Android的FragmentTabHost – 尚未完全烘焙?

我想看看是否有人使用新的Android API级别17附带的FragmentTabHost自定义标签。

我很兴奋能够在我的ViewPager SherlockFragments中嵌套一个tabHost,但是我很难做简单的事情,比如将标签移动到底部或者改变标签的布局。

有没有人看过使用这个function的好例子?

这是我可以在Android文档中find的唯一示例,并且几乎没有任何内容描述它的使用。 它似乎也忽略了R.id.fragment1的布局中定义的内容。

我想如果有人遇到一个很好的教程:FragmentTabHost或如果他们有一个想法如何a)把嵌套的标签在底部或b)改变所述标签的布局。

我已经尝试了所有常用的方法,但是由于XML布局文件被覆盖,所以我没有太多的运气。

 private FragmentTabHost mTabHost; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { setContentView(R.layout.fragment_tabs); mTabHost = (FragmentTabHost)findViewById(android.R.id.tabhost); mTabHost.setup(this, getSupportFragmentManager(), R.id.realtabcontent); mTabHost.addTab(mTabHost.newTabSpec("simple").setIndicator("Simple"), FragmentStackSupport.CountingFragment.class, null); mTabHost.addTab(mTabHost.newTabSpec("contacts").setIndicator("Contacts"), LoaderCursorSupport.CursorLoaderListFragment.class, null); mTabHost.addTab(mTabHost.newTabSpec("custom").setIndicator("Custom"), LoaderCustomSupport.AppListFragment.class, null); mTabHost.addTab(mTabHost.newTabSpec("throttle").setIndicator("Throttle"), LoaderThrottleSupport.ThrottledLoaderListFragment.class, null); return mTabHost; } 

在做了一些研究之后,似乎在支持库中初始化FragmentTabHost可能会有一个小问题。 Google代码中的用户对此提供了一个build议:

FragmentTabHost.java

 private void initFragmentTabHost(Context context, AttributeSet attrs) { TypedArray a = context.obtainStyledAttributes(attrs, new int[] { android.R.attr.inflatedId }, 0, 0); mContainerId = a.getResourceId(0, 0); a.recycle(); super.setOnTabChangedListener(this); // If owner hasn't made its own view hierarchy, then as a convenience // we will construct a standard one here. /***** HERE COMMENT CODE BECAUSE findViewById(android.R.id.tabs) EVERY TIME IS NULL WE HAVE OWN LAYOUT ******// // if (findViewById(android.R.id.tabs) == null) { // LinearLayout ll = new LinearLayout(context); // ll.setOrientation(LinearLayout.VERTICAL); // addView(ll, new FrameLayout.LayoutParams( // ViewGroup.LayoutParams.FILL_PARENT, // ViewGroup.LayoutParams.FILL_PARENT)); // // TabWidget tw = new TabWidget(context); // tw.setId(android.R.id.tabs); // tw.setOrientation(TabWidget.HORIZONTAL); // ll.addView(tw, new LinearLayout.LayoutParams( // ViewGroup.LayoutParams.FILL_PARENT, // ViewGroup.LayoutParams.WRAP_CONTENT, 0)); // // FrameLayout fl = new FrameLayout(context); // fl.setId(android.R.id.tabcontent); // ll.addView(fl, new LinearLayout.LayoutParams(0, 0, 0)); // // mRealTabContent = fl = new FrameLayout(context); // mRealTabContent.setId(mContainerId); // ll.addView(fl, new LinearLayout.LayoutParams( // LinearLayout.LayoutParams.FILL_PARENT, 0, 1)); // } } 

片段的XML布局:

 <android.support.v4.app.FragmentTabHost xmlns:android="http://schemas.android.com/apk/res/android" android:id="@android:id/tabhost" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <FrameLayout android:id="@android:id/tabcontent" android:layout_width="0dp" android:layout_height="0dp" android:layout_weight="0"/> <FrameLayout android:id="@+id/realtabcontent" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1"/> <TabWidget android:id="@android:id/tabs" android:orientation="horizontal" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="0"/> </LinearLayout> </android.support.v4.app.FragmentTabHost> 

Solutions Collecting From Web of "Android的FragmentTabHost – 尚未完全烘焙?"

