Tech Stack Migration (技术迁移)

Instructions

• 仅在需要渐进式迁移时使用
• 依照下方章节顺序套用
• 一次只替换一个技术栈
• 完成后对照 Quick Checklist

When to Use

• Scenario C：旧项目现代化

Example Prompts

• “请依照 View → Compose 章节，帮我嵌入 ComposeView”
• “用 RxJava → Flow 对照表，改写这段 stream”
• “请用 LiveData → StateFlow 的步骤规划迁移”

Workflow

1. 先确认要迁移的技术栈与范围
2. 依序套用对应章节的范例与对照表
3. 最后用 Quick Checklist 验收

Practical Notes (2026)

• 迁移必先有可验证的测试安全网
• 一次只迁移一个维度（UI 或 Data 或 DI）
• 指标回归后才能推进下一步

Minimal Template

目标: 
迁移范围: 
测试安全网: 
回归指标: 
验收: Quick Checklist

View → Compose Interoperability

Compose in XML

<!-- layout/activity_main.xml -->
<androidx.compose.ui.platform.ComposeView
    android:id="@+id/compose_view"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        
        findViewById<ComposeView>(R.id.compose_view).setContent {
            AppTheme {
                NewFeatureCard()
            }
        }
    }
}

XML in Compose

@Composable
fun LegacyMapView(modifier: Modifier = Modifier) {
    AndroidView(
        modifier = modifier,
        factory = { context ->
            MapView(context).apply {
                onCreate(null)
            }
        },
        update = { mapView ->
            mapView.getMapAsync { /* configure */ }
        },
        onRelease = { mapView ->
            mapView.onDestroy()
        }
    )
}

Fragment in Compose

@Composable
fun LegacyFragmentContainer() {
    AndroidViewBinding(LegacyFragmentContainerBinding::inflate) {
        val fragment = LegacyFragment()
        fragmentContainerView.getFragment<Fragment>() ?: run {
            (LocalContext.current as FragmentActivity)
                .supportFragmentManager
                .beginTransaction()
                .replace(fragmentContainerView.id, fragment)
                .commit()
        }
    }
}

RxJava → Coroutines/Flow

Operator Mapping

范例：Search with Debounce

// Before (RxJava)
searchEditText.textChanges()
    .debounce(300, TimeUnit.MILLISECONDS)
    .switchMap { query -> api.search(query) }
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe { results -> updateUI(results) }

// After (Flow)
searchFlow
    .debounce(300)
    .flatMapLatest { query -> api.search(query) }
    .flowOn(Dispatchers.IO)
    .collect { results -> updateUI(results) }

Error Handling 差异

// RxJava: onError 终止 stream
observable
    .onErrorReturn { defaultValue }
    .subscribe()

// Flow: catch 不终止 stream
flow
    .catch { emit(defaultValue) }
    .collect()

// Flow: 重试
flow
    .retry(3) { e -> e is IOException }
    .collect()

LiveData → StateFlow

渐进式替换

// Step 1: ViewModel 内部用 StateFlow
private val _uiState = MutableStateFlow(UiState())
val uiState: StateFlow<UiState> = _uiState.asStateFlow()

// Step 2: 暴露 LiveData 给旧 UI (过渡期)
val uiStateLiveData: LiveData<UiState> = uiState.asLiveData()

// Step 3: 新 UI 直接 collect StateFlow
@Composable
fun Screen(viewModel: MyViewModel) {
    val uiState by viewModel.uiState.collectAsStateWithLifecycle()
}

Dagger → Hilt

渐进式迁移

// 1. 保留 Dagger Component，加入 Hilt
@HiltAndroidApp
class MyApp : Application() {
    // 保留旧的 Dagger component (过渡期)
    val legacyComponent by lazy { DaggerLegacyComponent.create() }
}

// 2. 新模块用 Hilt
@Module
@InstallIn(SingletonComponent::class)
object NewModule { }

// 3. 桥接旧模块
@Module
@InstallIn(SingletonComponent::class)
object LegacyBridgeModule {
    @Provides
    fun provideLegacyService(): LegacyService {
        return (application as MyApp).legacyComponent.legacyService()
    }
}

Quick Checklist

• Compose 与 View 的生命周期对齐
• AndroidView 正确处理 onRelease
• Flow operator 对照 RxJava 正确
• StateFlow 使用 collectAsStateWithLifecycle
• Hilt 迁移维持向后兼容