FragmentTabHostUnderLineDemo【FragmentTabHost带下划线】

版权声明：本文为HaiyuKing原创文章，转载请注明出处！

前言

使用FragmentTabHost实现顶部选项卡（带下划线效果）展现。

效果图

代码分析

1、该Demo中采用的是FragmentTabHost的布局方案之一【命名为常规布局写法】；

2、使用自定义的FragmentTabHost；

3、切换回来后，可以保持打开的网页，而不是显示首页。【因为切换时执行的是show/hide，而不是attach/detach】

使用步骤

一、项目组织结构图

注意事项：

1、  导入类文件后需要change包名以及重新import R文件路径

2、  Values目录下的文件（strings.xml、dimens.xml、colors.xml等），如果项目中存在，则复制里面的内容，不要整个覆盖

二、导入步骤

将自定义的MyFragmentTabHost复制到项目中

package com.why.project.fragmenttabhostunderlinedemo.views.tab;
 
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
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.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.TabHost;
import android.widget.TabWidget;
 
import java.util.ArrayList;
 
/**
 * Created by HaiyuKing
 * Used 仿照FragmentTabHost并更改doTabChanged方法实现切换Fragment的时候不刷新fragment
 */
 
public class MyFragmentTabHost extends TabHost
        implements TabHost.OnTabChangeListener {
    private final ArrayList<MyFragmentTabHost.TabInfo> mTabs = new ArrayList<>();
 
    private FrameLayout mRealTabContent;
    private Context mContext;
    private FragmentManager mFragmentManager;
    private int mContainerId;
    private TabHost.OnTabChangeListener mOnTabChangeListener;
    private MyFragmentTabHost.TabInfo mLastTab;
    private boolean mAttached;
 
    static final class TabInfo {
        final
        @NonNull
        String tag;
        final
        @NonNull
        Class<?> clss;
        final
        @Nullable
        Bundle args;
        Fragment fragment;
 
        TabInfo(@NonNull String _tag, @NonNull Class<?> _class, @Nullable 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);
        }
 
        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 "MyFragmentTabHost.SavedState{"
                    + Integer.toHexString(System.identityHashCode(this))
                    + " curTab=" + curTab + "}";
        }
 
        public static final Parcelable.Creator<MyFragmentTabHost.SavedState> CREATOR
                = new Parcelable.Creator<MyFragmentTabHost.SavedState>() {
            @Override
            public MyFragmentTabHost.SavedState createFromParcel(Parcel in) {
                return new MyFragmentTabHost.SavedState(in);
            }
 
            @Override
            public MyFragmentTabHost.SavedState[] newArray(int size) {
                return new MyFragmentTabHost.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) {
        final TypedArray a = context.obtainStyledAttributes(attrs,
                new int[]{android.R.attr.inflatedId}, 0, 0);
        mContainerId = a.getResourceId(0, 0);
        a.recycle();
 
        super.setOnTabChangedListener(this);
    }
 
    private void ensureHierarchy(Context context) {
        // If owner hasn't made its own view hierarchy, then as a convenience
        // we will construct a standard one here.
        if (findViewById(android.R.id.tabs) == null) {
            LinearLayout ll = new LinearLayout(context);
            ll.setOrientation(LinearLayout.VERTICAL);
            addView(ll, new FrameLayout.LayoutParams(
                    ViewGroup.LayoutParams.MATCH_PARENT,
                    ViewGroup.LayoutParams.MATCH_PARENT));
 
            TabWidget tw = new TabWidget(context);
            tw.setId(android.R.id.tabs);
            tw.setOrientation(TabWidget.HORIZONTAL);
            ll.addView(tw, new LinearLayout.LayoutParams(
                    ViewGroup.LayoutParams.MATCH_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.MATCH_PARENT, 0, 1));
        }
    }
 
