android 对activity进行管理

         今天在写项目的时候遇到的一个问题，从mainActivity开始连续跳转了五个activity，再从最后一个回到mainActivity的时候，点击back键退出程序的时候遇到了问题，虽然点击back了，但是却回退到了上一页，这时想到了需要一个activityManager管理类进行activity的管理，代码如下。

public class ActivityManager {public static Stack<Activity> mActivityStack;private static ActivityManager instance;private ActivityManager() {}public static ActivityManager getInstance() {if (instance == null) {instance = new ActivityManager();}return instance;}// 退出栈顶Activitypublic void popActivity(Activity activity) {if (activity != null) {activity.finish();mActivityStack.remove(activity);activity = null;}}// 获得当前栈顶Activitypublic Activity currentActivity() {Activity activity = mActivityStack.lastElement();return activity;}/** 获取栈底部的Activity **/public Activity firstElement() {Activity activity = mActivityStack.firstElement();return activity;}// 将当前Activity推入栈中public void pushActivity(Activity activity) {if (mActivityStack == null) {mActivityStack = new Stack<Activity>();}mActivityStack.add(activity);}// 退出栈中所有Activitypublic void popAllActivityExceptOne(Class<? extends Activity> cls) {while (true) {Activity activity = firstElement();if (activity == null) {break;}if (activity.getClass().equals(cls)) {break;}popActivity(activity);}}// 退出其他的activitypublic void popAllOtherActivity(Class<? extends Activity> cls) {for (int i = 0; i < mActivityStack.size(); i++) {Activity activity = mActivityStack.get(i);if (!activity.getClass().equals(cls)) {popActivity(activity);}}}}

         但是这还不算完，需要在BaseActivity中的OnCreate方法和OnDestory方法里分别写pushActivity和popActivity，将MainActivity的启动模式设置为            android:launchMode="singleTask"，好了，写到这里，我们就需要去测试一下，发现不会再出现上述的问题了。