Android控件使用之FragmentTabHost实现底部菜单

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/Greathfs/article/details/71336423

前言

现在大部分App底部都有一个菜单，实现这个功能也有好多办法：
- TabHost+Fragment
- RadioGroup+Fragment
- FragmentTabHost+Fragment
- 5.0以后有个新控件，BottomNavigator

这篇主要介绍下FragmentTabHost配合Fragment使用

运行效果图

效果图分析

FragmentTabHost简单介绍

首先我们看下官方文档的介绍

OK，接着官方还给出了一份使用的代码，我们也来看下

Activity中使用

import com.example.android.supportv4.R;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTabHost;

/**
 * This demonstrates how you can implement switching between the tabs of a
 * TabHost through fragments, using FragmentTabHost.
 */
public class FragmentTabs extends FragmentActivity {
    private FragmentTabHost mTabHost;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(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);
    }
}

Fragment中使用

import com.example.android.supportv4.R;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTabHost;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class FragmentTabsFragmentSupport extends Fragment {
    private FragmentTabHost mTabHost;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        mTabHost = new FragmentTabHost(getActivity());
        mTabHost.setup(getActivity(), getChildFragmentManager(), R.id.fragment1);

        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;
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        mTabHost = null;
    }
}

FragmentTabHost 布局问题

官方在给出例子的时候，并没有贴出对应的布局文件，这个布局文件有一些要求，所以我就把我自己写的贴出来吧，方便大家观看

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.study.buttomtabdemo.MainActivity">

    <FrameLayout
        android:id="@+id/flayout_content"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

    <com.study.buttomtabdemo.widget.FragmentTabHost
        android:id="@android:id/tabhost"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#ffffff">
        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_weight="0"/>
    </com.study.buttomtabdemo.widget.FragmentTabHost>

</LinearLayout>

这里要注意以下几点：

1.我自己自定义了一个FragmentTabHost，因为原来的FragmentTabHost每次切换Fragment事都会走一遍onCreateView（）和onResume（）方法；

2.id必须是android:id=”@android:id/tabhost”这个；

3.里面的FrameLayout的id必须是android:id=”@android:id/tabcontent”

FragmentTabHost 使用

下面就到了具体使用的过程了

1.定义Tab类

因为它属于Tab的一个组合吧，里面包含好多个Tab，所以我们先定义一个Tab类

/**
 * 主页TAB对应实体
 * Created by HFS on 2017/5/7.
 */

public class Tab {
    private int title; // 文字
    private int icon; // 图标
    private Class fragment; // 对应fragment

    public Tab(Class fragment,int title, int icon ) {
        this.title = title;
        this.icon = icon;
        this.fragment = fragment;
    }

    public int getTitle() {
        return title;
    }

    public void setTitle(int title) {
        this.title = title;
    }

    public int getIcon() {
        return icon;
    }

    public void setIcon(int icon) {
        this.icon = icon;
    }

    public Class getFragment() {
        return fragment;
    }

    public void setFragment(Class fragment) {
        this.fragment = fragment;
    }
}

这里面要对应相应的Fragment，所以需要一个Fragment对象

2.初始化Tab集合

有几个Tab就往Tab集合添加几个Tab

        Tab tab_home = new Tab(HomeFragment.class,R.string.home,R.drawable.selector_icon_home);
        Tab tab_hot = new Tab(HotFragment.class,R.string.hot,R.drawable.selector_icon_hot);
        Tab tab_category = new         Tab(CategoryFragment.class,R.string.catagory,R.drawable.selector_icon_category);
        Tab tab_cart = new Tab(CartFragment.class,R.string.cart,R.drawable.selector_icon_cart);
        Tab tab_mine = new Tab(MineFragment.class,R.string.mine,R.drawable.selector_icon_mine);

        mTabs.add(tab_home);
        mTabs.add(tab_hot);
        mTabs.add(tab_category);
        mTabs.add(tab_cart);
        mTabs.add(tab_mine);

3.setUp

找到该控件之后，就要调用对应的这个方法

 mInflater = LayoutInflater.from(this);
        mTabhost = (FragmentTabHost) this.findViewById(android.R.id.tabhost);
        mTabhost.setup(this,getSupportFragmentManager(),R.id.flayout_content);

4.添加TabSpec

到这一步就要添加TabSpec了，有几个Tab，就添加几个TabSpec

           for (Tab tab : mTabs){

            TabHost.TabSpec tabSpec = mTabhost.newTabSpec(getString(tab.getTitle()));

            tabSpec.setIndicator(buildIndicator(tab));

            mTabhost.addTab(tabSpec,tab.getFragment(),null);

        }

      //构建Indicator
        private View buildIndicator(Tab tab){

            View view =mInflater.inflate(R.layout.tab_indicator,null);
            ImageView img = (ImageView) view.findViewById(R.id.icon_tab);
            TextView text = (TextView) view.findViewById(R.id.txt_indicator);

            img.setBackgroundResource(tab.getIcon());
            text.setText(tab.getTitle());

        return  view;
    }

5.设置默认显示第一个

mTabhost.setCurrentTab(0);

6.设置没有分割线

mTabhost.getTabWidget().setShowDividers(LinearLayout.SHOW_DIVIDER_NONE);

自定义FragmentTabHost类

package com.study.buttomtabdemo.widget;



/**
 * Created by monkey
 * on 2014/9/24
 * 功能描述：修改过的FragmentTabHost,保存fragment实例不销毁
 */
/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */



        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.view.ViewGroup;
        import android.widget.FrameLayout;
        import android.widget.LinearLayout;
        import android.widget.TabHost;
        import android.widget.TabWidget;

/**
 * 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.
 *
 * <p>
 * Here is a simple example of using a FragmentTabHost in an Activity:
 *
 * {@sample
 * development/samples/Support4Demos/src/com/example/android/supportv4/app/
 * FragmentTabs.java complete}
 *
 * <p>
 * This can also be used inside of a fragment through fragment nesting:
 *
 * {@sample
 * development/samples/Support4Demos/src/com/example/android/supportv4/app/
 * FragmentTabsFragmentSupport.java complete}
 */
public class FragmentTabHost 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 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 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 Creator<SavedState> CREATOR = new Creator<SavedState>() {
            public SavedState createFromParcel(Parcel in) {
                return new SavedState(in);
            }

            public SavedState[] newArray(int size) {
                return new SavedState[size];
            }
        };
    }

    public FragmentTabHost(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 FragmentTabHost(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);
    }

    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 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 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(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.hide(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.fragment != null) {
                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);
                    ft.hide(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.commitAllowingStateLoss();
            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);
                    ft.hide(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);
                    ft.show(newTab.fragment);
                }
            }

            mLastTab = newTab;
        }
        return ft;
    }
}