Android开发基础教程（2019）第17集 页面导航 Navigation(1)笔记

Navigation 基础知识概述

• NavHost 装碎片的容器
• Fragment 碎片，用于在界面上设置一小块布局
• NavController 用来控制碎片切换逻辑
• NavGraph 图形化设置页面切换逻辑

例子

1. 两碎片，布局分别是一个按钮一个标签
2. 从developers中将navigation的依赖添加进来
3. 设置resourceFile->navigation(my_nav_graph)，将刚刚添加的两个碎片相互连线
4. 在主布局中放置NavHostFragment
5. 在碎片中添加跳转的代码，两种方式实现相同的功能

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        button1.setOnClickListener {
            val controller = Navigation.findNavController(it)
            controller.navigate(R.id.action_homeFragment_to_detailFragment)
        }
    }

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        button2.setOnClickListener(Navigation.createNavigateOnClickListener(R.id.action_detailFragment_to_homeFragment))
    }

6. 设置页面切换的过渡效果，my_nav_graph.xml -> 点线 -> Animation -> 设置enterAnim和exitAnim，可以弄默认动画
7. 设置第二个碎片的setupActionBar

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        //先拿NavHostFragment
        val navHostFragment = supportFragmentManager.findFragmentById(R.id.fragmentContainerView) as NavHostFragment
        //再拿NavController
        val controller : NavController = navHostFragment.navController
        NavigationUI.setupActionBarWithNavController( this,controller)
    }

    override fun onSupportNavigateUp(): Boolean {
        //先拿NavHostFragment
        val navHostFragment = supportFragmentManager.findFragmentById(R.id.fragmentContainerView) as NavHostFragment
        //再拿NavController
        val controller : NavController = navHostFragment.navController
        return controller.navigateUp()
    }
}

8. 设置导航栏的标签，resourceFile->navigation(my_nav_graph)->点碎片->label 修改即可

效果展示

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