Android 如何安全地关闭Activity

方法一：使用缓存

1、创建BaseActivity继承ActionBarActivity
2、定义缓存

private List<BaseActivity> mActivities = new LinkedList<BaseActivity>();
public static BaseActivity activity;

3、在onCreate里添加activity

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); 
        synchronized (mActivities) {
            mActivities.add(this);
        }
}

4、在onPause把activity置空

@Override
    protected void onPause() {
        activity = null;
        super.onPause();
    }

5、在onResume赋值

@Override
    protected void onResume() {
        activity = this;
        super.onResume();
    }

6、在onDestroy方法里移除

@Override
    protected void onDestroy() {
        synchronized (mActivities) {
            mActivities.remove(this);
        }
            super.onDestroy();
    }

7、定义方法，用来关闭所有的activity，因为mActivities是正在使用的，不能关闭，如何关闭呢?
可以创建一个拷贝类，代码如下：

/**
     * 关闭所有的activity
     */
    public void finishAll() {
        List<BaseActivity> copyActivities = null;
        synchronized (mActivities) {
            copyActivities = new LinkedList<BaseActivity>(mActivities);
        }
        if (copyActivities != null && copyActivities.size() > 0) {
            for (BaseActivity activity : copyActivities) {
                activity.finish();
            }
            android.os.Process.killProcess(android.os.Process.myPid());
        }
    }

8、使用方法：
在项目中的每个方法都继承BaseActivity
然后在MainActivity里写方法：

@Override
     public boolean dispatchKeyEvent(KeyEvent event) {
       if (event.getAction()==KeyEvent.ACTION_DOWN&&event.getKeyCode()==KeyEvent.KEYCODE_BACK) {
        new AlertDialog.Builder(this)
               .setCancelable(false)
               .setTitle("温馨提示")
               .setMessage("您确定要退出吗?")
               .setPositiveButton("确定",new DialogInterface.OnClickListener() {
                   public void onClick(DialogInterface dialog, int which) { 
                       //关闭所有的activity
                       finishAll();
                   }
               })
               .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                   public void onClick(DialogInterface dialog, int which) { 

                   }
               }).show();
        return true;
      }

      return super.dispatchKeyEvent(event);

     }

9、全部代码：

package com.android.shop;

import java.util.LinkedList;
import java.util.List;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.widget.Toast;

/**
 * @描述 基础activity
 * @项目名称 App_Shop
 * @包名 com.android.shop
 * @类名 BaseActivity
 * @author chenlin
 * @date 2013-3-25 下午10:47:47
 * @version 1.0
 */

public abstract class BaseActivity extends ActionBarActivity {
    public final static  String KILLACTION= "com.android.killreceiver";
    public static BaseActivity activity;

    private List<BaseActivity> mActivities = new LinkedList<BaseActivity>();
    private KillReceiver mReceiver;

    private class KillReceiver extends BroadcastReceiver{
        @Override
        public void onReceive(Context context, Intent intent) {
            finish();
        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);     
        synchronized (mActivities) {
            mActivities.add(this);
        }

        init();
        initViews();
        initActionBar();
        initEvents();
    }

    //---onPause --onResume  用来判断activity是否存在--------在util.startActivity里使用--------------------------------

    @Override
    protected void onPause() {
        activity = null;
        super.onPause();
    }

    @Override
    protected void onResume() {
        activity = this;
        super.onResume();
    }

    /**
     * 关闭所有的activity
     */
    public void finishAll() {
        List<BaseActivity> copyActivities = null;
        synchronized (mActivities) {
            copyActivities = new LinkedList<BaseActivity>(mActivities);
        }
        if (copyActivities != null && copyActivities.size() > 0) {
            for (BaseActivity activity : copyActivities) {
                activity.finish();
            }
            android.os.Process.killProcess(android.os.Process.myPid());
        }
    }

    public abstract void init();
    public abstract void initViews();


    protected void initEvents() {

    }

    protected void initActionBar() {
    }

    public void toast(String text){
        Toast.makeText(getApplicationContext(), text, Toast.LENGTH_LONG).show();
    }

    public void alert(final String text){
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(getApplicationContext(), text, Toast.LENGTH_LONG).show();
            }
        });

    }



    @Override
    protected void onDestroy() {
        synchronized (mActivities) {
            mActivities.remove(this);
        }

        super.onDestroy();
    }
}

方法二：使用广播

1、创建BaseActivity继承ActionBarActivity
2、创建广播：

private class KillReceiver extends BroadcastReceiver{
        @Override
        public void onReceive(Context context, Intent intent) {
            finish();
        }
    }

3、在oncreate方法里注册广播

public final static  String KILLACTION= "com.android.killreceiver";
KillReceiver mReceiver = new KillReceiver();
registerReceiver(mReceiver, new IntentFilter(KILLACTION));

4、在ondestroy里取消广播

@Override
    protected void onDestroy() {        
        if (mReceiver != null) {
            unregisterReceiver(mReceiver);
            mReceiver = null;
        }

        super.onDestroy();
    }

5、让每个activity继承baseActivity
在oncreate方法里发送广播关闭activity

sendBroadcast(new Intent(KILLACTION));