mybatis使用foreach遍历list集合或者array数组方式

dataSource.driver=com.mysql.jdbc.DriverdataSource.url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf8dataSource.username=blogdataSource.password=blog2.主配置文件

<?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><!-- 引入外部配置文件--><properties resource='db.properties'></properties><!-- 别名设置，不设置时引用要使用全包名，设置后可以使用自定义别名，更加简洁 --><typeAliases><!-- 别名设置有两种，一种是一个一个设置，另外一种是设置某个包，默认别名为类名（大小写都可以，建议小写） --><!-- 第一种设置 <typeAlias type='com.mybatis_demo.domain.User' alias='user'/>--> <!-- 第二种设置，整个包下面的类都进行别名设置，推荐第二种 --> <package name='com.mybatis_demo.domain'/> </typeAliases><!-- 环境模式：development开发模式 work工作模式 --> <environments default='development'> <!-- 环境变量 --> <environment id='development'> <!-- 使用jdbc的事务管理 --> <transactionManager type='JDBC'/> <!-- 使用连接池 --> <dataSource type='POOLED'><property name='driver' value='${dataSource.driver}'/><property name='url' value='${dataSource.url}'/><property name='username' value='${dataSource.username}'/><property name='password' value='${dataSource.password}'/> </dataSource> </environment> </environments> <!-- 引入mapper映射文件 --> <mappers> <!-- 1.相对路径引入--> <!-- <mapper resource='mapper/UserMapper.xml'/> --> <!-- 2.绝对路径引入 --> <!-- <mapper url='file:D:sts-bundleworkplacemybatis_demosrcmainresourcesmapperUserMapper.xml'/> --> <!-- 3.对应mapper接口全包名引入，需要对应的mapper.xml与接口mapper处于同一包下才可以，且xml文件名与接口名要相同，xml文件中的namespace必须是对应接口的全包名 --> <!-- <mapper /> --> <!-- 4.包引入，要求跟接口引入一样 --> <!-- <mapper resource='mapper/UserMapper2.xml'/> --> <package name='com.mybatis_demo.mapper'/> </mappers></configuration>3.创建User类和包装类UserVo

User.java

package com.mybatis_demo.domain;public class User {private Integer uid;private String uname;private Integer age;private String address;public Integer getUid() {return uid;}public void setUid(Integer uid) {this.uid = uid;}public String getUname() {return uname;}public void setUname(String uname) {this.uname = uname;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}@Overridepublic String toString() {return 'User [uid=' + uid + ', uname=' + uname + ', age=' + age + ', address=' + address + ']';}}

UserVo.java

package com.mybatis_demo.domain;import java.util.List;public class UserVo extends User {private Integer[] ids;private List<Integer> idList;public Integer[] getIds() {return ids;}public void setIds(Integer[] ids) {this.ids = ids;}public List<Integer> getIdList() {return idList;}public void setIdList(List<Integer> idList) {this.idList = idList;}}二、遍历数组和集合的映射文件和对应的接口1.mapper映射文件

<?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.mybatis_demo.mapper.UserMapper'><!-- 遍历list集合，collection='list'，如果你传参的时候是直接传递list集合，那么这里只能填list,不能填参数名 --><select resultType='User'>select * from t_user where uid in<foreach collection='list' item='item' open='(' separator=',' close=')'>#{item}</foreach></select><!-- 遍历数组 ，collection='array'，如果你传参的时候是直接传递数组，那么这里只能填array,不能填参数名--><select resultType='User'>select * from t_user where uid in<foreach collection='array' item='item' open='(' separator=',' close=')'>#{item}</foreach></select><!-- 遍历包装类中的数组，collection='ids'，这里不再是array,而是包装类中对应的变量名，因为你传递的参数是一个包装类，mybatis是通过get方法获取包装类中的数组 --><select parameterType='UserVo' resultType='User'>select * from t_user where uid in<foreach collection='ids' item='item' open='(' separator=',' close=')'>#{item}</foreach></select><!-- 遍历包装类中的list集合，collection='idList'，这里不再是list,而是包装类中对应的变量名，因为你传递的参数是一个包装类，mybatis是通过get方法获取包装类中的list集合 --><select parameterType='UserVo' resultType='User'>select * from t_user where uid in<foreach collection='idList' item='item' open='(' separator=',' close=')'>#{item}</foreach></select></mapper>2.mapper接口