    /**
     * @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) {
        ensureHierarchy(context);  // Ensure views required by super.setup()
        super.setup();
        mContext = context;
        mFragmentManager = manager;
        ensureContent();
    }
 
    public void setup(Context context, FragmentManager manager, int containerId) {
        ensureHierarchy(context);  // Ensure views required by super.setup()
        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 ourselves.
        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(@NonNull TabHost.TabSpec tabSpec, @NonNull Class<?> clss,
                       @Nullable Bundle args) {
        tabSpec.setContent(new MyFragmentTabHost.DummyTabFactory(mContext));
 
        final String tag = tabSpec.getTag();
        final MyFragmentTabHost.TabInfo info = new MyFragmentTabHost.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()) {
                final FragmentTransaction ft = mFragmentManager.beginTransaction();
                ft.detach(info.fragment);
                ft.commit();
            }
        }
 
        mTabs.add(info);
        addTab(tabSpec);
    }
 
    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
 
        final String currentTag = getCurrentTabTag();
 
        // Go through all tabs and make sure their fragments match
        // the correct state.
        FragmentTransaction ft = null;
        for (int i = 0, count = mTabs.size(); i < count; i++) {
            final MyFragmentTabHost.TabInfo tab = mTabs.get(i);
            tab.fragment = mFragmentManager.findFragmentByTag(tab.tag);
            if (tab.fragment != null && !tab.fragment.isDetached()) {
                if (tab.tag.equals(currentTag)) {
                    // 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(currentTag, ft);
        if (ft != null) {
            ft.commit();
            mFragmentManager.executePendingTransactions();
        }
    }
 
    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        mAttached = false;
    }
 
    @Override
    protected Parcelable onSaveInstanceState() {
        Parcelable superState = super.onSaveInstanceState();
        MyFragmentTabHost.SavedState ss = new MyFragmentTabHost.SavedState(superState);
        ss.curTab = getCurrentTabTag();
        return ss;
    }
 
    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        if (!(state instanceof MyFragmentTabHost.SavedState)) {
            super.onRestoreInstanceState(state);
            return;
        }
        MyFragmentTabHost.SavedState ss = (MyFragmentTabHost.SavedState) state;
        super.onRestoreInstanceState(ss.getSuperState());
        setCurrentTabByTag(ss.curTab);
    }
 
    @Override
    public void onTabChanged(String tabId) {
        if (mAttached) {
            final FragmentTransaction ft = doTabChanged(tabId, null);
            if (ft != null) {
                ft.commit();
            }
        }
        if (mOnTabChangeListener != null) {
            mOnTabChangeListener.onTabChanged(tabId);
        }
    }
 
    @Nullable
    private FragmentTransaction doTabChanged(@Nullable String tag,
                                             @Nullable FragmentTransaction ft) {
        final MyFragmentTabHost.TabInfo newTab = getTabInfoForTag(tag);
        if (mLastTab != newTab) {
            if (ft == null) {
                ft = mFragmentManager.beginTransaction();
            }
 
            if (mLastTab != null) {
                if (mLastTab.fragment != null) {
//                    ft.detach(mLastTab.fragment);
                    ft.hide(mLastTab.fragment);//http://blog.csdn.net/w1054993544/article/details/37658183
                }
            }
 
            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);
                    ft.show(newTab.fragment);//http://blog.csdn.net/w1054993544/article/details/37658183
                }
            }
 
            mLastTab = newTab;
        }
 
        return ft;
    }
 
    @Nullable
    private MyFragmentTabHost.TabInfo getTabInfoForTag(String tabId) {
        for (int i = 0, count = mTabs.size(); i < count; i++) {
            final MyFragmentTabHost.TabInfo tab = mTabs.get(i);
            if (tab.tag.equals(tabId)) {
                return tab;
            }
        }
        return null;
    }
}

MyFragmentTabHost

代码是复制的系统的FragmentTabHost，只有一小部分和系统不一样的代码：

将tab_top_underline_item.xml文件复制到项目中

<?xml version="1.0" encoding="utf-8"?>
<!-- 带有下划线的顶部选项卡子项的布局文件(选择图片界面) -->
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/toptabLayout"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:paddingTop="@dimen/tab_top_underline_padding"
    android:paddingLeft="@dimen/tab_top_underline_padding"
    android:paddingRight="@dimen/tab_top_underline_padding"
    >
    <!-- 标题 -->
    <TextView
        android:id="@+id/top_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text=""
        android:textSize="@dimen/tab_top_underline_title_size"
        android:textColor="@color/tab_text_normal_top"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />
    <!-- 下划线-->
    <!-- android:background="@color/tab_underline_selected_top" -->
    <View
        android:id="@+id/top_underline"
        android:layout_width="match_parent"
        android:layout_height="@dimen/tab_top_underline_height"
        android:background="@color/tab_underline_normal_top"
        android:layout_below="@id/top_title"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="@dimen/tab_top_underline_padding"
        />
 
</RelativeLayout>

tab_top_underline_item

在colors.xml文件中添加以下代码：【后续可根据实际情况更改背景颜色、文字颜色值】

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#3F51B5</color>
    <color name="colorPrimaryDark">#303F9F</color>
    <color name="colorAccent">#FF4081</color>
 
    <!-- *********************************顶部选项卡区域********************************* -->
    <!-- 顶部选项卡下划线背景色 -->
    <color name="tab_underline_normal_top">#00ffffff</color>
    <color name="tab_underline_selected_top">#FF7700</color>
    <!-- 顶部选项卡文本颜色 -->
    <color name="tab_text_normal_top">#191919</color>
    <color name="tab_text_selected_top">#FF7700</color>
 
</resources>

在dimens.xml文件中添加以下代码：【后续可根据实际情况更改底部选项卡区域的高度值、文字大小值】

<resources>
    <!-- Default screen margins, per the Android Design guidelines. -->
    <dimen name="activity_horizontal_margin">16dp</dimen>
    <dimen name="activity_vertical_margin">16dp</dimen>
 
    <!-- *********************************顶部选项卡区域********************************* -->
    <!-- 选项卡的内边距 -->
    <dimen name="tab_top_underline_padding">10dp</dimen>
    <!-- 选项卡标题的文字大小 -->
    <dimen name="tab_top_underline_title_size">18sp</dimen>
    <!-- 选项卡标题的下划线高度 -->
    <dimen name="tab_top_underline_height">3dp</dimen>
 
</resources>

至此，选项卡子项的布局所需的文件已集成到项目中了。

在AndroidManifest.xml文件中添加网络请求的权限【demo中用到的】

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.why.project.fragmenttabhostunderlinedemo">
 
    <!-- ======================授权访问网络（HttpUtil）========================== -->
    <!-- 允许程序打开网络套接字 -->
    <uses-permission android:name="android.permission.INTERNET"/>
 
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
 
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>
 
</manifest>

三、使用方法

在Activity布局文件中引用MyFragmentTabHost【注意：TabWidget的android:layout_width="match_parent"】

<?xml version="1.0" encoding="utf-8"?>
<!-- 顶部选项卡区域 -->
<com.why.project.fragmenttabhostunderlinedemo.views.tab.MyFragmentTabHost
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tab_top_underline_ftabhost_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
 
    <!-- 必须要有LinearLayout，因为FragmentTabHost属于FrameLayout帧布局 -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
 
        <!-- 选项卡区域 -->
        <!--注意：原来的配置：android:layout_height="?attr/actionBarSize"-->
        <TabWidget
            android:id="@android:id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="top|center_horizontal"/>
 
        <!-- 分割线 -->
        <View
            android:layout_width="match_parent"
            android:layout_height="1dp"
            android:background="#cfcfcf">
        </View>
 
        <!-- 碎片切换区域，且其id必须为@android:id/tabcontent -->
        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            />
 
    </LinearLayout>
 
</com.why.project.fragmenttabhostunderlinedemo.views.tab.MyFragmentTabHost>

创建需要用到的fragment类和布局文件【后续可根据实际情况更改命名，并且需要重新import R文件】

 

fragment_web.xml文件布局如下

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
 
    <!-- webview -->
    <WebView
        android:id="@+id/web_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"></WebView>
 
</LinearLayout>

WebViewFragment

package com.why.project.fragmenttabhostunderlinedemo.fragment;
 
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebView;
import android.webkit.WebViewClient;
 
import com.why.project.fragmenttabhostunderlinedemo.R;
 
/**
 * @Created HaiyuKing
 * @Used  首页界面——碎片界面
 */
public class WebViewFragment extends BaseFragment{
 
    private static final String TAG = "WebViewFragment";
    /**View实例*/
    private View myView;
 
    private WebView web_view;
 
    /**传递过来的参数*/
    private String bundle_param;
 