我终于明白了这一点。 FragmentTabHost.java存在一个问题,无论您在XML中定义了什么,都会为您创build一个TabHost元素,并且事先膨胀。

因此,在编写我自己版本的FragmentTabHost.java时,我注意到了部分代码。

请确保在您的XML布局中使用您的新版本, <com.example.app.MyFragmentTabHost

当然,它膨胀了:

Fragment1.java:

 mTabHost = (MyFragmentTabHost) view.findViewById(android.R.id.tabhost); mTabHost.setup(getActivity(), getChildFragmentManager(), android.R.id.tabcontent); 

MyFragmentTabHost.java:

 package com.example.app; import java.util.ArrayList; import android.content.Context; import android.content.res.TypedArray; import android.os.Bundle; import android.os.Parcel; import android.os.Parcelable; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentTransaction; import android.util.AttributeSet; import android.view.View; import android.widget.FrameLayout; import android.widget.TabHost; /** * Special TabHost that allows the use of {@link Fragment} objects for * its tab content. When placing this in a view hierarchy, after inflating * the hierarchy you must call {@link #setup(Context, FragmentManager, int)} * to complete the initialization of the tab host. * */ public class MyFragmentTabHost extends TabHost implements TabHost.OnTabChangeListener { private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>(); private FrameLayout mRealTabContent; private Context mContext; private FragmentManager mFragmentManager; private int mContainerId; private TabHost.OnTabChangeListener mOnTabChangeListener; private TabInfo mLastTab; private boolean mAttached; static final class TabInfo { private final String tag; private final Class<?> clss; private final Bundle args; private Fragment fragment; TabInfo(String _tag, Class<?> _class, Bundle _args) { tag = _tag; clss = _class; args = _args; } } static class DummyTabFactory implements TabHost.TabContentFactory { private final Context mContext; public DummyTabFactory(Context context) { mContext = context; } @Override public View createTabContent(String tag) { View v = new View(mContext); v.setMinimumWidth(0); v.setMinimumHeight(0); return v; } } static class SavedState extends BaseSavedState { String curTab; SavedState(Parcelable superState) { super(superState); } private SavedState(Parcel in) { super(in); curTab = in.readString(); } @Override public void writeToParcel(Parcel out, int flags) { super.writeToParcel(out, flags); out.writeString(curTab); } @Override public String toString() { return "FragmentTabHost.SavedState{" + Integer.toHexString(System.identityHashCode(this)) + " curTab=" + curTab + "}"; } public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } public MyFragmentTabHost(Context context) { // Note that we call through to the version that takes an AttributeSet, // because the simple Context construct can result in a broken object! super(context, null); initFragmentTabHost(context, null); } public MyFragmentTabHost(Context context, AttributeSet attrs) { super(context, attrs); initFragmentTabHost(context, attrs); } private void initFragmentTabHost(Context context, AttributeSet attrs) { TypedArray a = context.obtainStyledAttributes(attrs, new int[] { android.R.attr.inflatedId }, 0, 0); mContainerId = a.getResourceId(0, 0); a.recycle(); super.setOnTabChangedListener(this); /*** REMOVE THE REST OF THIS FUNCTION ***/ /*** findViewById(android.R.id.tabs) IS NULL EVERY TIME ***/ } /** * @deprecated Don't call the original TabHost setup, you must instead * call {@link #setup(Context, FragmentManager)} or * {@link #setup(Context, FragmentManager, int)}. */ @Override @Deprecated public void setup() { throw new IllegalStateException( "Must call setup() that takes a Context and FragmentManager"); } public void setup(Context context, FragmentManager manager) { super.setup(); mContext = context; mFragmentManager = manager; ensureContent(); } public void