Mybatis的配置文件参数详解

偏执的太偏执、 2023-06-04 10:56 142阅读 0赞

# 1.Myatis配置文件主要是mybatis-config.xml #

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我们来看一下这里的详细的配置和需要注意的地方：

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<?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>
    
        
        <settings>
            
            <setting name="cacheEnabled" value="true" />
            
            <setting name="lazyLoadingEnabled" value="true" />
            
            <setting name="aggressiveLazyLoading" value="true" />
            
            <setting name="multipleResultSetsEnabled" value="true" />
            
            <setting name="useColumnLabel" value="true" />
            
            <setting name="useGeneratedKeys" value="true" />
            
            <setting name="autoMappingBehavior" value="PARTIAL" />
            
            <setting name="autoMappingUnknownColumnBehavior" value="WARNING" />
            
            <setting name="defaultExecutorType" value="SIMPLE" />
            
            <setting name="defaultStatementTimeout" value="25000" />
            
            <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>
    
        
        <typeAliases>
            <typeAlias alias="pageAccessURL" type="com.lgm.mybatis.model.PageAccessURL" />
        </typeAliases>
    
        
        <typeHandlers>
            
            
            <package name="com.xhm.util" />
        </typeHandlers>
    
        
        <plugins>
            <plugin interceptor="com.xhm.util.PageInterceptor"></plugin>
        </plugins>
    
        
        <environments default="development">
            
            <environment id="development1">
                
                <transactionManager type="JDBC" />
                
                
                <dataSource type="UNPOOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver" />
                    <property name="url" value="jdbc:mysql://localhost:3306/xhm" />
                    <property name="username" value="root" />
                    <property name="password" value="root" />
                    
                </dataSource>
            </environment>
    
            
            <environment id="development2">
                <transactionManager type="JDBC" />
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver" />
                    <property name="url" value="jdbc:mysql://localhost:3306/xhm" />
                    <property name="username" value="root" />
                    <property name="password" value="root" />
                    
                    <property name="poolMaximumActiveConnections" value="10" />
                    
                    <property name="poolMaximumIdleConnections" value="5" />
                    
                    <property name="poolMaximumCheckoutTime" value="20000" />
                    
                    <property name="poolTimeToWait" value="20000" />
                    
                    <property name="poolPingQuery" value="NO PING QUERY SET" />
                    
                    <property name="poolPingEnabled" value="false" />
                    
                    <property name="poolPingConnectionsNotUsedFor" value="0" />
                </dataSource>
            </environment>
    
            
            <environment id="development3">
                <transactionManager type="JDBC" />
                <dataSource type="JNDI">
                    <property name="data_source" value="java:comp/env/jndi/mybatis" />
                    <property name="env.encoding" value="UTF8" />
                    
                </dataSource>
            </environment>
        </environments>
    
        
        <mappers>
            
            <mapper resource="com/xhm/mapper/UserMapper.xml" />
            
            <package name="com.xhm.mapper" />
        </mappers>
    
    </configuration>

# 2.Mybatis配合文件节点详细解释 #

下面我们看看关于参数的配置情况，下面的信息是在mybatis配置文件中的每个配置大节点的详细解释（标注是红色的，需要重点知道的）

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# 3.Mybatie配置文件中的setting节点下面配置信息的诠释。 #

![1672408-20190826114111087-299963013.png][]

![1672408-20190826114348094-1032890926.png][]

![1672408-20190826114429848-2058789256.png][]

# 4.Mybatis中environments配置信息解释 #

*   environment 元素是配置一个数据源的开始，属性id是它的唯一标识
 *  transactionManager 元素配置数据库事务，其中type属性有三种配置方式
    
     *   jdbc，采用jdbc的方式管理事务；
     *   managed，采用容器的方式管理事务，在JNDI数据源中使用；
     *   自定义，自定义数据库事务管理办法；
 *  dataSource 元素配置数据源连接信息，type属性是连接数据库的方式配置，有四种配置方式
    
     *  UNPOOLED 非连接池方式连接
     *  POOLED 使用连接池连接
     *  JNDI 使用JNDI数据源
     *  自定义数据源

# 5.数据库字段和java中bean的对应的类是：TypeHandlerReigser #

# 6.Mapper.xml配置文件讲解 #

## 6.1具体标签的使用（这里的标签，需要都知道，既然学了，就要记住） ##

 cache – 给定命名空间的缓存配置。  
 cache-ref – 其他命名空间缓存配置的引用。  
 resultMap – 是最复杂也是最强大的元素，用来描述如何从数据库结果集中来加载对象。  
 sql – 可被其他语句引用的可重用语句块。  
 insert – 映射插入语句  
 update – 映射更新语句  
 delete – 映射删除语句  
 select – 映射查询语句

