在Android开发中，我们可能需要和服务器保持连接不断开，这时需要用到socket通信的长连接，并且定时发送消息检测是否是连接状态——心跳检测。
我们需要一个客户端和一个服务器端的demo，现在我就贴出重要代码，主要是android客户端的，服务器端的demo供大家下载。
首先我们需要新建一个BackService类来继承Service：
package com.example.sockettest;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.ref.WeakReference;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Arrays;
import android.annotation.SuppressLint;
import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;
public class BackService extends Service {
private static final String TAG = "BackService";
/** 心跳检测时间*/
private static final long HEART_BEAT_RATE = 3 * 1000;
/** 主机IP地址*/
private static final String HOST = "192.168.1.104";
/** 端口号*/
public static final int PORT = 9800;
/** 消息广播*/
public static final String MESSAGE_ACTION = "org.feng.message_ACTION";
/** 心跳广播*/
public static final String HEART_BEAT_ACTION = "org.feng.heart_beat_ACTION";
private long sendTime = 0L;
/** 弱引用 在引用对象的同时允许对垃圾对象进行回收*/
private WeakReference mSocket;
private ReadThread mReadThread;
private IBackService.Stub iBackService = new IBackService.Stub() {
@Override
public boolean sendMessage(String message) throws RemoteException {
return sendMsg(message);
}
};
@Override
public IBinder onBind(Intent arg0) {
return (IBinder) iBackService;
}@Override
public void onCreate() {
super.onCreate();
new InitSocketThread().start();
}// 发送心跳包
private Handler mHandler = new Handler();
private Runnable heartBeatRunnable = new Runnable() {
@Override
public void run() {
if (System.currentTimeMillis() - sendTime >= HEART_BEAT_RATE) {
boolean isSuccess = sendMsg("");
// 就发送一个\r\n过去, 如果发送失败，就重新初始化一个socket
if (!isSuccess) {
mHandler.removeCallbacks(heartBeatRunnable);
mReadThread.release();
releaseLastSocket(mSocket);
new InitSocketThread().start();
}
}
mHandler.postDelayed(this, HEART_BEAT_RATE);
}
};
public boolean sendMsg(String msg) {
if (null == mSocket || null == mSocket.get()) {
return false;
}
Socket soc = mSocket.get();
try {
if (!soc.isClosed() && !soc.isOutputShutdown()) {
OutputStream os = soc.getOutputStream();
String message = msg + "\r\n";
os.write(message.getBytes());
os.flush();
sendTime = System.currentTimeMillis();
// 每次发送成功数据，就改一下最后成功发送的时间，节省心跳间隔时间
Log.i(TAG, "发送成功的时间：" + sendTime);
} else {
return false;
}
} catch (IOException e) {
e.printStackTrace();
return false;
}
return true;
}// 初始化socket
private void initSocket() throws UnknownHostException, IOException {
Socket socket = new Socket(HOST, PORT);
mSocket = new WeakReference(socket);
mReadThread = new ReadThread(socket);
mReadThread.start();
mHandler.postDelayed(heartBeatRunnable, HEART_BEAT_RATE);
// 初始化成功后，就准备发送心跳包
}// 释放socket
private void releaseLastSocket(WeakReference mSocket) {
try {
if (null != mSocket) {
Socket sk = mSocket.get();
if (!sk.isClosed()) {
sk.close();
}
sk = null;
mSocket = null;
}
} catch (IOException e) {
e.printStackTrace();
}
}class InitSocketThread extends Thread {
@Override
public void run() {
super.run();
try {
initSocket();
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}public class ReadThread extends Thread {
private WeakReference mWeakSocket;
private boolean isStart = true;
public ReadThread(Socket socket) {
mWeakSocket = new WeakReference(socket);
}public void release() {
isStart = false;
releaseLastSocket(mWeakSocket);
}@SuppressLint("NewApi")
@Override
public void run() {
super.run();
Socket socket = mWeakSocket.get();
if (null != socket) {
try {
InputStream is = socket.getInputStream();
byte[] buffer = new byte[1024 * 4];
int length = 0;
while (!socket.isClosed() && !socket.isInputShutdown()
&& isStart && ((length = is.read(buffer)) != -1)) {
if (length > 0) {
String message = new String(Arrays.copyOf(buffer,
length)).trim();
Log.i(TAG, "收到服务器发送来的消息："+message);
// 收到服务器过来的消息，就通过Broadcast发送出去
if (message.equals("ok")) {// 处理心跳回复
Intent intent = new Intent(HEART_BEAT_ACTION);
sendBroadcast(intent);
} else {
// 其他消息回复
Intent intent = new Intent(MESSAGE_ACTION);
intent.putExtra("message", message);
sendBroadcast(intent);
}
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}关键代码已经注释了，相信大家应该可以看懂。在这个类中关联了一个IBackService的类，新建一个IBackService.aidl。对，没错，就是新建一个IBackService.aidl，关于aidl的知识请查阅相关文档。代码如下：
package com.example.sockettest;
interface IBackService{
boolean sendMessage(String message);
}
现在就是MainActivity了，这就是一个activity，接收广播，改变UI，就不多说了：
package com.example.sockettest;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.os.RemoteException;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
private static final String TAG = "MainActivity";
private Intent mServiceIntent;
private IBackService iBackService;
private TextView tv;
private EditText et;
private Button btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initViews();
initData();
}private void initViews() {
tv = (TextView) findViewById(R.id.tv);
et = (EditText) findViewById(R.id.editText1);
btn = (Button) findViewById(R.id.button1);
}private void initData() {
mServiceIntent = new Intent(this, BackService.class);
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String string = et.getText().toString().trim();
Log.i(TAG, string);
try {
Log.i(TAG, "是否为空：" + iBackService);
if (iBackService == null) {
Toast.makeText(getApplicationContext(),
"没有连接，可能是服务器已断开", Toast.LENGTH_SHORT).show();
} else {
boolean isSend = iBackService.sendMessage(string);
Toast.makeText(MainActivity.this,
isSend ? "success" : "fail", Toast.LENGTH_SHORT)
.show();
et.setText("");
}
} catch (RemoteException e) {
e.printStackTrace();
}
}
});
}@Override
protected void onStart() {
super.onStart();
bindService(mServiceIntent, conn, BIND_AUTO_CREATE);
// 开始服务
registerReceiver();
}@Override
protected void onResume() {
super.onResume();
// 注册广播 最好在onResume中注册
// registerReceiver();
}@Override
protected void onPause() {
super.onPause();
// 注销广播 最好在onPause上注销
unregisterReceiver(mReceiver);
// 注销服务
unbindService(conn);
}// 注册广播
private void registerReceiver() {
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(BackService.HEART_BEAT_ACTION);
intentFilter.addAction(BackService.MESSAGE_ACTION);
registerReceiver(mReceiver, intentFilter);
}private BroadcastReceiver mReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// 消息广播
if (action.equals(BackService.MESSAGE_ACTION)) {
String stringExtra = intent.getStringExtra("message");
tv.setText(stringExtra);
} else if (action.equals(BackService.HEART_BEAT_ACTION)) {// 心跳广播
tv.setText("正常心跳");
}
}
};
private ServiceConnection conn = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
// 未连接为空
iBackService = null;
}@Override
public void onServiceConnected(ComponentName name, IBinder service) {
// 已连接
iBackService = IBackService.Stub.asInterface(service);
}
};
}
【Android socket通信的长连接与心跳检测】好了，我们可以运行项目了。
Demo
