导读:

    使用 Kotlin 和 BottomNavigationBar 实现Android底部导航栏

1. BottomNavigationBar - Kotlin 下载:

BottomNavigationBar-KotlinDemo

2.使用方式:

2.1 gradle(Module)添加依赖库:(FIle -> Project Structure -> app -> Dependencies)

 implementation 'com.ashokvarma.android:bottom-navigation-bar:2.0.2'

2.2 BottomNavigationBar布局:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.lijiangbing.bottomnavigationbar.MainActivity">
    <TextView
        android:id="@+id/tv_test"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <com.ashokvarma.bottomnavigation.BottomNavigationBar
        android:id="@+id/bottom_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"></com.ashokvarma.bottomnavigation.BottomNavigationBar>
    <!--留给Fragment使用-->
    <FrameLayout
        android:id="@+id/fl"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

2.3 MainActivity 使用 BottomNavigationBar

class MainActivity : AppCompatActivity(),BottomNavigationBar.OnTabSelectedListener {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        with(bottom_bar){
    //设置显示模式,必须在初始化完成之前设置
           setBackgroundStyle(BottomNavigationBar.BACKGROUND_STYLE_STATIC)
           setMode(BottomNavigationBar.MODE_FIXED)
           addItem(BottomNavigationItem(R.drawable.icon_wechat_g,R.string.nv_bottom).setActiveColorResource(R.color.colorPrimaryDark).setBadgeItem(TextBadgeItem().setText("2")));
           addItem(BottomNavigationItem(R.drawable.icon_wechat_g,R.string.nv_bottom).setActiveColorResource(R.color.colorPrimaryDark));
           addItem(BottomNavigationItem(R.drawable.icon_wechat_g,R.string.nv_bottom).setActiveColorResource(R.color.colorPrimaryDark));
           addItem(BottomNavigationItem(R.drawable.icon_wechat_g,R.string.nv_bottom).setActiveColorResource(R.color.colorPrimaryDark));
           setFirstSelectedPosition(0);// 默认选中 的item 
           initialise();
        }

        bottom_bar.setTabSelectedListener(this);
        // 设置默认 Fragment
        val manager = getSupportFragmentManager();
        val transaction = manager.beginTransaction();
        transaction.replace(R.id.fl,fragment("first"));
        transaction.commit();
    }

  //复写点击监听,替换Fragment
    override fun onTabSelected(position: Int) {
        val manager = getSupportFragmentManager();
        val transaction = manager.beginTransaction();
        when (position){
            0 -> {
                    transaction.replace(R.id.fl, fragment("first"))
                    transaction.commit();

            }
            1 -> {
                transaction.replace(R.id.fl, fragment("second"));
                transaction.commit();
            }
            2 -> {
                transaction.replace(R.id.fl, fragment("third"));
                transaction.commit();
            }
            else -> {
                transaction.replace(R.id.fl, fragment("last"));
                transaction.commit();
            }
        }
    }

    override fun onTabUnselected(position: Int) {

    }

    override fun onTabReselected(position: Int) {

    }
}

2.4 Fragment 布局文件:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <TextView
        android:id="@+id/tv_titleView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Fragement"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>

</android.support.constraint.ConstraintLayout>