mybatismapper文件详解

表结构:

CREATE TABLE customer (
id int(11) NOT NULL COMMENT ‘ 企业用户 ID’,
name varchar(45) DEFAULT NULL COMMENT ‘ 名称 ’,
logo varchar(80) DEFAULT ” COMMENT ‘ 企业标识 ’,
describe varchar(500) DEFAULT ” COMMENT ‘ 企业班车说明 ’,
is_enable tinyint(1) DEFAULT ‘0’ COMMENT ‘ 是否启用 1= 启用 0= 不启用 ’,
phone varchar(20) DEFAULT NULL COMMENT ‘ 客服电话 ’,
admin varchar(50) DEFAULT NULL COMMENT ‘ 管理员账号 ’,
password varchar(80) DEFAULT NULL COMMENT ‘ 管理员密码 ’,
uuid varchar(80) DEFAULT NULL COMMENT ‘ 企业唯一 ID’,
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 ;

Mapper 映射文件是在实际开发过程中使用最多的。Mapper 文件中包含的元素有：

• cache – 配置给定命名空间的缓存。
• cache-ref – 从其他命名空间引用缓存配置。
• resultMap – 映射复杂的结果对象。
• sql – 可以重用的 SQL 块, 也可以被其他语句引用。
• 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

本文的代码都是用 mybatis-generator 生成的：

<?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">
<!--
  namespace 绑定了与之对应的接口, 值是该接口的全限定名; 这个参数有且只有一个
-->
<mapper namespace="cn.rainbowbus.dao.CustomerMapper">

  <!--
    用来描述 select 语句返回字段与 java 属性的映射关系。可以有多个 resultMap 标签，用不同 id 区分不同标签。-->
  <resultMap id="BaseResultMap" type="cn.rainbowbus.entity.Customer">
    <!--
     column 是表中的字段名。property 是对应的 java 属性。jdbcTyep: 数据库中字段类型，它与 Java 中属性类型有对应关系，详情看下表。id：数据库主键字段。result：普通字段。-->
    <id column="id" jdbcType="INTEGER" property="id" />
    <result column="name" jdbcType="VARCHAR" javaType="string"  property="name" />
    <result column="logo" jdbcType="VARCHAR" property="logo" />
    <result column="describe" jdbcType="VARCHAR" property="describe" />
    <result column="is_enable" jdbcType="BIT" property="isEnable" />
    <result column="phone" jdbcType="VARCHAR" property="phone" />
    <result column="admin" jdbcType="VARCHAR" property="admin" />
    <result column="password" jdbcType="VARCHAR" property="password" />
    <result column="uuid" jdbcType="VARCHAR" property="uuid" />
  </resultMap>
  <!--
  可以重用的 SQL 块, 也可以被其他语句引用。-->
  <sql id="Example_Where_Clause">
    <where>/* where 可以自动去除 sql 语句 where 关键字后的 and 关键字 */
    /*
      向 sql 传递数组或 List,  mybatis 使用 foreach 解析, 可以做批量处理。collection: 传入的集合的变量名称(要遍历的值)。item: 每次循环将循环出的数据放入这个变量中。open: 循环开始拼接的字符串。close: 循环结束拼接的字符串。separator: 循环中拼接的分隔符。*/
      <foreach collection="oredCriteria" item="criteria" separator="or">
        /*
        判断语句，test 值等于 true 执行等于 false 跳过
        test 可以是一个值为 Boolean 型的计算语句
        */
        <if test="criteria.valid">
        /*
          前缀 'and' 被 '('  替换
          prefix：前缀覆盖并增加其内容 不写的话默认替换为空
          suffix：后缀覆盖并增加其内容 不写的话默认替换为空
          prefixOverrides：前缀判断的条件
          suffixOverrides：后缀判断的条件
        */
          <trim prefix="(" prefixOverrides="and" suffix=")">
            <foreach collection="criteria.criteria" item="criterion">
              /*
                choose 是或 (or) 的关系。choose 标签是按顺序判断其内部 when 标签中的 test 条件出否成立，如果有一个成立，则 choose 结束。当 choose 中所有 when 的条件都不满则时，则执行 otherwise 中的 sql。类似于 Java 的 switch 语句，choose 为 switch，when 为 case，otherwise 则为 default。*/
              <choose>
                <when test="criterion.noValue">
                  and ${criterion.condition}
                </when>
                <when test="criterion.singleValue">
                  and ${criterion.condition} #{criterion.value}
                </when>
                <when test="criterion.betweenValue">
                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                </when>
                <when test="criterion.listValue">
                  and ${criterion.condition}
                  <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                    #{listItem}
                  </foreach>
                </when>
              </choose>
            </foreach>
          </trim>
        </if>
      </foreach>
    </where>
  </sql>
  <sql id="Update_By_Example_Where_Clause">
    <where>
      <foreach collection="example.oredCriteria" item="criteria" separator="or">
        <if test="criteria.valid">
          <trim prefix="(" prefixOverrides="and" suffix=")">
            <foreach collection="criteria.criteria" item="criterion">
              <choose>
                <when test="criterion.noValue">
                  and ${criterion.condition}
                </when>
                <when test="criterion.singleValue">
                  and ${criterion.condition} #{criterion.value}
                </when>
                <when test="criterion.betweenValue">
                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                </when>
                <when test="criterion.listValue">
                  and ${criterion.condition}
                  <foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
                    #{listItem}
                  </foreach>
                </when>
              </choose>
            </foreach>
          </trim>
        </if>
      </foreach>
    </where>
  </sql>
  <sql id="Base_Column_List">
    <if test="fields == null">
      id, name, logo, describe, is_enable, phone, admin, password, uuid
    </if>
    <if test="fields != null">
      ${fields}
    </if>
  </sql>

