Hibernate双向多对多关联关系

最新推荐文章于 2024-10-26 09:57:50 发布

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本文介绍了一种使用ORM技术实现多表关联的方法，包括项目表、员工表及其关联表的设计与实现过程。通过具体的Java代码示例，展示了如何在Hibernate框架下进行实体类定义、DAO层操作及业务层处理。

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两张普通表：

Projecttable:

proID number(6) primary key,
proName nvarchar2(50)

Employee

empID number(6) primary key,

empName nvarchar2(50)

一张关系表：

proEmp:联合主键+外键

rproID number(6),
rempID number(6),
CONSTRAINT PK_ProjectTable_Employee PRIMARY KEY (rproID,rempID),
constraint FK_Employee_empID foreign key(rempID)
references Employee(empID),
constraint FK_ProjectTable_proID foreign key(rproID)
references ProjectTable(proID)

pojo:Projecttable

	private Set<Employee> employees = new HashSet<Employee>(0);//负责项目的员工集合

pojo:Employee

private Set<Projecttable> projecttables = new HashSet<Projecttable>(0);//员工负责的项目集合

dao:Projecttable

public void save(Projecttable projecttable){
		currentSession().save(projecttable);
	}

dao:Employee

public void save(Employee employee){
		currentSession().save(employee);
	}

service:Projecttable

ProjecttatbleDao projecttatbleDao=new ProjecttatbleDao();
	public void addProjecttable(Projecttable projecttable){
		Transaction tx=null;
		try {
			tx=HibernateUtil.currentSession().beginTransaction();
			projecttatbleDao.save(projecttable);
			tx.commit();
		} catch (HibernateException e) {
			e.printStackTrace();
			if(tx!=null){
				tx.rollback();
			}
		}
		
	}

service:Employee

EmployeeDao employeeDao=new EmployeeDao();
	public void addEmployee(Employee employee){
		Transaction tx=null;
		try {
			tx=HibernateUtil.currentSession().beginTransaction();
			employeeDao.save(employee);
			tx.commit();
		} catch (HibernateException e) {
			e.printStackTrace();
			if(tx!=null){
				tx.rollback();
			}
		}
		
	}

Test:

//两个项目
		Projecttable projecttable1=new Projecttable();
		projecttable1.setProid(1);
		projecttable1.setProname("易买网");
		Projecttable projecttable2=new Projecttable();
		projecttable2.setProid(2);
		projecttable2.setProname("新闻发布系统");
		
		//四个员工
		Employee employee1=new Employee();
		employee1.setEmpid(1);
		employee1.setEmpname("李林");
		Employee employee2=new Employee();
		employee2.setEmpid(2);
		employee2.setEmpname("王尼玛");
		Employee employee3=new Employee();
		employee3.setEmpid(3);
		employee3.setEmpname("李尼玛");
		Employee employee4=new Employee();
		employee4.setEmpid(4);
		employee4.setEmpname("张尼玛");
		
	
		employee1.getProjecttables().add(projecttable1);
		employee1.getProjecttables().add(projecttable2);
		employee2.getProjecttables().add(projecttable2);
		employee3.getProjecttables().add(projecttable2);
		employee4.getProjecttables().add(projecttable2);
		
		
		projecttable1.getEmployees().add(employee1);
		projecttable2.getEmployees().add(employee1);
		projecttable2.getEmployees().add(employee2);
		projecttable2.getEmployees().add(employee3);
		projecttable2.getEmployees().add(employee4);
		
		//执行添加数据,关联关系体现在PROEMP表中

		new ProjecttableService().addProjecttable(projecttable1);
		new ProjecttableService().addProjecttable(projecttable2);
		//或者
		new EmployeeService().addEmployee(employee1);
		new EmployeeService().addEmployee(employee2);
		new EmployeeService().addEmployee(employee3);
		new EmployeeService().addEmployee(employee4);