How to send an retrieved image from Mongo using Gr

2019-03-22 02:40发布

问题:

I have retrieved the image from Mongo DB using Spring Data and GridFs Template

so i don't know how to serve that retrieved input stream back to user .

Say they requested for the http://host.com/apple as a spring rest call . Now my application process the request by using the name apple it retrieves the apple image from a mongodb database . Now without saving anywhere i want to display the response as an image to user that will show http://host.com/apple image in the browser. How exactly i need to implement this ?

Could you please share any code repository for processing the image request in Rest Call ?

Controller Code

 @RestController
    public class GreetingController {

    @RequestMapping("/image")
    public GridFSDBFile imageReponse() {
        App.getImage();
        return App.getImageResponse();
    }
}

This function will fetch the image from the mongodb

public static GridFSDBFile getImageResponse() {
        try {

            ApplicationContext context = new FileSystemXmlApplicationContext(
                    "file:C:\\workspace\\gs-rest-service-complete\\spring-config.xml");
            FileStorageDao fileStorageDao = (FileStorageDao) context
                    .getBean("fileStorageDao");

            GridFSDBFile retrive = fileStorageDao.retrive("audi.jpg");
            return retrive;
        } catch (Exception e) {
            System.out.println("IOException:-" + e.getMessage());
        } finally {
            System.out.println("Clean up herer:-");
        }
        return null;

    }

Error

Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Fri Sep 04 17:21:05 IST 2015
There was an unexpected error (type=Internal Server Error, status=500).
Could not write content: No serializer found for class com.mongodb.gridfs.GridFSDBFile$MyInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.mongodb.gridfs.GridFSDBFile["inputStream"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class com.mongodb.gridfs.GridFSDBFile$MyInputStream and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.mongodb.gridfs.GridFSDBFile["inputStream"])

回答1:

I have used the spring boot and rest where this following code will work if you are using latest version of spring i.e.,Spring 4.1

@RequestMapping(value = "/image", method = RequestMethod.GET)
    @ResponseBody
    public ResponseEntity<InputStreamResource> getImage() {
        GridFSDBFile gridFsFile = App.getImageResponse();

        return ResponseEntity.ok()
                .contentLength(gridFsFile.getLength())
                .contentType(MediaType.parseMediaType(gridFsFile.getContentType()))
                .body(new InputStreamResource(gridFsFile.getInputStream()));
    }

I followed this post , Check out . Spring MVC: How to return image in @ResponseBody?