  <!--
  select 查询语句标签
  id: 与 namespace 接口中的方法名对应
  parameterType: 参数类型
  resultMap : 返回值类型
  自增 IDset 到对象中: useGeneratedKeys="true" keyProperty="id" keyColumn="id" 
  支持类型简写, 详情看下表
  -->
  <select id="selectByExample" useGeneratedKeys="true" keyProperty="id" keyColumn="id" parameterType="cn.rainbowbus.entity.CustomerExample" resultMap="BaseResultMap">
    select
    <if test="distinct">
      distinct
    </if>
    <include refid="Base_Column_List" />/* 引入一个 SQL 模块 */
    from customer
    <if test="_parameter != null">
      <include refid="Example_Where_Clause" />
    </if>
    <if test="orderByClause != null">
      order by ${orderByClause}
    </if>
    <if test="startRow != null">
      limit #{startRow} , #{pageSize}
    </if>
  </select>
  <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
    select 
    id,name,logo,describe,is_enable,phone,admin,password,uuid
    from customer
    where id = #{id,jdbcType=INTEGER}
  </select>
  <!--
  delete 删除语句标签
  id: 与 namespace 接口中的方法名对应
  parameterType: 参数类型
  -->
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
    delete from customer
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <delete id="deleteByExample" parameterType="cn.rainbowbus.entity.CustomerExample">
    delete from customer
    <if test="_parameter != null">
      <include refid="Example_Where_Clause" />
    </if>
  </delete>

