ViewPager+Fragment避免重复createview

其他 2019-05-14 17:37:20 阅读次数: 0
版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/u014736095/article/details/54946315

ViewPager+Fragment避免重复createview
每次使用ViewPager+Fragment来作为app的框架的时候都要格外小心，因为他们的生命周期有点奇怪，并没有Activity那样来得自然。如何奇怪呢，请看下面日志 

打开app，一开始为第一个Fragment
02-09 14:02:12.551 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1 setUserVisibleHint.isVisibleToUser=false
02-09 14:02:12.551 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2 setUserVisibleHint.isVisibleToUser=false
02-09 14:02:12.551 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1 setUserVisibleHint.isVisibleToUser=true
02-09 14:02:12.551 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onAttach
02-09 14:02:12.551 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onCreate
02-09 14:02:12.551 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onAttach
02-09 14:02:12.551 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onCreate
02-09 14:02:12.551 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onCreateView
02-09 14:02:12.561 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onActivityCreated
02-09 14:02:12.561 30159-30159/com.tianjiyun.glycuresis W/FragmentManager: moveToState: Fragment state for MainFragment2{5434690 #0 id=0x7f0c0056 android:switcher:2131492950:1} not updated inline; expected state 3 found 2
02-09 14:02:12.561 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onCreateView
02-09 14:02:12.561 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onActivityCreated
02-09 14:02:12.561 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onStart
02-09 14:02:12.561 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onResume
02-09 14:02:12.561 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onStart
02-09 14:02:12.561 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onResume

切换到第二个Fragment
02-09 14:03:21.981 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3 setUserVisibleHint.isVisibleToUser=false
02-09 14:03:21.981 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1 setUserVisibleHint.isVisibleToUser=false
02-09 14:03:21.981 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2 setUserVisibleHint.isVisibleToUser=true
02-09 14:03:21.981 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onAttach
02-09 14:03:21.981 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onCreate
02-09 14:03:21.981 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onCreateView
02-09 14:03:21.991 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onActivityCreated
02-09 14:03:21.991 30159-30159/com.tianjiyun.glycuresis W/FragmentManager: moveToState: Fragment state for MainFragment3{863ec84 #2 id=0x7f0c0056 android:switcher:2131492950:2} not updated inline; expected state 3 found 2
02-09 14:03:21.991 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onStart
02-09 14:03:21.991 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onResume

切换到第三个Fragment
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4 setUserVisibleHint.isVisibleToUser=false
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2 setUserVisibleHint.isVisibleToUser=false
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3 setUserVisibleHint.isVisibleToUser=true
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onAttach
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onCreate
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onPause
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onStop
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onDestroyView
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onCreateView
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onActivityCreated
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis W/FragmentManager: moveToState: Fragment state for MainFragment4{6fa481c #3 id=0x7f0c0056 android:switcher:2131492950:3} not updated inline; expected state 3 found 2
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onStart
02-09 14:04:54.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onResume

切换到第四个Fragment
02-09 14:05:30.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3 setUserVisibleHint.isVisibleToUser=false
02-09 14:05:30.941 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4 setUserVisibleHint.isVisibleToUser=true
02-09 14:05:30.951 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onPause
02-09 14:05:30.951 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onStop
02-09 14:05:30.951 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onDestroyView

最后且回到第一个Fragment
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1 setUserVisibleHint.isVisibleToUser=false
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2 setUserVisibleHint.isVisibleToUser=false
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4 setUserVisibleHint.isVisibleToUser=false
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1 setUserVisibleHint.isVisibleToUser=true
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onCreateView
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onActivityCreated
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onStart
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment1onResume
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onCreateView
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onActivityCreated
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis W/FragmentManager: moveToState: Fragment state for MainFragment2{5434690 #0 id=0x7f0c0056 android:switcher:2131492950:1} not updated inline; expected state 3 found 2
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onStart
02-09 14:06:05.651 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment2onResume
02-09 14:06:06.101 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onPause
02-09 14:06:06.101 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onStop
02-09 14:06:06.101 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment3onDestroyView
02-09 14:06:06.101 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onPause
02-09 14:06:06.101 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onStop
02-09 14:06:06.101 30159-30159/com.tianjiyun.glycuresis V/Kuby_test: MainFragment4onDestroyView

一般createView都是一次就行了，因为有时候请求网络啊，或者一些数据已经改变了，后来再切回来就恢复了初始状态。Android官方为了性能，做了这样的灵活设置，切换到下一个fragment的时候会预加载相邻的Fragment，然后把不相邻的都销毁掉，切回被销毁掉的Fragment的时候又会重新createView一次。这样做可能性能得到提高，可是实际开发中却显得有点不方便，也许是我没有领会到更高级的写法。那么我只想要他们老老实实的像Activity一样怎么办呢？这就是这篇文章的目的

解决办法：
具体情况看我写的这个demo，自定义了一个Fragment的超类BaseFragment，只要继承这个BaseFragment，不要复写生命周期，复写几个方法就可以了。使用情况请看上面的注释。

下载地址：http://download.csdn.net/detail/u014736095/9750716


很多时候开发者我为了方便使用了show和hind的方法去控制他们，因为这样可以解决viewpager的预加载问题。但是这样没有切换动画，如重Fragment1切换到Fragment4，用show和hind就不会按照1.2.3-->4这样的切换动画，而是1-->4。


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