feat: 新增底部四 Tab 导航骨架与路由表

app/src/main/java/com/placeholder/ringhealth/MainActivity.kt

@@ -4,15 +4,12 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
-import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
-import androidx.compose.material3.Text
-import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.res.stringResource
 import com.placeholder.ringhealth.core.designsystem.RingHealthTheme
+import com.placeholder.ringhealth.core.navigation.RingHealthApp
 
 /** 唯一 Activity，承载 Compose 界面。 */
 class MainActivity : ComponentActivity() {
@@ -25,10 +22,8 @@ class MainActivity : ComponentActivity() {
                     modifier = Modifier.fillMaxSize(),
                     color = MaterialTheme.colorScheme.background,
                 ) {
-                    Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
-                        // 文案取自 res/values/strings.xml，不在 Kotlin 里硬编码用户可见文字
-                        Text(stringResource(R.string.app_name))
-                    }
+                    // 界面骨架（底部导航 + 路由）在 core/navigation/RingHealthApp.kt
+                    RingHealthApp()
                 }
             }
         }

app/src/main/java/com/placeholder/ringhealth/core/navigation/RingHealthApp.kt

@@ -0,0 +1,117 @@
+package com.placeholder.ringhealth.core.navigation
+
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.FitnessCenter
+import androidx.compose.material.icons.filled.Home
+import androidx.compose.material.icons.filled.Person
+import androidx.compose.material.icons.filled.Settings
+import androidx.compose.material3.Icon
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.NavigationBar
+import androidx.compose.material3.NavigationBarItem
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.res.stringResource
+import androidx.navigation.NavGraph.Companion.findStartDestination
+import androidx.navigation.NavHostController
+import androidx.navigation.NavType
+import androidx.navigation.compose.NavHost
+import androidx.navigation.compose.composable
+import androidx.navigation.compose.currentBackStackEntryAsState
+import androidx.navigation.compose.rememberNavController
+import androidx.navigation.navArgument
+import com.placeholder.ringhealth.R
+import com.placeholder.ringhealth.domain.model.MetricType
+import com.placeholder.ringhealth.feature.device.DeviceScreen
+import com.placeholder.ringhealth.feature.device.DeviceSettingsPlaceholder
+import com.placeholder.ringhealth.feature.detail.MetricDetailPlaceholder
+import com.placeholder.ringhealth.feature.home.HomeScreen
+import com.placeholder.ringhealth.feature.profile.ProfileScreen
+import com.placeholder.ringhealth.feature.workout.WorkoutHistoryPlaceholder
+import com.placeholder.ringhealth.feature.workout.WorkoutScreen
+
+/** 底部导航项定义。 */
+private data class BottomTab(
+    val route: String,
+    val labelRes: Int,
+    val icon: ImageVector,
+)
+
+private val BOTTOM_TABS = listOf(
+    BottomTab(Routes.HOME, R.string.tab_home, Icons.Filled.Home),
+    BottomTab(Routes.WORKOUT, R.string.tab_workout, Icons.Filled.FitnessCenter),
+    BottomTab(Routes.DEVICE, R.string.tab_device, Icons.Filled.Settings),
+    BottomTab(Routes.PROFILE, R.string.tab_profile, Icons.Filled.Person),
+)
+
+/**
+ * 应用主界面：Scaffold + 底部导航 + NavHost。
+ */
+@Composable
+fun RingHealthApp(navController: NavHostController = rememberNavController()) {
+    val backStackEntry by navController.currentBackStackEntryAsState()
+    val currentRoute = backStackEntry?.destination?.route
+
+    Scaffold(
+        containerColor = MaterialTheme.colorScheme.background,
+        bottomBar = {
+            NavigationBar(containerColor = MaterialTheme.colorScheme.surface) {
+                BOTTOM_TABS.forEach { tab ->
+                    NavigationBarItem(
+                        selected = currentRoute == tab.route,
+                        onClick = { navController.navigateToTab(tab.route) },
+                        icon = { Icon(imageVector = tab.icon, contentDescription = null) },
+                        label = { Text(stringResource(tab.labelRes)) },
+                    )
+                }
+            }
+        },
+    ) { innerPadding ->
+        NavHost(
+            navController = navController,
+            startDestination = Routes.HOME,
+            modifier = Modifier.padding(innerPadding),
+        ) {
+            composable(Routes.HOME) {
+                HomeScreen(onOpenDetail = { metric -> navController.navigate(Routes.detail(metric)) })
+            }
+            composable(Routes.WORKOUT) {
+                WorkoutScreen()
+            }
+            composable(Routes.DEVICE) {
+                DeviceScreen()
+            }
+            composable(Routes.PROFILE) {
+                ProfileScreen()
+            }
+            composable(Routes.DEVICE_SETTINGS) {
+                DeviceSettingsPlaceholder()
+            }
+            composable(Routes.WORKOUT_HISTORY) {
+                WorkoutHistoryPlaceholder()
+            }
+            composable(
+                route = Routes.DETAIL_PATTERN,
+                arguments = listOf(navArgument(Routes.DETAIL_ARG_METRIC) { type = NavType.StringType }),
+            ) { entry ->
+                val raw = entry.arguments?.getString(Routes.DETAIL_ARG_METRIC).orEmpty()
+                val metric = MetricType.entries.firstOrNull { it.name == raw } ?: MetricType.STEP
+                MetricDetailPlaceholder(metric = metric)
+            }
+        }
+    }
+}
+
+/** 底部 Tab 切换：保留状态、避免回退栈堆积。 */
+private fun NavHostController.navigateToTab(route: String) {
+    navigate(route) {
+        popUpTo(graph.findStartDestination().id) { saveState = true }
+        launchSingleTop = true
+        restoreState = true
+    }
+}