  <!-- 插入语句 -->
  <insert id="insert" parameterType="cn.rainbowbus.entity.Customer">
    insert into customer (id, name, logo, 
      describe, is_enable, phone, 
      admin, password, uuid
      )
    values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{logo,jdbcType=VARCHAR}, 
      #{describe,jdbcType=VARCHAR}, #{isEnable,jdbcType=BIT}, #{phone,jdbcType=VARCHAR}, 
      #{admin,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, #{uuid,jdbcType=VARCHAR}
      )
  </insert>
  <insert id="insertSelective" parameterType="cn.rainbowbus.entity.Customer">
    insert into customer
    <trim prefix="(" suffix=")" suffixOverrides=",">
      <if test="id != null">
        id,
      </if>
      <if test="name != null">
        name,
      </if>
      <if test="logo != null">
        logo,
      </if>
      <if test="describe != null">
        describe,
      </if>
      <if test="isEnable != null">
        is_enable,
      </if>
      <if test="phone != null">
        phone,
      </if>
      <if test="admin != null">
        admin,
      </if>
      <if test="password != null">
        password,
      </if>
      <if test="uuid != null">
        uuid,
      </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="logo != null">
        #{logo,jdbcType=VARCHAR},
      </if>
      <if test="describe != null">
        #{describe,jdbcType=VARCHAR},
      </if>
      <if test="isEnable != null">
        #{isEnable,jdbcType=BIT},
      </if>
      <if test="phone != null">
        #{phone,jdbcType=VARCHAR},
      </if>
      <if test="admin != null">
        #{admin,jdbcType=VARCHAR},
      </if>
      <if test="password != null">
        #{password,jdbcType=VARCHAR},
      </if>
      <if test="uuid != null">
        #{uuid,jdbcType=VARCHAR},
      </if>
    </trim>
  </insert>
  <select id="countByExample" parameterType="cn.rainbowbus.entity.CustomerExample" resultType="java.lang.Long">
    select count(*) from customer
    <if test="_parameter != null">
      <include refid="Example_Where_Clause" />
    </if>
  </select>
  <update id="updateByExampleSelective" parameterType="map">
    update customer
    <set>
      <if test="record.id != null">
        id = #{record.id,jdbcType=INTEGER},
      </if>
      <if test="record.name != null">
        name = #{record.name,jdbcType=VARCHAR},
      </if>
      <if test="record.logo != null">
        logo = #{record.logo,jdbcType=VARCHAR},
      </if>
      <if test="record.describe != null">
        describe = #{record.describe,jdbcType=VARCHAR},
      </if>
      <if test="record.isEnable != null">
        is_enable = #{record.isEnable,jdbcType=BIT},
      </if>
      <if test="record.phone != null">
        phone = #{record.phone,jdbcType=VARCHAR},
      </if>
      <if test="record.admin != null">
        admin = #{record.admin,jdbcType=VARCHAR},
      </if>
      <if test="record.password != null">
        password = #{record.password,jdbcType=VARCHAR},
      </if>
      <if test="record.uuid != null">
        uuid = #{record.uuid,jdbcType=VARCHAR},
      </if>
    </set>
    <if test="_parameter != null">
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateByExample" parameterType="map">
    update customer
    set id = #{record.id,jdbcType=INTEGER},
      name = #{record.name,jdbcType=VARCHAR},
      logo = #{record.logo,jdbcType=VARCHAR},
      describe = #{record.describe,jdbcType=VARCHAR},
      is_enable = #{record.isEnable,jdbcType=BIT},
      phone = #{record.phone,jdbcType=VARCHAR},
      admin = #{record.admin,jdbcType=VARCHAR},
      password = #{record.password,jdbcType=VARCHAR},
      uuid = #{record.uuid,jdbcType=VARCHAR}
    <if test="_parameter != null">
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateByPrimaryKeySelective" parameterType="cn.rainbowbus.entity.Customer">
    update customer
    <set>
      <if test="name != null">
        name = #{name,jdbcType=VARCHAR},
      </if>
      <if test="logo != null">
        logo = #{logo,jdbcType=VARCHAR},
      </if>
      <if test="describe != null">
        describe = #{describe,jdbcType=VARCHAR},
      </if>
      <if test="isEnable != null">
        is_enable = #{isEnable,jdbcType=BIT},
      </if>
      <if test="phone != null">
        phone = #{phone,jdbcType=VARCHAR},
      </if>
      <if test="admin != null">
        admin = #{admin,jdbcType=VARCHAR},
      </if>
      <if test="password != null">
        password = #{password,jdbcType=VARCHAR},
      </if>
      <if test="uuid != null">
        uuid = #{uuid,jdbcType=VARCHAR},
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="cn.rainbowbus.entity.Customer">
