在BroadcastReceiver中打开数据库的困难

Question

我在课堂上打开我的数据库时遇到困难。我试图让我的应用程序在电话启动时启动，只有当数据库中的布尔值为true时，如果为false，它将不会在启动时启动应用程序。我有错误的底部

public class My_BroadcastReceiver extends BroadcastReceiver { 

SQLiteDatabase sqlDB; 
private static String DBNAME2 = "database2.db"; 
private static String Table2 = "options"; 

Boolean isOk = true; 
Context context; 

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


    try { 

     sqlDB = SQLiteDatabase.openOrCreateDatabase(DBNAME2, null); 

     Cursor r = sqlDB.rawQuery("SELECT Apponstart FROM " + Table2, null); 
     System.out.println("COUNT of Location: " + r.getCount()); 
     int loc = r.getColumnIndex("Apponstart"); 

     int j = 0; 
     if (r.moveToFirst()) { 
      do { 
       System.out.println("Apponstart is " + r.getString(loc)); 

       isOk = Boolean.parseBoolean(r.getString(loc)); 

       j++; 
      } while (r.moveToNext()); 
      if (j == 0) { 
       System.out.println("No data found"); 
      } 

     } 
     r.close(); 
     // sqlDB.close(); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } finally { 
     sqlDB.close(); 
    } 

    if(isOk){ 
     Intent i = new Intent(context, JoshTwoActivity.class);     
     i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);     
     context.startActivity(i); 
    } 
} 



09-23 08:10:05.615: WARN/System.err(208): android.database.sqlite.SQLiteException: unable to open database file 
     09-23 08:10:05.625: WARN/System.err(208):  at android.database.sqlite.SQLiteDatabase.dbopen(Native Method) 
     09-23 08:10:05.625: WARN/System.err(208):  at    android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1812) 
     09-23 08:10:05.625: WARN/System.err(208):  at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:817) 
     09-23 08:10:05.625: WARN/System.err(208):  at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:851) 
     09-23 08:10:05.625: WARN/System.err(208):  at three.three.My_BroadcastReceiver.onReceive(My_BroadcastReceiver.java:31) 
     09-23 08:10:05.625: WARN/System.err(208):  at android.app.ActivityThread.handleReceiver(ActivityThread.java:2810) 
     09-23 08:10:05.625: WARN/System.err(208):  at android.app.ActivityThread.access$3200(ActivityThread.java:125) 
      09-23 08:10:05.625: WARN/System.err(208):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2083) 
      09-23 08:10:05.625: WARN/System.err(208):  at android.os.Handler.dispatchMessage(Handler.java:99) 
      09-23 08:10:05.625: WARN/System.err(208):  at android.os.Looper.loop(Looper.java:123) 
      09-23 08:10:05.625: WARN/System.err(208):  at android.app.ActivityThread.main(ActivityThread.java:4627) 
      09-23 08:10:05.625: WARN/System.err(208):  at java.lang.reflect.Method.invokeNative(Native Method) 
      09-23 08:10:05.625: WARN/System.err(208):  at java.lang.reflect.Method.invoke(Method.java:521) 
     09-23 08:10:05.625: WARN/System.err(208):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
     09-23 08:10:05.625: WARN/System.err(208):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
     09-23 08:10:05.625: WARN/System.err(208):  at dalvik.system.NativeStart.main(Native Method) 

再次以

 09-23 08:10:06.046: ERROR/AndroidRuntime(208): FATAL EXCEPTION: main 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208): java.lang.RuntimeException: Unable to start receiver three.three.My_BroadcastReceiver: java.lang.NullPointerException 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at android.app.ActivityThread.handleReceiver(ActivityThread.java:2821) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at android.app.ActivityThread.access$3200(ActivityThread.java:125) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2083) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at android.os.Handler.dispatchMessage(Handler.java:99) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at android.os.Looper.loop(Looper.java:123) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at android.app.ActivityThread.main(ActivityThread.java:4627) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at java.lang.reflect.Method.invokeNative(Native Method) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at java.lang.reflect.Method.invoke(Method.java:521) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at dalvik.system.NativeStart.main(Native Method) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208): Caused by: java.lang.NullPointerException 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at three.three.My_BroadcastReceiver.onReceive(My_BroadcastReceiver.java:57) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  at android.app.ActivityThread.handleReceiver(ActivityThread.java:2810) 
     09-23 08:10:06.046: ERROR/AndroidRuntime(208):  ... 10 more 

Answer 1

数据库是问题。我创建了一个方法并为数据库的打开添加了上下文。这是我的解决方案。

public void guru(Context ctx){ 

    System.out.println("Flax"); 
    try { 
     Log.e("troll", "alol"); 
     sqlDB = ctx.openOrCreateDatabase(DBNAME2, 0,null); 
     //sqlDB = SQLiteDatabase.openOrCreateDatabase(DBNAME2, null);   
     Cursor r = sqlDB.rawQuery("SELECT Apponstart FROM " + Table2, null); 
     System.out.println("COUNT of Location: " + r.getCount()); 
     int loc = r.getColumnIndex("Apponstart"); 

     int j = 0; 
     if (r.moveToFirst()) { 
      do { 
       System.out.println("Apponstart is " + r.getString(loc)); 
       Log.d("happening", "here"); 
       isOk = Boolean.parseBoolean(r.getString(loc)); 

       j++; 
      } while (r.moveToNext()); 
      if (j == 0) { 
       System.out.println("No data found"); 
      } 

     } 
     r.close(); 
     // sqlDB.close(); 
    } catch (Exception e) { 
     e.printStackTrace(); 
     Log.e("exception", e.toString()); 
    } finally { 
     sqlDB.close(); 
    } 
} 

Answer 2

可能会需要更多的代码来解决这个问题，但我想这个问题有事情做与德的方式，接收器注册。你是用XML还是通过registerReceiver声明？这是不是接触到了？

阅读关于这个参考页面上的广播接收器的生命周期：http://developer.android.com/reference/android/content/BroadcastReceiver.html