app/src/main/java/com/placeholder/ringhealth/core/navigation/Routes.kt

@@ -0,0 +1,23 @@
+package com.placeholder.ringhealth.core.navigation
+
+import com.placeholder.ringhealth.domain.model.MetricType
+
+/**
+ * 全局路由表。字符串集中定义，避免散落在各处。
+ */
+object Routes {
+    const val HOME = "home"
+    const val WORKOUT = "workout"
+    const val DEVICE = "device"
+    const val PROFILE = "profile"
+
+    const val DEVICE_SETTINGS = "device/settings"
+    const val WORKOUT_HISTORY = "workout/history"
+
+    /** 指标详情路由模板，参数为 MetricType.name。 */
+    const val DETAIL_PATTERN = "detail/{metric}"
+    const val DETAIL_ARG_METRIC = "metric"
+
+    /** 拼出某个指标的详情路由。 */
+    fun detail(metric: MetricType): String = "detail/${metric.name}"
+}

app/src/main/java/com/placeholder/ringhealth/feature/detail/MetricDetailScreen.kt

@@ -0,0 +1,19 @@
+package com.placeholder.ringhealth.feature.detail
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import com.placeholder.ringhealth.R
+import com.placeholder.ringhealth.domain.model.MetricType
+
+/** 指标详情子页（占位，待 Task 12 实现）。 */
+@Composable
+fun MetricDetailPlaceholder(metric: MetricType, modifier: Modifier = Modifier) {
+    Box(modifier = modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+        Text(stringResource(R.string.placeholder_metric_detail))
+    }
+}

app/src/main/java/com/placeholder/ringhealth/feature/device/DeviceScreen.kt

@@ -0,0 +1,18 @@
+package com.placeholder.ringhealth.feature.device
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import com.placeholder.ringhealth.R
+
+/** 设备页（占位，待 Task 10 实现）。 */
+@Composable
+fun DeviceScreen(modifier: Modifier = Modifier) {
+    Box(modifier = modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+        Text(stringResource(R.string.tab_device))
+    }
+}

app/src/main/java/com/placeholder/ringhealth/feature/device/DeviceSettingsScreen.kt

@@ -0,0 +1,18 @@
+package com.placeholder.ringhealth.feature.device
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import com.placeholder.ringhealth.R
+
+/** 设备设置子页（占位，待 Task 10 实现）。 */
+@Composable
+fun DeviceSettingsPlaceholder(modifier: Modifier = Modifier) {
+    Box(modifier = modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+        Text(stringResource(R.string.placeholder_device_settings))
+    }
+}

app/src/main/java/com/placeholder/ringhealth/feature/home/HomeScreen.kt

@@ -0,0 +1,22 @@
+package com.placeholder.ringhealth.feature.home
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import com.placeholder.ringhealth.R
+import com.placeholder.ringhealth.domain.model.MetricType
+
+/** 健康首页（占位，待 Task 8 实现）。 */
+@Composable
+fun HomeScreen(
+    onOpenDetail: (MetricType) -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    Box(modifier = modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+        Text(stringResource(R.string.tab_home))
+    }
+}

app/src/main/java/com/placeholder/ringhealth/feature/profile/ProfileScreen.kt

@@ -0,0 +1,18 @@
+package com.placeholder.ringhealth.feature.profile
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import com.placeholder.ringhealth.R
+
+/** 我的页（占位，待 Task 11 实现）。 */
+@Composable
+fun ProfileScreen(modifier: Modifier = Modifier) {
+    Box(modifier = modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+        Text(stringResource(R.string.tab_profile))
+    }
+}

app/src/main/java/com/placeholder/ringhealth/feature/workout/WorkoutHistoryScreen.kt

@@ -0,0 +1,18 @@
+package com.placeholder.ringhealth.feature.workout
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import com.placeholder.ringhealth.R
+
+/** 运动历史子页（占位，待 Task 9 实现）。 */
+@Composable
+fun WorkoutHistoryPlaceholder(modifier: Modifier = Modifier) {
+    Box(modifier = modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+        Text(stringResource(R.string.placeholder_workout_history))
+    }
+}

app/src/main/java/com/placeholder/ringhealth/feature/workout/WorkoutScreen.kt

@@ -0,0 +1,18 @@
+package com.placeholder.ringhealth.feature.workout
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import com.placeholder.ringhealth.R
+
+/** 运动页（占位，待 Task 9 实现）。 */
+@Composable
+fun WorkoutScreen(modifier: Modifier = Modifier) {
+    Box(modifier = modifier.fillMaxSize(), contentAlignment = Alignment.Center) {
+        Text(stringResource(R.string.tab_workout))
+    }
+}

app/src/main/res/values/strings.xml

@@ -6,4 +6,12 @@
     <string name="stress_normal">正常</string>
     <string name="stress_medium">中等</string>
     <string name="stress_high">偏高</string>
+
+    <string name="tab_home">健康</string>
+    <string name="tab_workout">运动</string>
+    <string name="tab_device">设备</string>
+    <string name="tab_profile">我的</string>
+    <string name="placeholder_device_settings">设备设置</string>
+    <string name="placeholder_workout_history">运动历史</string>
+    <string name="placeholder_metric_detail">指标详情</string>
 </resources>