Mybatis基础配置以及元素

配置

详见mybatis文档
https://mybatis.org/mybatis-3/sqlmap-xml.html#Auto-mapping

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <properties resource="db.properties"/>
    
    <settings>
        <setting name="cacheEnabled" value="true"/>
        <setting name="lazyLoadingEnabled" value="true"/>
        <setting name="multipleResultSetsEnabled" value="true"/>
        <setting name="useColumnLabel" value="true"/>
        <setting name="useGeneratedKeys" value="false"/>
        <setting name="autoMappingBehavior" value="PARTIAL"/>
        <setting name="autoMappingUnknownColumnBehavior" value="WARNING"/>
        <setting name="defaultExecutorType" value="SIMPLE"/>
        <setting name="defaultStatementTimeout" value="25"/>
        <setting name="defaultFetchSize" value="100"/>
        <setting name="safeRowBoundsEnabled" value="false"/>
        <setting name="mapUnderscoreToCamelCase" value="false"/>
        <setting name="localCacheScope" value="SESSION"/>
        <setting name="jdbcTypeForNull" value="OTHER"/>
        <setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString"/>
    </settings>
    <!--定义别名-->
    <typeAliases>
        <package name="org.sang.bean"/>
        <typeAlias alias="Author" type="domain.blog.Author"/>
    </typeAliases>
    
    <typeHandlers>
        <typeHandler handler="org.apache.ibatis.type.EnumOrdinalTypeHandler" javaType="java.math.RoundingMode"/>
        <package name="org.mybatis.example"/>
    </typeHandlers>
    <!--Mybatis在返回一个结果的时候，会调用ObjectFactory去构建POJO,一般使用默认就可以了-->
    <objectFactory type="org.mybatis.example.ExampleObjectFactory">
      <property name="someProperty" value="100"/>
    </objectFactory>
    
    <plugins>
      <plugin interceptor="org.mybatis.example.ExamplePlugin">
        <property name="someProperty" value="100"/>
      </plugin>
    </plugins>
    
   
    <environments default="development">
      <environment id="development">
      <!--采用JDBC事务管理-->
        <transactionManager type="JDBC">
          <property name="..." value="..."/>
        </transactionManager>
        <dataSource type="POOLED">
          <property name="driver" value="${driver}"/>
          <property name="url" value="${url}"/>
          <property name="username" value="${username}"/>
          <property name="password" value="${password}"/>
        </dataSource>
      </environment>
    </environments>
    <!--type="DB_VENDOR" 是启动mybatis内部注册的策略器。通过配置mapper的databaseid识别-->
    <databaseIdProvider type="DB_VENDOR">
      <property name="SQL Server" value="sqlserver"/>
      <property name="DB2" value="db2"/>
      <property name="Oracle" value="oracle" />
    </databaseIdProvider>
    <!--定义映射器 -->
    <mappers>
        <mapper resource="org/mybatis/builder/AuthorMapper.xml"/>
        <mapper url="file:///var/mappers/AuthorMapper.xml"/>
        <mapper class="org.mybatis.builder.BlogMapper"/>
        <package name="org.mybatis.builder"/>
    </mappers>
</configuration>

映射器

映射器主要元素

元素	描述	备注
select	查询语句	可以自定义参数，返回结果集
insert	插入语句	执行后返回一个整数，代表插入条数
update	更新语句	执行后返回一个整数，代表更新条数
delete	删除语句	执行后返回一个整数，代表删除条数
parameterMap	定义参数映射关系	不建议使用
sql	定义sql	可以被到处引用
resultMap	数据库结果集	提供映射规则
cache	命名空间缓存配置
cache-ref	其他命名空间缓存配置

select元素

元素	描述	备注
id	id+mapper的namespace的组合是唯一的	如果不唯一抛出异常
parameterType	可以给出类的全限定名，也可以是别名	可以选择javabean,map等复杂参数传递
resultType	可以给出类的全限定名，在允许自动匹配的情况下通过javabean映射规范映射或者定义为int，double,float也可以使用别名	常用参数之一
resultMap	自定义映射规范	非常复杂
flushCache	调用sql后。是否要求mybatis清除之前查询的本地和二级缓存	默认false
useCache	启动二级缓存开关	默认True
timeout	超时参数，默认秒，超时抛异常	默认是jdbc设置的秒
fetchSize	获取记录总条数	默认是jdbc设置的条数
databaseId	-	提供多种数据库支持

<select
  id="selectPerson"
  parameterType="int"
  parameterMap="deprecated"
  resultType="hashmap"
  resultMap="personResultMap"
  flushCache="false"
  useCache="true"
  timeout="10"
  fetchSize="256"
  statementType="PREPARED"
  resultSetType="FORWARD_ONLY">

insert,update,delete

  <insert
    id="insertAuthor"
    parameterType="domain.blog.Author"
    flushCache="true"
    statementType="PREPARED"
    keyProperty=""
    keyColumn=""
    useGeneratedKeys=""
    timeout="20">
  
