android - 单activity+多fragment场景，应用长时间在后台进入前台时，fragment全部是空白

问题描述

1,问题： 应用长期在后台的场景下，进入前台时，fragment显示为空白2,app框架大体实现： 1个activity+多个Fragment,使用的是add（）方法以及 hide(),show()方法，显示fragment3,相关代码：

onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // 判断 savedInstanceState是否为空: setCanResizeWindow(false); maskView = new View(getApplicationContext()); maskView.setBackground(new ColorDrawable(Color.parseColor('#30000000'))); maskView.setClickable(true); maskView.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) { removeMask();} }); setContentView(R.layout.activity_home); EventBus.getDefault().register(this); //3,个推 PushManager.getInstance().initialize(getApplicationContext()); initView(savedInstanceState); getUserData(); getDataFromMsgBrief();} private void initView(Bundle savedInstanceState) {mBottomDial = (LinearLayout) findViewById(R.id.btn_Dial);mBottomComm = (LinearLayout) findViewById(R.id.btn_comm);mBottomContact = (LinearLayout) findViewById(R.id.btn_contact);mBottomLife = (LinearLayout) findViewById(R.id.btn_life);mBottomDialIv = (ImageView) findViewById(R.id.tab_dial_image);mBottomDiaTv = (TextView) findViewById(R.id.tab_dial_text);mSmsIV = (SmsImageView) findViewById(R.id.siv_sms_icon_homeact);//第一次登录系统时，修改数据库的Istravelrely字段if (!SpUtils.getSynDB(getApplicationContext())) { ThreadPoolUtil.getmExecutor().execute(new Runnable() {@Overridepublic void run() { CopyLocalContactsUtils.checkIsTravelRely(getApplication()); SpUtils.setSynDB(getApplicationContext());} });}//初始化mBottomDial为选中状态，fl_content填充DialFragmentmBottomDial.setSelected(true);//if (savedInstanceState != null) {// LogUtils.d('HomeActivity savedInstanceState != null');//// Fragment dialFragment = getSupportFragmentManager().findFragmentByTag(DIAL_TAG);// Fragment contactFragment = getSupportFragmentManager().findFragmentByTag(CONTACT_TAG);// Fragment commFragment = getSupportFragmentManager().findFragmentByTag(COMM_TAG);// Fragment lifeFragment = getSupportFragmentManager().findFragmentByTag(LIFE_TAG);//// getSupportFragmentManager().beginTransaction()//// getSupportFragmentManager().beginTransaction().hide(contactFragment)// .hide(commFragment).hide(lifeFragment).show(dialFragment).commit();////} else { getSupportFragmentManager().beginTransaction(). add(R.id.fl_content, FragmentFactory.createFragment(0), 'DialFragment'). add(R.id.fl_content, FragmentFactory.createFragment(1), 'CommFragment'). add(R.id.fl_content, FragmentFactory.createFragment(2), 'ContactFragment'). add(R.id.fl_content, FragmentFactory.createFragment(3), 'LifeFragment'). hide(FragmentFactory.createFragment(1)). hide(FragmentFactory.createFragment(2)). hide(FragmentFactory.createFragment(3)). show(FragmentFactory.createFragment(0)).commit();//}initClick(); }

尝试过的解决办法：1，为了解决多个fragment重叠显示，在activity的中执行了如下：

@Override protected void onSaveInstanceState(Bundle outState) {//super.onSaveInstanceState(outState); }

问题现象：

问题解答

@Override protected void onSaveInstanceState(Bundle outState) {//super.onSaveInstanceState(outState); }

这样的解决办法是不对的，这样会导致从activity被销毁是不能记住之前的显示内容，从而使界面空白、为了解决fragment重叠，你可以在注释掉super.onSaveInstanceState(outState)的同时，加上保存当前fragment的代码

@Overrideprotected void onSaveInstanceState(Bundle outState) { outState.putString(SPConst.SHOW_TAG, showFragmentTag);}

然后在回来的时候重新获取之前的fragment，然后再显示出来

@Overrideprotected void onRestoreInstanceState(Bundle savedInstanceState) { super.onRestoreInstanceState(savedInstanceState); if (savedInstanceState != null) {showFragmentTag = savedInstanceState.getString(SPConst.SHOW_TAG);if (showFragmentTag != null) { showFragment = fragmentManager.findFragmentByTag(showFragmentTag); switch (showFragmentTag) {case fragmentTag1: workFragment = showFragment; break;case fragmentTag2: patientFragment = showFragment; break;case fragmentTag3: synergyFragment = showFragment; break;case fragmentTag4: toolFragment = showFragment; break;case fragmentTag5: mineFragment = showFragment; break; }} }}回答2：

内容有点乱，对于你这种需求，推荐使用FragmentTabHost,也就没有这种乱七八糟的问题了。

直接用ViewPager就行