setup(Context context, FragmentManager manager, int containerId) { super.setup(); mContext = context; mFragmentManager = manager; mContainerId = containerId; ensureContent(); mRealTabContent.setId(containerId); // We must have an ID to be able to save/restore our state. If // the owner hasn't set one at this point, we will set it ourself. if (getId() == View.NO_ID) { setId(android.R.id.tabhost); } } private void ensureContent() { if (mRealTabContent == null) { mRealTabContent = (FrameLayout)findViewById(mContainerId); if (mRealTabContent == null) { throw new IllegalStateException( "No tab content FrameLayout found for id " + mContainerId); } } } @Override public void setOnTabChangedListener(OnTabChangeListener l) { mOnTabChangeListener = l; } public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) { tabSpec.setContent(new DummyTabFactory(mContext)); String tag = tabSpec.getTag(); TabInfo info = new TabInfo(tag, clss, args); if (mAttached) { // If we are already attached to the window, then check to make // sure this tab's fragment is inactive if it exists. This shouldn't // normally happen. info.fragment = mFragmentManager.findFragmentByTag(tag); if (info.fragment != null && !info.fragment.isDetached()) { FragmentTransaction ft = mFragmentManager.beginTransaction(); ft.detach(info.fragment); ft.commit(); } } mTabs.add(info); addTab(tabSpec); } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); String currentTab = getCurrentTabTag(); // Go through all tabs and make sure their fragments match // the correct state. FragmentTransaction ft = null; for (int i=0; i<mTabs.size(); i++) { TabInfo tab = mTabs.get(i); tab.fragment = mFragmentManager.findFragmentByTag(tab.tag); if (tab.fragment != null && !tab.fragment.isDetached()) { if (tab.tag.equals(currentTab)) { // The fragment for this tab is already there and // active, and it is what we really want to have // as the current tab. Nothing to do. mLastTab = tab; } else { // This fragment was restored in the active state, // but is not the current tab. Deactivate it. if (ft == null) { ft = mFragmentManager.beginTransaction(); } ft.detach(tab.fragment); } } } // We are now ready to go. Make sure we are switched to the // correct tab. mAttached = true; ft = doTabChanged(currentTab, ft); if (ft != null) { ft.commit(); mFragmentManager.executePendingTransactions(); } } @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); mAttached = false; } @Override protected Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState ss = new SavedState(superState); ss.curTab = getCurrentTabTag(); return ss; } @Override protected void onRestoreInstanceState(Parcelable state) { SavedState ss = (SavedState)state; super.onRestoreInstanceState(ss.getSuperState()); setCurrentTabByTag(ss.curTab); } @Override public void onTabChanged(String tabId) { if (mAttached) { FragmentTransaction ft = doTabChanged(tabId, null); if (ft != null) { ft.commit(); } } if (mOnTabChangeListener != null) { mOnTabChangeListener.onTabChanged(tabId); } } private FragmentTransaction doTabChanged(String tabId, FragmentTransaction ft) { TabInfo newTab = null; for (int i=0; i<mTabs.size(); i++) { TabInfo tab = mTabs.get(i); if (tab.tag.equals(tabId)) { newTab = tab; } } if (newTab == null) { throw new IllegalStateException("No tab known for tag " + tabId); } if (mLastTab != newTab) { if (ft == null) { ft = mFragmentManager.beginTransaction(); } if (mLastTab != null) { if (mLastTab.fragment != null) { ft.detach(mLastTab.fragment); } } if (newTab != null) { if (newTab.fragment == null) { newTab.fragment = Fragment.instantiate(mContext, newTab.clss.getName(), newTab.args); ft.add(mContainerId, newTab.fragment, newTab.tag); } else { ft.attach(newTab.fragment); } } mLastTab = newTab; } return ft; } } 

