mybatis高级扩展-批量映射优化-mappers标签中使用package批量注册的前提条件

1、建库建表

create database `mybatis-example`;
use `mybatis-example`;
create table emp
(
    empNo   varchar(40),
    empName varchar(100),
    sal int,
    deptno varchar(10)
);
insert into emp values('e001','张三',8000,'d001');
insert into emp values('e002','李四',9000,'d001');
insert into emp values('e003','王五',10000,'d001');
insert into emp values('e004','赵六',11000,'d002');
insert into emp values('e005','田七',12000,'d002');
insert into emp values('e006','周八',13000,'d003');
insert into emp values('e007','吴九',14000,'d004');
insert into emp values('e008','郑十',15000,'d004');
insert into emp values('d8f9b794-95ba-11ee-ab75-84a93ea22bfb','张三丰',16000,'d001');

2、pom.xml

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
        </dependency>
 
        <!-- MySQL驱动 mybatis底层依赖jdbc驱动实现,本次不需要导入连接池,mybatis自带! -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
 
        <!--junit5测试-->
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
        </dependency>
 
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
 
        <!-- 日志 ， 会自动传递slf4j门面-->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
        </dependency>
    </dependencies>

3、Emp.java

package com.atguigu.mybatis.pojo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Emp {
    private String empNo;
    private Integer sal;
    private String empName;
    private String deptno;
}

4、com/atguigu/mybatis/mappper/EmpMapper.java

package com.atguigu.mybatis.mapper;
import com.atguigu.mybatis.pojo.Emp;
import org.apache.ibatis.annotations.Param;
import java.util.List;
public interface EmpMapper {
    //1.演示where-if标签
    List<Emp> getEmpList(Emp emp);

    //2、演示set标签
    void updateEmp(Emp emp);

    //3、演示trim标签
    List<Emp> getEmpList2(Emp emp);

    //4、演示choose/when/otherwise标签
    List<Emp> getEmpList3(Emp emp);

    //5、演示foreach标签
    List<Emp> getEmpList4(@Param("empNoList") List<String> empNoList);
}

5、mybatis-config.xml

<?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>

    <!-- 具体配置 -->
    <!-- 从org.apache.ibatis.session.Configuration类中可以查看能使用的配置项 -->
    <!-- 将mapUnderscoreToCamelCase属性配置为true，表示开启自动映射驼峰式命名规则 -->
    <!-- 规则要求数据库表字段命名方式：单词_单词 -->
    <!-- 规则要求Java实体类属性名命名方式：首字母小写的驼峰式命名 -->
    <settings>
        <setting name="lazyLoadingEnabled" value="true"/>
        <setting name="autoMappingBehavior" value="FULL"/>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>

    <typeAliases>
        <!--<typeAlias type="com.atguigu.mybatis.pojo.Employee" alias="emp"/>-->
        <package name="com.atguigu.mybatis.pojo"/>
    </typeAliases>

    <!-- environments表示配置Mybatis的开发环境，可以配置多个环境，在众多具体环境中，使用default属性指定实际运行时使用的环境。default属性的取值是environment标签的id属性的值。 -->
    <environments default="development">
        <!-- environment表示配置Mybatis的一个具体的环境 -->
        <environment id="development">
            <!-- Mybatis的内置的事务管理器 -->
            <transactionManager type="JDBC"/>
            <!-- 配置数据源 -->
            <dataSource type="POOLED">
                <!-- 建立数据库连接的具体信息 -->
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis-example"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!-- Mapper注册：指定Mybatis映射文件的具体位置 -->
        <!-- mapper标签：配置一个具体的Mapper映射文件 -->
        <!-- resource属性：指定Mapper映射文件的实际存储位置，这里需要使用一个以类路径根目录为基准的相对路径 -->
        <!-- 对Maven工程的目录结构来说，resources目录下的内容会直接放入类路径，所以这里我们可以以resources目录为基准 -->
        <!--<mapper resource="mappers/EmpMapper.xml"/>-->
        <package name="com.atguigu.mybatis.mapper"/>
    </mappers>

</configuration>

6、com/atguigu/mybatis/mappper/EmpMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- namespace等于mapper接口类的全限定名,这样实现对应 -->
<mapper namespace="com.atguigu.mybatis.mapper.EmpMapper">

    <select id="getEmpList" resultType="Emp">
        select * from emp
        <where>
            <if test="empNo!= null">
                empNo=#{empNo}
            </if>
            <if test="empName!= null">
                and empName=#{empName}
            </if>
            <if test="sal!=null">
                and sal &lt; #{sal}
            </if>
            <if test="deptno!=null">
                and deptno=#{deptno}
            </if>
        </where>
        <!--
                select * from emp
                select * from emp WHERE empNo=?
                select * from emp WHERE sal < ?
                select * from emp WHERE empName=?
                select * from emp WHERE deptno=?
                select * from emp WHERE empNo=? and sal < ?
                select * from emp WHERE empNo=? and empName=? and sal < ?
                select * from emp WHERE empNo=? and empName=? and sal < ? and deptno=?
        -->
    </select>

