我终于明白了这一点。FragmentTabHost.java存在一个问题，该问题将始终为您创建一个TabHost元素，无论您用XML定义什么并事先进行膨胀。
因此，在编写自己的FragmentTabHost.java版本时，我注释掉了那部分代码。
确保在XML布局中使用此版本的新版本，
<com.example.app.MyFragmentTabHost
并且当然要膨胀它：
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;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); }@Override @Deprecatedpublic 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); } }}@Overridepublic 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);}@Overrideprotected 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(); }}@Overrideprotected void onDetachedFromWindow() { super.onDetachedFromWindow(); mAttached = false;}@Overrideprotected Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState ss = new SavedState(superState); ss.curTab = getCurrentTabTag(); return ss;}@Overrideprotected void onRestoreInstanceState(Parcelable state) { SavedState ss = (SavedState)state; super.onRestoreInstanceState(ss.getSuperState()); setCurrentTabByTag(ss.curTab);}@Overridepublic 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;}}
