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298 changes: 298 additions & 0 deletions week03/hyunji/README.md
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## 3주차 - 회원 관리 예제(웹 MVC 개발)

### **[홈화면]**
<pre>
<code>
<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<body>
<div class="container">
<div>
<h1>Hello Spring</h1> <p>회원 기능</p>
<p>
<a href="/members/new">회원 가입</a>
<a href="/members">회원 목록</a>
</p>
</div>
</div> <!-- /container -->
</body>
</html>
</code>
</pre>
### : 회원 가입과 회원 목록 중 선택해 해당하는 창으로 넘어감

* * *

### **[등록]**
<pre>
<code>
@Controller
public class MemberController {

private MemberService memberService;

@Autowired
public MemberController(MemberService memberService) {
this.memberService = memberService;
}

@GetMapping(value = "/members/new")
public String createForm() {
return "members/createMemberForm";
}
}
</code>
</pre>
### : 기존에 작성해둔 MemberController에 @GetMapping 추가해 createMemberForm 반환

->
<pre>
<code>
<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<body>
<div class="container">
<form action="/members/new" method="post">
<div class="form-group">
<label for="name">이름</label>
<input type="text" id="name" name="name" placeholder="이름을 입력하세요">
</div>
<button type="submit">등록</button> </form>
</div> <!-- /container -->
</body>
</html>
</code>
</pre>
### : input 박스에 이름을 입력해 등록 버튼을 누르면 등록

<pre>
<code>
@PostMapping(value = "/members/new")
public String create(MemberForm form) {
Member member = new Member();
member.setName(form.getName());
memberService.join(member);
return "redirect:/";
}
</code>
</pre>
### : 회원 컨트롤러에서 회원을 실제로 등록하는 역할
### @PostMapping : 데이터를 폼에 넣어서 전달할 때 사용
- 데이터를 등록할 때 -> PostMapping
- 조회할 때 -> GetMapping

* * *

### **[조회]**
<pre>
<code>
@GetMapping(value = "/members")
public String list(Model model) {
List<Member> members = memberService.findMembers();
model.addAttribute("members", members);
return "members/memberList";
}
</code>
</pre>
### : 등록된 모든 멤버를 꺼내서 리스트에 저장하고 그 리스트를 모델에 담아서 넘김

->
<pre>
<code>
<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<body>
<div class="container">
<div>
<table>
<thead>
<tr>
<th>#</th>
<th>이름</th> </tr>
</thead>
<tbody>
<tr th:each="member : ${members}">
<td th:text="${member.id}"></td>
<td th:text="${member.name}"></td>
</tr>
</tbody>
</table>
</div>
</div> <!-- /container -->
</body>
</code>
</pre>
### : 루프가 돌면서 객체를 하나씩 꺼내 멤버에 담고 아이디와 이름 출력

## 3주차 - 스프링 DB 접근 기술

<pre>
<code>
import hello.hello_spring.repository.JdbcMemberRepository;
import hello.hello_spring.repository.MemberRepository;
import hello.hello_spring.repository.MemoryMemberRepository;
import hello.hello_spring.service.MemberService;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class SpringConfig {

private final DataSource dataSource;
public SpringConfig(DataSource dataSource) {
this.dataSource = dataSource;
}

@Bean
public MemberService memberService() {
return new MemberService(memberRepository());
}

@Bean
public MemberRepository memberRepository() {
// return new MemoryMemberRepository();
return new JdbcMemberRepository(dataSource);
}
}
</code>
</pre>
### : 기존 메모리 버전의 멤버 리포지토리를 빼고 jdbc 버전의 멤버 리토지토리를 등록하면 구현체만 바꿔줌
### 개방-폐쇄 원칙(OCP, Open-Closed Principle) : 확장에는 열려있고, 수정, 변경에는 닫혀있다
### 스프링의 DI(Dependencies Injection)를 사용하면 기존 코드에 손대지 않고, 설정 수정만으로 구현 클래스 변경 가능