我认为,将方法initFragmentTabHost()设置为构造函数是一个错误。 当时TabHost不要他的孩子 – 这发生在之后。 例如, LinearLayoutonMeasure()方法( grepcode )中与他的孩子一起工作。 在构造函数ViewGroup只是初始化variables,并设置mChildrenCount = 0 ( grepcode )。

所有我能做的,这只是成本FragmentTabHost

 <android.support.v4.app.FragmentTabHost xmlns:a="http://schemas.android.com/apk/res/android" a:id="@android:id/tabhost" style="@style/Widget.TabHost" a:inflatedId="@+id/content" /> 

和成本Tabs (有问题的标签高度,我解决他们的代码):

 <LinearLayout xmlns:a="http://schemas.android.com/apk/res/android" style="@style/Widget.Tab" > <TextView a:id="@android:id/title" style="@style/Widget.TabTitle" /> </LinearLayout> 

在代码中:

  tabSpec = mTabHost.newTabSpec(tag).setIndicator(createTab(caption)); ... private View createTab(CharSequence title) { final View v = View.inflate(getActivity(), LAYOUT_TAB, null); ((TextView) v.findViewById(android.R.id.title)).setText(title); return v; } 

我认为用TabWidget其他自定义我们只能通过编程操作来完成,就像这样:

  final View tabs = (TabWidget) mTabHost.findViewById(android.R.id.tabs); final ViewGroup parent = (ViewGroup) mTabHost.getChildAt(0); parent.removeView(tabs); parent.addView(tabs); 

恕我直言,这不好。

据我testingjamisOn解决scheme是好的。 不要用它的构造函数来初始化MyFragmentTabHost。 至less如果持有MyFragmentTabHost的类是一个片段。 我还没有用FragmentActivity进行testing…

我想提一些FragmentTabHost的问题。 我使用的ViewPager其中每个页面(视图)包含FragmenTabHost,我不得不克服几个问题:

1)FragmentTabHost假定它是其父FragmentManager( FragmentTabHost.setup()第二个参数FragmentTabHost.setup()唯一的FragmentTabHost。 这导致其余的问题…

2)调用addTab()时提供的“标签”会直接传递给FragmentManager,所以如果你只是使用硬编码标签来完成所有的页面(一个完全合理的事情),你的第一页将创build标签片段,而其他所有页面页面将重用这些选项卡。 是的,第2页控制页面1 …

解决scheme是生成唯一的标签名称。 我将页码附加到硬编码的string:

 public Object instantiateItem( ViewGroup container, int position ) { ... tabHost.addTab( tabHost.newTabSpec( "tab1_" + position ) ...); tabHost.addTab( tabHost.newTabSpec( "tab2_" + position ) ...); tabHost.addTab( tabHost.newTabSpec( "tab3_" + position ) ...); ... } 

3)所有的标签片段都放在一个只有“view id”( FragmentTabHost.setup()的第三个参数FragmentTabHost.setup()标识的容器中。 这意味着当FragmentManager将viewIdparsing为View时,它始终会查找第一个实例(从第一个页面开始)。 所有其他页面都被忽略。

解决scheme是为您的“标签内容”视图分配唯一的ID,例如:

 public Object instantiateItem( ViewGroup container, int position ) { View view = m_inflater.inflate(R.layout.page, null); View tabContent = view.findViewById(R.id.realtabcontent); tabContent.setId(m_nextViewId); m_nextViewId++; MyFragmentTabHost tabHost = (MyFragmentTabHost) view.findViewById(android.R.id.tabhost); tabHost.setup(m_activity, m_activity.getSupportFragmentManager(), tabContent.getId()); ... } 

4)销毁时不会移除标签片段。 当你滑动的时候,ViewPager会破坏未使用的视图,这些视图中包含的FragmentTabHosts会“泄漏”选项卡片段。 当ViewPager重新实例化一个先前看到的页面(使用之前使用过的标签)时,FragmentTabHost会注意到这些标签的片段已经存在,并简单地重新连接它们。 这是因为这些碎片指向ViewPager已经销毁的视图。

解决方法是在FragmentTabHost被销毁时删除碎片。 你需要在FragmentTabHost.java的本地副本中添加这段代码到onDetachedFromWindow()

 class MyFragmentTabHost { ... protected void onDetachedFromWindow() { super.onDetachedFromWindow(); mAttached = false; boolean removeFragments = false; if( mContext instanceof Activity ) { Activity activity = (Activity)mContext; removeFragments = !activity.isDestroyed(); } if( removeFragments ) { FragmentTransaction ft = null; for (int i = 0; i < mTabs.size(); i++) { TabInfo tab = mTabs.get(i); if (tab.fragment != null) { if (ft == null) { ft = mFragmentManager.beginTransaction(); } ft.remove(tab.fragment); } } if (ft != null) { ft.commit(); mFragmentManager.executePendingTransactions(); } } } 

您也可以通过使用FragmentPagerAdapter或FragmentStatePagerAdapter(使Fragments)而不是标准的PagerAdapter(使视图)来解决这些问题。 然后你会调用FragmentTabHost.setup( ... fragment.getChildFragmentManager() ... )