Android 中常见的内存泄露

最新推荐文章于 2025-03-12 22:07:06 发布

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本文详细解析了Android开发中常见的内存泄漏问题，包括单例模式、非静态内部类、Handler、线程及WebView引起的内存泄漏，并提供了相应的解决方案。

1.单例造成的内存泄漏

public class SingletonActivityContext {
    private static SingletonActivityContext instance;
    private Context context;

    private SingletonActivityContext(Context context) {
        this.context = context;
    }
//正确写法
  private SingletonAppliationContext(Context context) {
        this.context = context.getApplicationContext();// 使用Application 的context
    }

    public static SingletonActivityContext getInstance(Context context) {
        if (instance == null) {
            instance = new SingletonActivityContext(context);
        }
        return instance;
    }
}

单例的生命周期和应用的一样长
SingletonActivityContext 的构造方法如果传入的是activity 当activity关闭的时候，无法被回收，因为SingletonActivityContext持有activity的引用；

2.非静态内部类创建静态实例造成的内存泄漏

public class StaticLeakActivity extends Activity {
    private static noneStaticClass mResource = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (mResource == null) {
            mResource = new noneStaticClass();
        }

    }

     private class noneStaticClass {

    }


}

非静态内部类noneStaticClass 默认会持有StaticLeakActivity的引用；
非静态内部类noneStaticClass又创建了一个静态实例，该静态实例生命周期根应用一样长，StaticLeakActivity无法被内存回收。

解决方案，将非静态内部类改为静态内部类即可

     private static class noneStaticClass {

    }

3.handler造成内存泄漏

public class HandlerLeakActivity extends Activity {
    private final Handler mLeakyHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {

        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mLeakyHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
            }
        }, 1000 * 60 * 10);

        finish();
    }
    /*
    * 解决办法：
    * 1.将 Handler 声明为静态的
    * 2.通过弱引用的方式引入 Activity
    *
    * */
}

此时关闭activity 由于message 持有handle引用 handle 持有Activity 导致activity不能被回收。

4.线程造成的内存泄漏

public class ThreadLeakActivity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        testThreadLeak();
    }

    private void testThreadLeak() {
        new AsyncTask<Void, Void, Void>() {
            @Override
            protected Void doInBackground(Void... params) {
                SystemClock.sleep(10000);
                return null;
            }
        }.execute();

        new Thread(new Runnable() {
            @Override
            public void run() {
                SystemClock.sleep(10000);
            }
        }).start();
    }

    static class MyAsyncTask extends AsyncTask<Void, Void, Void> {
        private WeakReference<Context> weakReference;

        public MyAsyncTask(Context context) {
            weakReference = new WeakReference<>(context);
        }

        @Override
        protected Void doInBackground(Void... params) {
            SystemClock.sleep(10000);
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            super.onPostExecute(aVoid);
            ThreadLeakActivity activity = (ThreadLeakActivity) weakReference.get();
            if (activity != null) {
                //...
            }
        }
    }

    static class MyRunnable implements Runnable {
        @Override
        public void run() {
            SystemClock.sleep(10000);
        }
    }
}

导致内存泄漏的原因：非静态内部类创建静态实例造成的内存泄漏

5.Webview造成的内存泄漏

public class WebviewLeakActivity extends AppCompatActivity {
    private WebView mWebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mWebView = (WebView) findViewById(R.id.wv_show);
        mWebView.loadUrl("http://www.baidu.com");
    }


    @Override
    protected void onDestroy() {
        destroyWebView();
        android.os.Process.killProcess(android.os.Process.myPid());
        super.onDestroy();
    }

    private void destroyWebView() {
        if (mWebView != null) {
            mWebView.pauseTimers();
            mWebView.removeAllViews();
            mWebView.destroy();
            mWebView = null;
        }
    }

}