图片上传Firebase数据库失败，如何通过代码授予应用权限？

明确说明：可以通过代码显式向用户申请必要权限，尤其是Android 6.0（API 23）及以上版本，相机、存储这类危险权限必须动态申请，仅在Manifest里声明无法自动获得权限。以下是具体实现步骤：

1. 先在AndroidManifest.xml中声明权限 #

根据你的Android版本，添加对应权限：

<!-- 相机权限 -->
<uses-permission android:name="android.permission.CAMERA" />
<!-- Android 13及以上存储权限 -->
<uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
<!-- Android 12及以下存储权限 -->
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="32" />

<!-- 可选：声明相机硬件特性，用于Google Play商店过滤设备 -->
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

2. 代码中动态申请权限 #

推荐方式：使用ActivityResultContracts（适配AndroidX及新版本） #

在你的Activity或Fragment中实现：

// 注册权限请求回调
private val requestPermissionLauncher = registerForActivityResult(
    ActivityResultContracts.RequestMultiplePermissions()
) { permissions ->
    // 校验权限申请结果
    val cameraGranted = permissions[android.Manifest.permission.CAMERA] ?: false
    val storageGranted = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
        permissions[android.Manifest.permission.READ_MEDIA_IMAGES] ?: false
    } else {
        permissions[android.Manifest.permission.READ_EXTERNAL_STORAGE] ?: false
    }

    if (cameraGranted && storageGranted) {
        // 权限全部授予，执行拍照/上传逻辑
        takePhoto()
    } else {
        // 权限被拒绝，提示用户开启
        Toast.makeText(this, "需要相机和存储权限才能完成操作", Toast.LENGTH_SHORT).show()
    }
}

// 检查并发起权限请求
private fun checkAndRequestPermissions() {
    val cameraPermission = android.Manifest.permission.CAMERA
    val storagePermission = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
        android.Manifest.permission.READ_MEDIA_IMAGES
    } else {
        android.Manifest.permission.READ_EXTERNAL_STORAGE
    }

    val hasCameraPerm = ContextCompat.checkSelfPermission(this, cameraPermission) == PackageManager.PERMISSION_GRANTED
    val hasStoragePerm = ContextCompat.checkSelfPermission(this, storagePermission) == PackageManager.PERMISSION_GRANTED

    if (!hasCameraPerm || !hasStoragePerm) {
        // 发起权限请求
        requestPermissionLauncher.launch(arrayOf(cameraPermission, storagePermission))
    } else {
        // 权限已存在，直接执行操作
        takePhoto()
    }
}

兼容旧版：使用onRequestPermissionsResult（逐步弃用） #

如果项目仍依赖旧版权限请求逻辑：

private static final int PERMISSION_REQUEST_CODE = 100;

private void checkAndRequestPermissions() {
    String[] permissions;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
        permissions = new String[]{Manifest.permission.CAMERA, Manifest.permission.READ_MEDIA_IMAGES};
    } else {
        permissions = new String[]{Manifest.permission.CAMERA, Manifest.permission.READ_EXTERNAL_STORAGE};
    }

    if (ContextCompat.checkSelfPermission(this, permissions[0]) != PackageManager.PERMISSION_GRANTED
            || ContextCompat.checkSelfPermission(this, permissions[1]) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, permissions, PERMISSION_REQUEST_CODE);
    } else {
        takePhoto();
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (requestCode == PERMISSION_REQUEST_CODE) {
        boolean allGranted = true;
        for (int result : grantResults) {
            if (result != PackageManager.PERMISSION_GRANTED) {
                allGranted = false;
                break;
            }
        }
        if (allGranted) {
            takePhoto();
        } else {
            Toast.makeText(this, "需要相机和存储权限才能完成操作", Toast.LENGTH_SHORT).show();
        }
    }
}

3. 额外排查点 #

• 检查Firebase Storage规则：测试阶段可临时设置为allow read, write: if true;，上线后需配置安全的访问规则。
• 确认拍照后图片的存储路径：避免访问无权限的目录，导致读取图片失败进而上传出错。

内容的提问来源于stack exchange，提问作者DB123