本文主要讲解在使用mybaties中通过mybaties generator生成基本操作代码，然后通过 mybaties mapper 继承机制来解决某些情况下经常改表导致改mapper文件的苦恼 本文主要讲解在使用mybaties中通过mybaties generator生成基本操作代码，然后通过 mybaties mapper 继承机制来解决某些情况下经常改表导致改mapper文件的苦恼。好了废话少说上代码了首先是 mapper java文件的继承$title(ArticleMapper.java)
public interface ArticleMapper {
int deleteByPrimaryKey(Integer id);
int insert(Article record);
int insertSelective(Article record);
Article selectByPrimaryKey(Integer id);
int updateByPrimaryKeySelective(Article record);
int updateByPrimaryKey(Article record);
}以上mapper文件为mybaties generator生成的代码。$title(ArticleExtMapper.java)
public interface ArticleExtMapper extends ArticleMapper {
Article getLast(@Param("id") Integer id, @Param("type") Integer type);
Article getNext(@Param("id") Integer id, @Param("type") Integer type);
List<Article> getList(@Param("title") String title, @Param("category") String category, @Param("type") Integer type);
} 以上为业务使用中扩展的一些应用查询方法下面上mapper xml文件的使用$title(ArticleMapper.xml)
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="net.ifok.ocms.business.mapper.ArticleMapper">
<resultMap id="BaseResultMap" type="net.ifok.ocms.business.model.Article">
<id column="id" jdbcType="INTEGER" property="id" />
<result column="title" jdbcType="VARCHAR" property="title" />
<result column="image" jdbcType="VARCHAR" property="image" />
<result column="url" jdbcType="VARCHAR" property="url" />
<result column="content" jdbcType="VARCHAR" property="content" />
<result column="content_text" jdbcType="VARCHAR" property="contentText" />
<result column="category" jdbcType="VARCHAR" property="category" />
<result column="type" jdbcType="INTEGER" property="type" />
<result column="create_time" jdbcType="TIMESTAMP" property="createTime" />
<result column="update_time" jdbcType="TIMESTAMP" property="updateTime" />
<result column="keywords" jdbcType="VARCHAR" property="keywords" />
<result column="description" jdbcType="VARCHAR" property="description" />
<result column="customer" jdbcType="VARCHAR" property="customer" />
</resultMap>
<sql id="Base_Column_List">
id, title, image, url, content, content_text, category, type, create_time, update_time,
keywords, description, customer
</sql>
<select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from article
where id = #{id,jdbcType=INTEGER}
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
delete from article
where id = #{id,jdbcType=INTEGER}
</delete>
<insert id="insert" parameterType="net.ifok.ocms.business.model.Article">
insert into article (id, title, image,
url, content, content_text,
category, type, create_time,
update_time, keywords, description,
customer)
values (#{id,jdbcType=INTEGER}, #{title,jdbcType=VARCHAR}, #{image,jdbcType=VARCHAR},
#{url,jdbcType=VARCHAR}, #{content,jdbcType=VARCHAR}, #{contentText,jdbcType=VARCHAR},
#{category,jdbcType=VARCHAR}, #{type,jdbcType=INTEGER}, #{createTime,jdbcType=TIMESTAMP},
#{updateTime,jdbcType=TIMESTAMP}, #{keywords,jdbcType=VARCHAR}, #{description,jdbcType=VARCHAR},
#{customer,jdbcType=VARCHAR})
</insert>
<insert id="insertSelective" parameterType="net.ifok.ocms.business.model.Article">
insert into article
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="id != null">
id,
</if>
<if test="title != null">
title,
</if>
<if test="image != null">
image,
</if>
<if test="url != null">
url,
</if>
<if test="content != null">
content,
</if>
<if test="contentText != null">
content_text,
</if>
<if test="category != null">
category,
</if>
<if test="type != null">
type,
</if>
<if test="createTime != null">
create_time,
</if>
<if test="updateTime != null">
update_time,
</if>
<if test="keywords != null">
keywords,
</if>
<if test="description != null">
description,
</if>
<if test="customer != null">
customer,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="id != null">
#{id,jdbcType=INTEGER},
</if>
<if test="title != null">
#{title,jdbcType=VARCHAR},
</if>
