Android优化笔记-LeakCanary使用及浅析

 

LeakCanary使用及浅析

基本使用步骤:

添加依赖:

implementation 'com.squareup.leakcanary:leakcanary-android:1.5'

import com.squareup.leakcanary.LeakCanary;
import com.squareup.leakcanary.RefWatcher;
public class MyApplication extends Application {
    RefWatcher refWatcher;
    @Override
    public void onCreate() {
        super.onCreate();
        refWatcher = LeakCanary.install(this);
        refWatcher.watch(this);
    }
}

从入口开始分析:

1   public static RefWatcher install(Application application) {
      return refWatcher(application).listenerServiceClass(DisplayLeakService.class)
        .excludedRefs(AndroidExcludedRefs.createAppDefaults().build())
        .buildAndInstall();
  }

 1.1 
  listenerServiceClass(DisplayLeakService.class)
  绑定DisplayLeakService 服务类，这个类负责将内存泄漏的消息通知给你

public class DisplayLeakService extends AbstractAnalysisResultService {
  @Override protected final void onHeapAnalyzed(HeapDump heapDump, AnalysisResult result) {
 pendingIntent = DisplayLeakActivity.createPendingIntent(this, heapDump.referenceKey);
}
DisplayLeakActivity.java
public static PendingIntent createPendingIntent(Context context, String referenceKey) {
    Intent intent = new Intent(context, DisplayLeakActivity.class);
    intent.putExtra(SHOW_LEAK_EXTRA, referenceKey);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
    return PendingIntent.getActivity(context, 1, intent, FLAG_UPDATE_CURRENT);
  }

1.2 
  excludedRefs(AndroidExcludedRefs.createAppDefaults().build())
  排除开发中可以忽略的泄漏路径(一般是系统级别BUG)，这些枚举在AndroidExcludedRefs这个类当中定义 

1.3
  buildAndInstall();
  public RefWatcher buildAndInstall() {
    RefWatcher refWatcher = build();
    if (refWatcher != DISABLED) {
      LeakCanary.enableDisplayLeakActivity(context);
      ActivityRefWatcher.installOnIcsPlus((Application) context, refWatcher);
    }
    return refWatcher;
  }
  实例化refWatcher 这个对象用来判断泄露对象
  ActivityRefWatcher.java
  
  public static void installOnIcsPlus(Application application, RefWatcher refWatcher) {
    if (SDK_INT < ICE_CREAM_SANDWICH) {
      // If you need to support Android < ICS, override onDestroy() in your base activity.
      return;
    }
    ActivityRefWatcher activityRefWatcher = new ActivityRefWatcher(application, refWatcher);
    activityRefWatcher.watchActivities();
  }
   public void watchActivities() {
    // Make sure you don't get installed twice.
    stopWatchingActivities();
    application.registerActivityLifecycleCallbacks(lifecycleCallbacks);
  }
private final Application.ActivityLifecycleCallbacks lifecycleCallbacks =
      new Application.ActivityLifecycleCallbacks() {
        @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
        }

       ...
        @Override public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
        }

        @Override public void onActivityDestroyed(Activity activity) {
          ActivityRefWatcher.this.onActivityDestroyed(activity);
        }
      };
   这个地方是关键，通过application注册监听，统一管理activity的生命周期，LeakCanay是在onDestory()方法实现对Activity监控.

2  refWatcher.watch(this);
  
  RefWatcher.java
  
  public void watch(Object watchedReference, String referenceName) {
    if (this == DISABLED) {
      return;
    }
    checkNotNull(watchedReference, "watchedReference");
    checkNotNull(referenceName, "referenceName");
    final long watchStartNanoTime = System.nanoTime();
    String key = UUID.randomUUID().toString();
    retainedKeys.add(key);
    final KeyedWeakReference reference =
        new KeyedWeakReference(watchedReference, key, referenceName, queue);

    ensureGoneAsync(watchStartNanoTime, reference);
  }
  
  final class KeyedWeakReference extends WeakReference