FragmentTabHost+ViewPager实现底部菜单和滑动界面效果

文中调用FragmentTabHost的addTab将fragmentArray中Fragments加入FragmentTabHost中，

（注：fragment是以class的形式传入，在FragmentTabHost的内部会将这些fragment的类实例化）

而在initPager函数中又新建了一遍所有的fragment，并加入到ViewPager中。

因此文中存在8个fragment的实例，而这个界面往往是放在应用启动后的第一个界面，这种资源的浪费是很严重的。

解决方案在最下面

一.layout

1.main_activity_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/wallpaper_0"
    android:orientation="vertical">
    
　　 ///主体内容页
    <android.support.v4.view.ViewPager
        android:id="@+id/main_content_fragment"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_weight="1">

    </android.support.v4.view.ViewPager>


    <android.support.v4.app.FragmentTabHost
        android:id="@+id/fragment_tab_host"
        android:layout_width="match_parent"
        android:layout_height="54dp">

　　　　　　//这里搞不懂，加了不加效果都没变，而且也没用到它
        <!--<FrameLayout-->
            <!--android:id="@+id/tab_content_fragment"-->
            <!--android:layout_width="0dp"-->
            <!--android:layout_height="0dp"-->
            <!--android:layout_weight="0" />-->

    </android.support.v4.app.FragmentTabHost>

</LinearLayout>

2.tab_item_fragment.xml

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


    ///FragmentTabHost菜单字体和图标
    <TextView
        android:id="@+id/tab_item_textview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_marginTop="10dp"
        android:gravity="center"
        android:textColor="@drawable/tab_text_selector"
        android:textSize="12sp"
        android:textStyle="normal" />

</LinearLayout>

3.weather_tab_fragment.xml

<?xml version="1.0" encoding="utf-8"?>

<!--Weather内容-->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:background="@color/gray_background_color">


</LinearLayout>

这里有四个菜单选项，所以有四个对应的Xml,我只写了一个，其他除了文件名都一样，记得把背景颜色改了，不然都一样看不出来

二.values

colors.xml添加

 <color name="black">#000000</color>
    <color name="white">#ffffff</color>
    <color name="grey">#888888</color>
    <color name="red">#ff0000</color>
    <color name="orange_light">#ffffdd</color>
    <color name="transparent">#00000000</color>
    <color name="blue">#0099ff</color>
    <color name="green">#00ff99</color>

    <color name="orange">#F9CC12</color>
    <color name="blue_light">#aaaaff</color>
    <color name="tab_text_selected">#0084e8</color>
    <color name="tab_text_normal">#7597b3</color>

三.drawable

1.tab_text_selector.xml

<!--选中和未选中的字体颜色-->
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_selected="true" android:color="@color/white" />
    <item android:color="@color/white_trans50" />
</selector>

2.tab_weather_bg_selector.xml

<!--天气选中与未选中的图片-->
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_selected="true" android:drawable="@drawable/tab_weather_select" />
    <item android:drawable="@drawable/tab_weather_unselect" />
</selector>

 这里也是有四个，每个xml设置不同的状态图片样式

四.drawable-hdpi

五.java

一个FragmentPagerAdapter

四个碎片

还有个MainActivity

WeatherFragment

package com.xinyibufang.xtool.Fragment_Dir;

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

import com.xinyibufang.xtool.R;

/**
 * 作者：XinYiBuFang（心以不防）
 * 时间：2018/1/10.
 * QQ：1107786562
 * 邮箱:1107786562@qq.com
 * 说明：XTool
 */

public class WeatherFragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.weather_tab_fragment, container, false);
        return view;
    }
}

同样有四个对应的Fragment,注意把layout设置成不同的就行

3.SecondFragment.java

public class SecondFragment extends Fragment {

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.second_fragment, container, false);
        return view;
    }
}

ViewPagerAdapter（适配器）

package com.xinyibufang.xtool.Adapter;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.PagerAdapter;
import android.view.ViewGroup;

import java.util.List;

/**
 * 作者: XYBF
 * 时间: 2018-01-11 10:59
 * QQ:1107786562
 */

public class ViewPagerAdapter extends FragmentPagerAdapter {

    List<Fragment> FragmentList;


    public ViewPagerAdapter(FragmentManager fm, List<Fragment> list) {
        super(fm);
        this.FragmentList = list;
    }//写构造方法，方便赋值调用

    @Override
    public Fragment getItem(int arg0) {
        return FragmentList.get(arg0);
    }//根据Item的位置返回对应位置的Fragment，绑定item和Fragment

    @Override
    public int getCount() {
        return FragmentList.size();
    }//设置Item的数量


