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qianran
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May 4, 2020
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app/src/main/java/com/holiday/jetpackstudy/navigation/FixFragmentNavigator.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,142 @@ | ||
| package com.holiday.jetpackstudy.navigation; | ||
|
|
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| import android.content.Context; | ||
| import android.os.Bundle; | ||
| import android.util.Log; | ||
| import android.view.View; | ||
|
|
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| import androidx.annotation.IdRes; | ||
| import androidx.annotation.NonNull; | ||
| import androidx.annotation.Nullable; | ||
| import androidx.fragment.app.Fragment; | ||
| import androidx.fragment.app.FragmentManager; | ||
| import androidx.fragment.app.FragmentTransaction; | ||
| import androidx.navigation.NavDestination; | ||
| import androidx.navigation.NavOptions; | ||
| import androidx.navigation.Navigator; | ||
| import androidx.navigation.fragment.FragmentNavigator; | ||
|
|
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| import java.lang.reflect.Field; | ||
| import java.util.ArrayDeque; | ||
| import java.util.List; | ||
| import java.util.Map; | ||
|
|
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| /** | ||
| * 支持fragment复用的导航器，搜"//fix"可快速定位到修复点 | ||
| */ | ||
| @Navigator.Name("fixFragment") //fix 5: 需要指定1个名字，源码里自带的名字有navigation、activity、fragment、dialog | ||
| public class FixFragmentNavigator extends FragmentNavigator { | ||
| private static final String TAG = "FixFragmentNavigator"; | ||
| private Context mContext; | ||
| private FragmentManager mFragmentManager; | ||
| private int mContainerId; | ||
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| public FixFragmentNavigator(@NonNull Context context, @NonNull FragmentManager manager, int containerId) { | ||
| super(context, manager, containerId); | ||
| mContext = context; | ||
| mFragmentManager = manager; | ||
| mContainerId = containerId; | ||
| } | ||
|
|
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| @Nullable | ||
| @Override | ||
| public NavDestination navigate(@NonNull Destination destination, @Nullable Bundle args, @Nullable NavOptions navOptions, @Nullable Navigator.Extras navigatorExtras) { | ||
| if (mFragmentManager.isStateSaved()) { | ||
| Log.i(TAG, "Ignoring navigate() call: FragmentManager has already" | ||
| + " saved its state"); | ||
| return null; | ||
| } | ||
| String className = destination.getClassName(); | ||
| if (className.charAt(0) == '.') { | ||
| className = mContext.getPackageName() + className; | ||
| } | ||
| //fix 1: 把类名作为tag，寻找已存在的Fragment | ||
| //（如果想只针对个别fragment进行保活复用，可以在tag上做些标记比如加个前缀） | ||
| Fragment frag = mFragmentManager.findFragmentByTag(className); | ||
| if (null == frag) { | ||
| //不存在，则创建 | ||
| frag = instantiateFragment(mContext, mFragmentManager, className, args); | ||
| } | ||
|
|
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| frag.setArguments(args); | ||
| final FragmentTransaction ft = mFragmentManager.beginTransaction(); | ||
|
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| int enterAnim = navOptions != null ? navOptions.getEnterAnim() : -1; | ||
| int exitAnim = navOptions != null ? navOptions.getExitAnim() : -1; | ||
| int popEnterAnim = navOptions != null ? navOptions.getPopEnterAnim() : -1; | ||
| int popExitAnim = navOptions != null ? navOptions.getPopExitAnim() : -1; | ||
| if (enterAnim != -1 || exitAnim != -1 || popEnterAnim != -1 || popExitAnim != -1) { | ||
| enterAnim = enterAnim != -1 ? enterAnim : 0; | ||
| exitAnim = exitAnim != -1 ? exitAnim : 0; | ||
| popEnterAnim = popEnterAnim != -1 ? popEnterAnim : 0; | ||
| popExitAnim = popExitAnim != -1 ? popExitAnim : 0; | ||
| ft.setCustomAnimations(enterAnim, exitAnim, popEnterAnim, popExitAnim); | ||
| } | ||
|
|
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| // ft.replace(mContainerId, frag); | ||
| //fix 2: replace换成show和hide | ||
| List<Fragment> fragments = mFragmentManager.getFragments(); | ||
| for (Fragment fragment : fragments) { | ||
| ft.hide(fragment); | ||
| } | ||
| if (!frag.isAdded()) { | ||
| ft.add(mContainerId, frag, className); | ||
| } | ||
| ft.show(frag); | ||
| ft.setPrimaryNavigationFragment(frag); | ||
|
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| final @IdRes int destId = destination.getId(); | ||
|
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| //fix 3: mBackStack是私有的，而且没有暴露出来，只能反射获取 | ||
| ArrayDeque<Integer> mBackStack; | ||
| try { | ||
| Field field = FragmentNavigator.class.getDeclaredField("mBackStack"); | ||
| field.setAccessible(true); | ||
| mBackStack = (ArrayDeque<Integer>) field.get(this); | ||
| } catch (Exception e) { | ||
| e.printStackTrace(); | ||
| return null; | ||
| } | ||
|
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| final boolean initialNavigation = mBackStack.isEmpty(); | ||
| final boolean isSingleTopReplacement = navOptions != null && !initialNavigation | ||
| && navOptions.shouldLaunchSingleTop() | ||
| && mBackStack.peekLast() == destId; | ||
|
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| boolean isAdded; | ||
| if (initialNavigation) { | ||
| isAdded = true; | ||
| } else if (isSingleTopReplacement) { | ||
| if (mBackStack.size() > 1) { | ||
| mFragmentManager.popBackStack( | ||
| generateBackStackName(mBackStack.size(), mBackStack.peekLast()), | ||
| FragmentManager.POP_BACK_STACK_INCLUSIVE); | ||
| ft.addToBackStack(generateBackStackName(mBackStack.size(), destId)); | ||
| } | ||
| isAdded = false; | ||
| } else { | ||
| ft.addToBackStack(generateBackStackName(mBackStack.size() + 1, destId)); | ||
| isAdded = true; | ||
| } | ||
| if (navigatorExtras instanceof Extras) { | ||
| Extras extras = (Extras) navigatorExtras; | ||
| for (Map.Entry<View, String> sharedElement : extras.getSharedElements().entrySet()) { | ||
| ft.addSharedElement(sharedElement.getKey(), sharedElement.getValue()); | ||
| } | ||
| } | ||
| ft.setReorderingAllowed(true); | ||
| ft.commit(); | ||
| if (isAdded) { | ||
| mBackStack.add(destId); | ||
| return destination; | ||
| } else { | ||
| return null; | ||
| } | ||
| } | ||
|
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| //fix 4: 从父类那边copy过来即可 | ||
| @NonNull | ||
| private String generateBackStackName(int backStackIndex, int destId) { | ||
| return backStackIndex + "-" + destId; | ||
| } | ||
| } |
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