Steps#

1. Create AccessingDataMysqlApplication.java

   package com.example.accessingdatamysql;
   @SpringBootApplication
   public class AccessingDataMysqlApplication {
       public static void main(String[] args) {
           SpringApplication.run(AccessingDataMysqlApplication.class, args);
       }
   }
   

2. Modify MainController.java about API linker

   package com.example.accessingdatamysql;
   
   @Controller
   @RequestMapping(path="/demo")
   @CrossOrigin(origins = "*")
   public class MainController {
       @Autowired
       private UserRepository userRepository;
       private static final Logger logger = LoggerFactory.getLogger(MainController.class);
   
       @PostMapping(path="/login")
       public @ResponseBody String login(@RequestBody User loginRequest) {
           String email = loginRequest.getEmail();
           String password = loginRequest.getPassword();
           User user = userRepository.findByEmail(email);
           if (user != null && user.getPassword().equals(password)) {
               logger.info("API '/login' Success");
               return "Login successful!";
           } else {
               logger.info("API '/login' Fail");
               return "Login failed. Invalid email or password.";
           }
       }
   }
   

3. Create UserRepository.java

   package com.example.accessingdatamysql;
   public interface UserRepository extends CrudRepository<User, Integer> {
       User findByEmail(String email);
   }
   

4. Create User.java for user interface

   package com.example.accessingdatamysql;
   @Entity
   public class User {
       @Id
       @GeneratedValue(strategy=GenerationType.AUTO)
       private String email;
       private String password;
       public String getEmail() {
           return email;
       }
       public void setEmail(String email) {
           this.email = email;
       }
       public String getPassword() {
           return password;
       }
       public void setPassword(String password) {
           this.password = password;
       }
   }
   

Then API can create in the backend and we can post the login API!#