Android：获取最近打开app列表

按下任务物理键，会显示最近打开的App列表，可以用来切换多任务，如何通过代码来实现这种效果呢？
类似下面这样：

利用反射即可实现这个功能，示例代码如下：

    private void showRecentApps() {
        Class serviceManagerClass;
        try {
            serviceManagerClass = Class.forName("android.os.ServiceManager");
            Method getService = serviceManagerClass.getMethod("getService",
                    String.class);
            IBinder retbinder = (IBinder) getService.invoke(
                    serviceManagerClass, "statusbar");
            Class statusBarClass = Class.forName(retbinder
                    .getInterfaceDescriptor());

            Object statusBarObject = statusBarClass.getClasses()[0].getMethod(
                    "asInterface", IBinder.class).invoke(null,
                    new Object[] { retbinder });
            Method clearAll = statusBarClass.getMethod("toggleRecentApps");
            clearAll.setAccessible(true);
            clearAll.invoke(statusBarObject);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }