android 退出机制

android sdk 退出机制的研究 有多种，

方法一、用list保存activity实例，然后逐一干掉

上代码:

import java.util.LinkedList;
import java.util.List;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Application;
import android.content.DialogInterface;
import android.content.Intent;

public class SysApplication extends Application {
    private List<Activity> mList = new LinkedList<Activity>();
    private static SysApplication instance;

    private SysApplication() {  
    }

    public synchronized static SysApplication getInstance() {
        if (null == instance) {
            instance = new SysApplication();
        }
        return instance;
    }

    // add Activity 
    public void addActivity(Activity activity) {
        mList.add(activity);
    }

    public void exit() {
        try {
            for (Activity activity : mList) {
                if (activity != null)
                    activity.finish();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.exit(0);
        }
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();    
        System.gc();
    }

}

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);     
    SysApplication.getInstance().addActivity(this);
}
public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState); 
  SysApplication.getInstance().addActivity(this);
}

SysApplication.getInstance().exit();
SysApplication.getInstance().exit();

简而言之，通过单例模式把每个Activity 的引用添加到一个全局链表中，每次退出程序调用System.exit(0)时，先调用链表中Activity 的finish方法

方法二、使用广播

ActivityManager manager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
manager.killBackgroundProcesses(package);

android.os.Process.killProcess(android.os.Process.myPid());

manager.restartPackage(package);

Intent MyIntent = new Intent(Intent.ACTION_MAIN);
MyIntent.addCategory(Intent.CATEGORY_HOME);
startActivity(MyIntent);
finish();

这个只是退回到桌面，如果打开多个Activity关闭重新打开也会有问题，还是还是不行

看到有说广播机制，发现是个好东东，能彻底解决这个问题，废话不说看代码：

public abstract class EnterActivity extends BaseActivity {
...
    // 写一个广播的内部类，当收到动作时，结束activity
    private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            unregisterReceiver(this); // 这句话必须要写要不会报错，不写虽然能关闭，会报一堆错
            ((Activity) context).finish();
        }
    };

    @Override
    public void onResume() {
        super.onResume();

        // 在当前的activity中注册广播
        IntentFilter filter = new IntentFilter();
        filter.addAction(Attribute.PAGENAME);
        registerReceiver(this.broadcastReceiver, filter); // 注册
    }

    /**
     * 关闭
     */
    public void close() {
        Intent intent = new Intent();
        intent.setAction(Attribute.PAGENAME); // 说明动作
        sendBroadcast(intent);// 该函数用于发送广播
        finish();
    }
...
}

这就是 我对android中的activity的退出机制的总结.

在以后的教程中，我们将一步步实现这样的效果.