Android WeakDataHolder保存數據

弱引用方式保存數據，防止內存泄漏

import java.lang.ref.WeakReference;
import java.util.HashMap;
import java.util.Map;


public class WeakDataHolder {
    private static WeakDataHolder instance;

    public static WeakDataHolder getInstance(){
        if(instance == null){
            synchronized (WeakDataHolder.class) {
                if (instance == null) {
                    instance = new WeakDataHolder();
                }
            }
        }
        return instance;
    }

    private Map<String, WeakReference<Object>> map = new HashMap<>();

    /**
     * 數據存儲
     * @param id
     * @param object
     */
    public void saveData(String id, Object object) {
        map.put(id, new WeakReference<>(object));
    }

    /**
     * 獲取數據
     * @param id
     * @return
     */
    public Object getData(String id) {
        WeakReference<Object> weakReference = map.get(id);
        return weakReference.get();
    }
}