Android后台运行的定时器实现

Android后台运行定时器，方便我们执行定位跟踪等任务需求。下面简要说明实现Android后台定时器的要点，文章末尾可以下载到工程代码，可直接编译执行。

AndroidManifest.xml 文件内容如下：

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.routing.videocamera"    android:versionCode="1"    android:versionName="1.0" >    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />    <uses-permission android:name="android.permission.INTERNET" />    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />        <uses-sdk        android:minSdkVersion="14"        android:targetSdkVersion="16" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name="com.routing.videocamera.Video"            android:label="@string/app_name" >            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>        <service android:enabled="true" android:name=".TimerService" /> <receiver android:name=".AutoReceiver" android:label="@string/app_name"> <intent-filter>    <action android:name="android.intent.action.BOOT_COMPLETED" />    <category android:name="android.intent.category.LAUNCHER" /></intent-filter></receiver>            </application>    </manifest>

其中关键的代码是赋予项目 RECEIVE_BOOT_COMPLETED 权限：

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

Video.java 文件的内容如下：

package com.routing.videocamera;public class Video extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_video);Intent intent=new Intent(this,AutoReceiver.class);  intent.setAction("VIDEO_TIMER"); PendingIntent sender = PendingIntent.getBroadcast(this, 0, intent, 0);  AlarmManager am = (AlarmManager)getSystemService(ALARM_SERVICE);   am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime(), 10*1000, sender); Button btnStart = (Button)findViewById(R.id.buttonSave);btnStart.setOnClickListener(clickListener);Context ctx = Video.this;       SharedPreferences sp = ctx.getSharedPreferences("VIDEO", MODE_PRIVATE);//存入数据Editor editor = sp.edit();String serverAddr = sp.getString("ServerAddr", "NULL");String cameraName = sp.getString("CameraName", "NULL");int cameraID   = sp.getInt("CameraID", 0);int cameraPort = sp.getInt("CameraPort", 0);        EditText editServerAddr = (EditText)findViewById(R.id.editServerAddr);          editServerAddr.setText(serverAddr);        EditText editCameraName = (EditText)findViewById(R.id.editCameraName);          editCameraName.setText(cameraName);                EditText editCameraID = (EditText)findViewById(R.id.editCameraID);          editCameraID.setText(Integer.toString(cameraID));                        EditText editCameraPort = (EditText)findViewById(R.id.editCameraPort);          editCameraPort.setText(Integer.toString(cameraPort));}private void saveSetting (){        EditText editServerAddr = (EditText)findViewById(R.id.editServerAddr);          String serverAddr = editServerAddr.getText().toString();        EditText editCameraName = (EditText)findViewById(R.id.editCameraName);          String cameraName = editCameraName.getText().toString();                EditText editCameraID = (EditText)findViewById(R.id.editCameraID);          int cameraID = Integer.parseInt(editCameraID.getText().toString());                        EditText editCameraPort = (EditText)findViewById(R.id.editCameraPort);          int cameraPort = Integer.parseInt(editCameraPort.getText().toString());        //获取SharedPreferences对象Context ctx = Video.this;       SharedPreferences sp = ctx.getSharedPreferences("VIDEO", MODE_PRIVATE);//存入数据Editor editor = sp.edit();if (serverAddr != "")editor.putString("ServerAddr", serverAddr);if (cameraName != "")editor.putString("CameraName", cameraName);editor.putInt("CameraID", cameraID);editor.putInt("CameraPort", cameraPort);editor.commit();        }@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.activity_video, menu);return true;}private OnClickListener clickListener = new OnClickListener() {@Overridepublic void onClick(View v) {int ret = 0;switch(v.getId()){case R.id.buttonSave:saveSetting ();break;}}};}

该文件关键的代码是OnCreate函数中的下面4行代码：

intent.setAction("VIDEO_TIMER"); PendingIntent sender = PendingIntent.getBroadcast(this, 0, intent, 0);  AlarmManager am = (AlarmManager)getSystemService(ALARM_SERVICE);   am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime(), 10*1000, sender);

intent.setAction("VIDEO_TIMER") 设置系统向应用程序发送的消息类型为 VIDEO_TIMER。

am.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime(), 10*1000, sender); 该行代码让系统多久发送一次消息，我这里设置的是10秒发送一次VIDEO_TIMER消息。