    //重写
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
 
        //使用FragmentTabHost时，Fragment之间切换时每次都会调用onCreateView方法，导致每次Fragment的布局都重绘，无法保持Fragment原有状态。
        //http://www.cnblogs.com/changkai244/p/4110173.html
        if(myView==null){
            myView = inflater.inflate(R.layout.fragment_web, container, false);
            //接收传参
            Bundle bundle = this.getArguments();
            bundle_param = bundle.getString("param");
        }
        //缓存的rootView需要判断是否已经被加过parent， 如果有parent需要从parent删除，要不然会发生这个rootview已经有parent的错误。
        ViewGroup parent = (ViewGroup) myView.getParent();
        if (parent != null) {
            parent.removeView(myView);
        }
 
        return myView;
    }
 
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onActivityCreated(savedInstanceState);
 
        //初始化控件以及设置
        initView();
        //初始化数据
        initData();
        //初始化控件的点击事件
          initEvent();
    }
    @Override
    public void onResume() {
        super.onResume();
    }
 
    @Override
    public void onPause() {
        super.onPause();
    }
 
    @Override
    public void onDestroy() {
        super.onDestroy();
    }
 
    /**
     * 初始化控件
     */
    private void initView() {
        web_view = (WebView) myView.findViewById(R.id.web_view);
        //设置支持js脚本
//        web_view.getSettings().setJavaScriptEnabled(true);
        web_view.setWebViewClient(new WebViewClient() {
            /**
             * 重写此方法表明点击网页内的链接由自己处理，而不是新开Android的系统browser中响应该链接。
             */
            @Override
            public boolean shouldOverrideUrlLoading(WebView webView, String url) {
                //webView.loadUrl(url);
                return false;
            }
        });
    }
 
    /**
     * 初始化数据
     */
    public void initData() {
        Log.e("tag","{initData}bundle_param="+bundle_param);
        web_view.loadUrl(bundle_param);//加载网页
    }
 
    /**
     * 初始化点击事件
     * */
    private void initEvent(){
    }
 
}

在Activity中使用如下【继承FragmentActivity或者其子类】

package com.why.project.fragmenttabhostunderlinedemo;
 
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TabHost;
import android.widget.TextView;
import android.widget.Toast;
 
import com.why.project.fragmenttabhostunderlinedemo.fragment.WebViewFragment;
import com.why.project.fragmenttabhostunderlinedemo.views.tab.MyFragmentTabHost;
 
import java.util.ArrayList;
 
public class MainActivity extends AppCompatActivity {
 
    private MyFragmentTabHost mTopUnderlineFTabHostLayout;
    //选项卡子类集合
    private ArrayList<TabItem> tabItemList = new ArrayList<TabItem>();
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        initTabList();
        initFTabHostLayout();
        setFTabHostData();
        initEvents();
    }
 
    /**
     * 初始化选项卡数据集合
     */
    private void initTabList() {
        //底部选项卡对应的Fragment类使用的是同一个Fragment，那么需要考虑切换Fragment时避免重复加载UI的问题】
        tabItemList.add(new TabItem(this,"百度",WebViewFragment.class));
        tabItemList.add(new TabItem(this,"博客园",WebViewFragment.class));
        tabItemList.add(new TabItem(this,"CSDN",WebViewFragment.class));
    }
 
    /**
     * 初始化FragmentTabHost
     */
    private void initFTabHostLayout() {
        //实例化
        mTopUnderlineFTabHostLayout = (MyFragmentTabHost) findViewById(R.id.tab_top_underline_ftabhost_layout);
        mTopUnderlineFTabHostLayout.setup(this, getSupportFragmentManager(), android.R.id.tabcontent);//最后一个参数是碎片切换区域的ID值
        // 去掉分割线
        mTopUnderlineFTabHostLayout.getTabWidget().setDividerDrawable(null);
 
