Android-Fragment中TextView.setFocusable(true)导致的内存泄露

转载请标明出处：http://blog.csdn.net/goldenfish1919/article/details/38272305

问题是这样的，页面中有EditText，为了让EditText失去焦点，只能让页面上的一个TextView获取焦点，因此设置了某个TextView的focusable和focusable都是true。但是很悲剧的是竟然出了内存泄露！复现代码：

MainActivity.java

public class MainActivity extends FragmentActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);openFragmentFoo();}public void openFragmentFoo(){FragmentManager m = getSupportFragmentManager();FragmentTransaction ft = m.beginTransaction();ft.replace(R.id.fragment_container, new FooFragment());ft.commit();}public void openFragmentBar(){FragmentManager m = getSupportFragmentManager();FragmentTransaction ft = m.beginTransaction();ft.replace(R.id.fragment_container, new BarFragment());ft.addToBackStack(null);ft.commit();}public void openFragmentThird(){FragmentManager m = getSupportFragmentManager();FragmentTransaction ft = m.beginTransaction();ft.replace(R.id.fragment_container, new ThirdFragment());ft.addToBackStack(null);ft.commit();}}

main.xml:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"       android:id="@+id/fragment_container"       android:layout_width="match_parent"       android:layout_height="match_parent">        /></FrameLayout>

FooFragment.java

public class FooFragment extends Fragment {    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,      Bundle savedInstanceState) {      View view = inflater.inflate(R.layout.fragment_foo, container, false);      Button btn = (Button)view.findViewById(R.id.button1);      btn.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {MainActivity main = (MainActivity)getActivity();main.openFragmentBar();}      });      return view;    }}

fragment_foo.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"     android:layout_height="match_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/textView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="foo" />     <Button        android:id="@+id/button1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="button" /></LinearLayout>

BarFragment.java:

public class BarFragment extends Fragment {private static final String tag = "BarFragment";private TextView textview2;@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {View view = inflater.inflate(R.layout.fragment_bar, container, false);textview2 = (TextView) view.findViewById(R.id.textView2);<span style="color:#ff0000;">textview2.requestFocus();</span>Button btn = (Button) view.findViewById(R.id.button2);btn.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {MainActivity main = (MainActivity) getActivity();main.openFragmentThird();}});return view;}@Overridepublic void onDestroyView() {// http://stackoverflow.com/questions/5038158/main-activity-is-not-garbage-collected-after-destruction-because-it-is-reference/23889598#23889598<span style="color:#ff0000;">fixInputMethodManager();</span>// ViewrootImpl:http://blog.csdn.net/gemmem/article/details/9967295<span style="color:#ff6666;">fixInputEventReceiver();</span>super.onDestroyView();}@Overridepublic void onDestroy() {super.onDestroy();    Log.e(tag, "BarFragment onDestroy");}@Overridepublic void onDetach() {super.onDetach();    Log.e(tag, "BarFragment onDetach");}private void fixInputEventReceiver() {View rootView = textview2.getRootView();//这个是PhoneWindow$DecorViewViewParent viewRootImpl = rootView.getParent();TypedObject param = new TypedObject(rootView, View.class);invokeMethodExceptionSafe(viewRootImpl, "clearChildFocus", param);}private void fixInputMethodManager() {final InputMethodManager imm = (InputMethodManager)this.getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);final TypedObject windowToken = new TypedObject(this.getActivity().getWindow().getDecorView().getWindowToken(), IBinder.class);invokeMethodExceptionSafe(imm, "windowDismissed", windowToken);final TypedObject view = new TypedObject(null,View.class);invokeMethodExceptionSafe(imm, "startGettingWindowFocus", view);}public static final class TypedObject {private final Object object;private final Class<?> type;public TypedObject(final Object object, final Class<?> type) {this.object = object;this.type = type;}Object getObject() {return object;}Class<?> getType() {return type;}}public static void invokeMethodExceptionSafe(final Object methodOwner,final String method, final TypedObject... arguments) {if (null == methodOwner) {return;}try {final Class<?>[] types = null == arguments ? new Class[0]: new Class[arguments.length];final Object[] objects = null == arguments ? new Object[0]: new Object[arguments.length];if (null != arguments) {for (int i = 0, limit = types.length; i < limit; i++) {types[i] = arguments[i].getType();objects[i] = arguments[i].getObject();}}final Method declaredMethod = methodOwner.getClass().getDeclaredMethod(method, types);declaredMethod.setAccessible(true);declaredMethod.invoke(methodOwner, objects);} catch (final Throwable ignored) {}}}

fragment_bar.xml：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/layout"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="vertical" >    <TextView        android:id="@+id/textView2"        android:layout_width="wrap_content"        android:layout_height="100dp"        android:text="bar"         <span style="color:#ff0000;">android:focusable="true"        android:focusableInTouchMode="true"</span>/>    <Button        android:id="@+id/button2"        android:layout_width="wrap_content"        android:layout_height="100dp"        android:text="button2" /></LinearLayout>

ThirdFragment.java:

public class ThirdFragment extends Fragment {    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,      Bundle savedInstanceState) {      View view = inflater.inflate(R.layout.fragment_third, container, false);      return view;    }}

fragment_third.xml:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"     android:layout_height="match_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/textView3"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="third" />    <Button        android:id="@+id/button3"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="button3" /></LinearLayout>

MainActivity首先是显示FooFragment，然后点击跳转到BarFragment，然后点击跳转到ThirdFragment，然后点击back->back->回到FooFragment，这个时候BarFragment和ThirdFragment肯定已经是被destroy了，控制台有输出。

假如在BarFragment的onDestroyView()中不调用fixInputMethodManager();和fixInputEventReceiver();，dump内存文件：

然后参考：http://stackoverflow.com/questions/5038158/main-activity-is-not-garbage-collected-after-destruction-because-it-is-reference/23889598#23889598

加入：fixInputMethodManager();

结果还是有：

同样的道理，继续反射之，加入：fixInputEventReceiver();终于不再泄露了。

看上去，TextView设置为focusable=true以后，InputMethodManager会把它记录为当前获取焦点的view，mNextServedView应该是点击next的时候获取焦点的view，但是，在Fragment销毁的时候，并没有通知InputMethodManager去删掉view的引用。WindowInputEventReceiver就比较坑爹了，它是ViewRootImpl的内部类，直接持有对外部类的引用，导致ViewRootImpl没有释放，而ViewRootImpl也会记录当前获取焦点的view，同样在fragment销毁的时候，引用没有被销毁！