當使用intent和BroadcastReceiver來獲取android電池電量時的怪異行爲

Question

我試圖在運行Android應用程序後找到電池電量。當手機啓動完全充電的應用程序時，代碼始終返回100％的電池電量（即使耗盡了大量電量）。如果我以75％電量或其他任何方式啓動應用程序，則會在測試結束時返回實際的電池電量。我開始我的測試，將手機插入我的電腦並保持充電狀態，然後在執行應用程序之前拔掉它。理想情況下，我希望能夠獲得開始％和結束％，但同時也讀取100％。因此，這裏是我在做什麼......我把這個從我的活動：

this.registerReceiver(this.mBatInfoReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED)); 

然後在廣播接收器我做了一堆東西（這需要一個多小時，以便電池電量的變化）。然後在BoradcastReceiver的結尾我打電話給這個

int level2 = intent.getIntExtra("level", 0); /* Ending battery level */ 
String end = "Ending battery level: " + String.valueOf(level2) + "%"; 

然後發送字符串結束到服務器。

這裏是我的代碼如下所示：

package com.mdog.datareceive; 

import java.io.IOException; 
import java.io.PrintWriter; 
import java.net.Socket; 
import java.net.UnknownHostException; 

import android.app.Activity; 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.os.Bundle; 
import android.os.PowerManager; 
import android.util.Log; 
import android.widget.TextView; 


public class Receive extends Activity { 

    /* Test parameters */ 
    static int BYTES_TO_READ = 1024*1024*50; /* The size of the data for each transfer */ 
    static int TIMES_TO_READ = 20;    /* The number of times the client will request the data */ 
    static int PLAYER_BUFFER_SIZE = 1638400; /* Clients buffer size 1638400 = 1.57MB */ 
    static int SLEEP_TIME_MS = 5000; 

    /* Display Info */ 
    String start = "empty";     /* String holder for the starting battery life */ 
    String end = "empty2";     /* String holder for the ending battery life */ 
    int allMBytes = 0;      /* Integer holder for the total number of megabytes received during the test */ 
    TextView tv;       /* The view the phone displays after completion of test */ 

    /* Server Info */ 
    String serverIP = "192.168.0.104";  /* Server IP */ 
    int serverPort = 11313;     /* Server port number */ 



    private BroadcastReceiver mBatInfoReceiver = new BroadcastReceiver(){ 

     @Override 
     public void onReceive(Context arg0, Intent intent) { 

      //int level = intent.getIntExtra("level", 0); 

      Socket connectionSocket = null;       /* Socket to communicate with server */ 
      byte[] inputHolderByteArray = new byte[PLAYER_BUFFER_SIZE]; /* Used to read from the socket */ 

      int bufferBytes = 0;  /* filling the second buffer */ 
      int totalBytesRead = 0;  /* The total number of bytes read for this transfer round */ 
      int read=0;     /* reading from stream, will contain the number of bytes read or -1 if the end has been hit */ 

      /* Acquire a wake lock for the phone so it does not go to sleep */ 
      PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE); 
      PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK, getClass().getName()); 

      /* Connect to Server */ 
      try { 

       connectionSocket = new Socket(serverIP, serverPort); 
       connectionSocket.setReceiveBufferSize(PLAYER_BUFFER_SIZE); //1.5ish MB 
       connectionSocket.setKeepAlive(true); 
       PrintWriter out = new PrintWriter(connectionSocket.getOutputStream(), true); 

       out.print("Client Info: Bytes expected per transfer:" + BYTES_TO_READ + ", Number of transfer to request:" + TIMES_TO_READ+ ", Buffer size:" +PLAYER_BUFFER_SIZE+ ", Sleep time(ms):" + SLEEP_TIME_MS + "\n"); 
       out.flush(); 

       wl.acquire(); 

       for(int i=0; i<TIMES_TO_READ; i++){ 

        out.print("Start\n"); 
        out.flush(); 

        while(totalBytesRead < BYTES_TO_READ){ 

         /* Read at most PLAYER_BUFFER_SIZE bytes */ 
         read = connectionSocket.getInputStream().read(inputHolderByteArray, 0, PLAYER_BUFFER_SIZE); 

         if(read != -1){ 
          bufferBytes += read; 
          totalBytesRead += read; 
          if(bufferBytes >= PLAYER_BUFFER_SIZE){ 
            try { 
             Thread.sleep(SLEEP_TIME_MS); 
            } catch (InterruptedException e) { 
             e.printStackTrace(); 
            } 
           bufferBytes = 0; 
          } 
         } 
         else{ 
          /* End of stream reached */ 
          break; 
         }  
        } 

        allMBytes += ((totalBytesRead/1024)/1024); 
        totalBytesRead = 0; 

        try { 
         Thread.sleep(1000); 
        } catch (InterruptedException e) { 
         e.printStackTrace(); 
        } 

       } 

       int level2 = intent.getIntExtra("level", 0); /* Ending battery level */ 

       /* Put data on screen */ 
       start = "Starting battery level: 100%"; 
       end = "Ending battery level: " + String.valueOf(level2) + "%"; 
       out.print("Test Completed: " + start + ", " + end + ", Megabytes Read: " + allMBytes + "\n"); 
       out.flush(); 

       wl.release(); 

       tv.setText(start + " \n" + end + " \n Total MB transferred:" + allMBytes); 
       setContentView(tv); 

      } catch (UnknownHostException e) { 
       Log.i("UnknownHost exception ", " ******************** Log Msg UHE " + e.getLocalizedMessage()); 
       e.printStackTrace(); 
      } catch (IOException e2) { 
       Log.i("IO exception ", "******************** Log Msg IOE " + e2.toString()); 
       e2.printStackTrace(); 
      } 
     } 
    }; 


    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 

     tv = new TextView(this);    /* The view to post text to */ 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
     this.registerReceiver(this.mBatInfoReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED)); 
    } 
} 

Answer 1

首先，intent.getIntExtra("level", 0);不是一個百分比。 intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 1)需要與intent.getIntExtra(BatteryManager.EXTRA_SCALE, 1)進行比較以獲得百分比。

其次，不要不主應用程序線程上做網絡I/O，如BroadcastReceiver的onReceive()。

第三，您正在比較電池電量與自身。您需要等待下一個ACTION_BATTERY_CHANGED廣播以找出新的電池電量。

Answer 2

你不應該把你的應用程序邏輯中的onReceive（）方法。這種方法應該只處理意圖。否則，你可能會阻止意向交付給其他應用程序。

您的電池狀態不會改變，因爲您在此方法中阻止時未獲得目標。傳遞的意圖本身不會改變。只要電池狀態發生變化，onReceive（）方法就會被調用 - 只要你不阻止它。