mybatis-分页查询学习笔记

Posted 2020-11-01

import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.session.SqlSession;
import cn.itcast.javaee.mybatis.util.MybatisUtil;

/**
 * 持久层 
 * @author AdminTC
 */
public class StudentDao {
    /**
     * 增加学生
     */
    public void add(Student student) throws Exception{
        SqlSession sqlSession = null;
        try{
            sqlSession = MybatisUtil.getSqlSession();
            sqlSession.insert(Student.class.getName()+".add",student);
            sqlSession.commit();
        }catch(Exception e){
            e.printStackTrace();
            sqlSession.rollback();
            throw e;
        }finally{
            MybatisUtil.closeSqlSession();
        }
    }
    /**
     * 无条件分页
     * @param start 表示在mysql中从第几条记录的索引号开始显示，索引从0开始
     * @param size 表示在mysql中最多显示几条记录
     */
    public List<Student> findAllWithFy(int start,int size) throws Exception{
        SqlSession sqlSession = null;
        try{
            sqlSession = MybatisUtil.getSqlSession();

            Map<String,Object> map = new LinkedHashMap<String,Object>();
            map.put("pstart",start);
            map.put("psize",size);
            return sqlSession.selectList(Student.class.getName()+".findAllWithFy",map);
        }catch(Exception e){
            e.printStackTrace();
            throw e;
        }finally{
            MybatisUtil.closeSqlSession();
        }
    }

    /**
     * 有条件分页
     */
    public List<Student> findAllByNameWithFy(String name,int start,int size) throws Exception{
        SqlSession sqlSession = null;
        try{
            sqlSession = MybatisUtil.getSqlSession();
            Map<String,Object> map = new LinkedHashMap<String, Object>();
            map.put("pname","%"+name+"%");
            map.put("pstart",start);
            map.put("psize",size);          
            return sqlSession.selectList(Student.class.getName()+".findAllByNameWithFy",map);
        }catch(Exception e){
            e.printStackTrace();
            throw e;
        }finally{
            MybatisUtil.closeSqlSession();
        }
    }

    public static void main(String[] args) throws Exception{
        StudentDao dao = new StudentDao();

        //for(int i=1;i<=10;i++){
        //  dao.add(new Student(i,"哈哈",7000D));
        //}

        System.out.println("--------------------第一页");
        List<Student> studentList1 = dao.findAllByNameWithFy("哈",0,3);
        for(Student s : studentList1){
            System.out.println(s.getId()+":"+s.getName()+":"+s.getSal());
        }
        System.out.println("--------------------第二页");
        List<Student> studentList2 = dao.findAllByNameWithFy("哈",3,3);
        for(Student s : studentList2){
            System.out.println(s.getId()+":"+s.getName()+":"+s.getSal());
        }
        System.out.println("--------------------第三页");
        List<Student> studentList3 = dao.findAllByNameWithFy("哈",6,3);
        for(Student s : studentList3){
            System.out.println(s.getId()+":"+s.getName()+":"+s.getSal());
        }

    }
}

<?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="cn.itcast.javaee.mybatis.app10.Student"> 

    <resultMap type="cn.itcast.javaee.mybatis.app10.Student" id="studentMap">
        <id property="id" column="students_id"/>
        <result property="name" column="students_name"/>
        <result property="sal" column="students_sal"/>
    </resultMap>

    <insert id="add" parameterType="cn.itcast.javaee.mybatis.app10.Student">
        insert into students(students_id,students_name,students_sal) 
        values(#{id},#{name},#{sal});
    </insert>

    <select id="findAllWithFy" parameterType="map" resultMap="studentMap">
        select students_id,students_name,students_sal 
        from students 
        limit #{pstart},#{psize}
    </select>

    <select id="findAllByNameWithFy" parameterType="map" resultMap="studentMap">
        select students_id,students_name,students_sal 
        from students 
        where students_name like #{pname}
        limit #{pstart},#{psize}
    </select>

</mapper>