CODEWITHSUNDEEP
javajsonspring-boot
Nilendu Kumar
Nilendu Kumar

Reputation: 83

How to download response as a JSON file created from Java Object

I am writing a code in Spring Boot where i want to download response as a .json file(Json file) which should not be created in any of my project directory but it should be created on the fly from java Object

@RequestMapping(value = "/", method = RequestMethod.GET,produces = "application/json")
public ResponseEntity<InputStreamResource> downloadPDFFile()
        throws IOException {


    User user = new User();

    user.setName("Nilendu");
    user.setDesignation("Software Engineer");
    createJsonFile(user);

    ClassPathResource jsonFile = new ClassPathResource("a.json");

    HttpHeaders headers = new HttpHeaders();
    headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
    headers.add("Pragma", "no-cache");
    headers.add("Expires", "0");

    return ResponseEntity
            .ok()
            .contentLength(jsonFile.contentLength())
            .contentType(
                    MediaType.parseMediaType("application/octet-stream"))
            .body(new InputStreamResource(jsonFile.getInputStream()));
}

void createJsonFile(User user) {

    ObjectMapper mapper = new ObjectMapper();   
    try {

        // Convert object to JSON string and save into a file directly
        File file = new File("src/main/resources/a.json");
        System.out.println(file.exists()+" ++++");
        mapper.writeValue(file, user);
        System.out.println("File Created");
    } catch (JsonGenerationException e) {
        e.printStackTrace();
    } catch (JsonMappingException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }


}

}

I am able to do this with above code but every time i make request it creates a new file a.json in src/main/resource directory Which i don't want . i don't want to create this file in any directoy but still i should be able to download the file

Upvotes: 6

Views: 13913

Answers (2)

TedTrippin
TedTrippin

Reputation: 3662

Then don't write it to a file!

byte[] buf = mapper.writeValueAsBytes(user);

return ResponseEntity
        .ok()
        .contentLength(buf.length)
        .contentType(
                MediaType.parseMediaType("application/octet-stream"))
        .body(new InputStreamResource(new ByteArrayInputStream(buf)));

EDIT

To prompt browser for .json file type add a header

.header("Content-Disposition", "attachment; filename=\"any_name.json\"")

Upvotes: 6

aksss
aksss

Reputation: 333

you dont need to create a file, just convert the object to json using Gson,

Gson gson = new Gson ();
String jsonString = gson.toJson (user);

Upvotes: -1

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