mybatis动态sql之foreach补充(三)
发布时间:2020-12-14 18:02:23 所属栏目:大数据 来源:网络整理
导读:public ListEmployee getEmpByForeach4(@Param("map") MapString,Object map); 如果传入的是Map, select id ="getEmpByForeach4" resultType ="com.gong.mybatis.bean.Employee" select * from tbl_employee where id in foreach collection ="map" index =
public List<Employee> getEmpByForeach4(@Param("map") Map<String,Object> map);
如果传入的是Map, <select id="getEmpByForeach4" resultType="com.gong.mybatis.bean.Employee"> select * from tbl_employee where id in foreach collection="map" index="index" item="item" separator="," open="(" close=")" #{index} </foreach> select> 这里需要注意index属性和item属性。index属性里的值是Map的键,item的值是Map的值。 如果我们在foreach中使用#{index}: 进行测试: package com.gong.mybatis.test; import java.io.IOException; java.io.InputStream; java.util.ArrayList; java.util.Arrays; java.util.HashMap; java.util.List; java.util.Map; 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; public 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.); Map<String,Object> map = new HashMap<String,Object>(); Employee e1 = Employee(); e1.setId(1); Employee e2 = Employee(); e2.setId(2); map.put("1",e1); map.put("2" mapper.getEmpByForeach4(map); for(Employee e:es) { System.out.println(e); } openSession.commit(); } finally { openSession.close(); } } } 输出: DEBUG 01-21 16:59:08,912 ==> Preparing: select * from tbl_employee where id in ( ?,? ) (BaseJdbcLogger.java:145) DEBUG 01-21 16:59:08,966 ==> Parameters: 1(String),2(String) (BaseJdbcLogger.java:145) DEBUG 01-21 16:59:09,019 == 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] 是根据Map中的键进行查询, 如果更改为: #{item.id} 结果: DEBUG 01-21 17:00:23,650 ==> Preparing: select * from tbl_employee where id in ( ?,? ) (BaseJdbcLogger.java:145) DEBUG 01-21 17:00:23,710 ==> Parameters: 1(Integer),2(Integer) (BaseJdbcLogger.java:145) DEBUG 01-21 17:00:23,762 =null] 根据值进行查询时,需要根据Map值里面存储的数据类型进行相应的操作。此处里面存储的是Employee对象,因此item就代表Employee对象,通过item.id的形式取得里面存储的id的值,再传给foreach进行操作。 foreach传入的参数几种形式就大致如此了。 (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |