Flutter实现Android原生相机拍照

方法1：使用Flutter的`camera`插件（完整实现）

1. 完整依赖与权限配置

# pubspec.yaml
dependencies:flutter:sdk: fluttercamera: ^0.10.5+2path_provider: ^2.0.15 # 用于获取存储路径path: ^1.8.3           # 用于路径操作permission_handler: ^10.4.0 # 权限处理

2. AndroidManifest.xml 配置

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /><!-- 在<application>标签内添加 -->
<providerandroid:name="androidx.core.content.FileProvider"android:authorities="${applicationId}.fileprovider"android:exported="false"android:grantUriPermissions="true"><meta-dataandroid:name="android.support.FILE_PROVIDER_PATHS"android:resource="@xml/file_paths" />
</provider>

3. 创建文件路径配置 (res/xml/file_paths.xml)

<?xml version="1.0" encoding="utf-8"?>
<paths><external-path name="my_images" path="Android/data/${applicationId}/files/Pictures" />
</paths>

4. Flutter端完整代码

import 'dart:async';
import 'dart:io';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:path/path.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';class CameraScreen extends StatefulWidget {@override_CameraScreenState createState() => _CameraScreenState();
}class _CameraScreenState extends State<CameraScreen> {late CameraController _controller;late Future<void> _initializeControllerFuture;bool _isCameraReady = false;String? _lastImagePath;@overridevoid initState() {super.initState();_setupCamera();}Future<void> _setupCamera() async {// 检查并请求权限final cameraStatus = await Permission.camera.status;final storageStatus = await Permission.storage.status;if (!cameraStatus.isGranted || !storageStatus.isGranted) {final results = await [Permission.camera,Permission.storage,].request();if (!results[Permission.camera]!.isGranted || !results[Permission.storage]!.isGranted) {return;}}// 获取可用相机final cameras = await availableCameras();final firstCamera = cameras.firstWhere((camera) => camera.lensDirection == CameraLensDirection.back,orElse: () => cameras.first,);// 初始化控制器_controller = CameraController(firstCamera,ResolutionPreset.high,enableAudio: false,imageFormatGroup: ImageFormatGroup.jpeg,);_initializeControllerFuture = _controller.initialize().then((_) {if (!mounted) return;setState(() => _isCameraReady = true);});}Future<String> _takePicture() async {if (!_isCameraReady) throw 'Camera not ready';final Directory appDir = await getApplicationDocumentsDirectory();final String fileName = '${DateTime.now().millisecondsSinceEpoch}.jpg';final String savePath = join(appDir.path, fileName);try {final XFile image = await _controller.takePicture();final File savedImage = await File(image.path).copy(savePath);return savedImage.path;} on CameraException catch (e) {throw 'Camera error: ${e.description}';}}@overridevoid dispose() {_controller.dispose();super.dispose();}@overrideWidget build(BuildContext context) {return Scaffold(body: FutureBuilder<void>(future: _initializeControllerFuture,builder: (context, snapshot) {if (snapshot.connectionState == ConnectionState.done) {return Stack(children: [CameraPreview(_controller),Positioned(bottom: 30,left: 0,right: 0,child: FloatingActionButton(onPressed: () async {try {final path = await _takePicture();setState(() => _lastImagePath = path);print('Image saved to: $path');} catch (e) {ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text('Error: $e')),);}},child: Icon(Icons.camera),),)],);} else {return Center(child: CircularProgressIndicator());}},),);}
}

方法2：通过平台通道调用原生相机（完整实现）

Flutter端完整代码

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';class NativeCameraScreen extends StatefulWidget {@override_NativeCameraScreenState createState() => _NativeCameraScreenState();
}class _NativeCameraScreenState extends State<NativeCameraScreen> {static const platform = MethodChannel('com.example/camera_channel');String? _imagePath;Future<void> _takePhoto() async {try {final String? path = await platform.invokeMethod('takePhoto');if (path != null) {setState(() => _imagePath = path);print('Photo path: $path');}} on PlatformException catch (e) {print("Failed to take photo: '${e.message}'.");}}@overrideWidget build(BuildContext context) {return Scaffold(body: Center(child: Column(mainAxisAlignment: MainAxisAlignment.center,children: [if (_imagePath != null)Image.file(File(_imagePath!), height: 300),ElevatedButton(onPressed: _takePhoto,child: Text('Take Photo'),),],),),);}
}

Android端完整实现 (Kotlin)