**下面我们看一个Mapper.xml的详细配置信息**

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<?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.youy.mybatis.mapper.TUserMapper">
      <resultMap id="BaseResultMap" type="com.youy.mybatis.entity.TUser">
        
        <id column="id" jdbcType="INTEGER" property="id" />
        <result column="user_name" jdbcType="VARCHAR" property="userName" />
        <result column="real_name" jdbcType="VARCHAR" property="realName" />
        <result column="sex" jdbcType="TINYINT" property="sex" />
        <result column="mobile" jdbcType="VARCHAR" property="mobile" />
        <result column="email" jdbcType="VARCHAR" property="email" />
        <result column="note" jdbcType="VARCHAR" property="note" />
        <result column="position_id" jdbcType="INTEGER" property="positionId" />
      </resultMap>
      <sql id="Base_Column_List">
        
        id, user_name, real_name, sex, mobile, email, note, position_id
      </sql>
      <resultMap id="userAndPosition1" type="com.youy.mybatis.entity.TUser" extends="BaseResultMap">
        <association property="tPosition" columnPrefix="post_"
                     javaType="com.youy.mybatis.entity.TPosition">
          <id column="id" property="id"/>
          <result column="name" property="postName"/>
          <result column="note" property="note"/>
        </association>
      </resultMap>
      <resultMap id="userAndPosition2" type="com.youy.mybatis.entity.TUser" extends="BaseResultMap">
        
        <association property="tPosition" fetchType="lazy" column="position_id" select="com.youy.mybatis.mapper.TPositionMapper.selectByPrimaryKey"/>
      </resultMap>
      <select id="selectUserPosition1" resultMap="userAndPosition1">
        select
          a.id,
          a.user_name,
          a.real_name,
          a.sex,
          a.mobile,
          a.email,
          a.note,
          b.id post_id,
          b.post_name,
          b.note post_note
        from
          t_user a,t_position b
        where
          a.position_id = b.id
      </select>
      <select id="selectUserPosition2" resultMap="userAndPosition2">
        select
          a.id,
          a.user_name,
          a.real_name,
          a.sex,
          a.mobile,
          a.email,
          a.note,
          a.position_id
        from
         t_user a
      </select>
      <select id="selectBeanByNameOrEmail" resultMap="BaseResultMap">
        select
        <include refid="Base_Column_List"/>
        from t_user
        <where>
          <choose>
            <when test="userName != null and userName != ''">
              and user_name = #{userName,jdbcType=VARCHAR}
            </when>
            <when test="email != null and email!= ''">
              and email like CONCAT('%',#{email,jdbcType=VARCHAR},'%')
            </when>
            <otherwise>
              and 1 = 1
            </otherwise>
          </choose>
        </where>
      </select>
      <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
        
        select 
        <include refid="Base_Column_List" />
        from t_user
        where id = #{id,jdbcType=INTEGER}
      </select>
      <resultMap id="userRoleInfo" extends= "BaseResultMap" type="com.youy.mybatis.entity.TUser">
        <collection property="roleList" column="id" columnPrefix="role_" ofType="com.youy.mybatis.entity.TRole">
          <id column="id" property="id"/>
          <result column="name" property="roleName"/>
          <result column="note" property="note"/>
        </collection>
      </resultMap>
      <select id="selectUserRole" resultMap="userRoleInfo">
        select a.id,
                  a.user_name,
                  a.real_name,
                  a.sex,
                  a.mobile,
                  a.note,
                  b.role_id,
                  c.role_name,
                  c.note role_note
            from t_user a,
                 t_user_role b,
                 t_role c
            where a.id = b.user_id AND
                  b.role_id = c.id
      </select>
      <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
        
        delete from t_user
        where id = #{id,jdbcType=INTEGER}
      </delete>
      <insert id="insert" parameterType="com.youy.mybatis.entity.TUser">
        
