标签：形式 com arraylist code array session 数据 builder util
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; import java.io.InputStream; import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; 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.Test; import com.gong.mybatis.bean.Employee; import 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 public void test() throws IOException { SqlSessionFactory sqlSessionFactory = getSqlSessionFactory(); SqlSession openSession = sqlSessionFactory.openSession(); try { EmployeeMapperDynamicSql mapper = openSession.getMapper(EmployeeMapperDynamicSql.class); Map<String,Object> map = new HashMap<String, Object>(); Employee e1 = new Employee(); e1.setId(1); Employee e2 = new Employee(); e2.setId(2); map.put("1", e1); map.put("2", e2); List<Employee> es = 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, gender=1, email=dema@qq.com, dept=null] Employee [id=2, lastName=jack, gender=1, email=675544321@qq.com, dept=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 <== Total: 2 (BaseJdbcLogger.java:145) Employee [id=1, lastName=dema, gender=1, email=dema@qq.com, dept=null] Employee [id=2, lastName=jack, gender=1, email=675544321@qq.com, dept=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。
标签：形式 com arraylist code array session 数据 builder util
原文地址：https://www.cnblogs.com/xiximayou/p/12222399.html
