spring-boot-style-guide's Introduction

Spring Boot Style Guide

A mostly reasonable approach to Spring Boot.

Dependency Injection

Never use field injection or setter injection. Use constructor injection instead.

Why? See Why field injection is evil for an in-depth discussion.

// really bad
@AutoWired
private PersonRepository personRepositoy;

// still bad
private PersonRepository personRespository;

@Autowired
public void setPersonRepository(PersonRepository personRepository) {
    this.personRepository = personRepository;
}

// good
private final PersonRepository personRepository;

public PersonService(PersonRepository personRepository) {
    this.personRepository = personRepository;
}

Controllers

Request Mapping

Use @GetMapping, @PostMapping etc. instead of @RequestMapping.

Why? They are easier to read and force you to declare the request method.

// bad
@RequestMapping(method = RequestMethod.GET, value = "/person/{id}")
public Person show(@PathVariable long id) {
}

// good
@GetMapping("/person/{id}")
public Person show(@PathVariable long id) {
}

Serialization

// good
public class Person {
    private final String firstname;
    private final String lastname;

    @JsonCreator
    public Person(String firstname, String lastname) {
        this.firstname = firstname;
        this.lastname = lastname;
    }

    public String getFirstname() {
        return firstname;
    }

    public String getLastname() {
        return lastname;
    }
}

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