android中雙擊退出程序的幫助類

package com.csdn.sunyudoong.csdn.ui;

import android.app.Activity;
import android.os.Handler;
import android.os.Looper;
import android.view.KeyEvent;
import android.widget.Toast;

import com.csdn.sunyudoong.csdn.AppManager;
import com.csdn.sunyudoong.csdn.R;


/**
 * 雙擊退出
 * Created by sunyudong on 2016/6/6.
 */
public class DoubleClickExitHelper {
    private final Activity mActivity;
    //是否退出
    private  boolean isOnKeyBacking;
    private Handler mHandler;
    private Toast mBackToast;

    public DoubleClickExitHelper(Activity activity) {
        mActivity = activity;
        mHandler = new Handler(Looper.getMainLooper());
    }
    /**
     * Activity onKeyDown事件
     * */
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(keyCode != KeyEvent.KEYCODE_BACK) {
            return false;
        }
        if(isOnKeyBacking) {
        //第二次點擊返回鍵
            mHandler.removeCallbacks(onBackTimeRunnable);
            if(mBackToast != null){
                mBackToast.cancel();
            }
            // 退出
            AppManager.getAppManager().AppExit(mActivity);
            return true;
        } else {
        //第一次點擊
            isOnKeyBacking = true;
            if(mBackToast == null) {
                mBackToast = Toast.makeText(mActivity, "再次點擊退出開源中國", Toast.LENGTH_SHORT);
            }

            mBackToast.show();
            //延遲兩秒
            mHandler.postDelayed(onBackTimeRunnable, 2000);
            return true;
        }
    }
    private Runnable onBackTimeRunnable = new Runnable() {
//兩秒過後執行的事情
        @Override
        public void run() {
            isOnKeyBacking = false;
            if(mBackToast != null){
                mBackToast.cancel();
            }
        }
    };

}

調用方式，在需要調用的activity中的onKeyDown方法中調用
下面我是簡寫的，大家應該能夠看懂，在一個activity中先定義對象
然後調用對象的方法

   private DoubleClickExitHelper mDoubleClickExit;

   mDoubleClickExit = new DoubleClickExitHelper(this);

  @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            // 是否退出應用

       return mDoubleClickExit.onKeyDown(keyCode, event);

        }
        return super.onKeyDown(keyCode, event);
    }