Spring @ControllerAdvice Annotation Example

In this section we will learn about @ControllerAdvice Annotation. 


The @ControllerAdvice is a specialization of the @Component annotation which sanctions to handle exceptions across the whole application in one global handling component. It can be viewed as an interceptor of exceptions thrown by methods annotated with @RequestMapping and kindred. 

It declares @ExceptionHandler, @InitBinder, or @ModelAttribute methods to be shared across multiple @Controller classes.

ResponseEntityExceptionHandler is a convenient base class for @ControllerAdvice classes that wish to provide centralized exception handling across all @RequestMapping methods through @ExceptionHandler methods. It provides an methods for handling internal Spring MVC exceptions. It returns a ResponseEntity in contrast to DefaultHandlerExceptionResolver which returns a ModelAndView.

The following example creates a Spring Boot web application which uses @ControllerAdvice. 

Project Directory


Pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
   https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>3.0.1</version>
      <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.knf.dev.demo</groupId>
   <artifactId>spring-controlleradvice-example</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <name>spring-controlleradvice-example</name>
   <description>Demo project for Spring Boot</description>
   <properties>
      <java.version>17</java.version>
   </properties>
   <dependencies>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-data-jpa</artifactId>
      </dependency>
      <dependency>
         <groupId>com.h2database</groupId>
         <artifactId>h2</artifactId>
         <scope>runtime</scope>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
      </dependency>
   </dependencies>

   <build>
      <plugins>
         <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
      </plugins>
   </build>

</project>


Create User Entity - User.java

package com.knf.dev.demo.entity;

import jakarta.persistence.*;

@Entity
@Table(name = "userTable")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    @Column(name = "first_name")
    private String firstName;
    @Column(name = "last_name")
    private String lastName;
    @Column(name = "email_id")
    private String emailId;

    public User() {
    }

    public User(String firstName, String lastName, String emailId) {
        super();
        this.firstName = firstName;
        this.lastName = lastName;
        this.emailId = emailId;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmailId() {
        return emailId;
    }

    public void setEmailId(String emailId) {
        this.emailId = emailId;
    }
}


UserRepository.java

package com.knf.dev.demo.repository;

import com.knf.dev.demo.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository extends JpaRepository<User, Long> {

}


CustomErrorResponse.java

package com.knf.dev.demo.exception;

import com.fasterxml.jackson.annotation.JsonFormat;
import java.time.LocalDateTime;

public class CustomErrorResponse {

    @JsonFormat(shape = JsonFormat.Shape.STRING,
            pattern = "yyyy-MM-dd hh:mm:ss")
    private LocalDateTime timestamp;
    private int status;
    private String error;
    public LocalDateTime getTimestamp() {
        return timestamp;
    }
    public void setTimestamp(LocalDateTime timestamp) {
        this.timestamp = timestamp;
    }
    public int getStatus() {
        return status;
    }
    public void setStatus(int status) {
        this.status = status;
    }
    public String getError() {
        return error;
    }
    public void setError(String error) {
        this.error = error;
    }
}


UserNotFoundException.java

package com.knf.dev.demo.exception;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;

public class UserNotFoundException extends RuntimeException{

   private static final long serialVersionUID = 1L;
   
   public UserNotFoundException(String message) {
      super(message);
   }
}


GlobalExceptionHandler.java

package com.knf.dev.demo.exception;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.context.request.WebRequest;
import java.time.LocalDateTime;

@ControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(UserNotFoundException.class)
    public ResponseEntity<CustomErrorResponse> userNotFound
                   (Exception ex, WebRequest request) {
        CustomErrorResponse errors = new CustomErrorResponse();
        errors.setTimestamp(LocalDateTime.now());
        errors.setError(ex.getMessage());
        errors.setStatus(HttpStatus.NOT_FOUND.value());
        return new ResponseEntity<>(errors, HttpStatus.NOT_FOUND);
    }
}


UserController.java

package com.knf.dev.demo.controller;

import com.knf.dev.demo.entity.User;
import com.knf.dev.demo.exception.UserNotFoundException;
import com.knf.dev.demo.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/v1")
public class UserController {

    @Autowired
    private UserRepository userRepository;
    // create user rest API
    @PostMapping("/users")
    public User createUser(@RequestBody User user) {
        return userRepository.save(user);
    }

    // get user by id rest api
    @GetMapping("/users/{id}")
    public ResponseEntity<User> getUserById(@PathVariable Long id) {
        User user = userRepository.findById(id)
                .orElseThrow(() -> new UserNotFoundException
                        ("User does not exist with id :" + id));
        return ResponseEntity.ok(user);
    }
}


Run Application - Application.java

Application is the entry point that sets up the Spring Boot application. The @SpringBootApplication annotation enables auto-configuration and component scanning.
Let's run this Spring boot application from either IntelliJ IDEA IDE by right click - Run 'Application.main()'
Or you can use the below maven command to run:

mvn spring-boot:run


Create User

New User is created, and id is 1.

Try to get User by id 2, you will get "User does not exist with id :2" message.

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