Spring Boot系列(十) 持久层框架--Mybatis

在Spring Boot中集成MyBatis，可以选用基于注解的方式，也可以选择xml文件配置的方式。在这里使用基于注解的方式进行集成。

1. 引入mybatis-spring-boot-starter

<dependency>    <groupId>org.mybatis.spring.boot</groupId>    <artifactId>mybatis-spring-boot-starter</artifactId>    <version>1.1.1</version></dependency>

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2. 创建Mapper.java文件及mapper.xml文件
自动扫描Mapper.java文件的方式有两种：
1）再Spring Boot的启动类上增加@MapperScan注解
2）在每个Mapper.java接口类中上增加@Mapper注解
使用第一种方法，需要指定包路径，例如：@MapperScan(“com.ft.turorial.spring.boot.mapper”)，但是有个缺点，它不支持@MapperScan(“com.ft...mapper.*”)这种方式，所以推荐第二种方式。
UserMapper.java

/** * Mapper接口的sql语句可以通过在方法上增加注解，也可以将sql语句配置在 mapper.xml文件中 *  * Mapper接口的扫描，可以在接口类上增加@Mapper，也可以在启动类上增加@MapperScan * @author ft * */@Mapperpublic interface UserMapper {    User insertSelective(User user);    User insert(User user);    @Select("select * from user where id= #{id,jdbcType=INTEGER} ")    User findOne(int id);    List<User> findAll();    User findLikeName(String name);    int deleteByPrimaryKey(int id);    int updateByPrimaryKeySelective(User user);    int updateByPrimaryKey(User user);}

userMapper.xml(在resource目录下建立\MATA-INF\mybatis\mappers文件夹来存放，可以自定义)

<?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="com.ft.turorial.spring.boot.mapper.UserMapper" >  <cache />  <resultMap id="User" type="com.ft.turorial.spring.boot.domain.User" >    <id column="id" property="id" jdbcType="INTEGER" />    <result column="name" property="name" jdbcType="VARCHAR" />    <result column="birthday" property="birthday" jdbcType="DATE" />  </resultMap>  <sql id="Base_Column_List" >    id, name, birthday  </sql>  <!-- <select id="findOne" resultMap="User" parameterType="java.lang.Integer">    select     <include refid="Base_Column_List" />    from user    where id = #{id,jdbcType=INTEGER}  </select> -->  <select id="findAll" resultMap="User" resultType="list">    select     <include refid="Base_Column_List" />    from user  </select>  <select id="findLikeName" resultMap="User" parameterType="string" resultType="list">    select     <include refid="Base_Column_List" />    from user    where name like concat('%',#{name,jdbcType=VARCHAR},'%')  </select>  <insert id="insert" parameterType="com.ft.turorial.spring.boot.domain.User" useGeneratedKeys="true" keyProperty="id">    insert into user (id, name, birthday)    values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{birthday,jdbcType=DATE})  </insert>  <insert id="insertSelective" parameterType="com.ft.turorial.spring.boot.domain.User" useGeneratedKeys="true" keyProperty="id">    insert into user    <trim prefix="(" suffix=")" suffixOverrides="," >      <if test="id != null" >        id,      </if>      <if test="name != null" >        name,      </if>      <if test="birthday != null" >        birthday,      </if>    </trim>    <trim prefix="values (" suffix=")" suffixOverrides="," >      <if test="id != null" >        #{id,jdbcType=INTEGER},      </if>      <if test="name != null" >        #{name,jdbcType=VARCHAR},      </if>      <if test="birthday != null" >        #{birthday,jdbcType=DATE},      </if>    </trim>  </insert>  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >    delete from user    where ID = #{id,jdbcType=INTEGER}  </delete>  <update id="updateByPrimaryKeySelective" parameterType="User" >    update user    <set >      <if test="name != null" >        name = #{name,jdbcType=VARCHAR},      </if>      <if test="birthday != null" >        birthday = #{birthday,jdbcType=DATE},      </if>    </set>    where ID = #{id,jdbcType=INTEGER}  </update>  <update id="updateByPrimaryKey" parameterType="com.ft.turorial.spring.boot.domain.User" >    update user    set name = #{name,jdbcType=VARCHAR},        birthday = #{birthday,jdbcType=DATE}    where id = #{id,jdbcType=INTEGER}  </update></mapper>

从上面代码可以看出，mapper.xml可以仅仅作为字段映射来用，sql语句可以通过Mybatis的注解(@Select，@Insert、@Delete、@Update)写在Mapper.java接口中。

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3. 指定映射文件(xml)的位置及自动扫描实体包名

在application.properties中配置如下信息：

# mybatis#   mapper.xml pathmybatis.mapperLocations=classpath*:/META-INF/mybatis/mappers/*.xml#   entity/domain autoscan packagemybatis.type-aliases-package=com.ft.turorial.spring.boot#   use auto-mapping    after you can remove @ResultMap on mapper of interfacemybatis.configuration.map-underscore-to-camel-case=true

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4. 其他