MyBatis入门

学习MyBatis已经很久了,也一直在使用,今天抽空来总结下MyBatis的基本使用,MyBatis真的是很好入门的,看完这篇文章基本上就能正常使用MyBatis了

首先创建一个Maven项目

如果还有不会使用Maven的同学可以去看我之前写的Maven配置
这是我的项目结构

1. 首先引入相应的pom.xml依赖，笔者这里用的是mysql8.0，如果使用的是5.7的同学引入5.7的以来就可以了

  4.0.0
  com.xx
  Demo
  0.0.1-SNAPSHOT
  
	
	
	    org.mybatis
	    mybatis
	    3.4.4
	
	
	    mysql
	    mysql-connector-java
	    8.0.13
	
  	
  		junit
	    junit
	    4.12
  	
  

2.撰写MyBatis的配置文件mybatis-config.xml，由于数据库存在时区问题，需要在url后面对时区进行修改

3.创建实体类Area.java

package com.xx.entity;

public class Area {

	private Integer areaId;
	private String areaName;
	private String cityCode;
	private String address;
	public Integer getAreaId() {
		return areaId;
	}
	public void setAreaId(Integer areaId) {
		this.areaId = areaId;
	}
	public String getAreaName() {
		return areaName;
	}
	public void setAreaName(String areaName) {
		this.areaName = areaName;
	}
	public String getCityCode() {
		return cityCode;
	}
	public void setCityCode(String cityCode) {
		this.cityCode = cityCode;
	}
	public String getAddress() {
		return address;
	}
	public void setAddress(String address) {
		this.address = address;
	}
	@Override
	public String toString() {
		return "Area [areaId=" + areaId + ", areaName=" + areaName + ", cityCode=" + cityCode + ", address=" + address
				+ "]";
	}
	
}

4.这时候我们开始编写映射文件AreaMapper.xml，这里写了6种最常见的情况，其中使用Map是最为强大的，基本上是万能的，适用于任何情况

	
		select * from bas_area where area_id = #{areaId}
	
	
	
		select * from bas_area
	
	
	
		insert into bas_area(city_code,area_name,address) values (#{cityCode},#{areaName},#{address})
		
			select last_insert_id()
		
	
	
	
		update bas_area set city_code = #{cityCode},area_name = #{areaName},address = #{address} where area_id = #{areaId}
	
	
	
		delete from bas_area where area_id = #{area_id}
	
	
	
		select * from bas_area a,bas_dictionary b where a.city_code = b.dic_code and b.dic_type = 'city'
	

5.创建JunitDemo.java进行单元测试

package com.xx.junit;

import java.io.IOException;
import java.io.Reader;
import java.util.List;
import java.util.Map;

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

import com.xx.entity.Area;

public class JunitDemo {
	private static SqlSession session = null;
	// 静态块
	static{
		try {
			Reader reader = Resources.getResourceAsReader("mybatis-config.xml");// 读取MyBatis配置文件
			SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader);// SqlSessionFactory是很消耗系统资源的一般只创建一次,所以这里将SqlSessionFactory抽取出来放到静态块中初始化
			session = factory.openSession();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}	
	
	@Test
	// 查询
	public void findAll() throws IOException {
		List list = session.selectList("AreaMapper.findAll");
		for (Area area : list) {
			System.out.println(area);
		}
		session.close();
	}
	
	@Test
	// 条件查询
	public void findById() {
		Area area = session.selectOne("AreaMapper.findById", 1);
		System.out.println(area);
	}
	
	@Test
	// 插入
	public void insert() throws IOException {
		Area area = new Area();
		area.setAreaName("天通苑");
		area.setCityCode("bj");
		area.setAddress("天通苑");
		session.insert("AreaMapper.insert",area);
		session.commit();// 提交事务
		session.close();
	}
	
	@Test
	// 修改
	public void update() {
		Area area = session.selectOne("AreaMapper.findById", 1);
		area.setAreaName("铂金时代");
		area.setCityCode("hz");
		area.setAddress("江南大道");
		session.update("AreaMapper.update", area);
		session.commit();
		session.close();
	}
	
	@Test
	// 删除
	public void delete() {
		session.delete("AreaMapper.delete",3);
		session.commit();
		session.close();
	}
	
	@Test
	// 无敌的Map
	public void findByMap() {
		List> list = session.selectList("AreaMapper.findByMap");
		for (Map map : list) {
			System.out.println(map);
		}
		session.close();
	}

}

到此为止MyBatis的基本用法就说完了,MyBatis是有中文官网的，学习起来也非常方便