我想知道是否有人在使用新的Android API级别17附带的FragmentTabHost自定义选项卡方面取得了成功。
我很高兴能够在我的ViewPager SherlockFragments中嵌入tabHost，但是我在执行简单的操作时遇到了麻烦，比如将标签移到底部或更改标签的布局。
有没有人看过使用此功能的好例子？
这是我在Android文档中找到的唯一示例，而且几乎没有任何描述它的用法。它似乎也忽略了R.id.fragment1。
我的问题我想如果有人遇到过一个好的教程：FragmentTabHost 或者如果他们知道如何a）将嵌套标签置于底部或b）更改所述标签的布局。
我已经尝试了所有常用的方法，但是由于看起来XML布局文件被覆盖了，所以我没有太多运气。
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;
}
在做了一些研究后，似乎可能会在支持库中初始化FragmentTabHost时出现故障。用户here on Google code已向此提出建议：
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>
答案 0 :(得分：14)
我终于到底了。 FragmentTabHost.java存在一个问题，它总是为您创建一个TabHost元素，无论您在XML中定义什么并事先膨胀。
因此，在编写我自己的FragmentTabHost.java版本时，我注释掉了部分代码。
请务必在XML布局<com.example.app.MyFragmentTabHost
当然要夸大它：
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;
}
}
答案 1 :(得分：2)
我认为，将方法initFragmentTabHost()设置为构造函数是错误的。当时TabHost不是他的孩子 - 它发生在之后。例如，LinearLayout以onMeasure()方法（grepcode）与他的孩子一起工作。构造函数中的ViewGroup只是init变量，并设置mChildrenCount = 0（grepcode）。
我能做的一切，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costumize Tabs（标签高度有问题，我在代码中解决它们）：
<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;
}
我认为使用TabWidget进行其他自定义我们只能通过编程方式进行操作，如下所示：
final View tabs = (TabWidget) mTabHost.findViewById(android.R.id.tabs);
final ViewGroup parent = (ViewGroup) mTabHost.getChildAt(0);
parent.removeView(tabs);
parent.addView(tabs);
答案 2 :(得分：0)
据我测试jamisOn解决方案是好的。重要的是不要使用其构造函数初始化MyFragmentTabHost。至少如果持有MyFragmentTabHost的类是片段。我没有用FragmentActivity进行测试......
答案 3 :(得分：0)
我想提一下FragmentTabHost的一些问题。我正在使用 ViewPager ，其中每个页面（View）都包含FragmenTabHost，我必须克服几个问题：
1）FragmentTabHost假设它是其父FragmentManager中的唯一FragmentTabHost（FragmentTabHost.setup()的第二个参数）。这会导致其他问题......
2）调用addTab()时提供的“标签”直接传递给FragmentManager，因此如果您只是为所有页面使用硬编码标签（完全合理的事情），您的第一页将会创建标签片段，而其他每个页面都重复使用这些标签。是的，第2页控制第1页......
解决方案是生成唯一标记名称。我将页码附加到硬编码字符串：
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）所有制表符片段都放在仅由“view id”（FragmentTabHost.setup()的第3个参数）标识的容器中。这意味着当FragmentManager将viewId解析为View时，它总是找到第一个实例（来自第一页）。您的所有其他页面都会被忽略。
解决方法是为“标签内容”视图分配唯一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）销毁时不会删除制表符片段。虽然ViewPager在您滑动时会破坏未使用的视图，但这些视图中包含的FragmentTabHosts会“泄漏”选项卡片段。当ViewPager重新实例化先前看到的页面（使用以前使用过的标签）时，FragmentTabHost会注意到这些选项卡的片段已经存在，只需重新附加它们即可。这会爆炸，因为碎片指向ViewPager已经破坏的视图。
解决方案是在FragmentTabHost被销毁时删除片段。您需要将此代码添加到FragmentTabHost.java的本地副本中的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();
}
}
}
您可能还可以通过使用FragmentPagerAdapter或FragmentStatePagerAdapter（制作片段）而不是标准的PagerAdapter（制作视图）来解决这些问题。然后你打电话给FragmentTabHost.setup( ... fragment.getChildFragmentManager() ... )。