CODEWITHSUNDEEP
springspring-mvc
linghu
linghu

Reputation: 133

discussion about @RequestParam and @RequestBody

I have a class:

public class user{
    private String id;

    private MultiPartFile file;
    **Getters And Setters**
}

And in the Controller:

@PostMapping(value="/upload)
public void upload(User user){
}

In the front end I post data with form-data.I can get the user object. But when I add @RequestBody and @RequestParam,it can't works.

in my opinion，@RequestParam is used to binding parameter to simple class . when I use @RequestBody ,spring will find HttpMessageConverter to convert http request body to class.But I'm not sure about that.Does anyone can explain to me?

Upvotes: 0

Views: 415

Answers (1)

rapasoft
rapasoft

Reputation: 961

So, I believe we are talking about org.springframework.web.multipart.MultipartFile, which is to be used together with @RequestParam variable. The mechanism is somewhat special in this case.

I had a similar problem, and what I ended up using was org.springframework.web.multipart.commons.CommonsMultipartResolver. From frontend I've constructed multipart request with two parts, in your scenario it could be user (containing just JSON data) and file (containing the file itself), e.g.:

@PostMapping(value="/upload")
public void upload(@RequestParam("user") User user, @RequestParam("file") MultipartFile file){
    ...
}

But then, you need to configure custom serialization of the User part, which can be done using org.springframework.web.multipart.commons.CommonsMultipartResolver. You can configure it using bean config like this:

@Configuration
public class MappingConfig {

    @Order(Integer.MIN_VALUE)
    @Bean(name = "multipartResolver")
    public CommonsMultipartResolver multipartResolver() {
        return new CommonsMultipartResolver();
    }

    @Bean
    public Converter<String, User> stringToUser() {
        return new Converter<String, User>() {
            @Override
            public User convert(String jsonString) {
                return new Gson().fromJson(jsonString, User.class);
            }
        };
    }
...
}

Also, as you can see I am using Gson manually, I couldn't find a better way how to do it. Also, it doesn't play with Java 8 lambdas, so it cannot be shortened (because of explicit types are needed for it to work).

I hope that this will at least points you to a right path.

Upvotes: 1

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