fix: 修复Android app UI不显示信息及拍照保存问题

- 切换到Light主题，解决深色模式下文字不可见
- 重新布局为横屏左右分栏，显示设备IP和连接方式
- 拍照改用MediaStore写入系统相册，修复原acquireLatestImage竞争导致的空帧
- 修正ImageFormat导入包路径
- 补充gradle-wrapper.jar

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

android-app/app/src/main/AndroidManifest.xml

@@ -11,7 +11,7 @@
     <application
         android:allowBackup="true"
         android:label="USB摄像头"
-        android:theme="@style/Theme.AppCompat.NoActionBar">
+        android:theme="@style/Theme.AppCompat.Light.NoActionBar">
 
         <activity
             android:name=".MainActivity"

android-app/app/src/main/java/com/usbwebcam/CameraHelper.kt

@@ -1,21 +1,16 @@
 package com.usbwebcam
 
+import android.content.ContentValues
 import android.content.Context
-import android.graphics.Bitmap
-import android.graphics.ImageFormat
-import android.graphics.Rect
-import android.graphics.YuvImage
 import android.hardware.camera2.*
-import android.media.Image
+import android.graphics.ImageFormat
 import android.media.ImageReader
+import android.os.Build
 import android.os.Handler
 import android.os.HandlerThread
+import android.provider.MediaStore
 import android.util.Size
-import android.view.Surface
 import android.view.SurfaceHolder
-import java.io.ByteArrayOutputStream
-import java.io.File
-import java.io.FileOutputStream
 import java.text.SimpleDateFormat
 import java.util.*
 
@@ -29,6 +24,9 @@ class CameraHelper(
     private var backgroundThread: HandlerThread? = null
     private var backgroundHandler: Handler? = null
 
+    @Volatile
+    private var latestJpeg: ByteArray? = null
+
     private val cameraManager = context.getSystemService(Context.CAMERA_SERVICE) as CameraManager
     private val cameraId = cameraManager.cameraIdList.firstOrNull {
         cameraManager.getCameraCharacteristics(it)
@@ -84,7 +82,6 @@ class CameraHelper(
 
     private fun createCameraPreviewSession() {
         try {
-            // 获取支持的尺寸
             val characteristics = cameraManager.getCameraCharacteristics(cameraId)
             val map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP)
             val previewSize = map?.getOutputSizes(SurfaceHolder::class.java)?.firstOrNull {
@@ -125,26 +122,47 @@ class CameraHelper(
             val buffer = image.planes[0].buffer
             val bytes = ByteArray(buffer.remaining())
             buffer.get(bytes)
+            latestJpeg = bytes
             onFrame(bytes, image.width, image.height)
         } finally {
             image.close()
         }
     }
 
-    fun captureAndSave() {
+    /**
-        // 保存最后一帧
+     * 保存最新一帧到系统相册，返回是否成功
-        imageReader?.acquireLatestImage()?.use { image ->
+     */
-            val buffer = image.planes[0].buffer
+    fun captureAndSave(): Boolean {
-            val bytes = ByteArray(buffer.remaining())
+        val jpeg = latestJpeg ?: return false
-            buffer.get(bytes)
 
         val timestamp = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(Date())
-            val file = File(
+        val filename = "envelope_$timestamp.jpg"
-                context.getExternalFilesDir(null),
-                "envelope_$timestamp.jpg"
-            )
 
-            FileOutputStream(file).use { it.write(bytes) }
+        val contentValues = ContentValues().apply {
+            put(MediaStore.Images.Media.DISPLAY_NAME, filename)
+            put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg")
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                put(MediaStore.Images.Media.RELATIVE_PATH, "Pictures/信封拍照")
+                put(MediaStore.Images.Media.IS_PENDING, 1)
+            }
+        }
+
+        val resolver = context.contentResolver
+        val uri = resolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, contentValues)
+            ?: return false
+
+        return try {
+            resolver.openOutputStream(uri)?.use { it.write(jpeg) }
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                contentValues.clear()
+                contentValues.put(MediaStore.Images.Media.IS_PENDING, 0)
+                resolver.update(uri, contentValues, null, null)
+            }
+            true
+        } catch (e: Exception) {
+            resolver.delete(uri, null, null)
+            e.printStackTrace()
+            false
         }
     }
 