// MainActivity.kt
package com.example.your_app_nameimport android.Manifest
import android.app.Activity
import android.content.Intent
import android.content.pm.PackageManager
import android.net.Uri
import android.os.Bundle
import android.provider.MediaStore
import androidx.annotation.NonNull
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import androidx.core.content.FileProvider
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugin.common.MethodChannel
import java.io.File
import java.io.IOException
import java.text.SimpleDateFormat
import java.util.*class MainActivity : FlutterActivity() {private val CHANNEL = "com.example/camera_channel"private var pendingResult: MethodChannel.Result? = nullprivate var currentPhotoPath: String? = nullprivate val REQUEST_IMAGE_CAPTURE = 1private val REQUEST_CAMERA_PERMISSION = 2override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {super.configureFlutterEngine(flutterEngine)MethodChannel(flutterEngine.dartExecutor.binaryMessenger, CHANNEL).setMethodCallHandler { call, result ->when (call.method) {"takePhoto" -> {pendingResult = resultcheckCameraPermission()}else -> result.notImplemented()}}}private fun checkCameraPermission() {if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {ActivityCompat.requestPermissions(this,arrayOf(Manifest.permission.CAMERA),REQUEST_CAMERA_PERMISSION)} else {dispatchTakePictureIntent()}}private fun dispatchTakePictureIntent() {Intent(MediaStore.ACTION_IMAGE_CAPTURE).also { takePictureIntent ->takePictureIntent.resolveActivity(packageManager)?.also {val photoFile: File? = try {createImageFile()} catch (ex: IOException) {pendingResult?.error("FILE_ERROR", ex.message, null)null}photoFile?.also {val photoURI: Uri = FileProvider.getUriForFile(this,"${BuildConfig.APPLICATION_ID}.fileprovider",it)takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI)startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE)}}}}@Throws(IOException::class)private fun createImageFile(): File {val timeStamp: String = SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(Date())val storageDir: File? = getExternalFilesDir("Pictures")return File.createTempFile("JPEG_${timeStamp}_",".jpg",storageDir).apply {currentPhotoPath = absolutePath}}override fun onRequestPermissionsResult(requestCode: Int,permissions: Array<out String>,grantResults: IntArray) {super.onRequestPermissionsResult(requestCode, permissions, grantResults)if (requestCode == REQUEST_CAMERA_PERMISSION) {if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {dispatchTakePictureIntent()} else {pendingResult?.error("PERMISSION_DENIED", "Camera permission denied", null)}}}override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {super.onActivityResult(requestCode, resultCode, data)if (requestCode == REQUEST_IMAGE_CAPTURE) {when (resultCode) {Activity.RESULT_OK -> {pendingResult?.success(currentPhotoPath)}Activity.RESULT_CANCELED -> {pendingResult?.error("CANCELLED", "User cancelled photo", null)}else -> {pendingResult?.error("CAPTURE_FAILED", "Image capture failed", null)}}pendingResult = null}}
}

关键问题解决方案

1. 文件存储问题（Android 10+适配）

// 在AndroidManifest.xml中添加
<application...android:requestLegacyExternalStorage="true" // 临时解决方案>

或使用MediaStore API（推荐）：

private fun saveImageToGallery(context: Context, file: File) {val contentValues = ContentValues().apply {put(MediaStore.Images.Media.DISPLAY_NAME, file.name)put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg")put(MediaStore.Images.Media.RELATIVE_PATH, Environment.DIRECTORY_PICTURES)}val resolver = context.contentResolverval uri = resolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, contentValues)uri?.let {resolver.openOutputStream(it).use { output ->FileInputStream(file).use { input ->input.copyTo(output!!)}}}
}

2. 相机方向问题

在Flutter端处理相机方向：

@override
void didChangeAppLifecycleState(AppLifecycleState state) {if (state == AppLifecycleState.resumed) {_controller?.initialize().then((_) {if (!mounted) return;setState(() {});});}
}// 监听设备方向
_controller.setOrientation(orientation);

3. 内存泄漏预防

@override
void dispose() {_controller?.dispose();super.dispose();
}

4. 异常处理最佳实践

try {// 相机操作
} on CameraException catch (e) {if (e.code == 'CameraAccessDenied') {// 处理权限问题} else {// 其他相机错误}
} on PlatformException catch (e) {// 平台通道错误
} catch (e) {// 通用错误
}

两种方法对比

特性	camera插件	平台通道
开发难度	★☆☆ (简单)	★★★ (复杂)
跨平台支持	是	需要单独实现iOS
功能控制	中等	完全控制
性能	较好	最优
依赖大小	较大	较小
定制能力	有限	无限
维护成本	低 (官方维护)	高 (需自行维护)