    update customer
    set name = #{name,jdbcType=VARCHAR},
      logo = #{logo,jdbcType=VARCHAR},
      describe = #{describe,jdbcType=VARCHAR},
      is_enable = #{isEnable,jdbcType=BIT},
      phone = #{phone,jdbcType=VARCHAR},
      admin = #{admin,jdbcType=VARCHAR},
      password = #{password,jdbcType=VARCHAR},
      uuid = #{uuid,jdbcType=VARCHAR}
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="batchUpdateByKeys" parameterType="java.util.List">
    update customer 
    <trim prefix="set" suffixOverrides=",">
      <trim prefix="id =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.id !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.id,jdbcType=INTEGER}
          </if>
          <if test="item.id ==null">
            when #{item.id,jdbcType=INTEGER} then customer.id
          </if>
        </foreach>
      </trim>
      <trim prefix="name =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.name !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.name,jdbcType=VARCHAR}
          </if>
          <if test="item.name ==null">
            when #{item.id,jdbcType=INTEGER} then customer.name
          </if>
        </foreach>
      </trim>
      <trim prefix="logo =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.logo !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.logo,jdbcType=VARCHAR}
          </if>
          <if test="item.logo ==null">
            when #{item.id,jdbcType=INTEGER} then customer.logo
          </if>
        </foreach>
      </trim>
      <trim prefix="describe =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.describe !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.describe,jdbcType=VARCHAR}
          </if>
          <if test="item.describe ==null">
            when #{item.id,jdbcType=INTEGER} then customer.describe
          </if>
        </foreach>
      </trim>
      <trim prefix="is_enable =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.isEnable !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.isEnable,jdbcType=BIT}
          </if>
          <if test="item.isEnable ==null">
            when #{item.id,jdbcType=INTEGER} then customer.is_enable
          </if>
        </foreach>
      </trim>
      <trim prefix="phone =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.phone !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.phone,jdbcType=VARCHAR}
          </if>
          <if test="item.phone ==null">
            when #{item.id,jdbcType=INTEGER} then customer.phone
          </if>
        </foreach>
      </trim>
      <trim prefix="admin =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.admin !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.admin,jdbcType=VARCHAR}
          </if>
          <if test="item.admin ==null">
            when #{item.id,jdbcType=INTEGER} then customer.admin
          </if>
        </foreach>
      </trim>
      <trim prefix="password =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.password !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.password,jdbcType=VARCHAR}
          </if>
          <if test="item.password ==null">
            when #{item.id,jdbcType=INTEGER} then customer.password
          </if>
        </foreach>
      </trim>
      <trim prefix="uuid =case id" suffix="end,">
        <foreach collection="recordList" index="index" item="item">
          <if test="item.uuid !=null">
            when #{item.id,jdbcType=INTEGER} then #{item.uuid,jdbcType=VARCHAR}
          </if>
          <if test="item.uuid ==null">
            when #{item.id,jdbcType=INTEGER} then customer.uuid
          </if>
        </foreach>
      </trim>
    </trim>
    where id in(
    <foreach collection="recordList" index="index" item="item" separator=",">
      #{item.id,jdbcType=INTEGER}
    </foreach>
    )
  </update>
  <insert id="batchInsert" parameterType="cn.rainbowbus.entity.Customer">
    insert into customer (id, 
      name, logo, describe, 
      is_enable, phone, admin, 
      password, uuid)
    values <foreach collection="list" item="item" index="index" separator="," > (#{item.id,jdbcType=INTEGER}, 
      #{item.name,jdbcType=VARCHAR}, #{item.logo,jdbcType=VARCHAR}, #{item.describe,jdbcType=VARCHAR}, 
      #{item.isEnable,jdbcType=BIT}, #{item.phone,jdbcType=VARCHAR}, #{item.admin,jdbcType=VARCHAR}, 
      #{item.password,jdbcType=VARCHAR}, #{item.uuid,jdbcType=VARCHAR})</foreach>
  </insert>
  <delete id="batchDeleteByKeys" parameterType="java.lang.Integer">
    delete from customer where id in (
    <foreach collection="ids" index="index" item="id" separator=",">
      #{id}
    </foreach>
    )
  </delete>
</mapper>

