android - Leakcanary 使用 AppCompatActivity 和 FragmentStatePagerAdapter 显示 fragment 泄漏

Question

这个问题我已经有一段时间了，我真的不知道还能尝试什么。我在我的项目中加入了 Leakcanary，这样我就可以强制自己“以正确的方式”学习 android，而不会选择导致内存泄漏的模式。我正在构建一个应用程序，我已经将它剥离了很多，但我仍然看到这种泄漏正在发生。

我有一个 Activity，里面有一个 viewpager 并实例化了 10 个 fragment 。如果我打开设备，一切似乎都很好，直到我按下“Home”，我才得到以下内存泄漏:

D/LeakCanary﹕ In com.doesnthaveadomain.leo.calendartracker:1.0:1.
D/LeakCanary﹕ * com.doesnthaveadomain.leo.calendartracker.MyFragment has leaked:
D/LeakCanary﹕ * GC ROOT static android.view.WindowManagerGlobal.sDefaultWindowManager
D/LeakCanary﹕ * references android.view.WindowManagerGlobal.mRoots
D/LeakCanary﹕ * references java.util.ArrayList.array
D/LeakCanary﹕ * references array java.lang.Object[].[0]
D/LeakCanary﹕ * references android.view.ViewRootImpl.mInvalidateOnAnimationRunnable
D/LeakCanary﹕ * references android.view.ViewRootImpl$InvalidateOnAnimationRunnable.mViews
D/LeakCanary﹕ * references java.util.ArrayList.array
D/LeakCanary﹕ * references array java.lang.Object[].[0]
D/LeakCanary﹕ * references android.support.v4.view.ViewPager.mAdapter
D/LeakCanary﹕ * references com.doesnthaveadomain.leo.calendartracker.MyAdapter.mCurrentPrimaryItem
D/LeakCanary﹕ * leaks com.doesnthaveadomain.leo.calendartracker.MyFragment instance

主要 Activity :

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;

import java.lang.ref.WeakReference;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ViewPager mViewPager = (ViewPager) findViewById(R.id.viewpager);
        MyAdapter myAdapter = new MyAdapter(getSupportFragmentManager(), this);
        mViewPager.setAdapter(myAdapter);
        mViewPager.setCurrentItem(5);
    }

}

class MyAdapter extends FragmentStatePagerAdapter {

    private int mNumberOfViews;
    private final WeakReference<AppCompatActivity> mActivityWeakRef;

    public MyAdapter(FragmentManager fm,
                     AppCompatActivity activity) {
        super(fm);

        mActivityWeakRef = new WeakReference<AppCompatActivity>(activity);
        mNumberOfViews = 10;
    }

    @Override
    public Fragment getItem(int position) {
        MyFragment myFragment = new MyFragment();
        AppCompatActivity activity = mActivityWeakRef.get();
        if (activity != null) {
            MyApp.getRefWatcher(mActivityWeakRef.get()).watch(myFragment);
        }
        return myFragment;
    }

    @Override
    public int getCount() {
        return mNumberOfViews;
    }
}

主要 Activity 布局:

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <android.support.design.widget.AppBarLayout
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/toolbar_appbar_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:fitsSystemWindows="true" >

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways"
            app:theme="@style/AppTheme.Toolbar"
            app:popupTheme="@style/AppTheme.Toolbar.Popup">

        </android.support.v7.widget.Toolbar>

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

fragment :

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * A placeholder fragment containing a simple view.
 */
public class MyFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_test, container, false);
    }

}

fragment 布局:

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingLeft="@dimen/activity_vertical_margin"
    android:paddingStart="@dimen/activity_vertical_margin"
    android:paddingRight="@dimen/activity_vertical_margin"
    android:paddingEnd="@dimen/activity_vertical_margin"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android">

</LinearLayout>

Answer 1

与我的其他问题相同，我在错误的时间初始化 ref watcher，在 fragment 创建时而不是在销毁时:https://stackoverflow.com/a/32881096/5278339