判断本应用是不是在前台

た入场券 2022-07-17 02:07 213阅读 0赞

首先由个比较通用的方法。

Activity切换的时候执行逻辑：

A.onCreate->A.onStart()->A.onResume()->A.onPause()->B.onCreate->B.onStart()->B.onResume()->B启动完毕->A.onStop()

所以只要统计onStart和onStop的次数就好了。

\--------------------------------------------------------------------------------------------------------------------------------------

由于我的项目里有特殊原因：

引入了另外的工程，包名相同但是和我负责的部分完全独立，也无法去改，于是使用了下面的方法

\------------------------------------------------------------------------------------------------------------------------------------------------------------------------

最近有个需求，在应用中增加一个全局的悬浮球，拟采用Toast方式实现，但Toast是系统级Alert。

应用后台运行时也会显示在桌面上，因此需要在每个Activity的生命周期中判断当前应用还在不在栈顶(用户可见、正在运行)。

先贴上实现代码吧，代码有项目依赖，如果有人需要的话拿去把依赖去掉就好了。

定义一个基类，所有Activity都需要继承这个基类。重写onResume( )实现显示逻辑，重写onStop( )显示隐藏逻辑。

package com.ct108.open.Base;
    
    import android.app.Activity;
    import android.os.Bundle;
    
    import com.ct108.open.Utils.GetTopInfo;
    import com.ct108.open.Utils.fordebug.LogUtil;
    import com.ct108.open.thm.test.FloatWindowUtil;
    
    /**
     * Created by thm on 2016/8/22.
     */
    public class BaseActivity extends Activity{
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
        }
    
        @Override
        protected void onResume() {
            super.onResume();
            LogUtil.d("BaseActivity onResume");
            if(FloatWindowUtil.getInstance().getService() == null){
                LogUtil.e("BaseActivity getService() == null");
                return;
            }
    
            if(FloatWindowUtil.getInstance().getService().isHide()){
                LogUtil.d("BaseActivity showFloat");
                FloatWindowUtil.getInstance().getService().showFloat();
            }
        }
    
        @Override
        protected void onPause() {
            super.onPause();
        }
    
        @Override
        protected void onStop() {
            super.onStop();
            String pkg = new GetTopInfo(this).getPkgName();
            LogUtil.d("BaseActivity onStop & pkg = "+ pkg);
            if(!pkg.equals("com.uc108.doudizhu")){
                if(FloatWindowUtil.getInstance().getService() == null)
                    return;
                FloatWindowUtil.getInstance().getService().hide();
                LogUtil.d("BaseActivity hide");
            }
        }
    
        @Override
        protected void onDestroy() {
            super.onDestroy();
        }
    }

工具类GetTopInfo()，获取栈顶Acativity的包名。

public class GetTopInfo {
        private final Context context;
        public GetTopInfo(Context context) {
            this.context = context;
        }
    
        public  String getPkgName(){
            if(CollectionUtils.isNotEmpty(get()))
                return get()[0];
            return "";
        }
        public String[] get() {
            LogUtil.d("GetTopInfo curSDK_INT = "+Build.VERSION.SDK_INT);
            if (Build.VERSION.SDK_INT < 21)
                return getPreLollipop();
            else
                return getLollipop();
        }
        private String[] getPreLollipop() {
            @SuppressWarnings("deprecation")
            List<ActivityManager.RunningTaskInfo> tasks =
                    activityManager().getRunningTasks(1);
            ActivityManager.RunningTaskInfo currentTask = tasks.get(0);
            ComponentName currentActivity = currentTask.topActivity;
            return new String[] { currentActivity.getPackageName() };
        }
    
        @TargetApi(Build.VERSION_CODES.KITKAT)
        private String[] getLollipop() {
            final int PROCESS_STATE_TOP = 2;
            try {
                Field processStateField = ActivityManager.RunningAppProcessInfo.class.getDeclaredField("processState");
    
                List<ActivityManager.RunningAppProcessInfo> processes =
                        activityManager().getRunningAppProcesses();
                for (ActivityManager.RunningAppProcessInfo process : processes) {
                    if (process.importance <= ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND
                               &&  process.importanceReasonCode == 0) {
                        int state = processStateField.getInt(process);
                        if (state == PROCESS_STATE_TOP)
                            return process.pkgList;
                    }
                }
            } catch (NoSuchFieldException | IllegalAccessException e) {
                throw new RuntimeException(e);
            }
            return new String[] { };
        }
    
        private ActivityManager activityManager() {
            return (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        }
    
        public  boolean isNotEmpty(Object[] array) {
            if(array == null)
                return false;
            if(array.length == 0)
                return false;
            else
                return true;
        }
    }