UserMapper.interface

package com.mybatis_demo.mapper;import java.util.List;import java.util.Map;import com.mybatis_demo.domain.User;import com.mybatis_demo.domain.UserVo;public interface UserMapper {//mybatis使用mapper动态代理//4大原则，一个注意//1.接口中的方法名需要与对应mapper.xml的id一致//2.接口中的返回值需要与对应mapper.xml的返回值类型保持一致//3.接口中的参数需要与对应mapper.xml的参数类型、个数、参数名保持一致//4.对应mapper.xml的名字空间需要修改成对应接口的全包名//注意：mapper动态代理根据返回值类型,mybatis会自动选择调用selectone还是selectlist....//用list封装条件public List<User> selectByList(List<Integer> testlist);//用数组封装条件public List<User> selectByArray(Integer[] ids);//用包装类中的数组封装条件public List<User> selectUserVoByArray(UserVo userVo);//用包装类中的list封装条件public List<User> selectUserVoByList(UserVo userVo);}三、测试代码

package com.mybatis_demo.test;import java.io.IOException;import java.io.InputStream;import java.util.ArrayList;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.mybatis_demo.domain.User;import com.mybatis_demo.domain.UserVo;import com.mybatis_demo.mapper.UserMapper;public class TestMapper {//用包装类中的list封装条件，传递参数是一个包装类@Testpublic void test_selectUserVoByList() {try { //读取配置文件InputStream in = Resources.getResourceAsStream('sqlMapConfig.xml');//创建SqlSessionFactoryBuilder对象，用来获取SqlSessionFactory对象SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();//利用SqlSessionFactoryBuilder对象build一个SqlSessionFactory对象SqlSessionFactory build = builder.build(in);//利用sqlSessionFactory获取session对象SqlSession session = build.openSession();//通过session对象获取对应mapper接口UserMapper mapper = session.getMapper(UserMapper.class);List<Integer> idList = new ArrayList<Integer>();idList.add(5);idList.add(3);idList.add(123);idList.add(19);UserVo userVo = new UserVo();userVo.setIdList(idList);List<User> users = mapper.selectUserVoByList(userVo);for (User user : users) {System.out.println(user);}} catch (IOException e) {e.printStackTrace();}}//用包装类中的array封装条件，传递参数是一个包装类@Testpublic void test_selectUserVoByArray() {try { //读取配置文件InputStream in = Resources.getResourceAsStream('sqlMapConfig.xml');//创建SqlSessionFactoryBuilder对象，用来获取SqlSessionFactory对象SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();//利用SqlSessionFactoryBuilder对象build一个SqlSessionFactory对象SqlSessionFactory build = builder.build(in);//利用sqlSessionFactory获取session对象SqlSession session = build.openSession();//通过session对象获取对应mapper接口UserMapper mapper = session.getMapper(UserMapper.class);Integer[] ids = new Integer[]{5,9,30};UserVo userVo = new UserVo();userVo.setIds(ids);List<User> users = mapper.selectUserVoByArray(userVo);for (User user : users) {System.out.println(user);}} catch (IOException e) {e.printStackTrace();}}//用数组封装条件，传递参数是一个数组@Testpublic void test_selectByArray() {try { //读取配置文件InputStream in = Resources.getResourceAsStream('sqlMapConfig.xml');//创建SqlSessionFactoryBuilder对象，用来获取SqlSessionFactory对象SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();//利用SqlSessionFactoryBuilder对象build一个SqlSessionFactory对象SqlSessionFactory build = builder.build(in);//利用sqlSessionFactory获取session对象SqlSession session = build.openSession();//通过session对象获取对应mapper接口UserMapper mapper = session.getMapper(UserMapper.class);Integer[] ids = new Integer[]{5,9,30};List<User> users = mapper.selectByArray(ids);for (User user : users) {System.out.println(user);}} catch (IOException e) {e.printStackTrace();}}//用list封装条件，传递参数是一个list集合@Testpublic void test_selectByList() {try { //读取配置文件InputStream in = Resources.getResourceAsStream('sqlMapConfig.xml');//创建SqlSessionFactoryBuilder对象，用来获取SqlSessionFactory对象SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();//利用SqlSessionFactoryBuilder对象build一个SqlSessionFactory对象SqlSessionFactory build = builder.build(in);//利用sqlSessionFactory获取session对象SqlSession session = build.openSession();//通过session对象获取对应mapper接口UserMapper mapper = session.getMapper(UserMapper.class);List<Integer> list = new ArrayList<Integer>();list.add(5);list.add(3);list.add(123);list.add(19);List<User> users = mapper.selectByList(list);for (User user : users) {System.out.println(user);}} catch (IOException e) {e.printStackTrace();}}}四、总结

1.如果你传参的时候直接传一个数组，那么使用foreach遍历时collection=“array”,这里是固定写法，即这里的array与你的实参名无关

2.如果你传参的时候直接传一list集合，那么使用foreach遍历时collection=“list”,这里是固定写法，即这里的list与你的实参名无关

3.如果你传参的时候直接传一个含有数组成员变量的类，那么使用foreach遍历时collection=“你的变量名”,这里不再是固定写法，即这里的命名取决于成员变量的变量名，例如：成员变量名是test,那么就是collection=“test”

4.如果你传参的时候直接传一个含有list集合成员变量的类，跟3的情况一样

以上为个人经验，希望能给大家一个参考，也希望大家多多支持好吧啦网。