使用LinearLayout+TextView实现底部导航栏,重复切换页面不会重新加载

    上次有写一篇“Fragment+RadioButton组合构成的底部导航栏的实现”的博客，
    本次写这篇博客：1、想用百度贴吧底部导航栏的方式实现；2、切换Fragment时用hide和add的方式进行切换，这样不会重新实例化。
    直接代码贴上：

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;

import java.util.List;

/**
 * 采用LinearLayout+TextView的方式构成的底部导航栏,重复切换页面不会重新加载
 */
public class MainActivity extends FragmentActivity {
    /**数组的形式*/
    private Fragment[] mFragments;
    /**fragment管理*/
    private FragmentManager fragmentManager;
    /**fragment的事务控制器*/
    FragmentTransaction fragmentTransaction;
    private int last_Fragment = 0;
    private LinearLayout tab_main;
    private LinearLayout tab_vip;
    private LinearLayout tab_tba;
    private LinearLayout tab_mine;
    /** 红点*/
    private ImageView bar_point;
    private int checkedNum = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.ly_main);
        bar_point = (ImageView) findViewById(R.id.bar_point);
        tab_main = (LinearLayout) findViewById(R.id.tab_main);
        tab_tba = (LinearLayout) findViewById(R.id.tab_tba);
        tab_vip = (LinearLayout) findViewById(R.id.tab_vip);
        tab_mine = (LinearLayout) findViewById(R.id.tab_mine);
        initmFagments();
    }
    /**初始化Fragment*/
    private void initmFagments() {
        mFragments = new Fragment[4];

        fragmentManager = getSupportFragmentManager();
        mFragments[0] = fragmentManager.findFragmentById(R.id.fr_main);
        mFragments[1] = fragmentManager.findFragmentById(R.id.fr_tba);
        mFragments[2] = fragmentManager.findFragmentById(R.id.fr_vip);
        mFragments[3] = fragmentManager.findFragmentById(R.id.fr_mine);

        fragmentTransaction = fragmentManager.beginTransaction().hide(mFragments[0]).hide(mFragments[1]).hide(mFragments[2]).hide(mFragments[3]);
        //默认显示第0 个
        fragmentTransaction.show(mFragments[0]).commit();
        tab_main.setSelected(true);


    }
    public void switchContent(Fragment from, Fragment to) {
        FragmentTransaction transaction = fragmentManager.beginTransaction();
            if (!to.isAdded()) {    // 先判断是否被add过
                transaction.hide(from).add(R.id.fr_main, to).commit(); // 隐藏当前的fragment，add下一个到Activity中
            } else {
                transaction.hide(from).show(to).commit(); // 隐藏当前的fragment，显示下一个
            }
    }
    /**
     * 点击切换不同tab
     */
    public void tab_click(View view) {
        switch (view.getId()) {
            case R.id.tab_main:
                tab_main.setSelected(true);
                tab_tba.setSelected(false);
                tab_vip.setSelected(false);
                tab_mine.setSelected(false);
                checkedNum = 0;
                break;
            case R.id.tab_tba:
                tab_tba.setSelected(true);
                tab_main.setSelected(false);
                tab_vip.setSelected(false);
                tab_mine.setSelected(false);
                checkedNum = 1;
                break;
            case R.id.tab_vip:
                tab_vip.setSelected(true);
                tab_tba.setSelected(false);
                tab_main.setSelected(false);
                tab_mine.setSelected(false);
                checkedNum = 2;
                break;
            case R.id.tab_mine:
                tab_mine.setSelected(true);
                tab_vip.setSelected(false);
                tab_tba.setSelected(false);
                tab_main.setSelected(false);
                bar_point.setVisibility(View.VISIBLE);
                checkedNum = 3;
                break;
        }
        Fragment to = mFragments[checkedNum];
        Fragment last = mFragments[last_Fragment];
        last_Fragment=checkedNum;
        switchContent(last,to);
    }


}

        xml文件：

<?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">

    <fragment
        android:id="@+id/fr_main"
        android:name="对应的fragment文件路径"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">
    </fragment>

    /**为节约篇幅，这里只放一个。。。。。。。。*/
    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="#ffcacacc" />

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <LinearLayout
                android:id="@+id/tab_main"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:onClick="tab_click">

                <TextView
                    style="@style/main_tab_radio_button_style"
                    android:drawableTop="@drawable/other_btn_image"
                    android:enabled="true"
                    android:text="XX" />
            </LinearLayout>

            <LinearLayout
                android:id="@+id/tab_tba"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:onClick="tab_click">

                <TextView
                    style="@style/main_tab_radio_button_style"
                    android:drawableTop="@drawable/other_btn_image"
                    android:text="XX" />
            </LinearLayout>

            <LinearLayout
                android:id="@+id/tab_vip"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:onClick="tab_click">


                <TextView
                    style="@style/main_tab_radio_button_style"
                    android:drawableTop="@drawable/other_btn_image"
                    android:text="XX" />
            </LinearLayout>

            <LinearLayout
                android:id="@+id/tab_mine"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:gravity="center"
                android:onClick="tab_click"
                android:orientation="vertical">

                <TextView
                    style="@style/main_tab_radio_button_style"
                    android:drawableTop="@drawable/other_btn_image"
                    android:text="XX" />

                <ImageView
                    android:id="@+id/bar_point"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginRight="-15dp"
                    android:layout_marginTop="-55dp"
                    android:background="@android:color/transparent"
                    android:src="@drawable/bar_dot"
                    android:visibility="gone" />
            </LinearLayout>
        </LinearLayout>
    </FrameLayout>
</LinearLayout>

    只在最后一个按钮上添加了显示红点的提示，其他按钮上也可用相同的方式添加；默认为隐藏的状态。