java：

rgGroup = (RadioGroup) findViewById(R.id.re_group);
        rbWeiHui = (RadioButton) findViewById(R.id.rb_wei_hui);
        rbAdd = (RadioButton) findViewById(R.id.rb_add);
        rbMine = (RadioButton) findViewById(R.id.rb_mine);

        //定義底部標籤圖片大小
        Drawable drawableWeiHui = getResources().getDrawable(R.drawable.btn_tab_wei_hui_selector);
        drawableWeiHui.setBounds(0, 0, 69, 69);//第一0是距左右邊距離，第二0是距上下邊距離，第三69長度,第四寬度
        rbWeiHui.setCompoundDrawables(null, drawableWeiHui, null, null);//只放上面

        Drawable drawableAdd = getResources().getDrawable(R.drawable.btn_tab_add_selector);
        drawableAdd.setBounds(0, 0, 168, 120);
        rbAdd.setCompoundDrawables(drawableAdd, null, null, null);

        Drawable drawableRight = getResources().getDrawable(R.drawable.btn_tab_mine_selector);
        drawableRight.setBounds(0, 0, 69, 69);
        rbMine.setCompoundDrawables(null, drawableRight, null, null);

        //初始化底部標籤
        rgGroup.check(R.id.rb_wei_hui);// 預設勾選首頁，初始化時候讓首頁預設勾選
 

<RadioGroup
        android:id="@+id/re_group"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/app_bg_color"
        android:orientation="horizontal" >

        <RadioButton
            android:id="@+id/rb_wei_hui"
            style="@style/BottomTabStyle"
            android:layout_marginTop="5dp"
            android:drawableTop="@drawable/btn_tab_wei_hui_selector"
            android:textSize="12sp"
            android:text="xx" />

        <RadioButton
            android:id="@+id/rb_add"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@color/app_bg_color"
            android:button="@null"
            android:drawableTop="@mipmap/ic_add_selected"
            android:gravity="center"
            android:paddingTop="10dip" />

        <RadioButton
            android:id="@+id/rb_mine"
            style="@style/BottomTabStyle"
            android:layout_marginTop="5dp"
            android:drawableTop="@drawable/btn_tab_mine_selector"
            android:textSize="12sp"
            android:text="xx" />
    </RadioGroup>
 

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >

    <item android:drawable="@mipmap/ic_mine_selected" android:state_checked="true" />
    <item android:drawable="@mipmap/ic_mine_normal" />


</selector>
 

 <!-- 低欄RadioButton首頁下面的標籤的樣式  -->
    <style name="BottomTabStyle">
        <item name="android:layout_width">wrap_content</item>
        <item name="android:layout_height">wrap_content</item>
        <item name="android:layout_gravity">center_vertical</item>
        <item name="android:button">@null</item>
        <item name="android:padding">5dp</item>
        <item name="android:drawablePadding">3dp</item>
        <item name="android:textColor">@drawable/btn_tab_text_selector</item>
        <item name="android:layout_weight">1</item>
        <item name="android:gravity">center</item>
        <item name="android:layout_marginTop">5dp</item>
    </style>