1.先引入pom文件
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.1</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.29</version>
</dependency>
</dependencies>
<!--这是方便后面编译时可以带着xml文件-->
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
</build>
2.编写实体类domain.student，定义好字段与getter,setter
package com.bjpowernode.domain; public class Student { private Integer id; private String phone; private String truename; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; }
3.定义接口文件dao.studentDao
package com.bjpowernode.dao; import com.bjpowernode.domain.Student; import java.util.List; public interface StudentDao { public List<Student> selectStudents(); }
4.定义 dao.studentDao.xml的mapper文件
注意： namespace必须是对应接口文件的全限定名称，resulttype必须是对应的实体类，不然报错
<?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.dao.StudentDao"> <select id="selectStudents" resultType="com.bjpowernode.domain.Student"> select id,phone,truename from user </select> </mapper>
5.定义resources下的mybatis配置文件
<?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>
//加这个可以打印日志
<settings>
<setting name="logImpl" value="STDOUT_LOGGING"/>
</settings>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/daikuan?characterEncoding=utf-8"/>
<property name="username" value="root"/>
<property name="password" value=""/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/bjpowernode/dao/StudentDao.xml"/>
</mappers>
</configuration>
6.编写功能测试类Myapp
<select id="pageList" resultType="com.jjccb.mall.modules.privilege.entity.ImsActivityPrivilegePrize"> SELECT p.*, ( CASE p.type WHEN 2 THEN c.activity_name WHEN 1 THEN w.white_name END ) AS 'name' FROM ims_activity_privilege_prize p LEFT JOIN ims_yidu_coupon c ON p.ref_id = c.id AND p.type = 2 LEFT JOIN ims_yidu_whitelist w ON p.ref_id = w.id AND p.type = 1 <where> <if test=" dto.type == 1 "> AND p.type = 1 </if> <if test=" dto.type == 2 "> AND p.type = 2 </if> </where> </select>
mybatis-plus批量更新指定条件的数据
ImsYiduAdmin update = new ImsYiduAdmin(); update.setAccount("1231231"); LambdaQueryWrapper<ImsYiduAdmin> where = new LambdaQueryWrapper(); where.eq(ImsYiduAdmin::getAccount, "123"); adminService.update(update, where);
方式2：
1.搭建好spring boot项目。
2.定义好application.properties
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver spring.datasource.url=jdbc:mysql://localhost:3306/bing spring.datasource.username=root spring.datasource.password= mybatis.mapper-locations=classpath*:/mapper/*.xml //这个很重要
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl//控制台打印SQL日志
3.创建好controller层，servive层(@service)，entity层,mapper层（@mapper），serviceImpl类中需要autowire引入mapper层的对象才能调用
4.然后在resources/mapper目录下写查询的xml文件，其中namespace是指mapper接口层的路径，resultType为返回的实体路径
mapper里的另一种用法
@Mapper public interface UserDAO { @Select("select * from user where name = #{name}") public User find(String name); @Select("select * from user where name = #{name} and pwd = #{pwd}") /** * 对于多个参数来说，每个参数之前都要加上@Param注解， * 要不然会找不到对应的参数进而报错 */ public User login(@Param("name")String name, @Param("pwd")String pwd); }
