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myBatis的mapper映射文件之批量处理方式

作者:曾卫

这篇文章主要介绍了myBatis的mapper映射文件之批量处理方式,具有很好的参考价值,希望对大家有所帮助。如有错误或未考虑完全的地方,望不吝赐教

#mybatis常见批量处理

在开发当中,可能经常会遇到批量处理这种情况,一般都再在java层面进行,

其本质是节省数据库连接打开关闭的的次数,占用更少的运行内存。

mybatis批量插入

<insert id="saveFeeRuleList" useGeneratedKeys="true" parameterType="java.util.List">
  <selectKey resultType="java.lang.String" keyProperty="id" order="AFTER">
   SELECT
   LAST_INSERT_ID()
 </selectKey>
 INSERT INTO t_product_fee_rule(
  <include refid="Base_Column_List"/>
 )
 VALUES
 <foreach collection="list" item="item" index="index" separator=",">
  (
   #{item.id},#{item.productId},
   #{item.feeCode},#{item.feeValue},
   #{item.remarks}
  )
 </foreach>
</insert>

mybatis批量删除

<delete id="removeProductAgent" parameterType="java.util.HashMap">
 <foreach collection="maps.agentIds" item="item" index="index" open="" close="" separator=";">
  DELETE FROM t_product_agent
  WHERE 1 = 1
  AND product_id = #{maps.productId}
  AND agent_id = #{item}
 </foreach>
</delete>

此处的maps接口中的@Param值对应,属于自定义变量。

void removeProductAgent(@Param("maps")Map<String, Object> map);

mybatis批量修改

<update id="saveUpdateFeeRuleList" parameterType="java.util.List">
  <foreach collection="list" item="item" index="index" open="" close="" separator=";">
   UPDATE t_product_fee_rule
   SET
 fee_value = #{item.feeValue},
 remarks = #{item.remarks}
   WHERE id = #{item.id}
  </foreach>
 </update>

myBatis mapper文件详解

本文的写作目的主要是带大家了解mapper的写法

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

本文的代码都是用mybatis-generator生成的注释部分是博主自己加的:

<?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。
    可以实现一对多,多对多关系
  -->
  <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。
     一对多标签 : 
     collection> property:对应的java属性名  ofType:对应的java属类型
     	<id property="java属性" column="author_third_id" jdbcType="BIGINT"/>
		<result property="java属性" column="account_id" jdbcType="VARCHAR"/>
    -->
    <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 v a l u e 如 果 传 入 的 参 数 是 p o j o 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)

动态SQL

Mybatis提供了9种动态sql标签:trim | where | set | foreach | if | choose | when | otherwise | bind。

1.判断语句if

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="true">  </if>

2.修剪语句:trim

 <trim prefix="(" suffix=")" prefixOverrides="and" ></trim>

3.循环语句:foreach

<foreach collection="oredCriteria" item="criteria" separator="or"></foreach>

4.选择语句:choose

类似于Java 的 switch 语句,choose 为 switch,when 为 case,otherwise 则为 default。

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。

    <choose>
                <when test="false">
                  ...
                </when>
                <when test="true">
     ...
                </when>
                <otherwise>
     ...同样这不是必须的
                </otherwise>               
              </choose>

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.URL[color=red][/color]

以上为个人经验,希望能给大家一个参考,也希望大家多多支持脚本之家。

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