发送出去的消息，会在 class AutoReceiver extends BroadcastReceiver 类里进行接收，并处理。

下面是 TimerService.java 文件：

package com.routing.videocamera;public class TimerService extends Service{    public void onCreate() {          super.onCreate();          Log.v("TimerService",  "OnCreate");    }            private static String mUrl;    public void onStart(Intent intent, int startId) {          Log.v("TimerService",  "onStart");                           Context ctx = TimerService.this;  //Context ctx = context;       SharedPreferences sp = ctx.getSharedPreferences("VIDEO", MODE_PRIVATE);//存入数据String serverAddr = sp.getString("ServerAddr", "");String cameraName = sp.getString("CameraName", "");int cameraID   = sp.getInt("CameraID", 0);int cameraPort = sp.getInt("CameraPort", 0);        if (serverAddr == "" || cameraName == "" || cameraID == 0 || cameraPort == 0 || serverAddr == "NULL" || cameraName == "NULL")return;        String Url = serverAddr + "/cameramgr.php?" + "CameraName=" + cameraName + "&CameraID=" + cameraID + "&CameraPort=" + cameraPort;        Log.v("FFMPEG URL=",  Url);                mUrl = Url;                         new Thread()         {           @Override           public void run()            {                HttpParams httpParams;                  // 创建 HttpParams 以用来设置 HTTP 参数（这一部分不是必需的）                  httpParams = new BasicHttpParams();                  // 设置连接超时和 Socket 超时，以及 Socket 缓存大小                  HttpConnectionParams.setConnectionTimeout(httpParams, 20 * 1000);                  HttpConnectionParams.setSoTimeout(httpParams, 20 * 1000);                  HttpConnectionParams.setSocketBufferSize(httpParams, 8192);                  // 设置重定向，缺省为 true                  HttpClientParams.setRedirecting(httpParams, true);                  // 设置 user agent                  String userAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2) Gecko/20100115 Firefox/3.6";                  HttpProtocolParams.setUserAgent(httpParams, userAgent);                  // 创建一个 HttpClient 实例                  // 注意 HttpClient httpClient = new HttpClient(); 是Commons HttpClient                  // 中的用法，在 Android 1.5 中我们需要使用 Apache 的缺省实现 DefaultHttpClient                  HttpClient httpClient = new DefaultHttpClient(httpParams);                                  //String s = this.getName();                HttpGet httpRequest = new HttpGet(mUrl);                  String strResult = "doGetError";                  try {                                          HttpResponse httpResponse = httpClient.execute(httpRequest);                                          if (httpResponse.getStatusLine().getStatusCode() == 200)                     {                                                   strResult = EntityUtils.toString(httpResponse.getEntity());                      }                     else                     {                          strResult = "Error Response: "  + httpResponse.getStatusLine().toString();                      }                  }                 catch (ClientProtocolException e)                 {                      strResult = e.getMessage().toString();                      e.printStackTrace();                  }                 catch (IOException e)                {                      strResult = e.getMessage().toString();                      e.printStackTrace();                  }                 catch (Exception e)                {                      strResult = e.getMessage().toString();                      e.printStackTrace();                  }                  Log.v("strResult", strResult);             }        }.start ();                }           public String doPost(String url, List<NameValuePair> params)     {          /* 建立HTTPPost对象 */          HttpPost httpRequest = new HttpPost(url);          String strResult = "doPostError";          try {              /* 添加请求参数到请求对象 */              httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));              /* 发送请求并等待响应 */                      HttpParams httpParams;          // 创建 HttpParams 以用来设置 HTTP 参数（这一部分不是必需的）          httpParams = new BasicHttpParams();          // 设置连接超时和 Socket 超时，以及 Socket 缓存大小          HttpConnectionParams.setConnectionTimeout(httpParams, 20 * 1000);          HttpConnectionParams.setSoTimeout(httpParams, 20 * 1000);          HttpConnectionParams.setSocketBufferSize(httpParams, 8192);          // 设置重定向，缺省为 true          HttpClientParams.setRedirecting(httpParams, true);          // 设置 user agent          String userAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2) Gecko/20100115 Firefox/3.6";          HttpProtocolParams.setUserAgent(httpParams, userAgent);                      HttpClient httpClient = new DefaultHttpClient(httpParams);             HttpResponse httpResponse = httpClient.execute(httpRequest);              /* 若状态码为200 ok */              if (httpResponse.getStatusLine().getStatusCode() == 200)             {                  /* 读返回数据 */                  strResult = EntityUtils.toString(httpResponse.getEntity());              }             else             {                  strResult = "Error Response: "  + httpResponse.getStatusLine().toString();              }          }         catch (ClientProtocolException e)         {              strResult = e.getMessage().toString();              e.printStackTrace();          }         catch (IOException e)        {              strResult = e.getMessage().toString();              e.printStackTrace();          }         catch (Exception e)         {              strResult = e.getMessage().toString();              e.printStackTrace();          }          Log.v("strResult", strResult);          return strResult;      }           public void onDestroy() {                  super.onDestroy();          Log.v("TimerService",  "onDestroy");    }    public IBinder onBind(Intent intent) {          return null;      }        public static String inStream2String(InputStream inputStream)     {          InputStreamReader inputStreamReader = null;          try         {              inputStreamReader = new InputStreamReader(inputStream, "utf8");          }        catch (UnsupportedEncodingException e1)         {              e1.printStackTrace();          }          BufferedReader reader = new BufferedReader(inputStreamReader);          StringBuffer sb = new StringBuffer("");          String line;          try        {              while ((line = reader.readLine()) != null)             {                  sb.append(line);                  sb.append("\n");              }          }         catch (IOException e)         {              e.printStackTrace();          }          return sb.toString();      }       }

