4.5、动态 SQL 之 foreach(对象类型)

接口方法：

public abstract List<Student> selectStudentList2(List<Student> listId);

mapper 文件：

<select id="selectStudentList2" resultType="com.wzy.pojo.Student">
    select id,name,gender,age,birthday,files from student
    <where>
        <if test="list != null and list.size > 0">
            id in
            <foreach collection="list" open="(" item="studentId"  separator="," close=")">
                #{studentId.id}
            </foreach>
        </if>
    </where>
</select>

测试方法：

package com.wzy.dao2;
import com.wzy.pojo.Student;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
public class StudentDao2Test003 {
    @Test
    public void selectStudentList2() throws IOException {
        //1.MyBatis2.xml 主配置文件
        String config = "MyBatis2.xml";
        //2.读取主配置文件
        InputStream resourceAsStream = Resources.getResourceAsStream(config);
        //3.创建 SqlSessionFactory 对象,用于获取 Dao 代理对象
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        //4.Dao 代理对象
        StudentDao2 studentDao2 = factory.openSession().getMapper(StudentDao2.class);
        //5.把筛选数据保存到集合
        List<Student> list = new ArrayList<>();
        Student student1 = new Student();
        student1.setId(1);
        list.add(student1);
        student1 = new Student();
        student1.setId(2);
        list.add(student1);
        //6.执行查询语句
        List<Student> studentList = studentDao2.selectStudentList2(list);
        //7.输出结果
        studentList.forEach(student -> System.out.println(student));
    }
}