问题：是查询一个部门中的员工？
一、web项目构架
二、lib文件的jar
三、配置大小配置和该工具类
1大配置mybatis-config.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration> <!-- 别名的定制 -->
<typeAliases>
<!-- 按类型名定制别名 -->
<!-- <typeAlias type="cn.happy.entity.Student" alias="Student"/> --> <!-- 拿当前指定包下的简单类名作为别名 -->
<package name="cn.happy.entity"/>
</typeAliases> <environments default="development">
<environment id="development"> <transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="oracle.jdbc.driver.OracleDriver"/>
<property name="url" value="jdbc:oracle:thin:@localhost:1521:orcl"/>
<property name="username" value="T2"/>
<property name="password" value="T2"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="cn/happy/dao/DeptDAO.xml" />
</mappers>
</configuration>
2小配置
<?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.happy.dao.IDeptDAO"> <resultMap type="Dept" id="deptMapper">
<id property="deptno" column="deptno"/>
<result property="deptname" column="deptname"/>
<collection property="emps" ofType="Emp">
<id property="empno" column="empno"/>
<result property="empname" column="empname"/>
</collection>
</resultMap> <!-- one2many --> <select id="getDeptById" resultMap="deptMapper">
select dept.deptno,deptname,empno,empname from dept,emp
where dept.deptno=emp.deptno and dept.deptno=#{deptno}
</select> </mapper>
3工具类
package cn.happy.util; import java.io.IOException;
import java.io.Reader; import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder; /**
* 工具类
* @author Happy
*
*/
public class MybatisUtil {
private static String config="mybatis-config.xml";
static Reader reader;
static{
try {
reader= Resources.getResourceAsReader(config);
} catch (IOException e) {
e.printStackTrace();
}
}
private static SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader);
//提供一个可以获取到session的方法
public static SqlSession getSession() throws IOException{ System.out.println("22222"+factory);
//弊病，就是工厂是
// 1.1 openSession到底做了什么
SqlSession session = factory.openSession();
System.out.println("3333");
return session;
}
}
四、配置实体类
1Emp
package cn.happy.entity;
/**
* 员工
* @author Administrator
*
*/
public class Emp {
private Integer empno;
private String empname;
private Integer empage;
public Integer getEmpno() {
return empno;
}
public void setEmpno(Integer empno) {
this.empno = empno;
}
public String getEmpname() {
return empname;
}
public void setEmpname(String empname) {
this.empname = empname;
}
public Integer getEmpage() {
return empage;
}
public void setEmpage(Integer empage) {
this.empage = empage;
} }
2Dept
package cn.happy.entity; import java.util.HashSet;
import java.util.Set; /**
* 部门
* @author Administrator
*
*/
public class Dept {
private Integer deptno;
private String deptname;
//配置一对多的关系
private Set<Emp> emps=new HashSet<Emp>(); public Set<Emp> getEmps() {
return emps;
}
public void setEmps(Set<Emp> emps) {
this.emps = emps;
}
public Integer getDeptno() {
return deptno;
}
public void setDeptno(Integer deptno) {
this.deptno = deptno;
}
public String getDeptname() {
return deptname;
}
public void setDeptname(String deptname) {
this.deptname = deptname;
} }
五接口
package cn.happy.dao;
import cn.happy.entity.Dept;
public interface IDeptDAO {
//根据部门编号查询该部门
public Dept getDeptById(Integer id);
}
六测试
package cn.happy.test; import java.io.IOException;
import java.util.ArrayList;
import java.util.List; import org.apache.ibatis.session.SqlSession;
import org.junit.Before;
import org.junit.Test; import cn.happy.dao.IDeptDAO;
import cn.happy.entity.Dept; import cn.happy.util.MybatisUtil; public class MyTest {
IDeptDAO dao;
@Before
public void initData() throws IOException{
SqlSession session = MybatisUtil.getSession();
dao = session.getMapper(IDeptDAO.class);
} @Test
public void getDeptById() throws IOException{
Dept dept = dao.getDeptById(2);
System.out.println(dept);
} }