该文件是定时器执行的代码，没什么特别的。

下面是 AutoReceiver.java 文件：

package com.routing.videocamera;  public class AutoReceiver extends BroadcastReceiver{    /*要接收的intent源*/    //static final String ACTION = "android.intent.action.BOOT_COMPLETED";private static final int MODE_PRIVATE = 0;    @Override    public void onReceive(Context context, Intent intent)     {        if (intent.getAction().equals("VIDEO_TIMER"))         {        Intent Intentservice = new Intent(context, TimerService.class);  // 要启动的Activity        Intentservice.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);        context.startService(Intentservice);                }    }        public static String inStream2String(InputStream inputStream)     {          InputStreamReader inputStreamReader = null;          try         {              inputStreamReader = new InputStreamReader(inputStream, "utf8");          }        catch (UnsupportedEncodingException e1)         {              e1.printStackTrace();          }          BufferedReader reader = new BufferedReader(inputStreamReader);          StringBuffer sb = new StringBuffer("");          String line;          try        {              while ((line = reader.readLine()) != null)             {                  sb.append(line);                  sb.append("\n");              }          }         catch (IOException e)         {              e.printStackTrace();          }          return sb.toString();      }              public void KeepAlive() {  new Thread() {public void run() {        HttpClient client = new DefaultHttpClient();          HttpGet get = new HttpGet("http://www.baidu.com");          HttpResponse response;        try {        response = client.execute(get);        if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK)         {              InputStream is = response.getEntity().getContent();              String result = inStream2String(is);              //Assert.assertEquals(result, "GET_SUCCESS");              //Toast.makeText(Video.this, "Http Get Success:", Toast.LENGTH_LONG).show();            Log.v("FFMPEG-----= ",  result);        }        else        {        //Toast.makeText(Video.this, "Http Get Fail", Toast.LENGTH_LONG).show();                }        }        catch (ClientProtocolException e)        {        // TODO Auto-generated catch block        e.printStackTrace();        }         catch (IOException e)        {        // TODO Auto-generated catch block        e.printStackTrace();        }        //super.run();}        }.start();    }          }

该文件的关键函数是onReceive函数，在这里接收到系统发送出来的 VIDEO_TIMER 消息，然后我们启动一个新任务来执行 TimerService 的代码：

    public void onReceive(Context context, Intent intent)     {        if (intent.getAction().equals("VIDEO_TIMER"))         {        Intent Intentservice = new Intent(context, TimerService.class);  // 要启动的Activity        Intentservice.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);        context.startService(Intentservice);                }    }

完整源代码下载地址：http://download.csdn.net/download/langeldep/7845831

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Android后台运行的定时器实现

完整源代码下载地址 ：http://download.csdn.net/download/langeldep/7845831

更多相关文章

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完整源代码下载地址：http://download.csdn.net/download/langeldep/7845831