MyBatis参数传入集合之foreach动态sql

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foreach的主要用在构建in条件中，它可以在SQL语句中进行迭代一个集合。foreach元素的属性主要有item，index，collection，open，separator，close。item表示集合中每一个元素进行迭代时的别名，index指定一个名字，用于表示在迭代过程中，每次迭代到的位置，open表示该语句以什么开始，separator表示在每次进行迭代之间以什么符号作为分隔符，close表示以什么结束，在使用foreach的时候最关键的也是最容易出错的就是collection属性，该属性是必须指定的，但是在不同情况下，该属性的值是不一样的，主要有一下3种情况： 

1. 如果传入的是单参数且参数类型是一个List的时候，collection属性值为list .
2. 如果传入的是单参数且参数类型是一个array数组的时候，collection的属性值为array .
3. 如果传入的参数是多个的时候，我们就需要把它们封装成一个Map了，当然单参数也可以封装成map，实际上如果你在传入参数的时候，在MyBatis里面也是会把它封装成一个Map的，map的key就是参数名，所以这个时候collection属性值就是传入的List或array对象在自己封装的map里面的key.

下面我们通过代码实践:   数据表: 采用Oracle的HR.Employees表         实体:Employees
public class Employees {
    private Integer employeeId;
    private String firstName;
    private String lastName;
    private String email;
    private String phoneNumber;
    private Date hireDate;
    private String jobId;
    private BigDecimal salary;
    private BigDecimal commissionPct;
    private Integer managerId;
    private Short departmentId;
}  
映射文件:

    <!--List:forech中的collection属性类型是List,collection的值必须是:list,item的值可以随意,Dao接口中参数名字随意 -->
    <select id="getEmployeesListParams" resultType="Employees">
        select *
        from EMPLOYEES e
        where e.EMPLOYEE_ID in
        <foreach collection="list" item="employeeId" index="index"
            open="(" close=")" separator=",">
            #{employeeId}
        </foreach>
    </select>

    <!--Array:forech中的collection属性类型是array,collection的值必须是:list,item的值可以随意,Dao接口中参数名字随意 -->
    <select id="getEmployeesArrayParams" resultType="Employees">
        select *
        from EMPLOYEES e
        where e.EMPLOYEE_ID in
        <foreach collection="array" item="employeeId" index="index"
            open="(" close=")" separator=",">
            #{employeeId}
        </foreach>
    </select>

    <!--Map:不单单forech中的collection属性是map.key,其它所有属性都是map.key,比如下面的departmentId -->
    <select id="getEmployeesMapParams" resultType="Employees">
        select *
        from EMPLOYEES e
        <where>
            <if test="departmentId!=null and departmentId!=‘‘">
                e.DEPARTMENT_ID=#{departmentId}
            </if>
            <if test="employeeIdsArray!=null and employeeIdsArray.length!=0">
                AND e.EMPLOYEE_ID in
                <foreach collection="employeeIdsArray" item="employeeId"
                    index="index" open="(" close=")" separator=",">
                    #{employeeId}
                </foreach>
            </if>
        </where>
    </select>
     
Mapper类:
public interface EmployeesMapper { 

    List<Employees> getEmployeesListParams(List<String> employeeIds);

    List<Employees> getEmployeesArrayParams(String[] employeeIds);

    List<Employees> getEmployeesMapParams(Map<String,Object> params);
}         测试方法(未贴完整代码):  @Test 
    public void testGetEmployeesListParams() {
        List<String> employeeIds = Arrays.asList("100", "101", "200");
        List<Employees> result = employeesMapper
                .getEmployeesListParams(employeeIds);
        assertEquals(3, result.size());
    }

    @Test
    public void testGetEmployeesArrayParams() {
        String[] employeeIds = new String[] { "100", "200" };
        List<Employees> result = employeesMapper
                .getEmployeesArrayParams(employeeIds);
        assertEquals(2, result.size());
    }

    @Test
    public void testGetEmployeesMapParams() {
        String departmentId = "60";
        List<String> employeeIdsList = Arrays.asList("103", "104", "105");
        String[] employeeIdsArray = new String[] { "103", "104" };
        // 传入多个参数
        Map<String, Object> params = new HashMap<String, Object>();
        params.put("departmentId", departmentId);
        params.put("employeeIdsList", employeeIdsList);
        params.put("employeeIdsArray", employeeIdsArray);
        List<Employees> result = employeesMapper.getEmployeesMapParams(params);
        assertEquals(3, result.size());
    }             　　以一下是全文 接口类

package com.ydssy.dao.product;

import java.util.List;
import java.util.Map;

import com.ydssy.model.product.ProductStore;

 

public interface ProductStoreMapper {
//接口 传入一个集合
List<ProductStore> parameterlist(String[] s);
}

 

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.ydssy.dao.product.ProductStoreMapper" >

<!--Array:forech中的collection属性类型是array,collection的值必须是:list,item的值可以随意,Dao接口中参数名字随意 -->
<select id="parameterlist" parameterType="com.ydssy.model.product.ProductStore" resultType="com.ydssy.model.product.ProductStore">
select ps.* from es_product_store ps where ps.goodsid in<foreach collection="array" item="employeeId" index="index"  open="(" close=")" separator=",">
#{employeeId}
</foreach>
</select>

</mapper>

 

 

 

测试类

package test;

import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;

import com.ydssy.dao.product.ProductStoreMapper;
import com.ydssy.model.product.ProductStore;
public class TestProductStoreMapper {
private SqlSession session;
private ProductStoreMapper dao;

@Before// @Before在··之前
public void init() {

SqlSessionFactoryBuilder ssfb = new SqlSessionFactoryBuilder();
// SqlSessionFactory通过SqlSessionFactoryBuilder的ssfb方法里的类加载器的getResourceAsStream方法获取配置文件信息
//getResourceAsStream会创建一个流 通过这个流去获取配置文件，这个文件会返回一个importString这个流
SqlSessionFactory ssf = ssfb.build(TestProductStoreMapper.class.getClassLoader().getResourceAsStream("com/ydssy/goods/goods.xml"));

// 获得SqlSession对象
// (SqlSession是执行sql的一个容器 通过session访问数据库)。
session = ssf.openSession();
//用session对象去获取接口 ，getMapper方法会返回符合Tapper映射器（ 即EmployeeDAO 接口） 要求的对象
dao = session.getMapper(ProductStoreMapper.class);
}

@Test
public void test3() {
String[] s = new String[] { "516","518" };
List<ProductStore> result = dao.parameterlist(s);
System.out.println(result);
session.commit();
session.close();
}
}

 

 

 

 

配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//ibatis.apache.org//DTD Config 3.0//EN"
"http://ibatis.apache.org/dtd/ibatis-3-config.dtd">
<configuration>
<environments default="environment">
<environment id="environment">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url"
value="jdbc:mysql:///symall_emoji?useUnicode=true&amp;characterEncoding=UTF-8&amp;allowMultiQueries=true&amp;useSSL=true" />
<property name="username" value="root" />
<property name="password" value="123456" />
</dataSource>
</environment>
</environments>
<mappers><!-- 配置文件连接 映射器文件 -->
<mapper resource="com/ydssy/mapping/goods/GoodsCatMapper.xml" />
<mapper resource="com/ydssy/mapping/product/ProductStoreMapper.xml" />

</mappers>
</configuration>

 

包

 

 

 

MyBatis参数传入集合之foreach动态sql

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