package chroya.demo; 

import java.lang.reflect.Constructor; 
import java.lang.reflect.Field; 
import java.lang.reflect.InvocationTargetException; 
import java.util.concurrent.CountDownLatch; 

import android.app.Activity; 
import android.content.Context; 
import android.content.pm.PackageStats; 
import android.content.pm.PackageManager.NameNotFoundException; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.util.Log; 

public class Main extends Activity { 
    private PackageStats ps; 

    public void getPackageStats(String packageName) { 
        try { 
            //獲取setting包的的Context 
            Context mmsCtx = createPackageContext("com.android.settings", 
                    Context.CONTEXT_INCLUDE_CODE | Context.CONTEXT_IGNORE_SECURITY); 
            //使用setting的classloader加載com.android.settings.ManageApplications類 
            Class<?> maClass = Class.forName("com.android.settings.ManageApplications", true, mmsCtx.getClassLoader()); 
            //創建它的一個對象 
            Object maObject = maClass.newInstance(); 

            /*
             * 將私有域mPm賦值。因為mPm在SizeObserver的invokeGetSize中用到了，
             * 卻因為沒有執行onCreate而沒有初始化，所以要在此處初始化。
             */ 
            Field f_mPm = maClass.getDeclaredField("mPm"); 
            f_mPm.setAccessible(true);             
            f_mPm.set(maObject, mmsCtx.getPackageManager()); 

            /*
             * 給mHandler賦值為重新定義的Handler，以便接收SizeObserver的
             * onGetStatsCompleted回調方法中dispatch的消息，從中取PackageStats對象。
             * */ 
            Field f_mHandler = maClass.getDeclaredField("mHandler"); 
            f_mHandler.setAccessible(true); 
            f_mHandler.set(maObject, new Handler() { 
                  public void handleMessage(Message msg) { 
                      if(msg.what == 1) { 
                          //此處獲取到PackageStats對象 
                          ps = (PackageStats) msg.getData().getParcelable("ApplicationPackageStats");                          
                          Log.d("", ""+ps.codeSize);                           
                      } 
                  } 
            }); 

            //加載內部類SizeObserver 
            Class<?> sizeObserverClass = Class.forName("com.android.settings.ManageApplications$SizeObserver", true, mmsCtx.getClassLoader()); 
            Constructor sizeObserverConstructor = sizeObserverClass.getDeclaredConstructors()[0]; 
            sizeObserverConstructor.setAccessible(true); 
            /*
             * 創建SizeObserver對象，兩個參數，第一個是外部類的對象，
             * 也就是ManageApplications對象，第二個是msgId，也就是
             * 分發消息的id，跟Handler接收的msgId一樣。
             * */ 
            Object soObject = sizeObserverConstructor.newInstance(maObject, 1); 
            //執行invokeGetSize方法 
            sizeObserverClass.getMethod("invokeGetSize", String.class, 
                    CountDownLatch.class).invoke(soObject, packageName, new CountDownLatch(1));          
        } catch (NameNotFoundException e) { 
            e.printStackTrace(); 
        } catch (ClassNotFoundException e) { 
            e.printStackTrace(); 
        } catch (IllegalAccessException e) { 
            e.printStackTrace(); 
        } catch (IllegalArgumentException e) { 
            e.printStackTrace(); 
        } catch (SecurityException e) { 
            e.printStackTrace(); 
        } catch (InvocationTargetException e) { 
            e.printStackTrace(); 
        } catch (NoSuchMethodException e) { 
            e.printStackTrace(); 
        } catch (InstantiationException e) { 
            e.printStackTrace(); 
        } catch (NoSuchFieldException e) { 
            e.printStackTrace(); 
        } 
    } 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState);   
        getPackageStats("chroya.demo");        
    } 
}