Mybatis getMapper查询方式

偏执的太偏执、 2022-06-05 02:52 329阅读 0赞

1、实体类映射文件 Users.xml

<?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.sz.hcq.dao.IEmpDAO">
    	
    	<select id="findallemp" resultType="cn.sz.hcq.pojo.Emp">
    		select
    		empno,ename,job,mgr,hiredate,sal,comm,deptno from emp
    	</select>
    </mapper>

2、实体类Users.java

package cn.sz.hcq.pojo;
    
    import java.io.Serializable;
    import java.util.Date;
    
    public class Emp implements Serializable {
    	private Integer empno;
    	private String ename;
    	private String job;
    	private Integer mgr;
    	private Date hiredate;
    	private Double sal;
    	private Double comm;
    	private Integer deptno;
    
    	public Integer getEmpno() {
    		return empno;
    	}
    
    	public void setEmpno(Integer empno) {
    		this.empno = empno;
    	}
    
    	public String getEname() {
    		return ename;
    	}
    
    	public void setEname(String ename) {
    		this.ename = ename;
    	}
    
    	public String getJob() {
    		return job;
    	}
    
    	public void setJob(String job) {
    		this.job = job;
    	}
    
    	public Integer getMgr() {
    		return mgr;
    	}
    
    	public void setMgr(Integer mgr) {
    		this.mgr = mgr;
    	}
    
    	public Date getHiredate() {
    		return hiredate;
    	}
    
    	public void setHiredate(Date hiredate) {
    		this.hiredate = hiredate;
    	}
    
    	public Double getSal() {
    		return sal;
    	}
    
    	public void setSal(Double sal) {
    		this.sal = sal;
    	}
    
    	public Double getComm() {
    		return comm;
    	}
    
    	public void setComm(Double comm) {
    		this.comm = comm;
    	}
    
    	public Integer getDeptno() {
    		return deptno;
    	}
    
    	public void setDeptno(Integer deptno) {
    		this.deptno = deptno;
    	}
    
    }

3、测试查询代码

package cn.sz.hcq.test;
    
    import java.io.Reader;
    import java.util.List;
    
    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 cn.sz.hcq.dao.IEmpDAO;
    import cn.sz.hcq.pojo.Emp;
    
    public class Test {
    	public static void main(String[] args) {
    		String resource = "mybatis_cfg.xml";// 配置文件的名字
    
    		Reader reader = null;
    		SqlSessionFactoryBuilder builder = null;
    		SqlSessionFactory factory = null;
    		SqlSession sqlSession = null;
    
    		try {
    			// 这里使用字符流，以流的形式来读取mybatis配置文件的内容
    			reader = Resources.getResourceAsReader(resource);
    			// 准备构建连接工厂的工具
    			builder = new SqlSessionFactoryBuilder();
    			// 准备连接工厂
    			factory = builder.build(reader);
    			// 获取连接
    			sqlSession = factory.openSession();
    
    			// 操作
    			// getMapper来获取实现类对象,如何调用其方法
    			IEmpDAO empdao = sqlSession.getMapper(IEmpDAO.class);
    			List<Emp> emplist = empdao.findallemp();
    
    			for (int i = 0; i < emplist.size(); i++) {
    				Emp emp = emplist.get(i);
    				System.out.println(emp.getEmpno() + "," + emp.getEname() + ","
    						+ emp.getJob() + "," + emp.getSal());
    			}
    
    		} catch (Exception e) {
    			e.printStackTrace();
    			// sqlSession.rollback();
    		} finally {
    			// 关闭连接
    			if (sqlSession != null) {
    				sqlSession.close();
    			}
    		}
    	}
    }

通过getMapper来获取实现类对象，如何调用方法查询  
IEmpDAO empdao = sqlSession.getMapper(IEmpDAO.class);  
List<Emp> emplist = empdao.findallemp();