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

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									sudo apt-get install mongodb

安装完成后找到mongofiles的位置

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									whereis mongofiles

找到之后进入目录就可以上传文件了

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

这时文件就添加成功了，进入mongodb查看

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									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

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									<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

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									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

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									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

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									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

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									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

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									@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

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									@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;

									    }

									}

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									@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

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									//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")));

									}