@@ -156,25 +174,15 @@ class CameraHelper(
             e.printStackTrace()
         }
 
-        try {
+        try { captureSession?.close() } catch (_: Exception) {}
-            captureSession?.close()
-        } catch (e: Exception) {
-            e.printStackTrace()
-        }
         captureSession = null
 
-        try {
+        try { imageReader?.close() } catch (_: Exception) {}
-            imageReader?.close()
-        } catch (e: Exception) {
-            e.printStackTrace()
-        }
         imageReader = null
 
-        try {
+        try { cameraDevice?.close() } catch (_: Exception) {}
-            cameraDevice?.close()
-        } catch (e: Exception) {
-            e.printStackTrace()
-        }
         cameraDevice = null
+
+        latestJpeg = null
     }
 }

android-app/app/src/main/java/com/usbwebcam/MainActivity.kt

@@ -3,12 +3,14 @@ package com.usbwebcam
 import android.Manifest
 import android.content.pm.PackageManager
 import android.os.Bundle
+import android.view.View
 import android.widget.Button
 import android.widget.TextView
 import android.widget.Toast
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
+import java.net.NetworkInterface
 
 class MainActivity : AppCompatActivity() {
     private var mjpegServer: MjpegServer? = null
@@ -28,29 +30,24 @@ class MainActivity : AppCompatActivity() {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
 
-        val btnStart = findViewById<Button>(R.id.btn_start)
+        findViewById<Button>(R.id.btn_start).setOnClickListener {
-        val btnStop = findViewById<Button>(R.id.btn_stop)
-        val btnCapture = findViewById<Button>(R.id.btn_capture)
-        val tvStatus = findViewById<TextView>(R.id.tv_status)
-
-        btnStart.setOnClickListener {
             if (checkPermission()) {
                 startCamera()
             }
         }
 
-        btnStop.setOnClickListener {
+        findViewById<Button>(R.id.btn_stop).setOnClickListener {
             stopCamera()
         }
 
-        btnCapture.setOnClickListener {
+        findViewById<Button>(R.id.btn_capture).setOnClickListener {
-            cameraHelper?.captureAndSave()
+            val saved = cameraHelper?.captureAndSave() == true
-            Toast.makeText(this, "图片已保存到相册", Toast.LENGTH_SHORT).show()
+            val msg = if (saved) "图片已保存到相册" else "保存失败，请先启动服务"
+            Toast.makeText(this, msg, Toast.LENGTH_SHORT).show()
         }
 
         if (ContextCompat.checkSelfPermission(
-                this,
+                this, Manifest.permission.CAMERA
-                Manifest.permission.CAMERA
             ) == PackageManager.PERMISSION_GRANTED
         ) {
             startCamera()
@@ -59,8 +56,7 @@ class MainActivity : AppCompatActivity() {
 
     private fun checkPermission(): Boolean {
         return if (ContextCompat.checkSelfPermission(
-                this,
+                this, Manifest.permission.CAMERA
-                Manifest.permission.CAMERA
             ) == PackageManager.PERMISSION_GRANTED
         ) {
             true
@@ -70,6 +66,19 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    private fun getDeviceIp(): String {
+        try {
+            NetworkInterface.getNetworkInterfaces()?.toList()?.forEach { intf ->
+                intf.inetAddresses?.toList()?.forEach { addr ->
+                    if (!addr.isLoopbackAddress && addr is java.net.Inet4Address) {
+                        return addr.hostAddress ?: "未知"
+                    }
+                }
+            }
+        } catch (_: Exception) {}
+        return "未知"
+    }
+
     private fun startCamera() {
         if (cameraHelper != null) return
 
@@ -78,16 +87,22 @@ class MainActivity : AppCompatActivity() {
             mjpegServer?.updateFrame(frame)
         }
 
