Android底部导航栏实现（二）之RadioGroup

这里简单记录一下Android底部导航栏通过RadioGroup+Fragment的实现。

这里写图片描述

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>

这里的drawableTop使用了状态选择器

<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>

<item name="android:gravity">center</item>
<item name="android:textSize">12sp</item>
</style>

###代码初始化的代码就不记录了，都是一些findViewById,实现过程无非就是对RadioButton进行监听一下：

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();//设置状态
transaction.commit(); }

####状态的设置

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)); } }

这里需要注意的是， setDefaultFragment();我写在onCreateVew里面并没有生效。这里我写在了onStart()方法里了。

@Override
public void onStart() {
setDefaultFragment();//写在onCreateView里面，当页面跑到其他Fragment再回来就不会生效
super.onStart(); }

>说明：这几篇文章没有过多的文字叙述，因为这些东西也不是很难，而且都是常用的，相信很多人都了如指掌了，多说亦是废话，直接上代码看的反而更清楚。

[DownLoad Demo](https://github.com/student9128/BottomNavigationBarForAndroid)