MyBatis逆向⼯程的生成过程
作者：@每天都要敲代码
MyBatis官方为我们提供了一个逆向工程，通过这个逆向工程，只要建立好数据表，那么MyBatis就会根据这个表自动生成pojo类、dao接口、sql映射文件
一、MyBatis的逆向⼯程
（1）所谓的逆向⼯程是：根据数据库表逆向⽣成Java的pojo类，SqlMapper.xml⽂件，以及Mapper接⼝类等，这真是一个很强大的功能。 要完成这个⼯作，需要借助别⼈写好的逆向⼯程插件。
（2）思考：使⽤这个插件的话，需要给这个插件配置哪些信息？
①pojo类名、包名以及⽣成位置。
②SqlMapper.xml⽂件名以及⽣成位置。
③Mapper接⼝名以及⽣成位置。
④连接数据库的信息。
⑤指定哪些表参与逆向⼯程。
......
1.逆向⼯程配置与⽣成
（1）基础环境准备
新建一个普通的Maven模块：mybatis-012-generator
打包⽅式：jar
（2）在pom.xml中添加逆向⼯程插件
①先引入mybatis逆向⼯程的插件，引入仓库中对应的插件坐标。
②允许覆盖：表示原来这些文件存在，true就以覆盖的方式生成文件，false就以追加的方式生成文件。
③引入插件的依赖：我们需要根据数据库表逆向生成pojo类、SqlMapper接口和里面的方法、SqlMapper.xml配置文件等，所以肯定需要mysql的驱动。
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.bjpowernode</groupId>
<artifactId>mybatis-012-generator</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<!--定制构建过程-->
<build>
<!--可配置多个插件-->
<plugins>
<!--其中的⼀个插件：mybatis逆向⼯程插件-->
<plugin>
<!--插件的GAV坐标-->
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.4.1</version>
<!--允许覆盖-->
<configuration>
<overwrite>true</overwrite>
</configuration>
<!--插件的依赖-->
<dependencies>
<!--mysql驱动依赖-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.23</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</project>（3）配置generatorConfig.xml（基础版）
该⽂件名必须叫做：generatorConfig.xml。
并且该⽂件必须放在类的根路径下。
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
"http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
<!--
targetRuntime有两个值：
MyBatis3Simple：生成的是基础版，只有基本的增删改查。
MyBatis3：生成的是增强版，除了基本的增删改查之外还有复杂的增删改查。
-->
<context id="DB2Tables" targetRuntime="MyBatis3Simple">
<!--防止生成重复代码-->
<plugin type="org.mybatis.generator.plugins.UnmergeableXmlMappersPlugin"/>
<commentGenerator>
<!--是否去掉生成日期-->
<property name="suppressDate" value="true"/>
<!--是否去除注释-->
<property name="suppressAllComments" value="true"/>
</commentGenerator>
<!--连接数据库信息-->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/mybatis"
userId="root"
password="123">
</jdbcConnection>
<!-- 生成pojo包名和位置 -->
<javaModelGenerator targetPackage="com.bjpowernode.mybatis.pojo" targetProject="src/main/java">
<!--是否开启子包-->
<property name="enableSubPackages" value="true"/>
<!--是否去除字段名的前后空白-->
<property name="trimStrings" value="true"/>
</javaModelGenerator>
<!-- 生成SQL映射文件的包名和位置 -->
<sqlMapGenerator targetPackage="com.bjpowernode.mybatis.mapper" targetProject="src/main/resources">
<!--是否开启子包-->
<property name="enableSubPackages" value="true"/>
</sqlMapGenerator>
<!-- 生成Mapper接口的包名和位置 -->
<javaClientGenerator
type="xmlMapper"
targetPackage="com.bjpowernode.mybatis.mapper"
targetProject="src/main/java">
<property name="enableSubPackages" value="true"/>
</javaClientGenerator>
<!-- 表名和对应的实体类名-->
<table tableName="t_car" domainObjectName="Car"/>
</context>
</generatorConfiguration>（4）双击运行插件，就可以生成基础版的配置信息
自动生成的CarMapper接口、pojo类Car、CarMapper.xml配置文件
CarMapper接口
package com.bjpowernode.mybatis.mapper;
import com.bjpowernode.mybatis.pojo.Car;
import java.util.List;
public interface CarMapper {
int deleteByPrimaryKey(Long id);
int insert(Car row);
Car selectByPrimaryKey(Long id);
List<Car> selectAll();
int updateByPrimaryKey(Car row);
}pojo类Car
注：生成的pojo类并没有重写toString方法
package com.bjpowernode.mybatis.pojo;
import java.math.BigDecimal;
public class Car {
private Long id;
private String carNum;
private String brand;
private BigDecimal guidePrice;
private String produceTime;
private String carType;
@Override
public String toString() {
return "Car{" +
"id=" + id +
", carNum='" + carNum + '\'' +
", brand='" + brand + '\'' +
", guidePrice=" + guidePrice +
", produceTime='" + produceTime + '\'' +
", carType='" + carType + '\'' +
'}';
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getCarNum() {
return carNum;
}
public void setCarNum(String carNum) {
this.carNum = carNum == null ? null : carNum.trim();
}
public String getBrand() {
return brand;
}
public void setBrand(String brand) {
this.brand = brand == null ? null : brand.trim();
}
public BigDecimal getGuidePrice() {
return guidePrice;
}
public void setGuidePrice(BigDecimal guidePrice) {
this.guidePrice = guidePrice;
}
public String getProduceTime() {
return produceTime;
}
public void setProduceTime(String produceTime) {
this.produceTime = produceTime == null ? null : produceTime.trim();
}
public String getCarType() {
return carType;
}
public void setCarType(String carType) {
this.carType = carType == null ? null : carType.trim();
}
}CarMapper.xml配置文件
<?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.bjpowernode.mybatis.mapper.CarMapper">
<resultMap id="BaseResultMap" type="com.bjpowernode.mybatis.pojo.Car">
<id column="id" jdbcType="BIGINT" property="id" />
<result column="car_num" jdbcType="VARCHAR" property="carNum" />
<result column="brand" jdbcType="VARCHAR" property="brand" />
<result column="guide_price" jdbcType="DECIMAL" property="guidePrice" />
<result column="produce_time" jdbcType="CHAR" property="produceTime" />
<result column="car_type" jdbcType="VARCHAR" property="carType" />
</resultMap>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
delete from t_car
where id = #{id,jdbcType=BIGINT}
</delete>
<insert id="insert" parameterType="com.bjpowernode.mybatis.pojo.Car">
insert into t_car (id, car_num, brand,
guide_price, produce_time, car_type
)
values (#{id,jdbcType=BIGINT}, #{carNum,jdbcType=VARCHAR}, #{brand,jdbcType=VARCHAR},
#{guidePrice,jdbcType=DECIMAL}, #{produceTime,jdbcType=CHAR}, #{carType,jdbcType=VARCHAR}
)
</insert>
<update id="updateByPrimaryKey" parameterType="com.bjpowernode.mybatis.pojo.Car">
update t_car
set car_num = #{carNum,jdbcType=VARCHAR},
brand = #{brand,jdbcType=VARCHAR},
guide_price = #{guidePrice,jdbcType=DECIMAL},
produce_time = #{produceTime,jdbcType=CHAR},
car_type = #{carType,jdbcType=VARCHAR}
where id = #{id,jdbcType=BIGINT}
</update>
<select id="selectByPrimaryKey" parameterType="java.lang.Long" resultMap="BaseResultMap">
select id, car_num, brand, guide_price, produce_time, car_type
from t_car
where id = #{id,jdbcType=BIGINT}
</select>
<select id="selectAll" resultMap="BaseResultMap">
select id, car_num, brand, guide_price, produce_time, car_type
from t_car
</select>
</mapper>2.测试生成的逆向⼯程
（1）环境准备
①依赖：mybatis依赖、mysql驱动依赖、junit依赖、logback依赖
②jdbc.properties、mybatis-config.xml、logback.xml
③拷贝工具类：SqlSessionUtil
（2）编写测试程序（基础版）
package com.bjpowernode.mybatis.test;
import com.bjpowernode.mybatis.mapper.CarMapper;
import com.bjpowernode.mybatis.pojo.Car;
import com.bjpowernode.mybatis.utils.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class CarMapperTest {
@Test
public void testSelectAll(){
SqlSession sqlSession = SqlSessionUtil.openSession();
CarMapper mapper = sqlSession.getMapper(CarMapper.class);
List<Car> cars = mapper.selectAll();
cars.forEach(car -> System.out.println(car));
sqlSession.close();
}
}执行结果：
（3）配置generatorConfig.xml（增强版）
生成了两个pojo类，并且对于接口中的方法也变多了
CarMapper接口
package com.bjpowernode.mybatis.mapper;
import com.bjpowernode.mybatis.pojo.Car;
import com.bjpowernode.mybatis.pojo.CarExample;
import java.util.List;
import org.apache.ibatis.annotations.Param;
public interface CarMapper {
long countByExample(CarExample example);
int deleteByExample(CarExample example);
int deleteByPrimaryKey(Long id);
int insert(Car row);
int insertSelective(Car row);
List<Car> selectByExample(CarExample example);