<if test="image != null">
#{image,jdbcType=VARCHAR},
</if>
<if test="url != null">
#{url,jdbcType=VARCHAR},
</if>
<if test="content != null">
#{content,jdbcType=VARCHAR},
</if>
<if test="contentText != null">
#{contentText,jdbcType=VARCHAR},
</if>
<if test="category != null">
#{category,jdbcType=VARCHAR},
</if>
<if test="type != null">
#{type,jdbcType=INTEGER},
</if>
<if test="createTime != null">
#{createTime,jdbcType=TIMESTAMP},
</if>
<if test="updateTime != null">
#{updateTime,jdbcType=TIMESTAMP},
</if>
<if test="keywords != null">
#{keywords,jdbcType=VARCHAR},
</if>
<if test="description != null">
#{description,jdbcType=VARCHAR},
</if>
<if test="customer != null">
#{customer,jdbcType=VARCHAR},
</if>
</trim>
</insert>
<update id="updateByPrimaryKeySelective" parameterType="net.ifok.ocms.business.model.Article">
update article
<set>
<if test="title != null">
title = #{title,jdbcType=VARCHAR},
</if>
<if test="image != null">
image = #{image,jdbcType=VARCHAR},
</if>
<if test="url != null">
url = #{url,jdbcType=VARCHAR},
</if>
<if test="content != null">
content = #{content,jdbcType=VARCHAR},
</if>
<if test="contentText != null">
content_text = #{contentText,jdbcType=VARCHAR},
</if>
<if test="category != null">
category = #{category,jdbcType=VARCHAR},
</if>
<if test="type != null">
type = #{type,jdbcType=INTEGER},
</if>
<if test="createTime != null">
create_time = #{createTime,jdbcType=TIMESTAMP},
</if>
<if test="updateTime != null">
update_time = #{updateTime,jdbcType=TIMESTAMP},
</if>
<if test="keywords != null">
keywords = #{keywords,jdbcType=VARCHAR},
</if>
<if test="description != null">
description = #{description,jdbcType=VARCHAR},
</if>
<if test="customer != null">
customer = #{customer,jdbcType=VARCHAR},
</if>
</set>
where id = #{id,jdbcType=INTEGER}
</update>
<update id="updateByPrimaryKey" parameterType="net.ifok.ocms.business.model.Article">
update article
set title = #{title,jdbcType=VARCHAR},
image = #{image,jdbcType=VARCHAR},
url = #{url,jdbcType=VARCHAR},
content = #{content,jdbcType=VARCHAR},
content_text = #{contentText,jdbcType=VARCHAR},
category = #{category,jdbcType=VARCHAR},
type = #{type,jdbcType=INTEGER},
create_time = #{createTime,jdbcType=TIMESTAMP},
update_time = #{updateTime,jdbcType=TIMESTAMP},
keywords = #{keywords,jdbcType=VARCHAR},
description = #{description,jdbcType=VARCHAR},
customer = #{customer,jdbcType=VARCHAR}
where id = #{id,jdbcType=INTEGER}
</update>
</mapper> 以上为mybaties generator生成的代码。 $title(ArticleExtMapper.xml)
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="net.ifok.ocms.business.mapper.ext.ArticleExtMapper">
<resultMap id="BaseResultMap" type="net.ifok.ocms.business.model.Article" extends="net.ifok.ocms.business.mapper.ArticleMapper.BaseResultMap">
</resultMap>
<select id="getLast" resultMap="BaseResultMap">
select * FROM article where type=${type} and id <![CDATA[ < ]]> #{id} order by id desc limit 1
</select>
<select id="getNext" resultMap="BaseResultMap">
select * FROM article where type=#{type} and id <![CDATA[ > ]]>#{id} order by id asc limit 1
</select>
<select id="getList" resultMap="BaseResultMap">
SELECT * from article where 1=1
and type=#{type}
<if test="title!=null">
and title like CONCAT(CONCAT('%', #{title}), '%')
</if>
<if test="category !=null and category !=''">
and category=#{category}
</if>
order by create_time desc
</select>
</mapper> 以上为扩展查询事项说明：ArticleMapper中有，ArticleExtMapper.xml中没有，ArticleExtMapper沿用ArticleMapper中的定义ArticleMapper中有，ArticleExtMapper.xml中也有，ArticleExtMapper使用ArticleExtMapper.xml中的定义ArticleMapper中没有，ArticleExtMapper.xml中有，ArticleExtMapper使用ArticleExtMapper.xml中的定义 ResultMap覆盖Mapper.xml继承机制只针对statement有效，对于sql、resultMap是无效的。如果要在ArticleExtMapper.xml中覆盖这些，必须要先覆盖ParentMapper.xml中的statement，然后让这些statement使用新的sql、resultMap等。总结通过上面的将扩展的部分分开来写，后续改表，生成部分的代码直接覆盖即可，不担心扩展的不见了，二使用的时候直接使用扩展的mapper即可，扩展的mapper包含所有的方法。over ,Enjoy