    }
 
    /**
     * 设置选项卡的内容
     */
    private void setFTabHostData() {
        //Tab存在于TabWidget内，而TabWidget是存在于TabHost内。与此同时，在TabHost内无需在写一个TabWidget，系统已经内置了一个TabWidget
        for (int i = 0; i < tabItemList.size(); i++) {
            //实例化一个TabSpec,设置tab的名称和视图
            TabHost.TabSpec spec = mTopUnderlineFTabHostLayout.newTabSpec(tabItemList.get(i).getTabTitle()).setIndicator(tabItemList.get(i).getTabView());
            // 添加Fragment
            //初始化传参：http://bbs.csdn.net/topics/391059505
            Bundle bundle = new Bundle();
            if(i == 0 ){
                bundle.putString("param", "http://www.baidu.com");
            }else if(i == tabItemList.size() - 1){
                bundle.putString("param", "http://blog.csdn.net");
            }else{
                bundle.putString("param", "http://www.cnblogs.com");
            }
 
            mTopUnderlineFTabHostLayout.addTab(spec, tabItemList.get(i).getTabFragment(), bundle);
        }
 
        //默认选中第一项
        mTopUnderlineFTabHostLayout.setCurrentTab(0);
        tabItemList.get(0).setChecked(true);
    }
 
    private void initEvents() {
        //选项卡的切换事件监听
        mTopUnderlineFTabHostLayout.setOnTabChangedListener(new TabHost.OnTabChangeListener() {
            @Override
            public void onTabChanged(String tabId) {
                //重置Tab样式
                for (int i = 0; i < tabItemList.size(); i++) {
                    TabItem tabitem = tabItemList.get(i);
                    if (tabId.equals(tabitem.getTabTitle())) {
                        tabitem.setChecked(true);
                    } else {
                        tabitem.setChecked(false);
                    }
                }
 
                Toast.makeText(MainActivity.this, tabId, Toast.LENGTH_SHORT).show();
 
            }
        });
    }
 
    /**
     * 选项卡子项类*/
    class TabItem{
 
        private Context mContext;
 
        private TextView top_title;
        private View top_underline;
 
        //底部选项卡对应的文字
        private String tabTitle;
        //底部选项卡对应的Fragment类
        private Class<? extends Fragment> tabFragment;
 
        public TabItem(Context mContext, String tabTitle, Class tabFragment){
            this.mContext = mContext;
 
            this.tabTitle = tabTitle;
            this.tabFragment = tabFragment;
        }
 
        public Class<? extends Fragment> getTabFragment() {
            return tabFragment;
        }
 
        public String getTabTitle() {
            return tabTitle;
        }
 
        /**
         * 获取底部选项卡的布局实例并初始化设置*/
        private View getTabView() {
            //============引用选项卡的各个选项的布局文件=================
            View toptabitemView = View.inflate(mContext,R.layout.tab_top_underline_item, null);
 
            //===========设置选项卡的文字==========
            top_title = (TextView) toptabitemView.findViewById(R.id.top_title);
            //设置选项卡的文字
            top_title.setText(tabTitle);
 
            //===========设置选项卡控件的下划线==========
            top_underline = (View) toptabitemView.findViewById(R.id.top_underline);
 
            return toptabitemView;
        }
 
        /**
         * 更新文字颜色
         */
        public void setChecked(boolean isChecked) {
            if(tabTitle != null){
                if(isChecked){
                    //修改文字颜色
                    top_title.setTextColor(getResources().getColor(R.color.tab_text_selected_top));
                    //修改下划线的颜色
                    top_underline.setBackgroundColor(getResources().getColor(R.color.tab_underline_selected_top));
                }else{
                    //修改文字颜色
                    top_title.setTextColor(getResources().getColor(R.color.tab_text_normal_top));
                    //修改下划线的颜色
                    top_underline.setBackgroundColor(getResources().getColor(R.color.tab_underline_normal_top));
                }
            }
        }
    }
}

混淆配置

无

参考资料

Android的FragmentTabHost使用(顶部或底部菜单栏)

FragmentTabHost使用方法

Android_ FragmentTabHost切换Fragment时避免重复加载UI

使用FragmentTabHost+TabLayout+ViewPager实现双层嵌套Tab

如何自定义FragmentTabHost中某一个Tab的点击效果

FragmentTabHost布局的使用及优化方式

改变FragmentTabHost选中的文字颜色

fragmenttabhost 传参问题

FragmentTabHost+fragment中获得fragment的对象

fragment中的attach/detach方法说明(网上拷贝，只为作笔记)

FragmentTabHost切换Fragment，与ViewPager切换Fragment时重新onCreateView的问题

Android选项卡动态滑动效果

项目demo下载地址

https://github.com/haiyuKing/FragmentTabHostUnderLineDemo