Compose 1.7.0及以上自定义输入法适配：替代弃用的LocalTextInputService

问题背景 #

Compose 1.7.0 中LocalTextInputService和TextInputService已被弃用，原有依赖这些API实现的自定义TextField无法再通过CoreTextField获取LocalTextInputService.current实例。官方标注需用PlatformTextInputModifierNode替代，但缺少明确落地指引。

一、过渡兼容方案（基于旧API适配） #

如果暂时不想大规模重构，可通过官方遗留适配器兼容原有逻辑，修改你的MyKeyboardContainer实现如下：

@Composable
fun MyKeyboardContainer(
    modifier: Modifier = Modifier,
    closeKeyboardClickOutside: Boolean = true,
    content: @Composable ColumnScope.() -> Unit,
) = Column(modifier = modifier) {
    val focusManager = LocalFocusManager.current
    val clickableModifier = if (closeKeyboardClickOutside) {
        Modifier.clickable(
            interactionSource = remember { MutableInteractionSource() },
            indication = null
        ) { focusManager.clearFocus(force = true) }
    } else {
        Modifier
    }

    // 替换原有MyLocalTextInputService的获取逻辑
    val legacyAdapter = remember { createLegacyPlatformTextInputServiceAdapter() }
    val myPlatformService = remember { MyPlatformTextInputService() }
    val textInputService = remember {
        TextInputService(object : PlatformTextInputService by myPlatformService {
            // 委托原有状态管理逻辑，同时通过适配器兼容遗留API
            override fun startInput(
                value: TextFieldValue,
                imeOptions: ImeOptions,
                onEditCommand: (List<EditCommand>) -> Unit,
                onImeActionPerformed: (ImeAction) -> Unit,
            ) {
                myPlatformService.startInput(value, imeOptions, onEditCommand, onImeActionPerformed)
                legacyAdapter.startInput(value, imeOptions, onEditCommand, onImeActionPerformed)
            }

            override fun stopInput() {
                myPlatformService.stopInput()
                legacyAdapter.stopInput()
            }

            override fun updateState(oldValue: TextFieldValue?, newValue: TextFieldValue) {
                myPlatformService.updateState(oldValue, newValue)
                legacyAdapter.updateState(oldValue, newValue)
            }

            override fun showSoftwareKeyboard() {
                myPlatformService.showSoftwareKeyboard()
                legacyAdapter.showSoftwareKeyboard()
            }

            override fun hideSoftwareKeyboard() {
                myPlatformService.hideSoftwareKeyboard()
                legacyAdapter.hideSoftwareKeyboard()
            }
        })
    }

    CompositionLocalProvider(LocalTextInputService provides textInputService) {
        Column(
            modifier = Modifier
                .weight(1f)
                .fillMaxWidth()
                .then(clickableModifier),
            content = content,
        )

        MyKeyboard(windowSize)
    }
}

该方案完整保留你原有MyPlatformTextInputService的状态管理逻辑，同时通过委托机制满足CoreTextField的API调用要求。

二、正式替代方案（基于PlatformTextInputModifierNode） #

官方推荐的PlatformTextInputModifierNode采用Modifier节点架构，需将输入服务逻辑从CompositionLocal迁移至Modifier体系，具体步骤如下：

1. 重构输入状态管理类 #

剥离原有PlatformTextInputService继承关系，保留核心状态管理逻辑：

internal class MyInputStateManager {
    val softKeyboardState = MutableStateFlow(MyPlatformTextInputService.KeyboardState.HIDDEN)
    val inputState = MutableStateFlow<MyPlatformTextInputService.InputState>(MyPlatformTextInputService.InputState.Idle)

    fun hideSoftwareKeyboard() {
        softKeyboardState.value = MyPlatformTextInputService.KeyboardState.HIDDEN
    }

    fun showSoftwareKeyboard() {
        softKeyboardState.value = MyPlatformTextInputService.KeyboardState.SHOWN
    }

