Android Handler内存泄漏和解决方法_handler 移除消息后还能收到消息-优快云博客

本文链接：https://blog.youkuaiyun.com/chenhande1990chenhan/article/details/95318207

博客主要介绍了Android中Handler内存泄漏的相关内容。阐述了其内存泄漏的原因，即非静态内部类Handler持有外部Activity引用，Activity结束时无法回收。还列举了几种泄漏情况，如隐式引用等，并给出解决方法，如用static修饰、添加弱引用等。

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一、Handler内存泄漏原因

handler发送的消息在当前handler的消息队列中，如果此时activity finish掉了，那么消息队列的消息依旧会由handler进行处理，若此时handler声明为内部类（非静态内部类），我们知道内部类天然持有外部类的实例引用，那么就会导致activity无法回收，进而导致activity泄露。

二、Handler内存泄漏几种情况
1、隐式引用

public class CameraVerifyActivity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }
    
    private class MyHandle extends Handler {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
    }
}

2、显示引用

public class CameraVerifyActivity extends Activity {
    MyHandle myHandler;
    
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        myHandle = new MyHandle(this);
    }
    
    private class MyHandle extends Handler {

        public MyHandle(Activity activity) {
        }
        
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
    }
}

3、Handle调用Runnable

public class CameraVerifyActivity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }
    class MyRunnable implements Runnable {
        private View view;
        public MyRunnable(View view) {
            this.view = view;
        }
        public void run() {
            // ... do something with the view
        }
    }
}

三、Handler内存泄漏解决方法

1、针对1（添加static）：

public class CameraVerifyActivity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }
    
    private static class MyHandle extends Handler {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
    }
}

2、针对2（添加弱引用）：

public class CameraVerifyActivity extends Activity {
    MyHandle myHandler;
    
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        myHandle = new MyHandle(this);
    }
    
    private static class MyHandle extends Handler {

        private WeakReference<CameraVerifyActivity> reference;


        MyHandle(CameraVerifyActivity activity) {
            reference = new WeakReference<CameraVerifyActivity>(activity);
        }
        
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
    }
}

3、同2一样

四、Handler内存泄漏总结

1.使用static 修饰的handler，但是一般会弱引用activity对象，因为要使用activity对象中的成员
2.单独定义handler，同样可以弱引用activity
3.使用内部类的handler，在onDestroy方法中removeCallbacksAndMessages