如何防止控制器方法在Chrome浏览器的Spring Boot中运行两次？

Question

I am using spring boot with postgresql to save row in table and print table rows. My problem is that all the WebController methods are being executed twice but only when I open the url in chrome. If I do this in internet explorer, it works fine. How can I stop this in chrome?

I am putting the code of four files for the reference although I don't think anything's wrong in the code. Do I need to change browser settings or something?

User.java

@Entity
@Table(name="users")
public class User implements Serializable{

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @Column(name="name")
    private String name;

    @Column(name="email")
    private String email;

    public User(String name, String email) {
        this.name = name;
        this.email = email;
    }

    @Override
    public String toString() {
        return String.format("User[id=%d, name='%s', email='%s']",this.id,this.name,this.email);
    }
}

UserRepository.java

public interface UserRepository extends JpaRepository<User, Long>{

}

WebController.java

@RestController 
public class WebController {

    @Autowired
    private UserRepository repository;

    @GetMapping("home")
    public String home() {
        System.out.println("whaaat");
        return "hi";
    }

    @GetMapping("/save")
    public String process() {

        repository.save(new User("vidhi","vd@gmail.com"));
        System.out.print("apple ");
        return "Done";
    }

    @RequestMapping("findall")
    public String findAll() {
        String result = "";

        for(User u: repository.findAll()) {
            result += u.toString() + "<br>";
        }

        return result;
    }

}

application.properties

spring.datasource.url=jdbc:postgresql://localhost:5432/test
spring.datasource.username=postgres
spring.datasource.password= 
spring.jpa.generate-ddl=true
spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults = false

I got to know that the methods are running twice because of double addition of rows in the table and "whaaat" is printed twice in console but only when in chrome. Any help would be wonderful.

Thanks for your time.

Answer 1

First. Try "Network" tab in Chrome Developer Tools (try F12 button) to identify how many requests are actually sent.

Second. It's generally not a good idea to save any data at "GET" request, because of it's semantic, browser doesn't expect changes on server side and can invoke request multiple times (can't produce a use case for that, but it's totally not forbiden for browser to do that) or get it from cache.