[Android]App 內存泄漏檢查工具MAT

Android App發生內存泄漏，常見的有Bitmap 使用後沒有recycle()，Drawable 使用後沒有setCallback(null)等。

Eclipse 有個插件工具MAT(Memory Analyzer Tool)能夠幫助定位內存泄漏的對象。

1. 安裝MAT Update site: http://archive.eclipse.org/mat/1.1/update-site/

2. 用DDMS工具Dump出問題App的.hprof文件 好比com.world.test2.hprof Dump以前最好先運行一下GC "Cause GC" , 確保dump出來的是還不能回收的對象等。

3. 用SDK tools下工具hprof-conv.exe 作轉換 hprof-conv com.world.test2.hprof appleak.hprof

4. 用Eclipse 「Open Head Dump」打開新轉換的.hprof 文件--appleak.hprof 查看圖形化界面，一個一個檢查懷疑的點。

總結： MAT tool不會直接告訴你哪裏內存泄漏，可是會列出懷疑的對象，須要你仔細檢查這些對象爲何沒有被釋放掉。

下面是測試code， 在Android 4.2.2上測試過。

1. 此種狀況能夠引發Activity沒法回收的狀況，由於直接用相似private static Activity a0引用建立的Activity,致使Activity沒法回收。

2. 此種狀況沒有引發Activity 沒法回收的狀況。 按理說這種狀況應該也會致使靜態Drawable 鎖定Activity, 引用關係mBackground1-->Button-->Activity. 待分析

   <!-- lang: java -->

   public class MainActivity extends Activity implements Button.OnClickListener{

   final private static String TAG = "MainActivity";

   private static Drawable mBackground1; private static Drawable mBackground2; private static Drawable mBackground3; private static Drawable mBackground4;

   private static Activity a0 ; private static Activity a1 ; private static Activity a2 ; private static Activity a3 ; private static Activity a4 ;

   /*

   • Shutdown intent */ private final String INTENT_ACTION_REQUEST_SHUTDOWN = "android.intent.action.ACTION_REQUEST_SHUTDOWN";

   @Override public void onCreate(Bundle savedInstanceState) { Log.v(TAG, "onCreate Activity="+this); super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);

   //1
    if(false){
    if(a0 == null){
    	a0 = this;
    	Log.v(TAG, "onCreate  Activity a0="+a0);
    }
    else if(a1 == null){
    	a1 = this;
    	Log.v(TAG, "onCreate  Activity a1="+a1);
    }
    else if(a2 == null){
    	a2 = this;
    	Log.v(TAG, "onCreate  Activity a2="+a2);
    }
    else if(a3 == null){
    	a3 = this;
    	Log.v(TAG, "onCreate  Activity a3="+a3);
    }
    else if(a4 == null){
    	a4 = this;
    	Log.v(TAG, "onCreate  Activity a4="+a4);
    }
    }
   
   
    //set up button listener
    Button myButton = (Button)findViewById(R.id.button_poweroff);
    myButton.setOnClickListener(this);
   
   
    myButton = (Button)findViewById(R.id.button_reboot);
    myButton.setOnClickListener(this);
   
    //2
    if (mBackground1 == null) {  
    	Log.v(TAG, "onCreate  mBackground1");
        mBackground1 = getResources().getDrawable(R.drawable.adbroot_004);  
        myButton.setBackgroundDrawable(mBackground1);
    }
    else if(mBackground2 == null){
    	Log.v(TAG, "onCreate  mBackground2");
    	mBackground2 = getResources().getDrawable(R.drawable.test002);
    	myButton.setBackgroundDrawable(mBackground2);
    }
    else if(mBackground3 == null){
    	Log.v(TAG, "onCreate  mBackground3");
    	mBackground3 = getResources().getDrawable(R.drawable.test003);
    	myButton.setBackgroundDrawable(mBackground3);
    }
    else if(mBackground4 == null){
    	Log.v(TAG, "onCreate  mBackground4");
    	mBackground4 = getResources().getDrawable(R.drawable.adbroot_003);
    	myButton.setBackgroundDrawable(mBackground4);
    }

   }