使用File Provider调用相机获取高清图片并显示于ImageView问题求助

1. 检查File Provider配置 #

• 在AndroidManifest.xml中确认File Provider配置正确，authorities需与代码中的一致：

<provider
    android:name="androidx.core.content.FileProvider"
    android:authorities="com.yourpackage.name.fileprovider"
    android:exported="false"
    android:grantUriPermissions="true">
    <meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/file_paths" />
</provider>

• 对应的res/xml/file_paths.xml需正确指向照片存储目录，示例：

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-files-path name="camera_images" path="Pictures" />
</paths>

2. 正确生成相机拍照的Uri与权限授予 #

• 创建存储照片的本地文件：

private File createImageFile() throws IOException {
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.getDefault()).format(new Date());
    String fileName = "CAMERA_" + timeStamp + ".jpg";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    return File.createTempFile(fileName, null, storageDir);
}

• 启动相机时通过File Provider生成Uri，并授予临时访问权限：

File photoFile = createImageFile();
Uri photoUri = FileProvider.getUriForFile(this, "com.yourpackage.name.fileprovider", photoFile);

Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoUri);

// 给相机APP授予Uri读写权限
List<ResolveInfo> resInfos = getPackageManager().queryIntentActivities(cameraIntent, PackageManager.MATCH_DEFAULT_ONLY);
for (ResolveInfo info : resInfos) {
    grantUriPermission(info.activityInfo.packageName, photoUri, 
                      Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
}

// 用Activity Result API启动相机（替代已废弃的startActivityForResult）
ActivityResultLauncher<Intent> cameraLauncher = registerForActivityResult(
    new ActivityResultContracts.StartActivityForResult(),
    result -> {
        if (result.getResultCode() == RESULT_OK) {
            // 传递图片路径到DisplayActivity
            Intent displayIntent = new Intent(this, DisplayActivity.class);
            displayIntent.putExtra("IMAGE_PATH", photoFile.getAbsolutePath());
            startActivity(displayIntent);
        }
    });
cameraLauncher.launch(cameraIntent);

3. 加载高清图片到ImageView #

直接加载原文件避免压缩模糊，推荐用Glide简化处理（需先添加Glide依赖）：

// DisplayActivity中获取图片路径并加载
String imagePath = getIntent().getStringExtra("IMAGE_PATH");
File imageFile = new File(imagePath);

Glide.with(this)
     .load(imageFile)
     .into(yourImageView);

如果手动处理Bitmap（需注意OOM）：

public Bitmap getSampledBitmap(File file, int targetWidth, int targetHeight) {
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(file.getAbsolutePath(), options);
    
    // 计算采样率，避免加载过大Bitmap
    options.inSampleSize = calculateSampleSize(options, targetWidth, targetHeight);
    options.inJustDecodeBounds = false;
    
    return BitmapFactory.decodeFile(file.getAbsolutePath(), options);
}

private int calculateSampleSize(BitmapFactory.Options options, int targetWidth, int targetHeight) {
    int width = options.outWidth;
    int height = options.outHeight;
    int sampleSize = 1;
    
    while (width / sampleSize > targetWidth || height / sampleSize > targetHeight) {
        sampleSize *= 2;
    }
    return sampleSize;
}

// 调用加载
Bitmap bitmap = getSampledBitmap(imageFile, yourImageView.getWidth(), yourImageView.getHeight());
yourImageView.setImageBitmap(bitmap);

4. 权限检查 #

• 确保已动态申请CAMERA权限；
• Android 10及以下需申请WRITE_EXTERNAL_STORAGE，Android 11+使用getExternalFilesDir存储无需该权限。

内容的提问来源于stack exchange，提问作者Muhammad Mubeen