MyBatis的级联查询（两种方式）

与上次唯一不同的一下几个类

Department.java

package com.cn.zhu.bean;

public class Department {
	private 	Integer  id;
	private  String  departmentName;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getDepartmentName() {
		return departmentName;
	}
	public void setDepartmentName(String departmentName) {
		this.departmentName = departmentName;
	}
	@Override
	public String toString() {
		return "Department [departmentName=" + departmentName + ", id=" + id
				+ "]";
	}
	
}

Employee.java

package com.cn.zhu.bean;

import org.apache.ibatis.type.Alias;

@Alias("emp")
public class Employee {
	private Integer id;
	private String lastName;
	private String email;
	private String gender;
	private Department dept;
	
	public Employee() {
		super();
		// TODO Auto-generated constructor stub
	}
	
	public Employee(Integer id, String lastName, String email, String gender) {
		super();
		this.id = id;
		this.lastName = lastName;
		this.email = email;
		this.gender = gender;
	}

	
	public Department getDept() {
		return dept;
	}

	public void setDept(Department dept) {
		this.dept = dept;
	}

	public String getLastName() {
		return lastName;
	}

	public void setLastName(String lastName) {
		this.lastName = lastName;
	}

	
	public Integer getId() {
		return id;
	}

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

	public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	@Override
	public String toString() {
		return "Employee [email=" + email + ", gender=" + gender + ", id=" + id
		+ ", lastName=" + lastName + "]";
	}

}

EmployeeMapperPlus.java

package com.cn.mybatis.dao;

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


import org.apache.ibatis.annotations.MapKey;
import org.apache.ibatis.annotations.Param;

import com.cn.zhu.bean.Employee;

public interface EmployeeMapperPlus {
	public Employee getEmpById(Integer id);
	public Employee getEmpAndDept(Integer id);
 }

EmployeeMapperPlus.xml

	
	
	
	
	

	
		
		
		
		
		
		
		
		
		
	

  
	
		
		
		
		
		
		
		
		  
		   
		
	


	
	
		SELECT e.id id,e.last_name last_name ,e.gender gender,e.d_id d_id,
		d.id did,d.dept_name dept_name from tbl_employee e,tbl_dept d
		where e.d_id=d.id and e.id=#{id}
	

以上是两种映射封装结果

增加EmployeeMapperPlus.xml 后，一定要在mybatis-config.xml里加上这个配置文件的声明，

另外sql语句一定要正确，可以先在navict数据库图形化管理工具中，测试sql

下面编写测试类（这里直接写测试方法吧）：详细请看映射一

@Test
	public void test05() throws IOException{
		SqlSessionFactory sqlsessionFactory=getSqlSessionFactory();
		// 1  获取到的sqlsession不会自动提交数据
		SqlSession openSession=sqlsessionFactory.openSession();

		try{
			
			EmployeeMapperPlus mapper=openSession.getMapper(EmployeeMapperPlus.class);
            Employee empAndDept=mapper.getEmpAndDept(1);
            System.out.println(empAndDept);
            System.out.println(empAndDept.getDept());
		}finally{
			openSession.commit();
		}
	}

测试完成

接下来，会写分布查询，请看下一篇文章