用户注册功能实现；用户表添加email字段

bookshelfplus/src/main/java/plus/bookshelf/Dao/Mapper/CategoryDOMapper.java

@@ -3,7 +3,7 @@ package plus.bookshelf.Dao.Mapper;
 import org.springframework.stereotype.Repository;
 import plus.bookshelf.Dao.DO.CategoryDO;
 
-@Repository
+@Repository // 添加这个注解，Autowired的时候idea就不会报错了
 public interface CategoryDOMapper {
     /**
      * This method was generated by MyBatis Generator.

bookshelfplus/src/main/java/plus/bookshelf/Dao/Mapper/FileDOMapper.java

@@ -3,7 +3,7 @@ package plus.bookshelf.Dao.Mapper;
 import org.springframework.stereotype.Repository;
 import plus.bookshelf.Dao.DO.FileDO;
 
-@Repository
+@Repository // 添加这个注解，Autowired的时候idea就不会报错了
 public interface FileDOMapper {
     /**
      * This method was generated by MyBatis Generator.

bookshelfplus/src/main/java/plus/bookshelf/Dao/Mapper/FileObjectDOMapper.java

@@ -3,7 +3,7 @@ package plus.bookshelf.Dao.Mapper;
 import org.springframework.stereotype.Repository;
 import plus.bookshelf.Dao.DO.FileObjectDO;
 
-@Repository
+@Repository // 添加这个注解，Autowired的时候idea就不会报错了
 public interface FileObjectDOMapper {
     /**
      * This method was generated by MyBatis Generator.

bookshelfplus/src/main/java/plus/bookshelf/Dao/Mapper/ThirdPartyUserAuthDOMapper.java

@@ -1,7 +1,9 @@
 package plus.bookshelf.Dao.Mapper;
 
+import org.springframework.stereotype.Repository;
 import plus.bookshelf.Dao.DO.ThirdPartyUserAuthDO;
 
+@Repository // 添加这个注解，Autowired的时候idea就不会报错了
 public interface ThirdPartyUserAuthDOMapper {
     /**
      * This method was generated by MyBatis Generator.

bookshelfplus/src/main/java/plus/bookshelf/Dao/Mapper/ThirdPartyUserDOMapper.java

@@ -1,7 +1,9 @@
 package plus.bookshelf.Dao.Mapper;
 
+import org.springframework.stereotype.Repository;
 import plus.bookshelf.Dao.DO.ThirdPartyUserDO;
 
+@Repository // 添加这个注解，Autowired的时候idea就不会报错了
 public interface ThirdPartyUserDOMapper {
     /**
      * This method was generated by MyBatis Generator.

bookshelfplus/src/main/java/plus/bookshelf/Dao/Mapper/UserDOMapper.java

@@ -3,7 +3,7 @@ package plus.bookshelf.Dao.Mapper;
 import org.springframework.stereotype.Repository;
 import plus.bookshelf.Dao.DO.UserDO;
 
-@Repository
+@Repository // 添加这个注解，Autowired的时候idea就不会报错了
 public interface UserDOMapper {
     /**
      * This method was generated by MyBatis Generator.
@@ -54,4 +54,12 @@ public interface UserDOMapper {
     int updateByPrimaryKey(UserDO record);
 
     UserDO selectByUsernameAndEncryptpwd(String username, String encryptPwd);
+
+    /**
+     * 获取是否存在该用户，用于注册时判断
+     * 若用户存在则返回大于0的整数，否则返回0
+     * @param username
+     * @return
+     */
+    Integer selectCountByUsername(String username);
 }