• Android中Uri和Path之间的转换


    Android Uri,Path与File的相互转换(新)
    
    一、path->file
    
    File file = new File(path);
    
    二、 file->path
    
    String path = file.getPath();
    
    注意URI和Uri的区别
    
    1 URI:是java.net的子类
    2 Uri :是android.net的子类,Uri 不能被实例化
    
    三、 URI->File
    
    File file = null;   //图片地址
            try {
                file = new File(new URI(uri.toString()));
            } catch (URISyntaxException e) {
                e.printStackTrace();
            }
    
    
    四、 File->URI
    
    URI uri = file.toURI(); 
    
    
    五、 Path->Uri
    
    Uri uri = Uri.parse(path);  
    
    六、Uri->Path
    网上很多通过context.getContentResolver().query方式可能会遇到空指针的问题
    这里通过使用:https://juejin.im/entry/5a508655f265da3e2d3340d5
    提供的封装方法 去处理Uri转Path的问题
    
    传入 context 和 Uri即可
    
    
    public class UriTofilePath {
        public static String getFilePathByUri(Context context, Uri uri) {
            String path = null;
            // 4.4及之后的 是以 content:// 开头的,比如 content://com.android.providers.media.documents/document/image%3A235700
            if (ContentResolver.SCHEME_CONTENT.equals(uri.getScheme()) && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                if (DocumentsContract.isDocumentUri(context, uri)) {
                    if (isExternalStorageDocument(uri)) {
                        // ExternalStorageProvider
                        final String docId = DocumentsContract.getDocumentId(uri);
                        final String[] split = docId.split(":");
                        final String type = split[0];
                        if ("primary".equalsIgnoreCase(type)) {
                            path = Environment.getExternalStorageDirectory() + "/" + split[1];
                            return path;
                        }
                    } else if (isDownloadsDocument(uri)) {
                        // DownloadsProvider
                        final String id = DocumentsContract.getDocumentId(uri);
                        final Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"),
                                Long.valueOf(id));
                        path = getDataColumn(context, contentUri, null, null);
                        return path;
                    } else if (isMediaDocument(uri)) {
                        // MediaProvider
                        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]};
                        path = getDataColumn(context, contentUri, selection, selectionArgs);
                        return path;
                    }
                }
            }else {
                // 以 file:// 开头的
                if (ContentResolver.SCHEME_FILE.equals(uri.getScheme())) {
                    path = uri.getPath();
                    return path;
                }
                // 以 content:// 开头的,比如 content://media/extenral/images/media/17766
                if (ContentResolver.SCHEME_CONTENT.equals(uri.getScheme()) && Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
                    Cursor cursor = context.getContentResolver().query(uri, new String[]{MediaStore.Images.Media.DATA}, null, null, null);
                    if (cursor != null) {
                        if (cursor.moveToFirst()) {
                            int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
                            if (columnIndex > -1) {
                                path = cursor.getString(columnIndex);
                            }
                        }
                        cursor.close();
                    }
                    return path;
                }
            }
            return null;
        }
    
        private 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;
        }
    
        private static boolean isExternalStorageDocument(Uri uri) {
            return "com.android.externalstorage.documents".equals(uri.getAuthority());
        }
    
        private static boolean isDownloadsDocument(Uri uri) {
            return "com.android.providers.downloads.documents".equals(uri.getAuthority());
        }
    
        private static boolean isMediaDocument(Uri uri) {
            return "com.android.providers.media.documents".equals(uri.getAuthority());
        }
    }
    
    
    **七、 Uri->file **
    可以先Uri->path 再path->file
    
    八、file->Uri
    可以先 file->path 再path->Uri
    
    九、 删除Uri
    
    MainActivity.this.getContentResolver().delete(imageUri, null, null);
    
    图片的Uri转Bitmap
    
    Bitmap bitmap = BitmapFactory.decodeStream(contentResolver.openInputStream(xxxUri))
    
    bitmap转为jpg文件
    
    BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
    bitmap.compress(Bitmap.CompressFormat.JPEG, 100, bos);
    
    资源文件转Bitmap
    
    BitmapFactory.decodeResource(getResources(),R.drawable.ic ); 
    
    jpg或者png文件转Bitmap
    
    String fileName = "/data/com.test/aa.png;  
    Bitmap bm = BitmapFactory.decodeFile(fileName); 
    ————————————————
    版权声明:本文为CSDN博主「5ingwings」的原创文章,遵循 CC 4.0 BY-SA 版权协议,转载请附上原文出处链接及本声明。
    原文链接:https://blog.csdn.net/weixin_37577039/article/details/79242455
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  • 原文地址:https://www.cnblogs.com/Free-Thinker/p/12565838.html
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