Car selectByPrimaryKey(Long id);
int updateByExampleSelective(@Param("row") Car row, @Param("example") CarExample example);
int updateByExample(@Param("row") Car row, @Param("example") CarExample example);
int updateByPrimaryKeySelective(Car row);
int updateByPrimaryKey(Car row);
}pojo类Car
package com.bjpowernode.mybatis.pojo;
import java.math.BigDecimal;
public class Car {
private Long id;
private String carNum;
private String brand;
private BigDecimal guidePrice;
private String produceTime;
private String carType;
@Override
public String toString() {
return "Car{" +
"id=" + id +
", carNum='" + carNum + '\'' +
", brand='" + brand + '\'' +
", guidePrice=" + guidePrice +
", produceTime='" + produceTime + '\'' +
", carType='" + carType + '\'' +
'}';
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getCarNum() {
return carNum;
}
public void setCarNum(String carNum) {
this.carNum = carNum == null ? null : carNum.trim();
}
public String getBrand() {
return brand;
}
public void setBrand(String brand) {
this.brand = brand == null ? null : brand.trim();
}
public BigDecimal getGuidePrice() {
return guidePrice;
}
public void setGuidePrice(BigDecimal guidePrice) {
this.guidePrice = guidePrice;
}
public String getProduceTime() {
return produceTime;
}
public void setProduceTime(String produceTime) {
this.produceTime = produceTime == null ? null : produceTime.trim();
}
public String getCarType() {
return carType;
}
public void setCarType(String carType) {
this.carType = carType == null ? null : carType.trim();
}
}pojo类CarExample：封装查询条件的类
package com.bjpowernode.mybatis.pojo;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;
public class CarExample {
protected String orderByClause;
protected boolean distinct;
protected List<Criteria> oredCriteria;
public CarExample() {
oredCriteria = new ArrayList<>();
}
public void setOrderByClause(String orderByClause) {
this.orderByClause = orderByClause;
}
public String getOrderByClause() {
return orderByClause;
}
public void setDistinct(boolean distinct) {
this.distinct = distinct;
}
public boolean isDistinct() {
return distinct;
}
public List<Criteria> getOredCriteria() {
return oredCriteria;
}
public void or(Criteria criteria) {
oredCriteria.add(criteria);
}
public Criteria or() {
Criteria criteria = createCriteriaInternal();
oredCriteria.add(criteria);
return criteria;
}
public Criteria createCriteria() {
Criteria criteria = createCriteriaInternal();
if (oredCriteria.size() == 0) {
oredCriteria.add(criteria);
}
return criteria;
}
protected Criteria createCriteriaInternal() {
Criteria criteria = new Criteria();
return criteria;
}
public void clear() {
oredCriteria.clear();
orderByClause = null;
distinct = false;
}
protected abstract static class GeneratedCriteria {
protected List<Criterion> criteria;
protected GeneratedCriteria() {
super();
criteria = new ArrayList<>();
}
public boolean isValid() {
return criteria.size() > 0;
}
public List<Criterion> getAllCriteria() {
return criteria;
}
public List<Criterion> getCriteria() {
return criteria;
}
protected void addCriterion(String condition) {
if (condition == null) {
throw new RuntimeException("Value for condition cannot be null");
}
criteria.add(new Criterion(condition));
}
protected void addCriterion(String condition, Object value, String property) {
if (value == null) {
throw new RuntimeException("Value for " + property + " cannot be null");
}
criteria.add(new Criterion(condition, value));
}
protected void addCriterion(String condition, Object value1, Object value2, String property) {
if (value1 == null || value2 == null) {
throw new RuntimeException("Between values for " + property + " cannot be null");
}
criteria.add(new Criterion(condition, value1, value2));
}
public Criteria andIdIsNull() {
addCriterion("id is null");
return (Criteria) this;
}
public Criteria andIdIsNotNull() {
addCriterion("id is not null");
return (Criteria) this;
}
public Criteria andIdEqualTo(Long value) {
addCriterion("id =", value, "id");
return (Criteria) this;
}
public Criteria andIdNotEqualTo(Long value) {
addCriterion("id <>", value, "id");
return (Criteria) this;
}
public Criteria andIdGreaterThan(Long value) {
addCriterion("id >", value, "id");
return (Criteria) this;
}
public Criteria andIdGreaterThanOrEqualTo(Long value) {
addCriterion("id >=", value, "id");
return (Criteria) this;
}
public Criteria andIdLessThan(Long value) {
addCriterion("id <", value, "id");
return (Criteria) this;
}
public Criteria andIdLessThanOrEqualTo(Long value) {
addCriterion("id <=", value, "id");
return (Criteria) this;
}
public Criteria andIdIn(List<Long> values) {
addCriterion("id in", values, "id");
return (Criteria) this;
}
public Criteria andIdNotIn(List<Long> values) {
addCriterion("id not in", values, "id");
return (Criteria) this;
}
public Criteria andIdBetween(Long value1, Long value2) {
addCriterion("id between", value1, value2, "id");
return (Criteria) this;
}
public Criteria andIdNotBetween(Long value1, Long value2) {
addCriterion("id not between", value1, value2, "id");
return (Criteria) this;
}
public Criteria andCarNumIsNull() {
addCriterion("car_num is null");
return (Criteria) this;
}
public Criteria andCarNumIsNotNull() {
addCriterion("car_num is not null");
return (Criteria) this;
}
public Criteria andCarNumEqualTo(String value) {
addCriterion("car_num =", value, "carNum");
return (Criteria) this;
}
public Criteria andCarNumNotEqualTo(String value) {
addCriterion("car_num <>", value, "carNum");
return (Criteria) this;
}
public Criteria andCarNumGreaterThan(String value) {
addCriterion("car_num >", value, "carNum");
return (Criteria) this;
}
public Criteria andCarNumGreaterThanOrEqualTo(String value) {
addCriterion("car_num >=", value, "carNum");
return (Criteria) this;
}
public Criteria andCarNumLessThan(String value) {
addCriterion("car_num <", value, "carNum");
return (Criteria) this;
}
public Criteria andCarNumLessThanOrEqualTo(String value) {
addCriterion("car_num <=", value, "carNum");
return (Criteria) this;
}
public Criteria andCarNumLike(String value) {
addCriterion("car_num like", value, "carNum");
return (Criteria) this;
}
public Criteria andCarNumNotLike(String value) {
addCriterion("car_num not like", value, "carNum");
return (Criteria) this;
}
public Criteria andCarNumIn(List<String> values) {
addCriterion("car_num in", values, "carNum");
return (Criteria) this;
}
public Criteria andCarNumNotIn(List<String> values) {
addCriterion("car_num not in", values, "carNum");
return (Criteria) this;
}
public Criteria andCarNumBetween(String value1, String value2) {
addCriterion("car_num between", value1, value2, "carNum");
return (Criteria) this;
}
public Criteria andCarNumNotBetween(String value1, String value2) {
addCriterion("car_num not between", value1, value2, "carNum");
return (Criteria) this;
}
public Criteria andBrandIsNull() {
addCriterion("brand is null");
return (Criteria) this;
}
public Criteria andBrandIsNotNull() {
addCriterion("brand is not null");
return (Criteria) this;
}
public Criteria andBrandEqualTo(String value) {
addCriterion("brand =", value, "brand");
return (Criteria) this;
}
public Criteria andBrandNotEqualTo(String value) {
addCriterion("brand <>", value, "brand");
return (Criteria) this;
}
public Criteria andBrandGreaterThan(String value) {
addCriterion("brand >", value, "brand");
return (Criteria) this;
}
public Criteria andBrandGreaterThanOrEqualTo(String value) {
addCriterion("brand >=", value, "brand");
return (Criteria) this;
}
public Criteria andBrandLessThan(String value) {
addCriterion("brand <", value, "brand");
return (Criteria) this;
}
public Criteria andBrandLessThanOrEqualTo(String value) {
addCriterion("brand <=", value, "brand");
return (Criteria) this;
}
public Criteria andBrandLike(String value) {
addCriterion("brand like", value, "brand");
return (Criteria) this;
}
public Criteria andBrandNotLike(String value) {
addCriterion("brand not like", value, "brand");
return (Criteria) this;
}
public Criteria andBrandIn(List<String> values) {
addCriterion("brand in", values, "brand");
return (Criteria) this;
}
public Criteria andBrandNotIn(List<String> values) {
addCriterion("brand not in", values, "brand");
return (Criteria) this;
}
public Criteria andBrandBetween(String value1, String value2) {
addCriterion("brand between", value1, value2, "brand");
return (Criteria) this;
}
public Criteria andBrandNotBetween(String value1, String value2) {
addCriterion("brand not between", value1, value2, "brand");
return (Criteria) this;
}
public Criteria andGuidePriceIsNull() {
addCriterion("guide_price is null");
return (Criteria) this;
}
public Criteria andGuidePriceIsNotNull() {
addCriterion("guide_price is not null");
return (Criteria) this;
}
public Criteria andGuidePriceEqualTo(BigDecimal value) {
addCriterion("guide_price =", value, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceNotEqualTo(BigDecimal value) {
addCriterion("guide_price <>", value, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceGreaterThan(BigDecimal value) {
addCriterion("guide_price >", value, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceGreaterThanOrEqualTo(BigDecimal value) {
addCriterion("guide_price >=", value, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceLessThan(BigDecimal value) {
addCriterion("guide_price <", value, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceLessThanOrEqualTo(BigDecimal value) {
addCriterion("guide_price <=", value, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceIn(List<BigDecimal> values) {
addCriterion("guide_price in", values, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceNotIn(List<BigDecimal> values) {
addCriterion("guide_price not in", values, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceBetween(BigDecimal value1, BigDecimal value2) {
addCriterion("guide_price between", value1, value2, "guidePrice");
return (Criteria) this;
}
public Criteria andGuidePriceNotBetween(BigDecimal value1, BigDecimal value2) {
addCriterion("guide_price not between", value1, value2, "guidePrice");
return (Criteria) this;
}
public Criteria andProduceTimeIsNull() {
addCriterion("produce_time is null");
return (Criteria) this;
}
public Criteria andProduceTimeIsNotNull() {
addCriterion("produce_time is not null");
return (Criteria) this;
}
public Criteria andProduceTimeEqualTo(String value) {
addCriterion("produce_time =", value, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeNotEqualTo(String value) {
addCriterion("produce_time <>", value, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeGreaterThan(String value) {
addCriterion("produce_time >", value, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeGreaterThanOrEqualTo(String value) {
addCriterion("produce_time >=", value, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeLessThan(String value) {
addCriterion("produce_time <", value, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeLessThanOrEqualTo(String value) {
addCriterion("produce_time <=", value, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeLike(String value) {
addCriterion("produce_time like", value, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeNotLike(String value) {
addCriterion("produce_time not like", value, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeIn(List<String> values) {
addCriterion("produce_time in", values, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeNotIn(List<String> values) {
addCriterion("produce_time not in", values, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeBetween(String value1, String value2) {
addCriterion("produce_time between", value1, value2, "produceTime");
return (Criteria) this;
}
public Criteria andProduceTimeNotBetween(String value1, String value2) {
addCriterion("produce_time not between", value1, value2, "produceTime");
return (Criteria) this;
}
public Criteria andCarTypeIsNull() {
addCriterion("car_type is null");
return (Criteria) this;
}
public Criteria andCarTypeIsNotNull() {
addCriterion("car_type is not null");
return (Criteria) this;
}
public Criteria andCarTypeEqualTo(String value) {
addCriterion("car_type =", value, "carType");
return (Criteria) this;
}
public Criteria andCarTypeNotEqualTo(String value) {
addCriterion("car_type <>", value, "carType");
return (Criteria) this;
}
public Criteria andCarTypeGreaterThan(String value) {
addCriterion("car_type >", value, "carType");
return (Criteria) this;
}
public Criteria andCarTypeGreaterThanOrEqualTo(String value) {
addCriterion("car_type >=", value, "carType");
return (Criteria) this;
}
public Criteria andCarTypeLessThan(String value) {
addCriterion("car_type <", value, "carType");
return (Criteria) this;
}
public Criteria andCarTypeLessThanOrEqualTo(String value) {
addCriterion("car_type <=", value, "carType");
return (Criteria) this;
}
public Criteria andCarTypeLike(String value) {
addCriterion("car_type like", value, "carType");
return (Criteria) this;
}
public Criteria andCarTypeNotLike(String value) {
addCriterion("car_type not like", value, "carType");
return (Criteria) this;
}
public Criteria andCarTypeIn(List<String> values) {
addCriterion("car_type in", values, "carType");
return (Criteria) this;
}
public Criteria andCarTypeNotIn(List<String> values) {
addCriterion("car_type not in", values, "carType");
return (Criteria) this;
}
public Criteria andCarTypeBetween(String value1, String value2) {
addCriterion("car_type between", value1, value2, "carType");
return (Criteria) this;
}
public Criteria andCarTypeNotBetween(String value1, String value2) {
addCriterion("car_type not between", value1, value2, "carType");
return (Criteria) this;
}
}
public static class Criteria extends GeneratedCriteria {
protected Criteria() {
super();
}
}
public static class Criterion {
private String condition;
private Object value;
private Object secondValue;
private boolean noValue;
private boolean singleValue;
private boolean betweenValue;
private boolean listValue;
private String typeHandler;
public String getCondition() {
return condition;
}
public Object getValue() {
return value;
}
public Object getSecondValue() {
return secondValue;
}
public boolean isNoValue() {
return noValue;
}
public boolean isSingleValue() {
return singleValue;
}
public boolean isBetweenValue() {
return betweenValue;
}
public boolean isListValue() {
return listValue;
}
public String getTypeHandler() {
return typeHandler;
}
protected Criterion(String condition) {
super();
this.condition = condition;
this.typeHandler = null;
this.noValue = true;
}
protected Criterion(String condition, Object value, String typeHandler) {
super();
this.condition = condition;
this.value = value;
this.typeHandler = typeHandler;
if (value instanceof List<?>) {
this.listValue = true;
} else {
this.singleValue = true;
}
}
protected Criterion(String condition, Object value) {
this(condition, value, null);
}
protected Criterion(String condition, Object value, Object secondValue, String typeHandler) {
super();
this.condition = condition;
this.value = value;
this.secondValue = secondValue;
this.typeHandler = typeHandler;
this.betweenValue = true;
}
protected Criterion(String condition, Object value, Object secondValue) {
this(condition, value, secondValue, null);
}
}
}CarMapper.xml配置文件
<?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.bjpowernode.mybatis.mapper.CarMapper">
<resultMap id="BaseResultMap" type="com.bjpowernode.mybatis.pojo.Car">
<id column="id" jdbcType="BIGINT" property="id" />
<result column="car_num" jdbcType="VARCHAR" property="carNum" />
<result column="brand" jdbcType="VARCHAR" property="brand" />
<result column="guide_price" jdbcType="DECIMAL" property="guidePrice" />
<result column="produce_time" jdbcType="CHAR" property="produceTime" />
<result column="car_type" jdbcType="VARCHAR" property="carType" />
</resultMap>
<sql id="Example_Where_Clause">
<where>
<foreach collection="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="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">
id, car_num, brand, guide_price, produce_time, car_type
</sql>
<select id="selectByExample" parameterType="com.bjpowernode.mybatis.pojo.CarExample" resultMap="BaseResultMap">
select
<if test="distinct">
distinct
</if>
<include refid="Base_Column_List" />
from t_car
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
<if test="orderByClause != null">
order by ${orderByClause}
</if>
</select>
<select id="selectByPrimaryKey" parameterType="java.lang.Long" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from t_car
where id = #{id,jdbcType=BIGINT}
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
delete from t_car
where id = #{id,jdbcType=BIGINT}
</delete>
<delete id="deleteByExample" parameterType="com.bjpowernode.mybatis.pojo.CarExample">
delete from t_car
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
</delete>
<insert id="insert" parameterType="com.bjpowernode.mybatis.pojo.Car">
insert into t_car (id, car_num, brand,
guide_price, produce_time, car_type
)
values (#{id,jdbcType=BIGINT}, #{carNum,jdbcType=VARCHAR}, #{brand,jdbcType=VARCHAR},
#{guidePrice,jdbcType=DECIMAL}, #{produceTime,jdbcType=CHAR}, #{carType,jdbcType=VARCHAR}
)
</insert>
<insert id="insertSelective" parameterType="com.bjpowernode.mybatis.pojo.Car">
insert into t_car
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="id != null">
id,
</if>
<if test="carNum != null">
car_num,
</if>
<if test="brand != null">
brand,
</if>
<if test="guidePrice != null">
guide_price,
</if>
<if test="produceTime != null">
produce_time,
</if>
<if test="carType != null">
car_type,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="id != null">
#{id,jdbcType=BIGINT},
</if>
<if test="carNum != null">
#{carNum,jdbcType=VARCHAR},
</if>
<if test="brand != null">
#{brand,jdbcType=VARCHAR},
</if>
<if test="guidePrice != null">
#{guidePrice,jdbcType=DECIMAL},
</if>
<if test="produceTime != null">
#{produceTime,jdbcType=CHAR},
</if>
<if test="carType != null">
#{carType,jdbcType=VARCHAR},
</if>
</trim>
</insert>
<select id="countByExample" parameterType="com.bjpowernode.mybatis.pojo.CarExample" resultType="java.lang.Long">
select count(*) from t_car
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
</select>
<update id="updateByExampleSelective" parameterType="map">
update t_car
<set>
<if test="row.id != null">
id = #{row.id,jdbcType=BIGINT},
</if>
<if test="row.carNum != null">
car_num = #{row.carNum,jdbcType=VARCHAR},
</if>
<if test="row.brand != null">
brand = #{row.brand,jdbcType=VARCHAR},
</if>
<if test="row.guidePrice != null">
guide_price = #{row.guidePrice,jdbcType=DECIMAL},
</if>
<if test="row.produceTime != null">
produce_time = #{row.produceTime,jdbcType=CHAR},
</if>
<if test="row.carType != null">
car_type = #{row.carType,jdbcType=VARCHAR},
</if>
</set>
<if test="example != null">
<include refid="Update_By_Example_Where_Clause" />
</if>
</update>
<update id="updateByExample" parameterType="map">
update t_car
set id = #{row.id,jdbcType=BIGINT},
car_num = #{row.carNum,jdbcType=VARCHAR},
brand = #{row.brand,jdbcType=VARCHAR},
guide_price = #{row.guidePrice,jdbcType=DECIMAL},
produce_time = #{row.produceTime,jdbcType=CHAR},
car_type = #{row.carType,jdbcType=VARCHAR}
<if test="example != null">
<include refid="Update_By_Example_Where_Clause" />
</if>
</update>
<update id="updateByPrimaryKeySelective" parameterType="com.bjpowernode.mybatis.pojo.Car">
update t_car
<set>
<if test="carNum != null">
car_num = #{carNum,jdbcType=VARCHAR},
</if>
<if test="brand != null">
brand = #{brand,jdbcType=VARCHAR},
</if>
<if test="guidePrice != null">
guide_price = #{guidePrice,jdbcType=DECIMAL},
</if>
<if test="produceTime != null">
produce_time = #{produceTime,jdbcType=CHAR},
</if>
<if test="carType != null">
car_type = #{carType,jdbcType=VARCHAR},
</if>
</set>
where id = #{id,jdbcType=BIGINT}
</update>
<update id="updateByPrimaryKey" parameterType="com.bjpowernode.mybatis.pojo.Car">
update t_car
set car_num = #{carNum,jdbcType=VARCHAR},
brand = #{brand,jdbcType=VARCHAR},
guide_price = #{guidePrice,jdbcType=DECIMAL},
produce_time = #{produceTime,jdbcType=CHAR},
car_type = #{carType,jdbcType=VARCHAR}
where id = #{id,jdbcType=BIGINT}
</update>
</mapper>（4）编写测试程序（增强版）
（1）增强版的查询方式就比较特殊，特别是根据条件查询，是QBC 风格：Query By Criteria 一种查询方式，比较面向对象，看不到sql语句！
（2）条件查询步骤：
①先封装条件，通过CarExample对象来封装查询条件
②调用carExample.createCriteria()方法来创建查询条件，后面通过" 点. "的方式跟上方法
package com.bjpowernode.mybatis.test;
import com.bjpowernode.mybatis.mapper.CarMapper;
import com.bjpowernode.mybatis.pojo.Car;
import com.bjpowernode.mybatis.pojo.CarExample;
import com.bjpowernode.mybatis.utils.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.math.BigDecimal;
import java.util.List;
public class CarMapperTest {
@Test
public void testSelect(){
SqlSession sqlSession = SqlSessionUtil.openSession();
CarMapper mapper = sqlSession.getMapper(CarMapper.class);
// 执行查询
// 1. 查询一个
Car car = mapper.selectByPrimaryKey(34L);
System.out.println(car);
// 2. 查询所有（selectByExample，根据条件查询，如果条件是null表示没有条件）
List<Car> cars = mapper.selectByExample(null);
cars.forEach(car1 -> System.out.println(car1));
System.out.println("==================");
// 3.按照条件进行查询
// QBC 风格：Query By Criteria 一种查询方式，比较面向对象，看不到sql语句。
// 3.1 封装条件，通过CarExample对象来封装查询条件
CarExample carExample = new CarExample();
// 3.2调用carExample.createCriteria()方法来创建查询条件
carExample.createCriteria().andBrandLike("帕萨特").
andGuidePriceGreaterThan(new BigDecimal(20.0));
// 添加or
carExample.or().andCarTypeEqualTo("燃油车");
// 执行查询
List<Car> cars1 = mapper.selectByExample(carExample);
cars1.forEach(car1 -> System.out.println(car1));
sqlSession.close();
}
}以上的SQL语句就等价于：
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