mybatis映射文件select_resultMap_关联查询_collection定义关联集合

知识点：查询一个实体类，并查出这个类下面的集合

Employee.java实体类

package com.hand.mybatis.bean;
public class Employee {
   private Integer eId;
   private String eName;
   private Integer gender;
   private String email;
   private Department dept;

   public Employee() {
       super();
   }
   public Employee(Integer eId,String eName, Integer gender, String email) {
       super();
       this.eId=eId;
       this.eName = eName;
       this.gender = gender;
       this.email = email;
   }

   public Integer geteId() {
       return eId;
   }
   public void seteId(Integer eId) {
       this.eId = eId;
   }

   public String getEName() {
       return eName;
   }
   public void setEname(String ename) {
       this.eName = ename;
   }
   public Integer getGender() {
       return gender;
   }
   public void setGender(Integer gender) {
       this.gender = gender;
   }
   public String getEmail() {
       return email;
   }
   public void setEmail(String email) {
       this.email = email;
   }
   public Department getDept() {
       return dept;
   }
   public void setDept(Department dept) {
       this.dept = dept;
   }
   @Override
   public String toString() {
       return "Employee [eId=" + eId + ", ename=" + eName + ", gender=" + gender + ", email=" + email + "]";
   }

}

Department.java实体类

package com.hand.mybatis.bean;
import java.util.List;

public class Department {
   private Integer id;
   private String departName;
    private List<Employee> empList;

   public Integer getId() {
       return id;
   }
   public void setId(Integer id) {
       this.id = id;
   }
   public String getDepartName() {
       return departName;
   }
   public void setDepartName(String departName) {
       this.departName = departName;
   }

   public List<Employee> getEmpList() {
       return empList;
   }
   public void setEmpList(List<Employee> empList) {
       this.empList = empList;
   }

   @Override
   public String toString() {
       return "Department [;
   }

}

DepartmentMapper.java接口

package com.hand.mybatis.dao;
import com.hand.mybatis.bean.Department;

public interface DepartmentMapper {

   Department getDeptById(Integer did);

   //根据部门id，查询部门信息，同时将部门下的所有员工信息查询出来
   Department getDeptByIdPlus(Integer did);

   //分步查询部门信息
   Department getDeptByIdStep(Integer did);
}

DepartmentMapper.xm l映射文件

<?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="com.hand.mybatis.dao.DepartmentMapper">

   
   <select >collection>
    </resultMap>

接口二：根据部门id分步查询员工信息
   <select :表示使用延迟加载
       - lazy:延迟
       - eager:立即-->

</mapper>

代码：https://github.com/shuaishuaihand/mybatis.git