    <update id="updateEmp">
        update emp
        <set>
            <if test="empName!=null">
                empName=#{empName},
            </if>
            <if test="sal!=null">
                sal=#{sal},
            </if>
            <if test="deptno!=null">
                deptno=#{deptno}
            </if>
        </set>
        where empNo=#{empNo}
        <!--
               update emp SET empName=?, sal=?, deptno=? where empNo=?
               update emp SET empName=? where empNo=?
               update emp                    where empNo=?
        -->
    </update>

    <select id="getEmpList2" resultType="Emp">
        select * from emp
        <trim prefix="where" suffix=";" prefixOverrides="or|and" suffixOverrides="or">
            <if test="empNo!=null">
                or empNo=#{empNo} or
            </if>
            <if test="empName!=null">
                or empName=#{empName} or
            </if>
            <if test="sal!=null">
                or sal &lt; #{sal} or
            </if>
            <if test="deptno!=null">
                or deptno=#{deptno} or
            </if>
        </trim>
    </select>

    <select id="getEmpList3" resultType="Emp">
        select * from emp where
        <choose>
            <when test="empNo!=null">
                empNo=#{empNo}
            </when>
            <when test="empName!=null">
                 empName=#{empName}
            </when>
            <when test="sal!=null">
                 sal &lt; #{sal}
            </when>
            <when test="deptno!=null">
                 deptno=#{deptno}
            </when>
            <otherwise>
                1=1
            </otherwise>
        </choose>
    </select>

    <select id="getEmpList4" resultType="Emp">
        <include refid="allColumns"></include>
        from emp where empNo in
        <foreach collection="empNoList" item="employeeNumber" open="(" close=")" separator=",">
            #{employeeNumber}
        </foreach>
    </select>

    <sql id="allColumns">
        select empNo,empName,sal,deptno,'China' as 'address'
    </sql>
</mapper>

7、logback.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration debug="true">
    <!-- 指定日志输出的位置，ConsoleAppender表示输出到控制台 -->
    <appender name="STDOUT"
              class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <!-- 日志输出的格式 -->
            <!-- 按照顺序分别是：时间、日志级别、线程名称、打印日志的类、日志主体内容、换行 -->
            <pattern>[%d{HH:mm:ss.SSS}] [%-5level] [%thread] [%logger] [%msg]%n</pattern>
            <charset>UTF-8</charset>
        </encoder>
    </appender>
 
    <!-- 设置全局日志级别。日志级别按顺序分别是：TRACE、DEBUG、INFO、WARN、ERROR -->
    <!-- 指定任何一个日志级别都只打印当前级别和后面级别的日志。 -->
    <root level="DEBUG">
        <!-- 指定打印日志的appender，这里通过“STDOUT”引用了前面配置的appender -->
        <appender-ref ref="STDOUT" />
    </root>
 
    <!-- 根据特殊需求指定局部日志级别，可以是包名或全类名。 -->
    <logger name="com.atguigu.mybatis" level="DEBUG" />
</configuration>

8、MybatisTest.java

package mybatis;
import com.atguigu.mybatis.mapper.EmpMapper;
import com.atguigu.mybatis.pojo.Emp;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
public class MybatisTest {
 
    SqlSessionFactory sqlSessionFactory;
    SqlSession sqlSession;
    EmpMapper empMapper;
 
    @BeforeEach
    public void setup() throws IOException {
        // 获取资源流，读取"mybatis-config.xml"文件
        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
        // 使用资源流创建SqlSessionFactory
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 使用SqlSessionFactory打开一个Session
        sqlSession = sqlSessionFactory.openSession();
        //基于Mapper接口编程
        empMapper=sqlSession.getMapper(EmpMapper.class);
    }
 
    // 在每个测试用例之后执行的清理方法
    @AfterEach
    public void teardown() {
        sqlSession.commit();  // 提交事务
        sqlSession.close();  // 关闭SqlSession
    }
 
    @Test
    public void selectWhereIFTest() {
        /**
         * 1、所有条件都不满足
         */
        Emp emp = new Emp();
        empMapper.getEmpList(emp).forEach(System.out::println);//select * from emp
        //Emp(empNo=e001, sal=8000, empName=张三, deptno=d001)
        //Emp(empNo=e002, sal=9000, empName=李四, deptno=d001)
        //Emp(empNo=e003, sal=10000, empName=王五, deptno=d001)
        //Emp(empNo=e004, sal=11000, empName=赵六, deptno=d002)
        //Emp(empNo=e005, sal=12000, empName=田七, deptno=d002)
        //Emp(empNo=e006, sal=13000, empName=周八, deptno=d003)
        //Emp(empNo=e007, sal=14000, empName=吴九, deptno=d004)
        //Emp(empNo=e008, sal=15000, empName=郑十, deptno=d004)
        //Emp(empNo=d8f9b794-95ba-11ee-ab75-84a93ea22bfb, sal=16000, empName=张三丰, deptno=d001)
 
        /**
         * 2、一个条件满足
         */
        Emp emp1 = new Emp();
        emp1.setEmpNo("e002");
        empMapper.getEmpList(emp1).forEach(System.out::println);//select * from emp WHERE empNo=?
        //Emp(empNo=e002, sal=9000, empName=李四, deptno=d001)
 
        Emp emp2 = new Emp();
        emp2.setSal(11000);
        empMapper.getEmpList(emp2).forEach(System.out::println);//select * from emp WHERE sal < ?
        //Emp(empNo=e001, sal=8000, empName=张三, deptno=d001)
        //Emp(empNo=e002, sal=9000, empName=李四, deptno=d001)
        //Emp(empNo=e003, sal=10000, empName=王五, deptno=d001)
 
        Emp emp3 = new Emp();
        emp3.setEmpName("张三丰");
        empMapper.getEmpList(emp3).forEach(System.out::println);//select * from emp WHERE empName=?
        //Emp(empNo=d8f9b794-95ba-11ee-ab75-84a93ea22bfb, sal=16000, empName=张三丰, deptno=d001)
 
        Emp emp4 = new Emp();
        emp4.setDeptno("d001");
        empMapper.getEmpList(emp4).forEach(System.out::println);//select * from emp WHERE deptno=?
        //Emp(empNo=e001, sal=8000, empName=张三, deptno=d001)
        //Emp(empNo=e002, sal=9000, empName=李四, deptno=d001)
        //Emp(empNo=e003, sal=10000, empName=王五, deptno=d001)
        //Emp(empNo=d8f9b794-95ba-11ee-ab75-84a93ea22bfb, sal=16000, empName=张三丰, deptno=d001)
 
        /**
         * 2、两个条件满足
         */
        Emp emp5 = new Emp();
        emp5.setEmpNo("e002");
        emp5.setSal(11000);
        empMapper.getEmpList(emp5).forEach(System.out::println);//select * from emp WHERE empNo=? and sal <?
        //Emp(empNo=e002, sal=9000, empName=李四, deptno=d001)
 
        /**
         * 3、三个条件都满足，以次类推
         */
        Emp emp6 = new Emp();
        emp6.setEmpNo("e002");
        emp6.setSal(11000);
        emp6.setEmpName("张三丰");
        empMapper.getEmpList(emp6).forEach(System.out::println);//select * from emp WHERE empNo=? and empName=? and sal < ?
 
 
        /**
         * 4、全部条件满足
         */
        Emp emp100 = new Emp("e001",8001,"张三","d001");
        empMapper.getEmpList(emp100).forEach(System.out::println);//select * from emp WHERE empNo=? and empName=? and sal < ? and deptno=?
        //Emp(empNo=e001, sal=8000, empName=张三, deptno=d001)
    }
 
    @Test
    public void updateSetIfTest() {
 
        /**
         * 1、所有条件都满足
         */
        Emp emp = new Emp("e001",4000,"张三","d001");
        empMapper.updateEmp(emp);//update emp SET empName=?, sal=?, deptno=? where empNo=?
 
        /**
         * 2、部分条件满足
         */
        Emp emp1 = new Emp();
        emp1.setEmpNo("e002");
        emp1.setEmpName("张无忌");
        empMapper.updateEmp(emp1);//update emp SET empName=? where empNo=?
 
        /**
         * 3、所有条件都不满足，报错SQLSyntaxErrorException
         */
        Emp emp2 = new Emp();
        emp2.setEmpNo("e003");
        empMapper.updateEmp(emp2);
 
    }
 
    @Test
    public void trimTest() {
        Emp emp = new Emp();
        empMapper.getEmpList2(emp).forEach(System.out::println);//select * from emp
 
        Emp emp1 = new Emp();
        emp1.setEmpNo("e001");
        empMapper.getEmpList2(emp1).forEach(System.out::println);//select * from emp where empNo=? ;
    }
 
    @Test
    public void chooseWhenTest() {
 
        Emp emp1 = new Emp();
        empMapper.getEmpList3(emp1).forEach(System.out::println);//select * from emp where 1=1
 
        Emp emp2 = new Emp();
        emp2.setEmpNo("e001");
        empMapper.getEmpList3(emp2).forEach(System.out::println);//select * from emp where empNo=?
 
        Emp emp3 = new Emp();
        emp3.setEmpNo("e002");
        emp3.setEmpNo("李四");
        empMapper.getEmpList3(emp3).forEach(System.out::println);//select * from emp where empNo=?
    }
 
    @Test
    public void foreachTest() {
        Emp emp = new Emp();
        empMapper.getEmpList4(Arrays.asList("e001","e002")).forEach(System.out::println);
        //select * from emp where empNo in ( ? , ? )
        //Emp(empNo=e001, sal=4000, empName=张三, deptno=d001)
        //Emp(empNo=e002, sal=9000, empName=李四, deptno=d001)
    }
}