Question

我正在开发一些应用程序，它允许从SD卡中选择图像，将其保存到数据库中并为ImageView设置此值。我需要知道将uri转换为字符串和字符串转换为uri的方法。现在我使用了Uri的getEncodedPath（）方法，但是，例如，这段代码不起作用：

ImageView iv=(ImageView)findViewById(R.id.imageView1);
Uri uri=Uri.parse("/external/images/media/470939");
Log.e("uri1", uri.toString());
iv.setImageURI(uri);

因此我不知道如何将Uri保存到数据库中并从保存的值创建新的Uri。请帮我修理一下。

Answer 1

我需要知道将uri转换为字符串和字符串转换为uri的方法。

使用toString()将Uri转换为String。使用Uri.parse()将String转换为Uri。

此代码不起作用

这不是Uri的有效字符串表示形式。 Uri有一个方案，"/external/images/media/470939"没有方案。

Answer 2

尝试将字符串转换为uri

String mystring="Hello"
Uri myUri = Uri.parse(mystring);

Uri to String

Uri uri;
String uri_to_string;
uri_to_string= uri.toString();

Answer 3

这将从MediaProvider，DownloadsProvider和ExternalStorageProvider获取文件路径，同时回退到您提到的非官方ContentProvider方法。

   /**
 * Get a file path from a Uri. This will get the the path for Storage Access
 * Framework Documents, as well as the _data field for the MediaStore and
 * other file-based ContentProviders.
 *
 * @param context The context.
 * @param uri The Uri to query.
 * @author paulburke
 */
public static String getPath(final Context context, final Uri uri) {

    final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;

    // DocumentProvider
    if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
        // ExternalStorageProvider
        if (isExternalStorageDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            if ("primary".equalsIgnoreCase(type)) {
                return Environment.getExternalStorageDirectory() + "/" + split[1];
            }

            // TODO handle non-primary volumes
        }
        // DownloadsProvider
        else if (isDownloadsDocument(uri)) {

            final String id = DocumentsContract.getDocumentId(uri);
            final Uri contentUri = ContentUris.withAppendedId(
                    Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));

            return getDataColumn(context, contentUri, null, null);
        }
        // MediaProvider
        else if (isMediaDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];

            Uri contentUri = null;
            if ("image".equals(type)) {
                contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
            } else if ("video".equals(type)) {
                contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
            } else if ("audio".equals(type)) {
                contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
            }

            final String selection = "_id=?";
            final String[] selectionArgs = new String[] {
                    split[1]
            };

            return getDataColumn(context, contentUri, selection, selectionArgs);
        }
    }
    // MediaStore (and general)
    else if ("content".equalsIgnoreCase(uri.getScheme())) {
        return getDataColumn(context, uri, null, null);
    }
    // File
    else if ("file".equalsIgnoreCase(uri.getScheme())) {
        return uri.getPath();
    }

    return null;
}

/**
 * Get the value of the data column for this Uri. This is useful for
 * MediaStore Uris, and other file-based ContentProviders.
 *
 * @param context The context.
 * @param uri The Uri to query.
 * @param selection (Optional) Filter used in the query.
 * @param selectionArgs (Optional) Selection arguments used in the query.
 * @return The value of the _data column, which is typically a file path.
 */
public static String getDataColumn(Context context, Uri uri, String selection,
        String[] selectionArgs) {

    Cursor cursor = null;
    final String column = "_data";
    final String[] projection = {
            column
    };

    try {
        cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
                null);
        if (cursor != null && cursor.moveToFirst()) {
            final int column_index = cursor.getColumnIndexOrThrow(column);
            return cursor.getString(column_index);
        }
    } finally {
        if (cursor != null)
            cursor.close();
    }
    return null;
}


/**
 * @param uri The Uri to check.
 * @return Whether the Uri authority is ExternalStorageProvider.
 */
public static boolean isExternalStorageDocument(Uri uri) {
    return "com.android.externalstorage.documents".equals(uri.getAuthority());
}

/**
 * @param uri The Uri to check.
 * @return Whether the Uri authority is DownloadsProvider.
 */
public static boolean isDownloadsDocument(Uri uri) {
    return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}

/**
 * @param uri The Uri to check.
 * @return Whether the Uri authority is MediaProvider.
 */
public static boolean isMediaDocument(Uri uri) {
    return "com.android.providers.media.documents".equals(uri.getAuthority());
}

Answer 4

我不确定您是否解决了此问题。跟进“ CommonsWare的”评论。

这不是Uri的有效字符串表示形式。 Uri有一个方案，而“ / external / images / media / 470939”没有一个方案。

更改

Uri uri=Uri.parse("/external/images/media/470939");

到

Uri uri=Uri.parse("content://external/images/media/470939");

就我而言

Uri uri = Uri.parse("content://media/external/images/media/6562");

Answer 5

您可以使用Drawable而不是Uri。

   ImageView iv=(ImageView)findViewById(R.id.imageView1);
   String pathName = "/external/images/media/470939"; 
   Drawable image = Drawable.createFromPath(pathName);
   iv.setImageDrawable(image);

这样可行。

将Uri转换为String，将String转换为Uri

5 个答案: