mybatis使用foreach遍历list集合或者array数组方式

mybatis使用foreach遍历list集合或者array数组方式

一、准备工作

1.db.properties文件（记得修改自己的数据库和用户名、密码）

dataSource.driver=com.mysql.jdbc.Driver

dataSource.url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf8

dataSource.username=blog

dataSource.password=blog

2.主配置文件

PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd">

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 = agemDlobMgQGz;

}

public String getAddress() {

return address;

}

public void setAddress(String address) {

this.address = address;

}

@Override

public 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 idList;

public Integer[] getIds() {

return ids;

}

public void setIds(Integer[] ids) {

this.ids = ids;

}

public List getIdList() {

return idList;

}

public void setIdList(List 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

PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-mapper.dtd">

select * from t_user where uid in

#{item}

select * from t_user where uid in

#{item}

select * fmDlobMgQGzrom t_user where uid in

#{item}

select * from t_user where uid in

#{item}

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 selectByList(List testlist);

//用数组封装条件

public List selectByArray(Integer[] ids);

//用包装类中的数组封装条件

public List selectUserVoByArray(UserVo userVo);

//用包装类中的list封装条件

public List 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

@Test

public 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 idList = new ArrayList();

idhttp://List.add(5);

idList.add(3);

idList.add(123);

idList.add(19);

UserVo userVo = new UserVo();

userVo.setIdList(idList);

List 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

@Test

public 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 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

@Test

public 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 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

@Test

public 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 list = new ArrayList();

list.add(5);

list.add(3);

list.add(123);

list.add(19);

List 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

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