessage(sb.toString());

                    MainActivity.this.adapter.add(record);
                    adapter.notifyDataSetChanged();
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        };
        SocketClient proxy = SocketClient.getInstance();
        proxy.putHandler("Send", handler);
    }

    private void serOnClick() {
        this.btnSend.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                btnSend.setEnabled(false);
                String txt = edtMessage.getText().toString();
                if (txt.equals("")) {
                    btnSend.setEnabled(true);
                    return;
                }
                SocketClient proxy = SocketClient.getInstance();
                proxy.sendMessage(txt);
                edtMessage.setText("");
                btnSend.setEnabled(true);
            }
        });
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {

        if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {

            AlertDialog alertDialog = new AlertDialog.Builder(
                    MainActivity.this).setTitle("询问").setMessage("是否注销登录？")
                    .setPositiveButton("确定",
                            new DialogInterface.OnClickListener() {

                                public void onClick(DialogInterface dialog,
                                        int which) {
                                    MainActivity.this.finish();
                                }

                            }).setNegativeButton("取消",

                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            return;
                        }
                    }).create(); // 创建对话框

            alertDialog.show(); // 显示对话框

            return false;

        }

        return false;
    }
}

 五、运行效果

 

  代码下载

  出处：http://www.cnblogs.com/GoodHelper/archive/2011/07/08/android_socket_chart.html

  欢迎转载，但需保留版权！