Androidx 下 Fragment 懒加载的新实现
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ViewPager 下实现懒加载
abstract class LazyFragment : Fragment() {
private var isLoaded = false
override fun onResume() {
super.onResume()
if (!isLoaded) {
lazyInit()
Log.d(TAG, "lazyInit:!!!!!!!”)
isLoaded = true
}
}
override fun onDestroyView() {
super.onDestroyView()
isLoaded = false
}
abstract fun lazyInit()
}add+show+hide 模式下的新方案
虽然我们实现了Androidx 包下 ViewPager下的懒加载，但是我们仍然要考虑 add+show+hide 模式下的 Fragment 懒加载的情况，基于 ViewPager 在
setPrimaryItem 方法中的思路，我们可以在调用 add+show+hide 时，这样处理：/**
* 使用add+show+hide模式加载fragment
*
* 默认显示位置[showPosition]的Fragment，最大Lifecycle为Lifecycle.State.RESUMED
* 其他隐藏的Fragment，最大Lifecycle为Lifecycle.State.STARTED
*
[email protected] containerViewId 容器id
[email protected] showPosition fragments
[email protected] fragmentManager FragmentManager
[email protected] fragments 控制显示的Fragments
*/
private fun loadFragmentsTransaction(
@IdRes containerViewId: Int,
showPosition: Int,
fragmentManager: FragmentManager,
vararg fragments: Fragment
) {
if (fragments.isNotEmpty()) {
fragmentManager.beginTransaction().apply {
for (index in fragments.indices) {
val fragment = fragments[index]
add(containerViewId, fragment, fragment.javaClass.name)
if (showPosition == index) {
setMaxLifecycle(fragment, Lifecycle.State.RESUMED)
} else {
hide(fragment)
setMaxLifecycle(fragment, Lifecycle.State.STARTED)
}
}
}.commit()
} else {
throw IllegalStateException(
"fragments must not empty”
)
}
}
/** 显示需要显示的Fragment[showFragment]，并设置其最大Lifecycle为Lifecycle.State.RESUMED。
* 同时隐藏其他Fragment,并设置最大Lifecycle为Lifecycle.State.STARTED
* @param fragmentManager
* @param showFragment
*/
private fun showHideFragmentTransaction(fragmentManager: FragmentManager, showFragment: Fragment) {
fragmentManager.beginTransaction().apply {
show(showFragment)
setMaxLifecycle(showFragment, Lifecycle.State.RESUMED)
//获取其中所有的fragment,其他的fragment进行隐藏
val fragments = fragmentManager.fragments
for (fragment in fragments) {
if (fragment != showFragment) {
hide(fragment)
setMaxLifecycle(fragment, Lifecycle.State.STARTED)
}
}
}.commit()
}各位看官，如果你觉得本文不错，请支持一下～
