将文件从Web服务器传输到客户端

Question

I have a simple Spring java web server. It does some processing that creates some xml files on the server. I would like to transfer those files to the client computer.

For some reason I do not even know how to start or search for an answer. It should not be hard because I am using Spring and they are only xml files not binary. Can someone direct me of what I should be looking for in a search?

I am using @RequestMapping in my controllers. They look something this:

@Controller
@RequestMapping(value = "/export")
public class ExportController {


    @RequestMapping(method = RequestMethod.GET)
    public String getExport(ModelMap map) throws Exception {

    return "export"
}

This returns to a jsp file.

Answer 1

The simplest (but not best) way would be to write them to disk and then to provide a link to them on your web page.

The other way would be to open a response stream and write back the contents.

Answer 2

There are two ways:

1) Controller Method:
Specify controller

@RequestMapping("/getFile")
public ResponseEntity<byte[]> getFile() throws IOException {
    InputStream in = fetchFile("test.png");

    final HttpHeaders headers = new HttpHeaders();
    //Specify MediaType of the file you want to return
    headers.setContentType(MediaType.IMAGE_PNG); 

    return new ResponseEntity<byte[]>(IOUtils.toByteArray(in), headers, HttpStatus.CREATED);
}

And the mvc annotation in servlet-context.xml file:

<mvc:annotation-driven>
    <mvc:message-converters>
        <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter">
            <property name="supportedMediaTypes">
                <list>
                    <value>image/jpeg</value>
                    <value>image/png</value>
                </list>
            </property>
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

2) Save file in the Server Context and expose a path to the browser.

Answer 3

This is what we have used in our project:

    @RequestMapping(value = "/export", method = RequestMethod.GET, produces = MediaType.APPLICATION_OCTET_STREAM_VALUE)
    @ResponseBody
    public FileSystemResource downloadDocument(@PathVariable Long docId, HttpServletRequest request, 
            HttpServletResponse response) throws IOException, DocumentServiceException {                    
        //set the default file name to be saved by user. 
        response.setContentType("application/octet-stream");
        response.setHeader("Content-Disposition","attachment;filename=XMLFileName");
        return new FileSystemResource(new File("XMLfilePath"));

    }

Note that XMLFileName is the name of file which the user will save by default and XMLfilePath is the physical path of the file.