Shulou(Shulou.com)06/03 Report--

In SpringMVC, the upload of files is achieved through MultipartResolver. So, if you want to upload files, just register the corresponding MultipartResolver in spring-mvc.xml.

There are two implementation classes for MultipartResolver:

CommonsMultipartResolver

StandardServletMultipartResolver

The difference between the two:

The first requires jar package support such as Apache's commons-fileupload, but it can be used in older versions of servlet.

The second one, which does not require third-party jar package support, uses servlet's built-in upload function, but can only be used in versions above Servlet 3.

The first step to use:

/ two packages used for CommonsMultipartResolver upload /

"commons-fileupload:commons-fileupload:1.3.1"

"commons-io:commons-io:2.4"

If it is a maven project, import it directly:

Commons-fileupload

Commons-fileupload

1.3.1

Dispatcher-servlet.xml configuration:

Web.xml:

Dispatcher org.springframework.web.servlet.DispatcherServlet contextConfigLocation classpath:dispatcher-servlet.xml dispatcher /

Backend java (upload and download) processing code:

Package edu.nf.ch08.controller

Import org.apache.commons.io.FileUtils

Import org.springframework.http.HttpHeaders

Import org.springframework.http.HttpStatus

Import org.springframework.http.MediaType

Import org.springframework.http.ResponseEntity

Import org.springframework.stereotype.Controller

Import org.springframework.web.bind.annotation.GetMapping

Import org.springframework.web.bind.annotation.PostMapping

Import org.springframework.web.multipart.MultipartFile

Import org.springframework.web.servlet.ModelAndView

Import java.io.File

Import java.io.IOException

/ * *

@ author wangl

@ date 2018 Universe 11 Universe /

@ Controllerbr/ > * /

@ Controller

/ * *

To upload a file, you only need to pass in a MultipartFile object by Spring, which can obtain the information about the file upload. A MultipartFile means that a single file is uploaded, and when you need to upload multiple files, you only need to declare it as an MultipartFile [] array. @ return*/

@ PostMapping ("/ upload") br/ > * /

@ PostMapping ("/ upload")

/ / get the current system user directory

String home = System.getProperty ("user.home")

/ / specify the uploaded folder directory

File uploadDir = new File (home + "/ files")

/ / if the directory does not exist, create

If (! uploadDir.exists ()) {

UploadDir.mkdir ()

}

/ / get the name of the uploaded file

String fileName = file.getOriginalFilename ()

/ / build a complete file upload object

File uploadFile = new File (uploadDir.getAbsolutePath () + "/" + fileName)

Try {

/ / upload via transferTo method

File.transferTo (uploadFile)

} catch (IOException e) {

E.printStackTrace ()

Throw new RuntimeException (e.getMessage ())

}

/ / Save the file name into Model and forward it to the index page

ModelAndView mv = new ModelAndView ("index")

Mv.addObject ("fileName", fileName)

Return mv

}

/ * *

The file download reads the server local file and encapsulates it as a ResponseEntity object response client, writing back an array of bytes @ param fileName file name @ return*/

@ GetMapping ("/ download") br/ > * /

@ GetMapping ("/ download")

/ / build a local file path based on the file name

String filePath = System.getProperty ("user.home") + "/ files/" + fileName

/ / build File objects based on the file path

File file = new File (filePath)

/ / create a response header object and set the response information

HttpHeaders headers = new HttpHeaders ()

Try {

/ / A pair of file names are re-encoded to prevent Chinese garbled in the response header

String headerFileName = new String (fileName.getBytes ("UTF-8"), "ISO-8859-1")

/ / set the response content to be handled as an attachment and specify a file name

Headers.setContentDispositionFormData ("attachment", headerFileName)

/ / set the response header type to application/octet-stream, which means it is a stream type

Headers.setContentType (MediaType.APPLICATION_OCTET_STREAM)

/ / convert the file to a byte array

Byte [] bytes = FileUtils.readFileToByteArray (file)

/ / create ResponseEntity object (encapsulate file byte array, response header, response status code)

ResponseEntity entity = new ResponseEntity (bytes, headers, HttpStatus.CREATED)

/ / finally, the entire ResponseEntity object is returned to DispatcherServlet

Return entity

} catch (Exception e) {

E.printStackTrace ()

Throw new RuntimeException ("File download failed")

}

}

}

The web page where the file is uploaded is html:

Title

File upload

File:

Jsp (download file) page forwarded after a successful upload:

Title

${fileName}

Project structure:

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