Android中的intentservice

在Android的应用中,往往需要在执行主界面的操作时,如果要执行耗时的操作,那么应该是另外开线程的,或者是用async或者handler,今天发现其实也可以用android中的一个Intentservice去实现。下面例子讲解下。

1 例子中是一个文本框，当用户输入内容后，模拟slepp 10秒，这个时候要是不分离线程，操作的话，用户再点界面，就会死死地停在那里，甚至是出现提示，要强行CLOSE，代码如下：

1. EditText input = (EditText) findViewById(R.id.txt_input);   
2.  String strInputMsg = input.getText().toString();     
3. 30000); // 30 seconds, pretend to do work   TextView result = (TextView) findViewById(R.id.txt_result); result.setText(strInputMsg + " " + DateFormat.format("MM/dd/yy h:mmaa", System.currentTimeMillis()));

EditText input = (EditText) findViewById(R.id.txt_input);
 String strInputMsg = input.getText().toString();  
 SystemClock.sleep(30000); // 30 seconds, pretend to do work   TextView result = (TextView) findViewById(R.id.txt_result); result.setText(strInputMsg + " " + DateFormat.format("MM/dd/yy h:mmaa", System.currentTimeMillis()));

2 下面是使用IntentService

   首先，我们搞一个类SimpleIntentService，继承了IntentService

​

1. public class SimpleIntentService extends
2. public static final String PARAM_IN_MSG = "imsg";   
3. public static final String PARAM_OUT_MSG = "omsg";   
4.   
5. public
6. super("SimpleIntentService");   
7.     }   
8.   
9. @Override
10. protected void
11.   
12.         String msg = intent.getStringExtra(PARAM_IN_MSG);   
13. 3000); // 30 seconds 
14. " "
15. "MM/dd/yy h:mmaa", System.currentTimeMillis());   
16. "SimpleIntentService", "Handling msg: "
17.   
18. new
19.         broadcastIntent.setAction(ResponseReceiver.ACTION_RESP);   
20.         broadcastIntent.addCategory(Intent.CATEGORY_DEFAULT);   
21.         broadcastIntent.putExtra(PARAM_OUT_MSG, resultTxt);   
22.         sendBroadcast(broadcastIntent);   
23.     }

public class SimpleIntentService extends IntentService {
    public static final String PARAM_IN_MSG = "imsg";
    public static final String PARAM_OUT_MSG = "omsg";

    public SimpleIntentService() {
        super("SimpleIntentService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {

        String msg = intent.getStringExtra(PARAM_IN_MSG);
        SystemClock.sleep(3000); // 30 seconds
        String resultTxt = msg + " "
            + DateFormat.format("MM/dd/yy h:mmaa", System.currentTimeMillis());
        Log.v("SimpleIntentService", "Handling msg: " + resultTxt);

        Intent broadcastIntent = new Intent();
        broadcastIntent.setAction(ResponseReceiver.ACTION_RESP);
        broadcastIntent.addCategory(Intent.CATEGORY_DEFAULT);
        broadcastIntent.putExtra(PARAM_OUT_MSG, resultTxt);
        sendBroadcast(broadcastIntent);
    }

   我们将跟主界面线程分离的操作都写在这里的ononHandleIntent中，这里首先通过

主线程传递的Intent中，获得用户文本框中输入的内容，放到变量msg中，然后

又建立一个Intent，把结果放到这个Intent中去，然后再sendBroadcast(broadcastIntent)广播出去，丢回给主线程。

3 在主线程中，这样启动：

1. EditText input = (EditText) findViewById(R.id.txt_input);   
2.        String strInputMsg = input.getText().toString();   
3.   
4. new Intent(this, SimpleIntentService.class);   
5.        msgIntent.putExtra(SimpleIntentService.PARAM_IN_MSG, strInputMsg);   
6.        startService(msgIntent);

EditText input = (EditText) findViewById(R.id.txt_input);
        String strInputMsg = input.getText().toString();

        Intent msgIntent = new Intent(this, SimpleIntentService.class);
        msgIntent.putExtra(SimpleIntentService.PARAM_IN_MSG, strInputMsg);
        startService(msgIntent);

4 同时，在主线程中，也要有一个receive接收

1. public class ResponseReceiver extends
2. public static final String ACTION_RESP = "com.mamlambo.intent.action.MESSAGE_PROCESSED";   
3. @Override
4. public void
5.               
6. // Update UI, new "message" processed by SimpleIntentService 
7.            TextView result = (TextView) findViewById(R.id.txt_result);   
8.            String text = intent.getStringExtra(SimpleIntentService.PARAM_OUT_MSG);   
9.            result.setText(text);   
10.         }   
11.            
12.     }   
13.   
14.

public class ResponseReceiver extends BroadcastReceiver {
        public static final String ACTION_RESP = "com.mamlambo.intent.action.MESSAGE_PROCESSED";
        @Override
        public void onReceive(Context context, Intent intent) {
           
            // Update UI, new "message" processed by SimpleIntentService
           TextView result = (TextView) findViewById(R.id.txt_result);
           String text = intent.getStringExtra(SimpleIntentService.PARAM_OUT_MSG);
           result.setText(text);
        }
        
    }

  当然，要注册这个broadcastReceiver,

​

1. public void
2. super.onCreate(savedInstanceState);   
3.        setContentView(R.layout.main);   
4.           
5. new
6.        filter.addCategory(Intent.CATEGORY_DEFAULT);   
7. new
8.        registerReceiver(receiver, filter);   
9.    }

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        IntentFilter filter = new IntentFilter(ResponseReceiver.ACTION_RESP);
        filter.addCategory(Intent.CATEGORY_DEFAULT);
        receiver = new ResponseReceiver();
        registerReceiver(receiver, filter);
    }

  可以看到，intent service还是比较清晰简单的，但至于性能方面，还是要继续学习，

迟点继续研究下这玩意哦