Spring MVC中x-www-form-urlencoded请求绑定嵌套请求参数

Hey there! I’ve run into this exact issue before, so let me break down how to get your nested parameter binding working smoothly.

First, Fix the Request Parameter Format #

Since you’re using x-www-form-urlencoded (not JSON), you can’t send a nested JSON structure directly. Instead, you need to represent nested properties using dot notation or bracket notation in your form parameters. Here’s what your request should look like:

Using Dot Notation (Recommended)

username=aaa&password=bbb&detail.gender=ccc&detail.location=ddd

Using Bracket Notation (Also Works)

username=aaa&password=bbb&detail[gender]=ccc&detail[location]=ddd

Spring MVC will automatically map these parameters to the nested Detail object inside your User class.

Critical Fix: Make the Detail Class Static #

Looking at your User class, the inner Detail class is not marked as static—this is a common pitfall! Non-static inner classes require an instance of the outer User class to be created, which Spring can’t do automatically during parameter binding.

Update your User class to make Detail a static inner class:

@ToString @NoArgsConstructor @Data
public class User {
    private String username;
    private String password;
    private Detail detail;
    
    // Add the static keyword here!
    @Data @NoArgsConstructor
    public static class Detail {
        private String gender;
        private String location;
    }
}

Your Controller Method is Already Correct #

You don’t need to change anything in your test method. Spring MVC will handle the binding automatically once the request format and entity class are fixed:

@RequestMapping(value = "/test")
public String test(User user) {
    return user.toString();
}

Test It Out #

You can test this with a tool like curl or Postman. Here’s an example curl command:

curl -X POST -d "username=aaa&password=bbb&detail.gender=ccc&detail.location=ddd" http://localhost:8080/test

You should get a string representation of the User object with all nested Detail properties correctly populated.

内容的提问来源于stack exchange，提问作者dailybird