GridFS

╰半夏微凉° 2022-04-22 14:20 192阅读 0赞

*GridFS介绍*

GridFS是MongoDB提供的用于持久化存储文件的模块，CMS使用MongoDB存储数据，使用GridFS可以快速集成开发。

//缺点是效率没有那么高效..

工作原理的话我在百度找了一张图,

![20181126163113984.png][]

// 详细的话可以参考 [https://docs.mongodb.com/manual/core/gridfs/][https_docs.mongodb.com_manual_core_gridfs]

gridfs使用 - . -

存储文件

@Resource
    GridFsTemplate gridFsTemplate;
    
    @Test
        public void test2() throws FileNotFoundException {
    
    
            File file = new File("D:\\Code\\xuecheng\\XcEduCode\\testfreemark\\src\\main\\resources\\templates\\index_banner.ftl");
    
            //创建输入流
            FileInputStream inputStream = new FileInputStream(file);
    
    
            //向 gridtemplate 存储文件
    
            ObjectId objId = gridFsTemplate.store(inputStream, "轮播图测试文件", "");
    
            //id 转换成字符串格式
            String id = objId.toString();
    
            System.out.println(id);
    //        5bfb661d4402c333342a9c6a
    //        gridFsTemplate.store(, );
        }

查询文件

1. 需要配置一个bean,这个bean的作用是打开下载流文件

import com.mongodb.MongoClient;
    import com.mongodb.client.MongoDatabase;
    import com.mongodb.client.gridfs.GridFSBucket;
    import com.mongodb.client.gridfs.GridFSBuckets;
    import org.springframework.beans.factory.annotation.Value;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    public class MongoConfig {
        @Value("${spring.data.mongodb.database}")
        String db;
    //
        @Bean
        public GridFSBucket getGridFSBucket(MongoClient mongoClient){
            MongoDatabase database = mongoClient.getDatabase(db);
            GridFSBucket bucket = GridFSBuckets.create(database);
            return bucket;
        }
    }

@Resource
        GridFSBucket gridFSBucket;
        //模板查询
        @Test
        public void fun02() throws IOException {
    
            String id = "5bfbad494402c33ad0b6dc05";
            GridFSFile fsFile = gridFsTemplate.findOne(Query.query(Criteria.where("_id").is(id)));
    
            //打开下载流文件
            GridFSDownloadStream gridFSDownloadStream = gridFSBucket.openDownloadStream(fsFile.getObjectId());
    
    
            //创建gridFsResource，用于获取流对象
            GridFsResource gridFsResource = new GridFsResource(fsFile, gridFSDownloadStream);
    
            //获取流中的数据
            String s = IOUtils.toString(gridFsResource.getInputStream(), "UTF‐8");
    
            System.out.println(s);
        }

[20181126163113984.png]: /images/20220414/670c0b87fa2043f99d618cde4cc85f2c.png
[https_docs.mongodb.com_manual_core_gridfs]: https://docs.mongodb.com/manual/core/gridfs/