-        // Start the server and update UI once started
         mjpegServer?.start {
             runOnUiThread {
-                findViewById<TextView>(R.id.tv_status).text = """
+                val ip = getDeviceIp()
-                    服务运行中
+                findViewById<TextView>(R.id.tv_status).text =
-                    端口: 8080
+                    "● 服务运行中\n\n" +
-                    IP: 无需IP (ADB模式)
+                    "端口: 8080\n" +
-                    USB连接命令:
+                    "设备IP: $ip\n\n" +
-                    adb forward tcp:8080 tcp:8080
+                    "USB连接 (推荐):\n" +
-                """.trimIndent()
+                    "  adb forward tcp:8080 tcp:8080\n\n" +
+                    "WiFi连接:\n" +
+                    "  http://$ip:8080"
+
+                findViewById<TextView>(R.id.tv_ip).apply {
+                    text = "在电脑端浏览器打开上述地址即可查看画面"
+                    visibility = View.VISIBLE
+                }
                 findViewById<Button>(R.id.btn_start).isEnabled = false
                 findViewById<Button>(R.id.btn_stop).isEnabled = true
             }
@@ -104,6 +119,7 @@ class MainActivity : AppCompatActivity() {
 
         runOnUiThread {
             findViewById<TextView>(R.id.tv_status).text = "服务已停止"
+            findViewById<TextView>(R.id.tv_ip).visibility = View.GONE
             findViewById<Button>(R.id.btn_start).isEnabled = true
             findViewById<Button>(R.id.btn_stop).isEnabled = false
         }

android-app/app/src/main/res/layout/activity_main.xml

@@ -2,50 +2,82 @@
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:orientation="vertical"
+    android:orientation="horizontal"
     android:padding="24dp"
-    android:gravity="center">
+    android:background="#FAFAFA">
+
+    <!-- 左侧：状态信息 -->
+    <LinearLayout
+        android:layout_width="0dp"
+        android:layout_height="match_parent"
+        android:layout_weight="1"
+        android:orientation="vertical"
+        android:gravity="center_vertical"
+        android:paddingEnd="24dp">
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="USB 摄像头服务"
+            android:textSize="22sp"
+            android:textColor="#212121"
+            android:textStyle="bold"
+            android:layout_marginBottom="16dp" />
 
         <TextView
             android:id="@+id/tv_status"
-        android:layout_width="wrap_content"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:text="等待启动..."
             android:textSize="16sp"
-        android:textColor="#333"
+            android:textColor="#424242"
-        android:layout_marginBottom="32dp" />
+            android:lineSpacingExtra="4dp"
+            android:background="#FFFFFF"
+            android:padding="16dp"
+            android:layout_marginBottom="16dp" />
 
+        <TextView
+            android:id="@+id/tv_ip"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:textSize="13sp"
+            android:textColor="#757575"
+            android:visibility="gone" />
+
+    </LinearLayout>
+
+    <!-- 右侧：按钮区 -->
     <LinearLayout
         android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
+        android:layout_height="match_parent"
-        android:orientation="horizontal"
+        android:orientation="vertical"
         android:gravity="center">
 
         <Button
             android:id="@+id/btn_start"
-            android:layout_width="120dp"
+            android:layout_width="160dp"
-            android:layout_height="60dp"
+            android:layout_height="56dp"
-            android:text="启动"
+            android:text="启动服务"
             android:textSize="18sp"
-            android:layout_marginEnd="16dp" />
+            android:layout_marginBottom="12dp" />
 
         <Button
             android:id="@+id/btn_stop"
-            android:layout_width="120dp"
+            android:layout_width="160dp"
-            android:layout_height="60dp"
+            android:layout_height="56dp"
-            android:text="停止"
+            android:text="停止服务"
             android:textSize="18sp"
-            android:enabled="false" />
+            android:enabled="false"
-
+            android:layout_marginBottom="24dp" />
-    </LinearLayout>
 
         <Button
             android:id="@+id/btn_capture"
-        android:layout_width="200dp"
+            android:layout_width="160dp"
-        android:layout_height="70dp"
+            android:layout_height="56dp"
             android:text="拍照保存"
-        android:textSize="20sp"
+            android:textSize="18sp"
-        android:layout_marginTop="24dp"
             android:backgroundTint="#4CAF50" />
 
+    </LinearLayout>
+
 </LinearLayout>