Hackforge Academy

Category: React • Beginner

Published on 11 Apr 2026

Explanation

@RequestBody is used in Spring Boot to map the HTTP request body (usually JSON data) to a Java object automatically. It is commonly used in POST and PUT APIs when the client sends structured data.

Code Example

@PostMapping("/user")
public String createUser(@RequestBody 
User user) {
    return "User received: " + 
user.getName();
}

Explanation

Spring Boot automatically converts incoming JSON into a Java object using Jackson library when @RequestBody is applied to a method parameter.

Code Example

public class User {
    private String name;
    private int age;

    public String getName() { return name; }
    public void setName(String name) { 
this.name = name; }

    public int getAge() { return age; }
    public void setAge(int age) { 
this.age = age; }
}

Explanation

Example JSON request sent from client that will be mapped to the User object using @RequestBody.

Code Example

{
  "name": "Praveen",
  "age": 25
}

Explanation

@RequestBody is mainly used when data is sent in the request body instead of URL parameters. It helps build REST APIs that accept JSON input from frontend apps like React or Angular. 🚀

Code Example

@PutMapping("/updateUser")
public String updateUser(
@RequestBody User user)
 {
    return "Updated user: " + 
user.getName();
}

Explanation

You can also validate request data using @Valid with @RequestBody to ensure input correctness before processing.

Code Example

@PostMapping("/save")
public String saveUser(@Valid @RequestBody 
User user) {
    return "User saved successfully";
}