一、MediaStore简介

MediaStore是android系统提供的一个多媒体数据库，专门用于存放多媒体信息的，通过ContentResolver即可对数据库进行操作。

MediaStore.Files: 共享的文件,包括多媒体和非多媒体信息

MediaStore.Audio: 存放音频信息

MediaStore.Image: 存放图片信息

MediaStore.Vedio: 存放视频信息

每个内部类中都又包含了Media,Thumbnails和相应的MediaColumns，分别提供了媒体信息，缩略信息和 操作字段。

二、MediaStore使用

都是通过 ContentResolver 和 Cursor 来操作的。

2.1、MediaStore.Files

2.1.1、查询所有类型文件

/**
 * 获取所有文件
 **/
public static List<FileEntity> getFilesByType(Context context) {
    List<FileEntity> files = new ArrayList<>();
    // 扫描files文件库
    Cursor c = null;
    try {
        mContentResolver = context.getContentResolver();
        c = mContentResolver.query(MediaStore.Files.getContentUri("external"), null, null, null, null);
        int columnIndexOrThrow_ID = c.getColumnIndexOrThrow(MediaStore.Files.FileColumns._ID);
        int columnIndexOrThrow_MIME_TYPE = c.getColumnIndexOrThrow(MediaStore.Files.FileColumns.MIME_TYPE);
        int columnIndexOrThrow_DATA = c.getColumnIndexOrThrow(MediaStore.Files.FileColumns.DATA);
        int columnIndexOrThrow_SIZE = c.getColumnIndexOrThrow(MediaStore.Files.FileColumns.SIZE);
        // 更改时间
        int columnIndexOrThrow_DATE_MODIFIED = c.getColumnIndexOrThrow(MediaStore.Files.FileColumns.DATE_MODIFIED); 

        int tempId = 0;
        while (c.moveToNext()) {
            String path = c.getString(columnIndexOrThrow_DATA);
            String minType = c.getString(columnIndexOrThrow_MIME_TYPE);
            LogUtil.d("FileManager", "path:" + path);
            int position_do = path.lastIndexOf(".");
            if (position_do == -1) {
                continue;
            }
            int position_x = path.lastIndexOf(File.separator);
            if (position_x == -1) {
                continue;
            }
            String displayName = path.substring(position_x + 1, path.length());
            long size = c.getLong(columnIndexOrThrow_SIZE);
            long modified_date = c.getLong(columnIndexOrThrow_DATE_MODIFIED);
            File file = new File(path);
            String time = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date(file.lastModified()));
            FileEntity info = new FileEntity();
            info.setName(displayName);
            info.setPath(path);
            info.setSize(ShowLongFileSzie(size));
            info.setId((tempId++) + "");
            info.setTime(time);
            files.add(info);
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (c != null) {
            c.close();
        }
    }
    return files;
}

2.1.2、指定获取的文件字段

String[] columns = new String[]{MediaStore.Files.FileColumns._ID, MediaStore.Files.FileColumns.MIME_TYPE, MediaStore.Files.FileColumns
            .SIZE, MediaStore.Files.FileColumns.DATE_MODIFIED, MediaStore.Files.FileColumns.DATA};
c = mContentResolver.query(MediaStore.Files.getContentUri("external"), columns, null, null, null);

2.1.3、根据文件夹的名称查询

//查找文件夹ScreenRecord下的文件
c = mContentResolver.query(MediaStore.Files.getContentUri("external"), null, MediaStore.Video.Media.BUCKET_DISPLAY_NAME+"=?", "ScreenRecord", null);

2.1.4、查询指定类型的文件

String select = "(" + MediaStore.Files.FileColumns.DATA + " LIKE '%.doc'" + " or " + MediaStore.Files.FileColumns.DATA + " LIKE '%.docx'" + ")";
c = mContentResolver.query(MediaStore.Files.getContentUri("external"), null, select , null, null);

2.1.5、指定排序类型，如根据id倒序查询

c = mContentResolver.query(MediaStore.Files.getContentUri("external"), null, null, null, MediaStore.Files.FileColumns._ID+"DESC");

2.2、MediaStore.Audio
2.2.1、查询音频文件

c = mContentResolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null, null, null);

2.3、MediaStore.Image
2.3.1、查询图片文件

c = mContentResolver.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, null, null, null, null);

2.4、MediaStore.Vedio
2.4.1、查询视频文件

/**
 * 获取视频文件
 **/
public static List<FileEntity> getFilesByVideo(Context context) {
    List<FileEntity> files = new ArrayList<>();
    // 扫描files文件库
    Cursor c = null;
    try {
        mContentResolver = context.getContentResolver();
        c = mContentResolver.query(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, null, null, null, null);
        int columnIndexOrThrow_ID = c.getColumnIndexOrThrow(MediaStore.Video.Media._ID);
        int columnIndexOrThrow_MIME_TYPE = c.getColumnIndexOrThrow(MediaStore.Video.Media.MIME_TYPE);
        int columnIndexOrThrow_DATA = c.getColumnIndexOrThrow(MediaStore.Video.Media.DATA);
        int columnIndexOrThrow_SIZE = c.getColumnIndexOrThrow(MediaStore.Video.Media.SIZE);
        // 更改时间
        int columnIndexOrThrow_DATE_MODIFIED = c.getColumnIndexOrThrow(MediaStore.Video.Media.DATE_MODIFIED); 

        int tempId = 0;
        while (c.moveToNext()) {
            String path = c.getString(columnIndexOrThrow_DATA);
            String minType = c.getString(columnIndexOrThrow_MIME_TYPE);
            LogUtil.d("FileManager", "path:" + path);
            int position_do = path.lastIndexOf(".");
            if (position_do == -1) {
                continue;
            }
            int position_x = path.lastIndexOf(File.separator);
            if (position_x == -1) {
                continue;
            }
            String displayName = path.substring(position_x + 1, path.length());
            long size = c.getLong(columnIndexOrThrow_SIZE);
            long modified_date = c.getLong(columnIndexOrThrow_DATE_MODIFIED);
            File file = new File(path);
            String time = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date(file.lastModified()));
            FileEntity info = new FileEntity();
            info.setName(displayName);
            info.setPath(path);
            info.setSize(ShowLongFileSzie(size));
            info.setId((tempId++) + "");
            info.setTime(time);
            files.add(info);
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (c != null) {
            c.close();
        }
    }
    return files;
}

2.5、query()参数解析：

public final Cursor query(
Uri uri,                //数据资源路径
String[] projection,    //查询的列
String selection,       //查询的条件
String[] selectionArgs, //条件填充值
String sortOrder){}     //排序依据

2.6、数据库字段
MediaStore 提供了所有数据库中的字段宏定义,操作起来十分方便。

比如：

INTERNAL_CONTENT_URI; //内部库URI
EXTERNAL_CONTENT_URI; //外部库URI
CONTENT_TYPE; //内容提供者类型
DEFAULT_SORT_ORDER; //排序方式

MediaStore.Files没有EXTERNAL_CONTENT_URI，所以只能用getContentUri()自行获取，得出的URI其实是Uri.parse("content://media/external/files")

这个不难理解，以MediaStore.Images.Media为例，其URI有三种写法：

Uri uri1 = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
Uri uri2 = MediaStore.Images.Media.getContentUri("external");
Uri uri3 = Uri.parse("content://media/external/images/media");