Android学习笔记之SoftReference软引用,弱引用WeakReference

SoftReference可以用于bitmap缓存

WeakReference 可以用于handler

 非静态内部类和匿名内部类容易造成内存泄漏

    private Handler mRemoteHandler = new SafeHandler(this);
    private static final int INIT_UI = 1;

    /**
     * safe handler 静态内部类
     */
    private static class SafeHandler extends Handler {
        private final WeakReference<MainActivity> mActivitys;

        public SafeHandler(MainActivity preview) {
            mActivitys = new WeakReference<MainActivity>(preview);
        }

        @Override
        public void handleMessage(Message msg) {
            MainActivity activity = mActivitys.get();
            if (activity != null) {
                if (null != msg) {
                    switch (msg.what) {
                        case INIT_UI:
                            activity.initView();
                            activity.updateUI();
                            break;
                        default:
                            break;
                    }
                }
            }
        }
    }

import android.os.AsyncTask;
import android.text.TextUtils;

import com.roadrover.settings.network.NetSupplier;
import com.roadrover.settings.network.NetworkBean;
import com.roadrover.utils.Logcat;

import java.lang.ref.WeakReference;
import java.util.Arrays;

/**
不是内部类
 */
public class HotSpotSafeTask extends AsyncTask<Void, Void, String[]> {
    // 弱引用允许Activity被垃圾收集器清理
    private final WeakReference<HotSpotFragment> weakFragment;

    public HotSpotSafeTask(HotSpotFragment fragment) {
        this.weakFragment = new WeakReference<>(fragment);
    }

    @Override
    public String[] doInBackground(Void... params) {
        // do async stuff here
        // 重新获取Fragment的强引用，并且判断是否存活
        HotSpotFragment fragment = weakFragment.get();
        if (fragment == null || fragment.isDetached()) {
            // Fragment死亡了，不再做任何的事情
            return null;
        }
        String[] config = fragment.getWifiApConfig();
        return config;
    }

    @Override
    public void onPostExecute(String[] config) {
        // 重新获取Fragment的强引用，并且判断是否存活
        HotSpotFragment fragment = weakFragment.get();
        if (fragment == null || fragment.isDetached()) {
            // Fragment死亡了，不再做任何的事情
            return;
        }
        // The Fragment is still valid, do main-thread stuff here
        if ((config != null) && (config.length == 3)) {
            if (null != fragment) {
                Logcat.d("getWifiApConfig " + Arrays.toString(config));
                fragment.setName(config[0]);
                if (!TextUtils.isEmpty(config[1])) {
                    fragment.setPassword(config[1]);
                } 
            }
        }

    }
}