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This article mainly explains "Spring Boot how to use GridFS to upload and download files", the content of the article is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "Spring Boot how to use GridFS to achieve file upload and download" bar!

Catalogue

Using GridFS to upload and download files

First, learn how to manipulate GridFS with commands.

Use Spring Boot to operate GridFS

Using GridFS in Spring Boot

What is GridFS?

Using GridFS in SpringBoot

Using GridFS to upload and download files

In this blog, we will show how to use mongodb's own file storage system GridFS in Spring Boot to upload and download files.

First, learn how to manipulate GridFS with commands.

Install mongodb

Sudo apt-get install mongodb

Find the location of mongofiles after installation is complete

Whereis mongofiles

After finding it, you can go to the directory and upload the file.

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

At this point, the file is added successfully. Go to mongodb to view it.

Mongoshow dbs # found an extra gridfsuse gridfsdb.fs.files.find () # to store some basic information of the file db.fs.chunks.find () # stores the binary contents of the file, a file has multiple fs.chunks, and each fs.chunks has one. Files_id corresponds to the id in fs.files, forming a many-to-one relationship. Files are stored separately, and Spring Boot is used to operate GridFS when fetching.

Introduce dependency

Org.springframework.boot spring-boot-starter-data-mongodb commons-io commons-io 2.4

Controller code

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;@RestControllerpublic 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 (); / / store the timestamp in mongodb String fileName = String.valueOf (System.currentTimeMillis ()) as the file name; 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 } / / query by file name (can also be queried based on MD5 values and other information) GridFSFindIterable result = operations.find (query (whereFilename (). Is (fileName)); GridFSFile gridFSFile = result.first (); GridFSDownloadStream gridFSDownloadStream = gridFSBucket.openDownloadStream (gridFSFile.getObjectId ()); / / create gridFsResource to get stream object GridFsResource gridFsResource = new GridFsResource (gridFSFile, gridFSDownloadStream) Return IOUtils.toByteArray (gridFsResource.getInputStream ());}}

Add a configuration class

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;@Configurationpublic 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;}}

The entity class returned by the picture

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;}}

Configuration file

Using GridFS in spring: data: mongodb: uri: mongodb://localhost:27017/gridfs database: gridfsSpring Boot what is GridFS

GirdFS is a module provided by MongoDB for persistent storage of files

In GridFS, files are stored in blocks, and files are stored in multiple blocks according to the size of 256KB. GridFS uses two sets (collection) to store files, one is chunks, which is used to store binary data of files, and the other is files, which is used to store meta-data information of files (file name, block size, upload time, etc.).

To read a file from GridFS, each block of the file is assembled and merged.

Using GridFS in SpringBoot

Storage file

@ AutowiredGridFsTemplate gridFsTemplate;@Testpublic void GridFsTest () throws FileNotFoundException {/ / Select the file to store File file = new File ("/ Users/xxx/Desktop/xxx.docx"); InputStream inputStream = new FileInputStream (file); / / store the file with the name ObjectId objectId = gridFsTemplate.store (inputStream, "interview Treasure Book"); String id = objectId.toString (); / / get the id of the file, and you can find System.out.println (id) from the database;}

Find a file

Create a GridFSBucket object

@ Configurationpublic 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;}} @ AutowiredGridFsTemplate gridFsTemplate;@AutowiredGridFSBucket gridFSBucket;@Testpublic void queryFile () throws IOException {String id = "5c1b8fac72884e389ae3df82" / / find the file GridFSFile gridFSFile = gridFsTemplate.findOne according to id (new Query (Criteria.where ("_ id"). Is (id)); / / Open the download stream object GridFSDownloadStream gridFS = gridFSBucket.openDownloadStream (gridFSFile.getObjectId ()); / / create a gridFsSource to get the stream object GridFsResource gridFsResource = new GridFsResource (gridFSFile,gridFS); / / get the data in the stream String string = IOUtils.toString (gridFsResource.getInputStream (), "UTF-8") System.out.println (string);}

Delete a file

/ / delete the file @ Testpublic void testDelFile () throws IOException {/ / delete the record gridFsTemplate.delete in fs.files and fs.chunks according to the file id (Query.query (Criteria.where ("_ id"). Is ("5c1b8fac72884e389ae3df82") } Thank you for reading, the above is the content of "how Spring Boot uses GridFS to upload and download files". After the study of this article, I believe you have a deeper understanding of how Spring Boot uses GridFS to achieve file upload and download, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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