Android Uri，Path与File、Bitmap的相互转换（新）

Android Uri，Path与File的相互转换（新）

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一、path->file

File file = new File(path);

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二、 file->path

String path = file.getPath();

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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();
        }

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四、 File->URI

URI uri = file.toURI(); 

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五、 Path->Uri

Uri uri = Uri.parse(path);  

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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

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八、file->Uri
可以先 file->path 再path->Uri

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九、 删除Uri

MainActivity.this.getContentResolver().delete(imageUri, null, null);

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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);

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资源文件转Bitmap

BitmapFactory.decodeResource(getResources(),R.drawable.ic ); 

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jpg或者png文件转Bitmap

String fileName = "/data/com.test/aa.png;  
Bitmap bm = BitmapFactory.decodeFile(fileName);