mybatis动态查询之foreach,sql标签查询

当中foreach标签使用了基本的List 集合和多态类型

sql 标签同时使用了includ标签。其用法和jstl中的标签用法一致。

dao

package com.cbh.dao;import java.util.List;import com.cbh.beans.Student;public interface IStudent {List<Student>selectStudentsByCondition(String name,int age,int score);List<Student>selectStudentsByConditionif(Student student);List<Student>selectStudentsByConditionwhere(Student student);//choose标签中可以包含<when/><otherwide/>，也可以包含多个<when/>与一个《otherwise》.//他们联合起来完成java中的开关语句switch。。case功能。List<Student> selectStudentsChoose(Student student);/* * foreach标签的使用对用于实现数组与集合的遍历，需要注意的 * collection表示遍历的集合类型这是数组，即arry。 * open，close ，separator 为对遍历内容的sql拼接 */List<Student> selectStudentForeachArry(Object[] student);//foreach标签遍历基本类型为list的集合List<Student> selectStudentForeachArryList(List<Integer> studentsid);//使用自定义型list类型List<Student> selectStudentForeachArryList2(List<Student> studentsid);List<Student> selectStudentForeacSQLFream(List<Student> studentsid);}

mapper

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.cbh.dao.IStudent"><select id="selectStudentsByConditionif" resultType="Student">select id,name,age,score from student1 where 1=1<if test="name !=null and name !=''">and name like '%' #{name} '%'</if><if test="age>0">and age> #{age}</if></select> <select id="selectStudentsByConditionwhere" resultType="Student">select id,name,age,score from student1 <where><if test="name !=null and name !=''">name like '%' #{name} '%'</if><if test="age>0">and age> #{age}</if><if test="score>0">and score>#{score}</if></where></select> <!-- #{}中可以放入的内容1.参数对象的属性2.随意的内容，此时#｛｝是个占位符3.参数为map时的key4.参数为map时，若key所对应的value为对象，则可以将该对象的属性放入5.参数的索引号（本次就是参数的索引号） --> <select id="selectStudentsChoose" resultType="Student"> select* from student1 <where> <choose> <when test="name !=null and name!=''"> and name like '%' #{name} '%' </when> <when test="age>0"> and age > #{age} </when> <when test="score>0"> and score>#{score} </when> <otherwise> and 1 !=1 </otherwise> </choose>  </where>  </select> <!--遍历数组  --><select id="selectStudentForeachArry" resultType="Student">select*from student1<if test="array!=null and array.length>0">where id in<foreach collection="array" open="(" close=")" item="myid"separator=",">#{myid}</foreach></if></select><select id="selectStudentForeachArryList" resultType="Student">select*from student1<if test="list!=null and list.size>0">where id in<foreach collection="list" item="myid" open="(" close=")"separator=",">#{myid}</foreach></if></select><select id="selectStudentForeachArryList2" resultType="Student">select*from student1<if test="list!=null and list.size>0">where id in<foreach collection="list" item="student" open="(" close=")"separator=",">#{student.id}</foreach></if></select><sql id="testsql">select*from student1</sql><select id="selectStudentForeacSQLFream" resultType="Student"><include refid="testsql" /><if test="list!=null and list.size>0">where id in<foreach collection="list" item="Student" open="(" close=")"separator=",">#{Student.id}</foreach></if></select></mapper>

测试类

package com.cbh.test;import java.util.ArrayList;import java.util.List;import java.util.Map;import org.apache.ibatis.session.SqlSession;import org.junit.Before;import org.junit.Test;import com.cbh.Utils.MybatisUtils;import com.cbh.beans.Student;import com.cbh.dao.IStudent;public class mytest {private IStudent dao;@Beforepublic void before() {SqlSession sqlSession=MybatisUtils.getSqlSession();dao =sqlSession.getMapper(IStudent.class) ;}@Afterpublic void after(){if(sqlsession!=null）｛sqlsession.close();｝｝@Testpublic void test8(){//Student stu=new Student("大",23,0);Student stu=new Student("",0,0);List<Student> student=dao.selectStudentsByConditionif(stu );for (Student student2 : student) {System.out.println(student2);}}@Testpublic void test9(){Student stu=new Student("",0,100);List<Student> student=dao.selectStudentsByConditionwhere(stu);for (Student student2 : student) {System.out.println(student2);}} @Testpublic void test10(){Student stu=new Student("",0,100);List<Student> student=dao.selectStudentsChoose(stu);for (Student student2 : student) {System.out.println(student2);}}@Testpublic void test11(){Object[] studentIds=new Object[]{1,3,4,20};List<Student> students=dao.selectStudentForeachArry(studentIds);for (Student student3 : students) {System.out.println(student3);}}@Testpublic void test12(){List<Integer> studentsid=new ArrayList<Integer>();studentsid.add(2);studentsid.add(5);studentsid.add(24);List<Student> student=dao.selectStudentForeachArryList(studentsid);for (Student student2 : student) {System.out.println(student2);}}@Testpublic void test13(){Student student1=new Student();Student student2=new Student();student1.setId(4);student2.setId(2);List<Student> studentid=new ArrayList<Student>();studentid.add(student1);studentid.add(student2);studentid=dao.selectStudentForeachArryList2(studentid);for (Student student : studentid) {System.out.println(student);}}@Testpublic void test14(){Student student1=new Student();Student student2=new Student();student1.setId(4);student2.setId(2);List<Student> studentsid=new ArrayList<Student>();studentsid.add(student1);studentsid.add(student2);studentsid=dao.selectStudentForeacSQLFream(studentsid);for (Student students : studentsid) {System.out.println(students);}}}


                                             
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