mybatis 处理枚举类型
2019-10-16 08:19:55来源:博客园 阅读 ()
mybatis 处理枚举类型
MyBatis支持持久化enum类型属性。假设t_user表中有一列gender(性别)类型为 varchar2(10),存储 MALE 或者 FEMALE 两种值。并且,User对象有一个enum类型的gender 属性,如下所示:
public enum Gender { MALE,FEMALE; }
默认情况下MyBatis使用EnumTypeHandler来处理enum类型的Java属性,并且将其存储为enum值的名称。我们不需要为此做任何额外的配置。可以像使用基本数据类型属性一样使用enum类型属性,如下:
create table t_user( id number primary key, name varchar2(50), gender varchar2(10) );
public class User{ private Integer id; private String name; private Gender gender; //setters and getters }
映射文件:
<insert id="insertUser" parameterType="User"> <selectKey keyProperty="id" resultType="int" order="BEFORE"> select my_seq.nextval from dual </selectKey> insert into t_user(id,name,gender) values(#{id},#{name},#{gender}) </insert>
映射接口:
public interface XxxxMapper{ int insertUser(User user); }
测试方法:
@Test public void test_insertUser(){ SqlSession sqlSession = null; try { sqlSession = MyBatisSqlSessionFactory.openSession(); SpecialMapper mapper = sqlSession.getMapper(SpecialMapper.class); User user = new User("tom",Gender.MALE); mapper.insertUser(user); sqlSession.commit(); } catch (Exception e) { e.printStackTrace(); } }
当执行insertStudent语句的时候MyBatis会取Gender枚举(FEMALE/MALE)的名称,存储到GENDER列中。
如果你想存储FEMALE为0,MALE为1到gender列中,需要在mybatis-config.xml文件中配置专门的类型处理器,并指定它处理的枚举类型是哪个。
<typeHandler handler="org.apache.ibatis.type.EnumOrdinalTypeHandler" javaType="com.briup.special.Gender"/>
EnumOrdinalTypeHandler这是个类型处理器,源码中有个set方法就是在帮助我们存值,源码如下
/** * Copyright 2009-2017 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.ibatis.type; import java.sql.CallableStatement; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; /** * @author Clinton Begin */ public class EnumOrdinalTypeHandler<E extends Enum<E>> extends BaseTypeHandler<E> { private final Class<E> type; private final E[] enums; public EnumOrdinalTypeHandler(Class<E> type) { if (type == null) { throw new IllegalArgumentException("Type argument cannot be null"); } this.type = type; this.enums = type.getEnumConstants(); if (this.enums == null) { throw new IllegalArgumentException(type.getSimpleName() + " does not represent an enum type."); } } @Override public void setNonNullParameter(PreparedStatement ps, int i, E parameter, JdbcType jdbcType) throws SQLException { ps.setInt(i, parameter.ordinal()); } @Override public E getNullableResult(ResultSet rs, String columnName) throws SQLException { int i = rs.getInt(columnName); if (rs.wasNull()) { return null; } else { try { return enums[i]; } catch (Exception ex) { throw new IllegalArgumentException("Cannot convert " + i + " to " + type.getSimpleName() + " by ordinal value.", ex); } } } @Override public E getNullableResult(ResultSet rs, int columnIndex) throws SQLException { int i = rs.getInt(columnIndex); if (rs.wasNull()) { return null; } else { try { return enums[i]; } catch (Exception ex) { throw new IllegalArgumentException("Cannot convert " + i + " to " + type.getSimpleName() + " by ordinal value.", ex); } } } @Override public E getNullableResult(CallableStatement cs, int columnIndex) throws SQLException { int i = cs.getInt(columnIndex); if (cs.wasNull()) { return null; } else { try { return enums[i]; } catch (Exception ex) { throw new IllegalArgumentException("Cannot convert " + i + " to " + type.getSimpleName() + " by ordinal value.", ex); } } } }
枚举类型的【顺序值】是根据enum中的声明顺序赋值的。如果改变了Gender里面对象的声明顺序,则数据库存储的数据和此顺序值就不匹配了。
原文链接:https://www.cnblogs.com/Magic-Li/p/11684218.html
如有疑问请与原作者联系
标签:
版权申明:本站文章部分自网络,如有侵权,请联系:west999com@outlook.com
特别注意:本站所有转载文章言论不代表本站观点,本站所提供的摄影照片,插画,设计作品,如需使用,请与原作者联系,版权归原作者所有
- MyBatis中的$和#,用不好,准备走人! 2020-06-11
- SpringBoot 2.3 整合最新版 ShardingJdbc + Druid + MyBatis 2020-06-11
- 秒懂系列,超详细Java枚举教程!!! 2020-06-08
- Spring Cloud Gateway 全局通用异常处理 2020-06-08
- 聊聊 OAuth 2.0 的 Token 续期处理 2020-06-08
IDC资讯: 主机资讯 注册资讯 托管资讯 vps资讯 网站建设
网站运营: 建站经验 策划盈利 搜索优化 网站推广 免费资源
网络编程: Asp.Net编程 Asp编程 Php编程 Xml编程 Access Mssql Mysql 其它
服务器技术: Web服务器 Ftp服务器 Mail服务器 Dns服务器 安全防护
软件技巧: 其它软件 Word Excel Powerpoint Ghost Vista QQ空间 QQ FlashGet 迅雷
网页制作: FrontPages Dreamweaver Javascript css photoshop fireworks Flash