MyBatis-ResultType的作用返回结果

ResultMap：用于类的属性和表的列名不一样时返回结果属性为空，通过ResultMap来定义类的属性和表的类的映射关系，就可以解决属性名和列值不同的问题

StudentDao接口：

package com.bjpowernode.dao;

import com.bjpowernode.domain.Student;
import com.bjpowernode.vo.CustomObject;
import com.bjpowernode.vo.QueryParama;
import org.apache.ibatis.annotations.Param;

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

public interface StudentDao {
    //查询学生
    Student selectById(Integer id);

    //定义方法,查询结果是一个自定义类型对象CustomObject
    CustomObject selectById2(@Param("stuid") Integer id);

    //查询数目，查询结果是Long类型
    long countStudnet();

    //查询结果返回是一个Map
    Map selectMap(@Param("stuid") Integer id);

}

StudentDao.xml:






    
        select id,name ,email,age from student where id=#{stuid}
    




    
        select id,name,email from student where id=#{stuid}

ProvinceDao接口：

package com.bjpowernode.dao;

import com.bjpowernode.vo.ProvinceCity;

import java.util.List;

public interface ProvinceDao {

    List selectProvinceCityLis(Integer provinceId);
}

ProvinceDao.xml：

CustomObject类：

package com.bjpowernode.vo;

public class CustomObject {
    private Integer cid;
    private String cname;
    private String email;
    private Integer age;

    public Integer getCid() {
        return cid;
    }

    public void setCid(Integer cid) {
        this.cid = cid;
    }

    public String getName() {
        return cname;
    }

    public void setName(String name) {
        this.cname = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "CustomObject{" +
                "cid=" + cid +
                ", cname='" + cname + ''' +
                ", email='" + email + ''' +
                ", age=" + age +
                '}';
    }
}

ProvinceCity类：

package com.bjpowernode.vo;

public class ProvinceCity {
    private Integer id;
    private String name;

    private Integer cid;
    private String cname;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getCid() {
        return cid;
    }

    public void setCid(Integer cid) {
        this.cid = cid;
    }

    public String getCname() {
        return cname;
    }

    public void setCname(String cname) {
        this.cname = cname;
    }

    @Override
    public String toString() {
        return "ProvinceCity{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", cid=" + cid +
                ", cname='" + cname + ''' +
                '}';
    }
}

QueryParama类：

package com.bjpowernode.vo;

public class QueryParama {
    private Object p1;
    private Object p2;

    public Object getP1() {
        return p1;
    }

    public void setP1(Object p1) {
        this.p1 = p1;
    }

    public Object getP2() {
        return p2;
    }

    public void setP2(Object p2) {
        this.p2 = p2;
    }
}

主配置文件 myBatis.xml

MyTest：

package com.bjpowernode;

import com.bjpowernode.dao.ProvinceDao;
import com.bjpowernode.dao.StudentDao;
import com.bjpowernode.domain.Student;
import com.bjpowernode.utils.MybatisUtil;
import com.bjpowernode.vo.CustomObject;
import com.bjpowernode.vo.ProvinceCity;
import com.bjpowernode.vo.QueryParama;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

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


public class MyTest {
    //查询测试
    @Test
    public void testSelectById(){
        //获取SqlSession
        SqlSession session= MybatisUtil.getSqlSession();
       //获取dao代理
        StudentDao dao=session.getMapper(StudentDao.class);
        //调用方法
        Student student=dao.selectById(1005);
        System.out.println("student="+student);
        //4.关闭SqlSession对象
        session.close();
    }

    //自定义对象进行查询id
    @Test
    public void testSelectById2(){
        //获取SqlSession
        SqlSession session= MybatisUtil.getSqlSession();
        //获取dao代理
        StudentDao dao=session.getMapper(StudentDao.class);
        //调用方法
       CustomObject co =dao.selectById2(1001);
        System.out.println("CustomObject="+co);
        //4.关闭SqlSession对象
        session.close();
    }
    //返回记录数
    @Test
    public void testCountStudent(){
        //获取SqlSession
        SqlSession session= MybatisUtil.getSqlSession();
        //获取dao代理
        StudentDao dao=session.getMapper(StudentDao.class);
        //调用方法
        Long nums=dao.countStudnet();
        System.out.println("nums="+nums);
        //4.关闭SqlSession对象
        session.close();
    }
//返回Map集合
    @Test
    public void testSelectMap(){
        //获取SqlSession
        SqlSession session= MybatisUtil.getSqlSession();
        //获取dao代理
        StudentDao dao=session.getMapper(StudentDao.class);
        //调用方法
        Map map=dao.selectMap(1006);
        System.out.println("map"+map);
        //4.关闭SqlSession对象
        session.close();

        System.out.println("name="+map.get("name"));
        System.out.println("id="+map.get("id"));
        System.out.println("email="+map.get("email"));
    }
    //
    @Test
    public void testSelectCity(){
        //获取SqlSession
        SqlSession session= MybatisUtil.getSqlSession();
        //新增加的接口，需要重新获取dao代理
        ProvinceDao dao=session.getMapper(ProvinceDao.class);
        List list = dao.selectProvinceCityLis(1);
        //关闭连接
        session.close();

        list.forEach(p-> System.out.println(p));
    }



}

第一个测试结果：

MyBatis-ResultType的作用 返回结果

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MyBatis-ResultType的作用返回结果