[#109] Refactor: Custom Exception 구조 생성

 - 최상위 CustomException인 BusinessException을 생성하고 그 하위 Exception으로 구조를 변경하였습니다.
 - User 생성시 validation에 실패하면 발생하는 Exception을 생성하였습니다.

BE/src/main/java/com/codesquad/team1/signup/api/ApiUserController.java

@@ -1,6 +1,7 @@
 package com.codesquad.team1.signup.api;
 
 import com.codesquad.team1.signup.common.constants.ErrorMessages;
+import com.codesquad.team1.signup.common.exception.UserCreateParameterInvalidException;
 import com.codesquad.team1.signup.common.response.ErrorResponse;
 import com.codesquad.team1.signup.common.exception.ForbiddenException;
 import com.codesquad.team1.signup.common.exception.UnauthorizedException;
@@ -59,7 +60,7 @@ public User createUser(@RequestBody User user) {
         if (user.validate()) {
             return userRepository.save(user);
         }
-        throw new InvalidParameterException(ErrorMessages.INVALID_PARAMETER);
+        throw new UserCreateParameterInvalidException(ErrorMessages.USER_CREATE_PARAMETER_INVALID);
     }
 
     @PostMapping("/login")

BE/src/main/java/com/codesquad/team1/signup/common/constants/ErrorMessages.java

@@ -4,7 +4,7 @@ public class ErrorMessages {
 
     public static final String FORBIDDEN = "접근 권한이 없습니다.";
     public static final String UNAUTHORIZED = "로그인이 필요합니다.";
-    public static final String INVALID_PARAMETER = "Validation을 통과하지 못한 값 입니다.";
+    public static final String USER_CREATE_PARAMETER_INVALID = "Validation을 통과하지 못한 값 입니다.";
 
     private ErrorMessages() {}
 }

BE/src/main/java/com/codesquad/team1/signup/common/exception/BusinessException.java

@@ -0,0 +1,9 @@
+package com.codesquad.team1.signup.common.exception;
+
+public class BusinessException extends RuntimeException {
+
+    public BusinessException(String message) {
+        super(message);
+    }
+
+}

BE/src/main/java/com/codesquad/team1/signup/common/exception/ForbiddenException.java

@@ -1,8 +1,9 @@
 package com.codesquad.team1.signup.common.exception;
 
-public class ForbiddenException extends RuntimeException {
+public class ForbiddenException extends BusinessException {
 
     public ForbiddenException(String message) {
         super(message);
     }
+
 }

BE/src/main/java/com/codesquad/team1/signup/common/exception/UnauthorizedException.java

@@ -1,8 +1,9 @@
 package com.codesquad.team1.signup.common.exception;
 
-public class UnauthorizedException extends RuntimeException {
+public class UnauthorizedException extends BusinessException {
 
     public UnauthorizedException(String message) {
         super(message);
     }
+
 }

BE/src/main/java/com/codesquad/team1/signup/common/exception/UserCreateParameterInvalidException.java

@@ -0,0 +1,9 @@
+package com.codesquad.team1.signup.common.exception;
+
+public class UserCreateParameterInvalidException extends BusinessException {
+
+    public UserCreateParameterInvalidException(String message) {
+        super(message);
+    }
+
+}

BE/src/main/java/com/codesquad/team1/signup/domain/user/User.java

@@ -5,6 +5,7 @@
 import org.springframework.data.relational.core.mapping.MappedCollection;
 import org.springframework.data.relational.core.mapping.Table;
 
+import java.io.Serializable;
 import java.time.LocalDate;
 import java.util.List;
 import java.util.Objects;
@@ -16,7 +17,7 @@
 import static com.codesquad.team1.signup.common.constants.ValidationConstants.USER_PHONE_NUMBER_VALIDATION_PATTERN;
 
 @Table("USERS")
-public class User {
+public class User implements Serializable {
 
     enum Gender {
         FEMALE,