<pre>
<code>
@SpringBootTest
@Transactional
class MemberServiceIntegrationTest {

@Autowired MemberService memberService;
@Autowired MemberRepository memberRepository;

@Test
public void 회원가입() throws Exception {
//Given
Member member = new Member();
member.setName("hello");
//When
Long saveId = memberService.join(member);
//Then
Member findMember = memberRepository.findById(saveId).get();
assertEquals(member.getName(), findMember.getName());
}

@Test
public void 중복_회원_예외() throws Exception {
//Given
Member member1 = new Member();
member1.setName("spring");

Member member2 = new Member();
member2.setName("spring");
//When
memberService.join(member1);
IllegalStateException e = assertThrows(IllegalStateException.class,
() -> memberService.join(member2)); //예외가 발생해야 한다.

assertThat(e.getMessage()).isEqualTo("이미 존재하는 회원입니다.");
}
}
</code>
</pre>
### **@SpringBootTest** : 스프링 컨테이너와 테스트를 함께 실행
### **@Transactional** : 테스트 시작 전에 트랜잭션을 시작하고, 테스트 완료 후에 항상 롤백. DB에 데이터가 남지 않아 다음 테스트에 영향 X

### **[Jdbc]**
<pre>
<code>
import hello.hello_spring.domain.Member;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
import org.springframework.jdbc.core.simple.SimpleJdbcInsert;
import javax.sql.DataSource;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;

public class JdbcTemplateMemberRepository implements MemberRepository {

private final JdbcTemplate jdbcTemplate;

public JdbcTemplateMemberRepository(DataSource dataSource) {
jdbcTemplate = new JdbcTemplate(dataSource);
}

@Override
public Member save(Member member) {
SimpleJdbcInsert jdbcInsert = new SimpleJdbcInsert(jdbcTemplate);
jdbcInsert.withTableName("member").usingGeneratedKeyColumns("id");

Map<String, Object> parameters = new HashMap<>();
parameters.put("name", member.getName());

Number key = jdbcInsert.executeAndReturnKey(new MapSqlParameterSource(parameters));
member.setId(key.longValue());
return member;
}

@Override
public Optional<Member> findById(Long id) {
List<Member> result = jdbcTemplate.query("select * from member where id = ?", memberRowMapper(), id);
return result.stream().findAny();
}

@Override
public List<Member> findAll() {
return jdbcTemplate.query("select * from member", memberRowMapper());
}

@Override
public Optional<Member> findByName(String name) {
List<Member> result = jdbcTemplate.query("select * from member where name = ?", memberRowMapper(), name);
return result.stream().findAny();
}

private RowMapper<Member> memberRowMapper() {
return (rs, rowNum) -> {
Member member = new Member();
member.setId(rs.getLong("id"));
member.setName(rs.getString("name"));
return member;
};
}
}
</code>
</pre>

<pre>
<code>
@Bean
public MemberRepository memberRepository() {
return new JdbcTemplateMemberRepository(dataSource);
}
</code>
</pre>
### : Jdbc를 Jdbc 템플릿으로 변경
- Jdbc와 동일한 환경설정
- JDBC API에서 본 반복 코드를 대부분 제거
- SQL 직접 작성

### **[JPA]**
- 반복 코드와 SQL 모두 JPA가 직접 만들어 실행
- SQL과 데이터 중심의 설계에서 객체 중심의 설계로 패러다임을 전환 가능

### **[스프링 데이터 JPA]**
- 스프링 부트와 JPA만으로도 개발 생산성 증가
- 스프링 데이터 JPA를 사용하면 리포지토리에 구현 클래스 없이 인터페이스 만으로 개발 가능
- 반복 개발해온 기본 CRUD 기능도 스프링 데이터 JPA가 모두 제공
- 단순하고 반복적 개발 코드들이 줄어들어 개발자가 핵심 비즈니스 로직을 개발하는데 집중할 수 있음
- 제공 기능
- 인터페이스를 통한 기본적인 CRUD
- 메서드 이름 만으로 조회 기능 제공 (findByName(),findByEmail() 등)
- 페이징 기능 자동 제공