  <update
    id="updateAuthor"
    parameterType="domain.blog.Author"
    flushCache="true"
    statementType="PREPARED"
    timeout="20">
  
  <delete
    id="deleteAuthor"
    parameterType="domain.blog.Author"
    flushCache="true"
    statementType="PREPARED"
    timeout="20">

resultMap

<resultMap id="detailedBlogResultMap" type="Blog">
  <constructor>
    <idArg column="blog_id" javaType="int"/>
  </constructor>
  <result property="title" column="blog_title"/>
  <association property="author" javaType="Author">
    <id property="id" column="author_id"/>
    <result property="username" column="author_username"/>
    <result property="password" column="author_password"/>
    <result property="email" column="author_email"/>
    <result property="bio" column="author_bio"/>
    <result property="favouriteSection" column="author_favourite_section"/>
  </association>
  <collection property="posts" ofType="Post">
    <id property="id" column="post_id"/>
    <result property="subject" column="post_subject"/>
    <association property="author" javaType="Author"/>
    <collection property="comments" ofType="Comment">
      <id property="id" column="comment_id"/>
    </collection>
    <collection property="tags" ofType="Tag" >
      <id property="id" column="tag_id"/>
    </collection>
    <discriminator javaType="int" column="draft">
      <case value="1" resultType="DraftPost"/>
    </discriminator>
  </collection>
</resultMap>

缓存

<cache
  eviction="FIFO"
  flushInterval="60000"
  size="512"
  readOnly="true"/>

<!--映射器 -->
<?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="dao.MUserMapper" >
  <resultMap id="BaseResultMap" type="rml.model.MUser" >
    <id column="ID" property="id" jdbcType="VARCHAR" />
    <result column="NAME" property="name" jdbcType="VARCHAR" />
    <result column="AGE" property="age" jdbcType="DECIMAL" />
    <result column="ADDRESS" property="address" jdbcType="VARCHAR" />
  </resultMap>
  
  <sql id="Base_Column_List" >
    ID, NAME, AGE, ADDRESS
  </sql>
  
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.String" >
    select 
    <include refid="Base_Column_List" />
    from MUSER
    where ID = #{id,jdbcType=VARCHAR}
  </select>
  
  <delete id="deleteByPrimaryKey" parameterType="java.lang.String" >
    delete from MUSER
    where ID = #{id,jdbcType=VARCHAR}
  </delete>
  
  <insert id="insert" parameterType="rml.model.MUser" >
    insert into MUSER (ID, NAME, AGE, 
      ADDRESS)
    values (#{id,jdbcType=VARCHAR}, #{name,jdbcType=VARCHAR}, #{age,jdbcType=DECIMAL}, 
      #{address,jdbcType=VARCHAR})
  </insert>
  
  <insert id="insertSelective" parameterType="rml.model.MUser" >
    insert into MUSER
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        ID,
      </if>
      <if test="name != null" >
        NAME,
      </if>
      <if test="age != null" >
        AGE,
      </if>
      <if test="address != null" >
        ADDRESS,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        #{id,jdbcType=VARCHAR},
      </if>
      <if test="name != null" >
        #{name,jdbcType=VARCHAR},
      </if>
      <if test="age != null" >
        #{age,jdbcType=DECIMAL},
      </if>
      <if test="address != null" >
        #{address,jdbcType=VARCHAR},
      </if>
    </trim>
  </insert>
  
  <update id="updateByPrimaryKeySelective" parameterType="rml.model.MUser" >
    update MUSER
    <set >
      <if test="name != null" >
        NAME = #{name,jdbcType=VARCHAR},
      </if>
      <if test="age != null" >
        AGE = #{age,jdbcType=DECIMAL},
      </if>
      <if test="address != null" >
        ADDRESS = #{address,jdbcType=VARCHAR},
      </if>
    </set>
    where ID = #{id,jdbcType=VARCHAR}
  </update>
  
  <update id="updateByPrimaryKey" parameterType="rml.model.MUser" >
    update MUSER
    set NAME = #{name,jdbcType=VARCHAR},
      AGE = #{age,jdbcType=DECIMAL},
      ADDRESS = #{address,jdbcType=VARCHAR}
    where ID = #{id,jdbcType=VARCHAR}
  </update>
  
  <select id="getAll" resultMap="BaseResultMap">
	select ID, NAME, AGE, ADDRESS from muser
  </select>
</mapper>

javalj_hz

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Mybatis基础配置以及元素

配置

映射器

映射器主要元素

select元素

insert,update,delete

resultMap

缓存

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