注意

#{}占位符: 占位
如果传入的是基本类型, 那么 #{}中的变量名称可以随意写
如果传入的参数是 pojo 类型, 那么 #{}中的变量名称必须是 pojo 中的属性. 属性名(user.username)

${}拼接符: 字符串原样拼接 (有 sql 注入的风险)
如果传入的是基本类型, 那么 ${}中的变量名必须是 value
如果传入的参数是 pojo 类型, 那么 ${}中的变量名称必须是 pojo 中的属性. 属性名 (user.username)
注意: 使用拼接符有可能造成 sql 注入, 在页面输入的时候可以加入校验, 不可输入 sql 关键字, 不可输入空格
注意：如果是取简单数量类型的参数，括号中的值必须为 value
例: select * from user where username like ‘%${value}%’
可以这样写来解决 sql 注入：select * from user where username like ‘%’#{name}’%'(开发经常使用)

mapper 对应的 Java 接口文件：

package cn.rainbowbus.dao;

import cn.rainbowbus.entity.Customer;
import cn.rainbowbus.entity.CustomerExample;
import java.util.List;
import org.apache.ibatis.annotations.Param;

public interface CustomerMapper {long countByExample(CustomerExample example);

    int deleteByExample(CustomerExample example);

    int deleteByPrimaryKey(Integer id);

    int insert(Customer record);

    int insertSelective(Customer record);

    List<Customer> selectByExample(CustomerExample example);

    Customer selectByPrimaryKey(Integer id);

    int updateByExampleSelective(@Param("record") Customer record, @Param("example") CustomerExample example);

    int updateByExample(@Param("record") Customer record, @Param("example") CustomerExample example);

    int updateByPrimaryKeySelective(Customer record);

    int updateByPrimaryKey(Customer record);

    int batchUpdateByKeys(@Param("recordList") List<Customer> recordList);

    void batchInsert(List<Customer> recordLst);

    int batchDeleteByKeys(@Param("ids") Integer[] ids);
}

mybatis 支持别名：

别名	映射类型
_byte	byte
_long	long
_short	short
_int	int
_integer	int
_double	double
_float	float
_boolean	boolean
string	String
byte	Byte
long	Long
short	Short
int	Integer
integer	Integer
double	Double
float	Float
boolean	Boolean
date	Date
decimal	BigDecimal
bigdecimal	BigDecimal
map	Map

jdbcType 与 JavaType 的映射关系

jdbcType	Java Type
CHAR	String
ARCHAR	String
ONGVARCHAR	String
UMERIC	java.math.BigDecimal
ECIMAL	java.math.BigDecimal
IT	boolean
OOLEAN	boolean
INYINT	byte
SMALLINT	short
INTEGER	int
BIGINT	long
REAL	float
FLOAT	double
DOUBLE	double
BINARY	byte[]
VARBINARY	byte[]
LONGVARBINARY	byte[]
DATE	java.sql.Date
TIME	java.sql.Time
TIMESTAMP	java.sql.Timestamp
CLOB	Clob
BLOB	Blob
ARRAY	Array
DISTINCT	mapping of underlying type
STRUCT	Struct
REF	Ref
DATALINK	java.net.URLcolor=red

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