dependencies {
  debugCompile 'com.squareup.leakcanary:leakcanary-android:1.5.1'
  releaseCompile 'com.squareup.leakcanary:leakcanary-android-no-op:1.5.1'
}

public class AppApplication extends Application {
  @Override
  public void onCreate() {
    super.onCreate();
    if (LeakCanary.isInAnalyzerProcess(this)) {
      // This process is dedicated to LeakCanary for heap analysis.
      // You should not init your app in this process.
      return;
    }
    LeakCanary.install(this);
    // Normal app init code...
  }

}

public class App extends Application {
  //Application为整个应用保存全局的RefWatcher
  private RefWatcher refWatcher;

  @Override
  public void onCreate() {
    super.onCreate();
    refWatcher = LeakCanary.install(this);
  }

  public static RefWatcher getRefWatcher(Context context) {
    App application = (App) context.getApplicationContext();
    return application.refWatcher;
  }
}

public abstract class BaseFragment extends Fragment {
  @Override
  public void onDestroy() {
    super.onDestroy();
    RefWatcher refWatcher = App.getRefWatcher(getActivity());
    refWatcher.watch(this);
  }
}

public class TestHelper {
  private Context mCtx;
  private TextView mTextView;

  private static TestHelper ourInstance = null;
  private TestHelper(Context context) {
    this.mCtx = context;
  }

  public static TestHelper getInstance(Context context) {
    if (ourInstance == null) {
      ourInstance = new TestHelper(context);
    }
    return ourInstance;
  }
}

public class ContextLeakActivity extends AppCompatActivity{

   private TestHelper mTestHelper;
  @Override
  protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //这里容易引起内存泄漏
    //我们在 ContextLeakActivity 里获取 TestHelper 实例时因为传入了 MainActivity 的 Context，
    // 这使得一旦这个 Activity 不在了之后，
    // TestHelper 依然会 hold 住它的 Context 不放，而这个时候因为 Activity 已经不在了，所以内存泄露自然就产生了。
    mTestHelper=TestHelper.getInstance(this);
    //避免内存泄漏的写法
    // mTestHelper=TestHelper.getInstance(this.getApplication());
  }
}

@Override
  protected void onDestroy() {
    super.onDestroy();
    getLocalBroadcastManager().unregisterReceiver(mExitReceiver);
  }