這里簡單記錄一下Android底部導航欄通過RadioGroup+Fragment的實現。 

布局：

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
                android:layout_width="match_parent" 
                android:layout_height="match_parent" 
                android:orientation="vertical"> 
 
    <include layout="@layout/fragment_content"/> 
 
    <View 
        android:layout_width="match_parent" 
        android:layout_height="1px" 
        android:background="@color/grey_300" 
        android:elevation="20dp"/> 
 
    <RadioGroup 
        android:id="@+id/radio_group" 
        android:layout_width="match_parent" 
        android:layout_height="56dp" 
        android:layout_alignParentBottom="true" 
        android:background="@color/white" 
        android:orientation="horizontal"> 
 
        <RadioButton 
            android:id="@+id/rb_home" 
            style="@style/radiobutton_style" 
            android:checked="true" 
            android:drawableTop="@drawable/radiobutton_bg_home" 
            android:text="@string/item_home" 
            /> 
 
        <RadioButton 
            android:id="@+id/rb_location" 
            style="@style/radiobutton_style" 
            android:drawableTop="@drawable/radiobutton_bg_location" 
            android:text="@string/item_location"/> 
 
        <RadioButton 
            android:id="@+id/rb_like" 
            style="@style/radiobutton_style" 
            android:drawableTop="@drawable/radiobutton_bg_like" 
            android:text="@string/item_like"/> 
 
        <RadioButton 
            android:id="@+id/rb_me" 
            style="@style/radiobutton_style" 
            android:drawableTop="@drawable/radiobutton_bg_me" 
            android:text="@string/item_person"/> 
 
    </RadioGroup> 
</RelativeLayout>  

這里的drawableTop使用了狀態選擇器

<selector xmlns:android="http://schemas.android.com/apk/res/android"> 
    <item android:drawable="@drawable/home_fill" android:state_checked="true"/> 
    <item android:drawable="@drawable/home"/> 
</selector>  

style

<style name="radiobutton_style"> 
        <item name="android:layout_width">0dp</item> 
        <item name="android:padding">3dp</item> 
        <item name="android:layout_height">match_parent</item> 
        <item name="android:layout_weight">1</item> 
        <item name="android:button">@null</item><!--去除RadioButton默認帶的圓點--> 
        <item name="android:gravity">center</item> 
        <item name="android:textSize">12sp</item> 
    </style>  

代碼

初始化的代碼就不記錄了，都是一些findViewById,實現過程無非就是對RadioButton進行監聽一下：

mRadioGroup.setOnCheckedChangeListener(this); 
 
 
    @Override 
    public void onCheckedChanged(RadioGroup group, int checkId) { 
        FragmentTransaction transaction = getFragmentManager().beginTransaction(); 
        switch (checkId) { 
            case R.id.rb_home: 
                if (mHomeFragment == null) { 
                    mHomeFragment = HomeFragment.newInstance(getString(R.string.item_home)); 
                } 
                transaction.replace(R.id.sub_content, mHomeFragment); 
                break; 
            case R.id.rb_location: 
                if (mLocationFragment == null) { 
                    mLocationFragment = LocationFragment.newInstance(getString(R.string.item_location)); 
                } 
                transaction.replace(R.id.sub_content, mLocationFragment); 
                break; 
            case R.id.rb_like: 
                if (mLikeFragment == null) { 
                    mLikeFragment = LikeFragment.newInstance(getString(R.string.item_like)); 
                } 
                transaction.replace(R.id.sub_content, mLikeFragment); 
                break; 
            case R.id.rb_me: 
                if (mPersonFragment == null) { 
                    mPersonFragment = PersonFragment.newInstance(getString(R.string.item_person)); 
                } 
                transaction.replace(R.id.sub_content, mPersonFragment); 
                break; 
        } 
        setTabState();//設置狀態 
        transaction.commit(); 
    }  

狀態的設置 

private void setTabState() { 
        setHomeState(); 
        setLocationState(); 
        setLikeState(); 
        setMeState(); 
 
    } 
 
    /** 
     * set tab home state 
     */ 
    private void setHomeState() { 
        if (mRadioHome.isChecked()) { 
            mRadioHome.setTextColor(ContextCompat.getColor(getActivity(), R.color.colorPrimary)); 
        } else { 
            mRadioHome.setTextColor(ContextCompat.getColor(getActivity(), R.color.black)); 
        } 
    } 
 
    private void setLocationState() { 
        if (mRadioLocation.isChecked()) { 
            mRadioLocation.setTextColor(ContextCompat.getColor(getActivity(), R.color.colorPrimary)); 
        } else { 
            mRadioLocation.setTextColor(ContextCompat.getColor(getActivity(), R.color.black)); 
        } 
    } 
 
    private void setLikeState() { 
        if (mRadioLike.isChecked()) { 
            mRadioLike.setTextColor(ContextCompat.getColor(getActivity(), R.color.colorPrimary)); 
        } else { 
            mRadioLike.setTextColor(ContextCompat.getColor(getActivity(), R.color.black)); 
        } 
    } 
 
    private void setMeState() { 
        if (mRadioMe.isChecked()) { 
            mRadioMe.setTextColor(ContextCompat.getColor(getActivity(), R.color.colorPrimary)); 
        } else { 
            mRadioMe.setTextColor(ContextCompat.getColor(getActivity(), R.color.black)); 
        } 
    }  

這里需要注意的是， setDefaultFragment();我寫在onCreateVew里面并沒有生效。這里我寫在了onStart()方法里了。

@Override 
   public void onStart() { 
       setDefaultFragment();//寫在onCreateView里面，當頁面跑到其他Fragment再回來就不會生效 
       super.onStart(); 
   }  

說明：這幾篇文章沒有過多的文字敘述，因為這些東西也不是很難，而且都是常用的，相信很多人都了如指掌了，多說亦是廢話，直接上代碼看的反而更清楚。