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[Android]创建TabBar

article 2024/9/24 9:22:17

创建一个包含“首页”、“分类”和“我的”选项卡的TabBar并实现切换功能，通常可以通过使用TabLayout结合ViewPager或ViewPager2来完成。以下是一个基本的示例，展示了如何使用Kotlin和XML来实现这个功能。

1.添加依赖项到build.gradle

dependencies {
    // ...
    implementation("com.google.android.material:material:1.8.0")
    implementation("androidx.viewpager2:viewpager2:1.0.0")
}

2.在你的布局XML文件中定义TabLayout和ViewPager2

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tabLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabMode="fixed"
        app:tabGravity="fill"
        app:tabIndicatorHeight="0dp" />

</LinearLayout>

3.在你的Activity中设置ViewPager2和TabLayout

package com.example.gatestdemol.tabbar

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentActivity
import androidx.viewpager2.adapter.FragmentStateAdapter
import com.example.gatestdemol.databinding.ActivityTabBarBinding
import com.google.android.material.tabs.TabLayoutMediator

class TabBarActivity : AppCompatActivity() {

    private lateinit var binding: ActivityTabBarBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // setContentView(R.layout.activity_tab_bar)
        binding = ActivityTabBarBinding.inflate(layoutInflater)
        setContentView(binding.root)

        val adapter = ViewPagerAdapter(this)
        binding.viewPager.adapter = adapter

        TabLayoutMediator(binding.tabLayout, binding.viewPager) { tab, position ->
            tab.text = when(position) {
                0 -> "首页"
                1 -> "分类"
                2 -> "我的"
                else -> null
            }
        }.attach()
    }

    private inner class ViewPagerAdapter(fa: FragmentActivity) : FragmentStateAdapter(fa) {
        override fun getItemCount(): Int {
            return 3
        }

        override fun createFragment(position: Int): Fragment {
            return when(position) {
                0 -> HomeFragment()
                1 -> CategoryFragment()
                2 -> ProfileFragment()
                else -> Fragment()
            }
        }
    }

}

在上面的代码中，我们创建了一个ViewPagerAdapter类继承自FragmentStateAdapter，并重写了getItemCount和createFragment方法来分别返回选项卡的数量和对应的Fragment。TabLayoutMediator用于将TabLayout和ViewPager2绑定起来，并设置每个选项卡的标题。

4.创建对应的Fragment类

package com.example.gatestdemol.tabbar

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import com.example.gatestdemol.databinding.FragmentHomeBinding

class HomeFragment: Fragment() {

    private var binding: FragmentHomeBinding? = null

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentHomeBinding.inflate(inflater,container,false)
        return binding?.root
    }

    override fun onDestroy() {
        super.onDestroy()
        binding = null
    }

}

class CategoryFragment : Fragment() {
    // 实现分类Fragment的布局和逻辑
}

class ProfileFragment : Fragment() {
    // 实现我的Fragment的布局和逻辑
}

每个Fragment对应一个页面，在这里你可以实现各自的布局和业务逻辑。

这是一个基本的TabBar实现，你可以根据自己的需求添加图标、自定义样式等。

简单TabBar示意图:

5.TabBar添加Icon

package com.example.gatestdemol.tabbar

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.core.content.ContextCompat
import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentActivity
import androidx.viewpager2.adapter.FragmentStateAdapter
import com.example.gatestdemol.R
import com.example.gatestdemol.databinding.ActivityTabBarBinding
import com.google.android.material.tabs.TabLayout
import com.google.android.material.tabs.TabLayoutMediator

class TabBarActivity : AppCompatActivity() {

    private lateinit var binding: ActivityTabBarBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityTabBarBinding.inflate(layoutInflater)
        setContentView(binding.root)

        val adapter = ViewPagerAdapter(this)
        binding.viewPager.adapter = adapter

        TabLayoutMediator(binding.tabLayout, binding.viewPager) { tab, position ->
            tab.text = when(position) {
                0 -> "首页"
                1 -> "分类"
                2 -> "我的"
                else -> null
            }
            tab.icon = when(position) {
                0 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_home_default)
                1 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_category_default)
                2 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_profile_default)
                else -> null
            }
        }.attach()

        binding.tabLayout.addOnTabSelectedListener(object : TabLayout.OnTabSelectedListener {
            override fun onTabSelected(tab: TabLayout.Tab?) {
                // 一套Icon时用这种方式
                //tab?.icon?.setTint(ContextCompat.getColor(applicationContext, R.color.your_selected_text_color))
                // 两套Icon时用这种方式，XML中不要配置app:tabIconTint="@color/your_icon_tint_color"
                tab?.icon = when(tab?.position) {
                    0 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_home_selected)
                    1 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_category_selected)
                    2 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_profile_selected)
                    else -> null
                }
            }

            override fun onTabUnselected(tab: TabLayout.Tab?) {
                // 一套Icon时用这种方式
                //tab?.icon?.setTint(ContextCompat.getColor(applicationContext, R.color.your_icon_tint_color))
                // 两套Icon时用这种方式，XML中不要配置app:tabIconTint="@color/your_icon_tint_color"
                tab?.icon = when(tab?.position) {
                    0 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_home_default)
                    1 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_category_default)
                    2 -> ContextCompat.getDrawable(this@TabBarActivity, R.drawable.ic_profile_default)
                    else -> null
                }
            }

            override fun onTabReselected(tab: TabLayout.Tab?) {
                // Do nothing
            }
        })
    }

    private inner class ViewPagerAdapter(fa: FragmentActivity) : FragmentStateAdapter(fa) {
        override fun getItemCount(): Int {
            return 3
        }

        override fun createFragment(position: Int): Fragment {
            return when(position) {
                0 -> HomeFragment()
                1 -> CategoryFragment()
                2 -> ProfileFragment()
                else -> Fragment()
            }
        }
    }

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewPager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tabLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:tabIndicatorColor="@color/your_indicator_color"
        app:tabSelectedTextColor="@color/your_selected_text_color"
        app:tabTextColor="@color/your_default_text_color"
        app:tabIconTint="@color/your_icon_tint_color"
        app:tabMode="fixed"
        app:tabGravity="fill"
        app:tabIndicatorHeight="0dp"
        app:tabRippleColor="@android:color/transparent" />

</LinearLayout>

<resources>
	......
    <color name="your_indicator_color">#FF0000</color>
    <color name="your_selected_text_color">#FF3700B3</color>
    <color name="your_default_text_color">#FFBB86FC</color>
    <color name="your_icon_tint_color">#FFBB86FC</color>
</resources>

示意图：