Android开发Activity管理工具类的操作方法

/**
 * Activity管理工具类
 */
public class ActivityManager {
    private static ActivityManager instance;
    private Stack<Activity> activityStack; // Activity栈
    private ActivityManager() {
    }
    /**
     * 单例模式
     */
    public static ActivityManager getInstance() {
        if (instance == null) {
            synchronized (ActivityManager.class) {
                if (instance == null) {
                    instance = new ActivityManager();
                }
            }
        }
        return instance;
    }
    /**
     * 添加Activity到堆栈
     */
    public void addActivity(Activity activity) {
        if (activityStack == null) {
            activityStack = new Stack<>();
        }
        activityStack.add(activity);
    }
    /**
     * 获取当前Activity（堆栈中最后一个压入的）
     */
    public Activity currentActivity() {
        if (activityStack == null || activityStack.isEmpty()) {
            return null;
        }
        return activityStack.lastElement();
    }
    /**
     * 结束当前Activity（堆栈中最后一个压入的）
     */
    public void finishActivity() {
        if (activityStack == null || activityStack.isEmpty()) {
            return;
        }
        Activity activity = activityStack.lastElement();
        finishActivity(activity);
    }
    /**
     * 结束指定的Activity
     */
    public void finishActivity(Activity activity) {
        if (activity != null && !activity.isFinishing()) {
            activityStack.remove(activity);
            activity.finish();
        }
    }
    /**
     * 结束指定类名的Activity
     */
    public void finishActivity(Class<?> cls) {
        for (Activity activity : activityStack) {
            if (activity.getClass().equals(cls)) {
                finishActivity(activity);
                break;
            }
        }
    }
    /**
     * 结束所有Activity
     */
    public void finishAllActivity() {
        if (activityStack == null) return;
        for (Activity activity : activityStack) {
            if (activity != null && !activity.isFinishing()) {
                activity.finish();
            }
        }
        activityStack.clear();
    }
    /**
     * 退出应用程序
     */
    public void exitApp() {
        try {
            finishAllActivity();
            // 退出JVM，释放所有内存
            System.exit(0);
            // 杀死该应用进程
            android.os.Process.killProcess(android.os.Process.myPid());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 获取指定类名的Activity
     */
    public Activity getActivity(Class<?> cls) {
        if (activityStack == null) return null;
        for (Activity activity : activityStack) {
            if (activity.getClass().equals(cls)) {
                return activity;
            }
        }
        return null;
    }
    /**
     * 移除Activity（但不finish）
     */
    public void removeActivity(Activity activity) {
        if (activity != null && activityStack != null) {
            activityStack.remove(activity);
        }
    }
    /**
     * 返回栈中Activity的数量
     */
    public int getActivityCount() {
        return activityStack == null ? 0 : activityStack.size();
    }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ActivityManager.getInstance().addActivity(this);
}

@Override
protected void onDestroy() {
    super.onDestroy();
    ActivityManager.getInstance().removeActivity(this);
}

// 获取当前Activity
Activity currentActivity = ActivityManager.getInstance().currentActivity();
// 结束当前Activity
ActivityManager.getInstance().finishActivity();
// 结束指定Activity
ActivityManager.getInstance().finishActivity(MainActivity.class);
// 退出应用程序
ActivityManager.getInstance().exitApp();
// 结束所有Activity但不退出应用
ActivityManager.getInstance().finishAllActivity();