        <selectKey keyProperty="id" order="BEFORE" resultType="java.lang.Integer">
          SELECT LAST_INSERT_ID()
        </selectKey>
        insert into t_user (id, user_name, real_name, 
          sex, mobile, email, 
          note, position_id)
        values (#{id,jdbcType=INTEGER}, #{userName,jdbcType=VARCHAR}, #{realName,jdbcType=VARCHAR}, 
          #{sex,jdbcType=TINYINT}, #{mobile,jdbcType=VARCHAR}, #{email,jdbcType=VARCHAR}, 
          #{note,jdbcType=VARCHAR}, #{positionId,jdbcType=INTEGER})
      </insert>
      <insert id="insertSelective" parameterType="com.youy.mybatis.entity.TUser">
        
        <selectKey keyProperty="id" order="BEFORE" resultType="java.lang.Integer">
          SELECT LAST_INSERT_ID()
        </selectKey>
        insert into t_user
        <trim prefix="(" suffix=")" suffixOverrides=",">
          id,
          <if test="userName != null">
            user_name,
          </if>
          <if test="realName != null">
            real_name,
          </if>
          <if test="sex != null">
            sex,
          </if>
          <if test="mobile != null">
            mobile,
          </if>
          <if test="email != null">
            email,
          </if>
          <if test="note != null">
            note,
          </if>
          <if test="positionId != null">
            position_id,
          </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
          #{id,jdbcType=INTEGER},
          <if test="userName != null">
            #{userName,jdbcType=VARCHAR},
          </if>
          <if test="realName != null">
            #{realName,jdbcType=VARCHAR},
          </if>
          <if test="sex != null">
            #{sex,jdbcType=TINYINT},
          </if>
          <if test="mobile != null">
            #{mobile,jdbcType=VARCHAR},
          </if>
          <if test="email != null">
            #{email,jdbcType=VARCHAR},
          </if>
          <if test="note != null">
            #{note,jdbcType=VARCHAR},
          </if>
          <if test="positionId != null">
            #{positionId,jdbcType=INTEGER},
          </if>
        </trim>
      </insert>
      <update id="updateByPrimaryKeySelective" parameterType="com.youy.mybatis.entity.TUser">
        
        update t_user
        <set>
          <if test="userName != null">
            user_name = #{userName,jdbcType=VARCHAR},
          </if>
          <if test="realName != null">
            real_name = #{realName,jdbcType=VARCHAR},
          </if>
          <if test="sex != null">
            sex = #{sex,jdbcType=TINYINT},
          </if>
          <if test="mobile != null">
            mobile = #{mobile,jdbcType=VARCHAR},
          </if>
          <if test="email != null">
            email = #{email,jdbcType=VARCHAR},
          </if>
          <if test="note != null">
            note = #{note,jdbcType=VARCHAR},
          </if>
          <if test="positionId != null">
            position_id = #{positionId,jdbcType=INTEGER},
          </if>
        </set>
        where id = #{id,jdbcType=INTEGER}
      </update>
      <update id="updateByPrimaryKey" parameterType="com.youy.mybatis.entity.TUser">
        
        update t_user
        set user_name = #{userName,jdbcType=VARCHAR},
          real_name = #{realName,jdbcType=VARCHAR},
          sex = #{sex,jdbcType=TINYINT},
          mobile = #{mobile,jdbcType=VARCHAR},
          email = #{email,jdbcType=VARCHAR},
          note = #{note,jdbcType=VARCHAR},
          position_id = #{positionId,jdbcType=INTEGER}
        where id = #{id,jdbcType=INTEGER}
      </update>
    </mapper>

### 6.1.1 select 标签的使用 ###

我们看一下该标签里面涉及到的属性

![1672408-20190826163346084-605325435.png][]

关于这个标签，我们需要西湖一的点

1.  我们首先需要注意的是resultType返回是集合的时候，返回的是集合的元素类型。不是list。
2.  使用自动映射的时候，也就是 resultType = "com.youy.mybatis.entity.TUser" ,这样的话，需要将setting配置节点中的属性                                                  <setting name="mapUnderscoreToCamelCase" value="true" /> 否则的话。带有下划线的列明，不能正常的对应高bean里面；
3.  如果使用的是resultMap的话，在节点里面将属性对应好，不用配置驼峰信息的话，也是可以的；

总结：1.请求参数，如果参数少于 5个 的话，我们需要传递固定的参数

2.传入的参数要是大于5 个的话，就要使用的是bean，不要使用 map 作为入参，因为不好维护；

3.resultType，要是使用这个参数的话，返回值耦合性比较大，需要动地方比较多。

4.所以使用resultMap，这样的配置信息，易于维护。便于解耦。

转载于:https://www.cnblogs.com/lys-lyy/p/11411650.html

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