}

MainActivity.java

package com.xinyibufang.xtool;

import android.graphics.drawable.Drawable;
import android.os.Build;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTabHost;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.TabHost;
import android.widget.TextView;

import com.xinyibufang.xtool.Adapter.ViewPagerAdapter;
import com.xinyibufang.xtool.Fragment_Dir.MoreFragment;
import com.xinyibufang.xtool.Fragment_Dir.NoteFragment;
import com.xinyibufang.xtool.Fragment_Dir.TimerFragment;
import com.xinyibufang.xtool.Fragment_Dir.WeatherFragment;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private FragmentTabHost Frag_TabHost;
    private List<Fragment> FragmentList = new ArrayList<Fragment>(4);       ///Fragment集合
    private ViewPager ViewPagerControl;                                     ///ViewPager


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_activity_layout);

        //背景与状态栏融合(状态栏设置透明)
        this.getWindow().addFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);

        Frag_TabHost = (FragmentTabHost) findViewById(R.id.fragment_tab_host);                  ///FragmentTabHost控件
        Frag_TabHost.setup(this, getSupportFragmentManager(), R.id.main_content_fragment);      ///内容界面

        ///绑定对应的碎片
        Frag_TabHost.addTab(GetTabView("天气", R.drawable.tab_weather_bg_selector), WeatherFragment
                .class, null);
        Frag_TabHost.addTab(GetTabView("便签", R.drawable.tab_note_bg_selector), NoteFragment
                .class, null);
        Frag_TabHost.addTab(GetTabView("计时器", R.drawable.tab_timer_bg_selector), TimerFragment
                .class, null);
        Frag_TabHost.addTab(GetTabView("更多", R.drawable.tab_more_bg_selector), MoreFragment
                .class, null);

        //添加内容碎片
        FragmentList.add(new WeatherFragment());
        FragmentList.add(new NoteFragment());
        FragmentList.add(new TimerFragment());
        FragmentList.add(new MoreFragment());
        ViewPagerControl = (ViewPager) findViewById(R.id.main_content_fragment);

        //设置适配器
        ViewPagerControl.setAdapter(new ViewPagerAdapter(getSupportFragmentManager(), FragmentList));

        //设置监听ViewPager
        ViewPagerControl.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                //设置选中
                Frag_TabHost.setCurrentTab(position);
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

        ///监听FragmentTabHost
        Frag_TabHost.setOnTabChangedListener(new TabHost.OnTabChangeListener() {
            @Override
            public void onTabChanged(String tabId) {
                ///获得FragmentTabHost选中
                int position = Frag_TabHost.getCurrentTab();
                // ViewPager滑动到对应的位置
                ViewPagerControl.setCurrentItem(position);
            }
        });

    }


    ///填充TabSpec
    private TabHost.TabSpec GetTabView(String text, int img_id) {
        Drawable drawable = ContextCompat.getDrawable(this, img_id);     //获取图片ID
        drawable.setBounds(0, 0, drawable.getMinimumWidth(), drawable.getMinimumHeight());      //设置图片
        View item_bar = getLayoutInflater().inflate(R.layout.tab_item_fragment, null);          //实例化单个菜单
        TextView tv_item = (TextView) item_bar.findViewById(R.id.tab_item_textview);            //实例化TextView
        tv_item.setText(text);                                                                  //TextView赋值
        tv_item.setCompoundDrawables(null, drawable, null, null);                               //设置图片位置
        TabHost.TabSpec spec = Frag_TabHost.newTabSpec(text).setIndicator(item_bar);            //绑定TabSpec
        return spec;
    }


}

六.效果

滑动切换中　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　切换界面

　　　　　　　　　　　　       

FragmenttabHost与ViewPager重复实例化 和多次onCreateView解决方案：重写FragmentTabHost

　　解决些问题的方向是如何做到只创建一个Fragment并切换时不走其生命周期方法

   将之前要传入的Class只接改成Fragment例，我们是能做到Fragment只new一次.

   在切换时是通过tag去寻找的，在原码中写的是这样，如果没有就通过反射来创建一个，这就是fragment第一次实例化的原因
　　

用下面重写的XFragmentTabHost替换v4的FragmentTabHost

package com.xinyibufang.xtool.Adapter;

/*
 * 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 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;

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.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;

/**
 * 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>
 * <p>Here is a simple example of using a FragmentTabHost in an Activity:
 * <p>
 * {@sample frameworks/support/samples/Support4Demos/src/com/example/android/supportv4/app/FragmentTabs.java
 * complete}
 * <p>
 * <p>This can also be used inside of a fragment through fragment nesting:
 * <p>
 * {@sample frameworks/support/samples/Support4Demos/src/com/example/android/supportv4/app/FragmentTabsFragmentSupport.java
 * complete}
 */
public class XFragmentTabHost extends TabHost
        implements TabHost.OnTabChangeListener {
    private final ArrayList<XFragmentTabHost.TabInfo> mTabs = new ArrayList<>();

    private FrameLayout mRealTabContent;
    private Context mContext;
    private FragmentManager mFragmentManager;
    private int mContainerId;
    private TabHost.OnTabChangeListener mOnTabChangeListener;
    private XFragmentTabHost.TabInfo mLastTab;
    private boolean mAttached;

    static final class TabInfo {
        final
        @NonNull
        String tag;
        final
        @NonNull
        Fragment clss;
        final
        @Nullable
        Bundle args;
        Fragment fragment;

        TabInfo(@NonNull String _tag, @NonNull Fragment _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 "FragmentTabHost.SavedState{"
                    + Integer.toHexString(System.identityHashCode(this))
                    + " curTab=" + curTab + "}";
        }

        public static final Parcelable.Creator<XFragmentTabHost.SavedState> CREATOR
                = new Parcelable.Creator<XFragmentTabHost.SavedState>() {
            @Override
            public XFragmentTabHost.SavedState createFromParcel(Parcel in) {
                return new XFragmentTabHost.SavedState(in);
            }

            @Override
            public XFragmentTabHost.SavedState[] newArray(int size) {
                return new XFragmentTabHost.SavedState[size];
            }
        };
    }

    public XFragmentTabHost(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 XFragmentTabHost(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 Fragment clss,
                       @Nullable Bundle args) {
        tabSpec.setContent(new XFragmentTabHost.DummyTabFactory(mContext));

        final String tag = tabSpec.getTag();
        final XFragmentTabHost.TabInfo info = new XFragmentTabHost.TabInfo(tag, clss, args);

        mTabs.add(info);
        addTab(tabSpec);
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();

    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        mAttached = false;
    }

    @Override
    protected Parcelable onSaveInstanceState() {
        Parcelable superState = super.onSaveInstanceState();
        XFragmentTabHost.SavedState ss = new XFragmentTabHost.SavedState(superState);
        ss.curTab = getCurrentTabTag();
        return ss;
    }

    @Override
    protected void onRestoreInstanceState(Parcelable state) {
        if (!(state instanceof XFragmentTabHost.SavedState)) {
            super.onRestoreInstanceState(state);
            return;
        }
        XFragmentTabHost.SavedState ss = (XFragmentTabHost.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) {
        TabInfo newTab = null;
        for (int i=0; i<mTabs.size(); i++) {
            TabInfo tab = mTabs.get(i);
            if (tab.tag.equals(tag)) {
                newTab = tab;
            }
        }
        if (newTab == null) {
            throw new IllegalStateException("No tab known for tag " + tag);
        }
        if (mLastTab != newTab) {
            if (ft == null) {
                ft = mFragmentManager.beginTransaction();
            }
            if (mLastTab != null) {
                if (mLastTab.fragment != null) {
                    ft.hide(mLastTab.fragment);
                }
            }
            if (newTab != null) {
                if (null == mFragmentManager.getFragments() || !mFragmentManager.getFragments().contains(newTab.fragment)) {
                        ft.add(mContainerId, newTab.fragment, newTab.tag);
                } else {
                    ft.show(newTab.fragment);
                }
            }

            mLastTab = newTab;
        }
        return ft;
    }

    @Nullable
    private XFragmentTabHost.TabInfo getTabInfoForTag(String tabId) {
        for (int i = 0, count = mTabs.size(); i < count; i++) {
            final XFragmentTabHost.TabInfo tab = mTabs.get(i);
            if (tab.tag.equals(tabId)) {
                return tab;
            }
        }
        return null;
    }
}

WeatherFragment修改

package com.xinyibufang.xtool.Fragment_Dir;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.xinyibufang.xtool.R;

/**
 * 作者：XinYiBuFang（心以不防）
 * 时间：2018/1/10.
 * QQ：1107786562
 * 邮箱:1107786562@qq.com
 * 说明：XTool
 */

public class WeatherFragment extends Fragment {

    private View mCacheView;
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
       //View view = inflater.inflate(R.layout.weather_tab_fragment, container, false);

        if (mCacheView == null) {
            Log.i("AAAA", "Weather onCreateView");
            mCacheView = inflater.inflate(R.layout.weather_tab_fragment, null);
        }
        ViewGroup parent = (ViewGroup) mCacheView.getParent();
        if (parent != null) {
            parent.removeView(mCacheView);
        }
        return mCacheView;
    }
}

 

看一下日志，onCreateView只执行了一次，切换界面也不会多次实例化和onCreateView

源码：链接：https://pan.baidu.com/s/1dYvoPw 密码：ek4y