회원가입 - 아이디 중복확인, Mapper Service

아이디 중복확인을 확인하기 위해서는 아이디를 DB에서 검색해야 하므로

UserMapper.java

public interface UserMapper {

 @Select("select user_name " + "from user_table "+ "where user_id = #{user_id}")
 String checkUserIdExist(String user_id);
}

ServletAppContext.java

@Bean
public MapperFactoryBean<UserMapper> getUserMapper(SqlSessionFactory factory) throws Exception{
			MapperFactoryBean<UserMapper> factoryBean = new MapperFactoryBean<UserMapper>(UserMapper.class);
			factoryBean.setSqlSessionFactory(factory);
			return factoryBean;
		}

UserService.java

@Service
public class UserService {
 
	@Autowired
	private UserMapper userMapper;	
}

UserService.java

@Service
public class UserService {
 
	@Autowired
	private UserMapper userMapper;
	
	public boolean checkuserIdExist(String user_id) {
		String user_name = userMapper.checkUserIdExist(user_id);
		
		if(user_name == null) {
			return true;
		}else {
			return false;
		}
	}
}

RestApiController.java

@RestController
public class RestApiController {

	@Autowired
	private UserService userService;
	
	@GetMapping("/user/check/{user_id}")
	public String checkUserIdExist(@PathVariable String user_id) {
		//유저 아이디가 없으면 true 있으면 false
		boolean check = userService.checkuserIdExist(user_id);
		return check + "";
	}
}

join.jsp

<div class="form-group">
                  <form:label path="user_id">아이디</form:label>
                  <div class="input-group">
                    <form:input path="user_id" class="form-control" />
                    <div class="input-group-append">
                     <button onclick="checkUserIdExist()" type="button" class="btn btn-primary">중복확인</button>
                    </div>
                  </div>
                  <form:errors path="user_id" style="color:coral"/>
 </div>
                
<div class="form-group" id="idCheck">
                <form:hidden path="userIdChecked"/>
                <form:errors path="userIdChecked" style="color:coral"/>

</div>
                
                
  <!--생략 ... -->
  
<script type="text/javascript" >

function checkUserIdExist(){
	
	const user_id = $("#user_id").val()
	
	if(user_id.length == 0){
		alert("아이디를 입력해주세요.")
		return 
	}
	
	$.ajax({
		url : '${root}user/check' + user_id,
		type: 'get',
			dataType : 'text',
			success : function(result){
				if(result.trim() == 'true'){
					alert('사용할 수 있는 아이디입니다')
					$("#userIdChecked").val('true')
					$("#joinUserBean #idCheck span").text('')
				} else {
					alert('사용할 수 없는 아이디 입니다')
					$("#userIdChecked").val('false')
				}
			}
	   })
	}

	function resetUserIdExist() {
		$("#userIdChecked").val('false')
	}
</script>