Android纯代码实现下如何高效处理屏幕方向等配置变更

针对纯代码编写的Android布局（非Jetpack Compose），推荐采用Android官方首选的「让系统自动重建组件+资源适配」方案，替代手动修改onConfigurationChanged的繁琐逻辑，具体实现方式如下：

方案1：利用资源限定符自动适配布局逻辑 #

通过Android资源系统的限定符（如land、sw600dp等），在不同配置下加载不同的布局参数，代码无需手动判断配置类型，由系统自动匹配资源。

步骤示例： #

1. 定义自定义布局属性
   在res/values/attrs.xml中创建用于控制布局的属性：

   <declare-styleable name="OrientationLayoutConfig">
       <attr name="editTextWidth" format="dimension" />
       <attr name="editTextAlignRule" format="integer" />
       <attr name="buttonRelativeRule" format="integer" />
   </declare-styleable>
   

2. 分配置编写资源

   • 竖屏配置（res/values/styles.xml）：

     <style name="LayoutStyle">
         <item name="editTextWidth">match_parent</item>
         <item name="editTextAlignRule">@integer/rule_align_parent_top</item>
         <item name="buttonRelativeRule">@integer/rule_below_edittext</item>
     </style>
     

   • 横屏配置（res/values-land/styles.xml）：

     <style name="LayoutStyle">
         <item name="editTextWidth">180dp</item>
         <item name="editTextAlignRule">@integer/rule_align_parent_left</item>
         <item name="buttonRelativeRule">@integer/rule_to_right_of_edittext</item>
     </style>
     

   （注：需在res/values/integers.xml中定义对应规则常量，如rule_align_parent_top对应RelativeLayout.ALIGN_PARENT_TOP的整数值）

3. 代码中读取资源并构建布局

   override fun onCreate(savedInstanceState: Bundle?) {
       super.onCreate(savedInstanceState)
       setContentView(buildLayout())
   }
   
   private fun buildLayout(): View {
       val attrs = obtainStyledAttributes(R.style.LayoutStyle, R.styleable.OrientationLayoutConfig)
       
       // 从资源中读取布局参数
       val editTextWidth = attrs.getDimensionPixelSize(
           R.styleable.OrientationLayoutConfig_editTextWidth,
           ViewGroup.LayoutParams.MATCH_PARENT
       )
       val editTextAlignRule = attrs.getInt(
           R.styleable.OrientationLayoutConfig_editTextAlignRule,
           RelativeLayout.ALIGN_PARENT_TOP
       )
       val buttonRelativeRule = attrs.getInt(
           R.styleable.OrientationLayoutConfig_buttonRelativeRule,
           RelativeLayout.BELOW
       )
       attrs.recycle()
   
       // 创建EditText
       val editText = EditText(this).apply {
           id = R.id.et_input // 设置唯一ID，让系统自动保存输入状态
           layoutParams = RelativeLayout.LayoutParams(editTextWidth, ViewGroup.LayoutParams.WRAP_CONTENT).apply {
               addRule(editTextAlignRule)
           }
       }
   
       // 创建Button
       val button = Button(this).apply {
           text = "提交"
           layoutParams = RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT).apply {
               addRule(buttonRelativeRule, editText.id)
               // 根据规则补充额外布局属性
               if (buttonRelativeRule == RelativeLayout.BELOW) {
                   addRule(RelativeLayout.ALIGN_PARENT_LEFT)
               } else {
                   addRule(RelativeLayout.CENTER_VERTICAL)
                   marginStart = 16.dpToPx()
               }
           }
       }
   
       // 构建根布局
       return RelativeLayout(this).apply {
           addView(editText)
           addView(button)
       }
   }
   
   // 扩展函数：dp转px
   private fun Int.dpToPx(): Int = (this * resources.displayMetrics.density).toInt()
   

方案2：拆分布局创建逻辑，根据配置自动调用 #

将不同配置下的布局创建逻辑拆分为独立方法，在组件创建时根据当前配置自动选择执行，系统重建时会自动适配新配置。

代码示例： #

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(createLayoutByOrientation())
}

private fun createLayoutByOrientation(): View {
    return if (resources.configuration.orientation == Configuration.ORIENTATION_LANDSCAPE) {
        createLandscapeLayout()
    } else {
        createPortraitLayout()
    }
}

// 竖屏布局逻辑
private fun createPortraitLayout(): View {
    val editText = EditText(this).apply {
        id = R.id.et_input
        layoutParams = RelativeLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT).apply {
            addRule(RelativeLayout.ALIGN_PARENT_TOP)
            setMargins(16.dpToPx(), 16.dpToPx(), 16.dpToPx(), 0)
        }
    }

    val button = Button(this).apply {
        text = "提交"
        layoutParams = RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT).apply {
            addRule(RelativeLayout.BELOW, editText.id)
            addRule(RelativeLayout.ALIGN_PARENT_LEFT)
            setMargins(16.dpToPx(), 16.dpToPx(), 0, 0)
        }
    }

    return RelativeLayout(this).apply { addView(editText); addView(button) }
}

// 横屏布局逻辑
private fun createLandscapeLayout(): View {
    val editText = EditText(this).apply {
        id = R.id.et_input
        layoutParams = RelativeLayout.LayoutParams(200.dpToPx(), ViewGroup.LayoutParams.WRAP_CONTENT).apply {
            addRule(RelativeLayout.ALIGN_PARENT_LEFT)
            addRule(RelativeLayout.CENTER_VERTICAL)
            setMargins(16.dpToPx(), 0, 0, 0)
        }
    }

    val button = Button(this).apply {
        text = "提交"
        layoutParams = RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT).apply {
            addRule(RelativeLayout.TO_RIGHT_OF, editText.id)
            addRule(RelativeLayout.CENTER_VERTICAL)
            setMargins(16.dpToPx(), 0, 0, 0)
        }
    }

    return RelativeLayout(this).apply { addView(editText); addView(button) }
}

private fun Int.dpToPx(): Int = (this * resources.displayMetrics.density).toInt()

关键注意点：状态自动恢复 #

• 所有需要保留状态的View（如EditText）必须设置唯一ID，系统会自动保存其输入内容、选中状态等。
• 若有自定义状态（如按钮点击计数），可通过重写onSaveInstanceState和onRestoreInstanceState实现：

  private var clickCount = 0
  
  override fun onSaveInstanceState(outState: Bundle) {
      super.onSaveInstanceState(outState)
      outState.putInt("click_count", clickCount)
  }
  
  override fun onRestoreInstanceState(savedInstanceState: Bundle) {
      super.onRestoreInstanceState(savedInstanceState)
      clickCount = savedInstanceState.getInt("click_count", 0)
  }
  

内容的提问来源于stack exchange，提问作者Jatin guglani