mybatis动态sql之foreach补充(一)
发布时间:2020-12-14 18:02:37 所属栏目:大数据 来源:网络整理
导读:EmployeeMapperDynamicSql.java package com.gong.mybatis.mapper; import java.util.List; java.util.Map; org.apache.ibatis.annotations.MapKey; org.apache.ibatis.annotations.Param; com.gong.mybatis.bean.Employee; public interface EmployeeMapper
EmployeeMapperDynamicSql.java package com.gong.mybatis.mapper; import java.util.List; java.util.Map; org.apache.ibatis.annotations.MapKey; org.apache.ibatis.annotations.Param; com.gong.mybatis.bean.Employee; public interface EmployeeMapperDynamicSql { public List<Employee> getEmpByConditionIf(Employee employee); void updateEmp(Employee employee); public List<Employee> getEmpByForeach(@Param("ids") List<Integer> ids); public List<Employee> getEmpByForeach2(List<Employee> employee); } EmployeeMapperDynamicSql.xml <?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.gong.mybatis.mapper.EmployeeMapperDynamicSql"> <!-- 查询,要查那个就带上那个条件 --> select id="getEmpByConditionIf" resultType="com.gong.mybatis.bean.Employee"> select * from tbl_employee where> choose> when test="id!=null" id=#{id} </when="lastName!=null" last_name like #{lastName} ="email!=null" email=#{email} otherwise> select> update ="updateEmp" update tbl_employee trim prefix="set" suffixOverrides=","if last_name=#{lastName},if="gender!=null and gender == 0 or gender == 1" gender=#{gender},1)"> email=#{email} trim where id=#{id} update="getEmpByForeach" select * from tbl_employee where id in foreach collection="ids" item="item_id" separator open="(" close=")" #{item_id} foreach="getEmpByForeach2"="list"="item" #{item.id} > mapper> 说明,现在我们使用public List<Employee> getEmpByForeach2(List<Employee> employee);,传入的是一个Employee集合,那么此时我们应该怎么使用foreach呢? 我们可以在collection中对应着list类型,即collection="list"。 测试: com.gong.mybatis.test; java.io.IOException; java.io.InputStream; java.util.ArrayList; java.util.Arrays; org.apache.ibatis.io.Resources; org.apache.ibatis.session.SqlSession; org.apache.ibatis.session.SqlSessionFactory; org.apache.ibatis.session.SqlSessionFactoryBuilder; org.junit.Test; com.gong.mybatis.bean.Employee; com.gong.mybatis.mapper.EmployeeMapperDynamicSql; class TestMybatis3 { public SqlSessionFactory getSqlSessionFactory() throws IOException { String resource = "mybatis-config.xml"; InputStream is = Resources.getResourceAsStream(resource); return new SqlSessionFactoryBuilder().build(is); } @Test void test() IOException { SqlSessionFactory sqlSessionFactory = getSqlSessionFactory(); SqlSession openSession = sqlSessionFactory.openSession(); try { EmployeeMapperDynamicSql mapper = openSession.getMapper(EmployeeMapperDynamicSql.); List<Employee> emps = new ArrayList<Employee>(); Employee e1 = Employee(); e1.setId(1); Employee e2 = Employee(); e2.setId(2); emps.add(e1); emps.add(e2); List<Employee> es = mapper.getEmpByForeach2(emps); for(Employee e:es) { System.out.println(e); } openSession.commit(); } finally { openSession.close(); } } } 结果: DEBUG 01-21 16:21:28,692 ==> Preparing: select * from tbl_employee where id in ( ?,? ) (BaseJdbcLogger.java:145) DEBUG 01-21 16:21:28,783 ==> Parameters: 1(Integer),2(Integer) (BaseJdbcLogger.java:145) DEBUG 01-21 16:21:28,813 == Total: 2 (BaseJdbcLogger.java:145) Employee [id=1,lastName=dema,1)">genderemail=dema@qq.com,1)">dept=null] Employee [id=2,1)">=jack,1)">=675544321@qq.com,1)">=null] 成功的通过id将对象取出来。 当然,我们也可以取别名: public List<Employee> getEmpByForeach2(@Param("emps") List<Employee> employee);
然后在使collection="emps",其余不变,还是可以达到一样的效果。
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