Spring Boot使用GridFS实现文件的上传和下载方式

使用GridFS实现文件的上传和下载

在这篇博客中，我们将展示如何使用Spring Boot中使用mongodb自带的文件存储系统GridFS实现文件的上传和下载功能

首先了解一下怎么用命令操作GridFS

安装mongodb

sudo apt-get install mongodb

安装完成后找到mongofiles的位置

whereis mongofiles

找到之后进入目录就可以上传文件了

mongofiles put /home/ubuntu/Desktop/1.jpg

这时文件就添加成功了，进入mongodb查看

mongo
show dbs  # 发现多了一个gridfs
use gridfs
db.fs.files.find() # 存放文件的一些基本信息
db.fs.chunks.find() # 存放文件二进制内容，一个文件有多个fs.chunks，每个fs.chunks都有一个，files_id与fs.files中的id相对应，形成多对一的关系，文件存的时候分开存，取的时候再合并

使用Spring Boot操作GridFS

引入依赖

<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
<dependency>
 <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.4</version>
</dependency>

controller代码

import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.client.gridfs.GridFSBucket;
import com.mongodb.client.gridfs.GridFSDownloadStream;
import com.mongodb.client.gridfs.GridFSFindIterable;
import com.mongodb.client.gridfs.model.GridFSFile;
import org.apache.commons.io.IOUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.gridfs.GridFsOperations;
import org.springframework.data.mongodb.gridfs.GridFsResource;
import org.springframework.data.mongodb.gridfs.GridFsTemplate;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import java.io.IOException;
import java.io.InputStream;
import static org.springframework.data.mongodb.core.query.Query.query;
import static org.springframework.data.mongodb.gridfs.GridFsCriteria.whereFilename;
@RestController
public class ImageController {
    @Autowired
    private GridFsTemplate gridFsTemplate;
    @Autowired
    private GridFsOperations operations;
    @Autowired
    private GridFSBucket gridFSBucket;
    @PostMapping("file/upload")
    public ImageResponse upload(@RequestParam("file") MultipartFile file) {
        DBObject metaData = new BasicDBObject();
        // 把时间戳作为文件名存入mongodb
        String fileName = String.valueOf(System.currentTimeMillis());
        InputStream inputStream = null;
        try {
            inputStream = file.getInputStream();
            gridFsTemplate.store(inputStream, fileName, "image", metaData);
        } catch (IOException e) {
            throw new RuntimeException();
        }
        return new ImageResponse(fileName);
    }
    @GetMapping(value = "file/download/${fileName}", produces = MediaType.IMAGE_JPEG_VALUE)
    @ResponseBody
    public byte[] getImage(@PathVariable("fileName") String fileName) throws IOException {
        if (fileName == null) {
            return null;
        }
        // 根据文件名查询(也可以根据md5值等信息查询)
        GridFSFindIterable result = operations.find(query(whereFilename().is(fileName)));
        GridFSFile gridFSFile = result.first();
        GridFSDownloadStream gridFSDownloadStream = gridFSBucket.openDownloadStream(gridFSFile.getObjectId());
        //创建gridFsResource，用于获取流对象
        GridFsResource gridFsResource = new GridFsResource(gridFSFile, gridFSDownloadStream);
        return IOUtils.toByteArray(gridFsResource.getInputStream());
    }
}

加入一个配置类

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;
    }
}

图片返回的实体类

public class ImageResponse implements Serializable {
    private String imageName;
    public ImageResponse(String imageName) {
        this.imageName = imageName;
    }
    public String getImageName() {
        return imageName;
    }
    public void setImageName(String imageName) {
        this.imageName = imageName;
    }
}

配置文件

spring:
  data:
    mongodb:
      uri: mongodb://localhost:27017/gridfs
      database: gridfs

Spring Boot中使用GridFS

什么是GridFS

GirdFS是MongoDB提供的用于持久化存储文件的模块

在GridFS存储文件是将文件分块存储，文件会按照256KB的大小分割成多个块进行存储，GridFS使用两个集合 (collection)存储文件，一个集合是chunks, 用于存储文件的二进制数据;一个集合是files，用于存储文件的元数 据信息(文件名称、块大小、上传时间等信息)。

从GridFS中读取文件要对文件的各各块进行组装、合并。

在SpringBoot中使用GridFS

存储文件

@Autowired
GridFsTemplate gridFsTemplate;
@Test
public void GridFsTest() throws FileNotFoundException {
   //选择要存储的文件
   File file = new File("/Users/xxx/Desktop/xxx.docx");
   InputStream inputStream = new FileInputStream(file);
   //存储文件并起名称
   ObjectId objectId = gridFsTemplate.store(inputStream, "面试宝典");
   String id = objectId.toString();
   //获取到文件的id，可以从数据库中查找
   System.out.println(id);
}

查找文件

创建GridFSBucket对象

@Configuration
public class MongoConfig {
    @Value("${spring.data.mongodb.database}")
    String db;
    @Bean
    public GridFSBucket getGridFSBucket(MongoClient mongoClient){
        MongoDatabase mongoDatabase = mongoClient.getDatabase(db);
        GridFSBucket bucket = GridFSBuckets.create(mongoDatabase);
        return bucket;
    }
}

@Autowired
GridFsTemplate gridFsTemplate;
@Autowired
GridFSBucket gridFSBucket;
@Test
public void queryFile() throws IOException {
   String id = "5c1b8fac72884e389ae3df82";
   //根据id查找文件
   GridFSFile gridFSFile = gridFsTemplate.findOne(new Query(Criteria.where("_id").is(id)));
   //打开下载流对象
   GridFSDownloadStream gridFS = gridFSBucket.openDownloadStream(gridFSFile.getObjectId());
   //创建gridFsSource，用于获取流对象
   GridFsResource gridFsResource = new GridFsResource(gridFSFile,gridFS);
   //获取流中的数据
   String string = IOUtils.toString(gridFsResource.getInputStream(), "UTF-8");
   System.out.println(string);
}

删除文件

 //删除文件
@Test
public void testDelFile() throws IOException {
//根据文件id删除fs.files和fs.chunks中的记录
       gridFsTemplate.delete(Query.query(Criteria.where("_id").is("5c1b8fac72884e389ae3df82")));
}

以上为个人经验，希望能给大家一个参考，也希望大家多多支持猪先飞。