    fun startInput(
        value: TextFieldValue,
        imeOptions: ImeOptions,
        onEditCommand: (List<EditCommand>) -> Unit,
        onImeActionPerformed: (ImeAction) -> Unit,
    ) {
        inputState.value = MyPlatformTextInputService.InputState.Active(
            textFieldValue = value,
            onEditCommand = onEditCommand,
            onImeActionPerformed = onImeActionPerformed,
            imeOptions = imeOptions,
        )
        softKeyboardState.value = MyPlatformTextInputService.KeyboardState.SHOWN
    }

    fun stopInput() {
        inputState.value = MyPlatformTextInputService.InputState.Idle
    }

    fun updateState(oldValue: TextFieldValue?, newValue: TextFieldValue) {
        (inputState.value as? MyPlatformTextInputService.InputState.Active)?.let { activeInputState ->
            inputState.value = activeInputState.copy(textFieldValue = newValue)
        }
    }
}

2. 实现自定义PlatformTextInputModifierNode #

创建自定义Modifier节点，关联状态管理类并实现官方接口：

internal class MyTextInputNode(
    private val inputStateManager: MyInputStateManager
) : ModifierNode, PlatformTextInputModifierNode {

    private var textInputSession: PlatformTextInputSession? = null

    override val platformTextInputSession: PlatformTextInputSession?
        get() = textInputSession

    override fun onDetach() {
        textInputSession?.close()
        textInputSession = null
    }

    override fun requestSoftwareKeyboardShow() {
        inputStateManager.showSoftwareKeyboard()
    }

    override fun requestSoftwareKeyboardHide() {
        inputStateManager.hideSoftwareKeyboard()
    }

    override fun startInput(
        value: TextFieldValue,
        imeOptions: ImeOptions,
        onEditCommand: (List<EditCommand>) -> Unit,
        onImeActionPerformed: (ImeAction) -> Unit
    ) {
        inputStateManager.startInput(value, imeOptions, onEditCommand, onImeActionPerformed)
        // 创建输入会话，处理系统IME交互（按需实现）
        textInputSession = object : PlatformTextInputSession {
            override fun updateState(newValue: TextFieldValue) {
                inputStateManager.updateState(null, newValue)
            }

            override fun close() {
                inputStateManager.stopInput()
            }
        }
    }

    override fun stopInput() {
        inputStateManager.stopInput()
        textInputSession?.close()
        textInputSession = null
    }

    override fun updateInputState(oldValue: TextFieldValue?, newValue: TextFieldValue) {
        inputStateManager.updateState(oldValue, newValue)
    }
}

// 扩展Modifier方法，简化使用
fun Modifier.myTextInputService(inputStateManager: MyInputStateManager): Modifier =
    this then modifierNodeOf { MyTextInputNode(inputStateManager) }

3. 修改MyKeyboardContainer使用新架构 #

移除CompositionLocal依赖，改为通过Modifier注入输入服务：

@Composable
fun MyKeyboardContainer(
    modifier: Modifier = Modifier,
    closeKeyboardClickOutside: Boolean = true,
    content: @Composable ColumnScope.(MyInputStateManager) -> Unit,
) = Column(modifier = modifier) {
    val focusManager = LocalFocusManager.current
    val clickableModifier = if (closeKeyboardClickOutside) {
        Modifier.clickable(
            interactionSource = remember { MutableInteractionSource() },
            indication = null
        ) { focusManager.clearFocus(force = true) }
    } else {
        Modifier
    }

    val inputStateManager = remember { MyInputStateManager() }

    Column(
        modifier = Modifier
            .weight(1f)
            .fillMaxWidth()
            .then(clickableModifier)
            .myTextInputService(inputStateManager),
    ) {
        content(inputStateManager)
    }

    MyKeyboard(windowSize)
}

4. 自定义TextField适配 #

在你的自定义TextField组件中，直接应用该Modifier即可让CoreTextField通过节点获取输入服务。

方案说明 #

• 过渡方案可快速兼容现有代码，但属于临时妥协，后续版本可能移除遗留API
• 正式方案符合Compose最新架构设计，基于Modifier节点的实现更贴合组件化状态管理理念，推荐逐步迁移

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