hibernate注解.doc

环境：Hibernate 3.3.1 Maven 3.0.4 MySQL 5.5.13 Myeclipse 8.6.1建表语句：DROP TABLE IF EXISTS t_company;CREATE TABLE t_company ( companyId int(10) unsigned NOT NULL AUTO_INCREMENT, companyName varchar(30) NOT NULL, PRIMARY KEY (companyId) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=gb2312;INSERT INTO t_company VALUES (1, Sun);INSERT INTO t_company VALUES (2, Apache);DROP TABLE IF EXISTS t_employee;CREATE TABLE t_employee ( employeeId int(10) unsigned NOT NULL AUTO_INCREMENT, employeeName varchar(15) NOT NULL, cid int(10) unsigned NOT NULL, PRIMARY KEY (employeeId) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=gb2312;INSERT INTO t_employee VALUES (1, Tom, 1);INSERT INTO t_employee VALUES (2, Summ, 1);INSERT INTO t_employee VALUES (3, Cat, 2);INSERT INTO t_employee VALUES (4, Vinylon, 1);INSERT INTO t_employee VALUES (5, Dog, 2);目录结构：Employee.javapackage com.fancy.po;import javax.persistence.CascadeType;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.ManyToOne;import javax.persistence.Table;/* * - * 文件: Employee.java * 作者: fancy * 邮箱: * 时间: 2012-6-10 * 描述: 实体类 * - */* * 下面只说ManyToOne,如需了解其他注解, * 可以参考上一篇：/fancyzero/archive/2012/06/10/hibernate-one-to-one-annotation.html */EntityTable(name = t_employee)public class Employee private Integer employeeId; private String employeeName; private Company company; Id GeneratedValue(strategy = GenerationType.AUTO) public Integer getEmployeeId() return employeeId; /* * ManyToOne：多对一,cascade：级联,请参考上一篇 * fetch = FetchType.LAZY,延迟加载策略,如果不想延迟加载可以用FetchType.EAGER */ ManyToOne(cascade = CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH,fetch = FetchType.LAZY) JoinColumn(name = cid) public Company getCompany() return company; public String getEmployeeName() return employeeName; public void setEmployeeId(Integer employeeId) this.employeeId = employeeId; public void setEmployeeName(String employeeName) this.employeeName = employeeName; public void setCompany(Company company) pany = company; Company.javapackage com.fancy.po;import java.util.Set;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.OneToMany;import javax.persistence.Table;/* * - * 文件: Company.java * 作者: fancy * 邮箱: * 时间: 2012-6-10 * 描述: 实体类 * - */* * 下面只说OneToMany,如需了解其他注解, * 可以参考上一篇：/fancyzero/archive/2012/06/10/hibernate-one-to-one-annotation.html */EntityTable(name = t_company)public class Company private Integer companyId; private String companyName; private Set employees; Id GeneratedValue(strategy = GenerationType.AUTO) public Integer getCompanyId() return companyId; /* * OneToMany 与 OneToOne相似的也用mappedBy,参考了Employee * 可以参考上一篇 */ OneToMany(mappedBy = company) public Set getEmployees() return employees; public String getCompanyName() return companyName; public void setCompanyId(Integer companyId) panyId = companyId; public void setCompanyName(String companyName) panyName = companyName; public void setEmployees(Set employees) this.employees = employees; pom.xml 4.0.0 com.fancy hibernate-annotation-many-to-one-example 0.0.1-SNAPSHOT jar hibernate-annotation-many-to-one-example UTF-8 org.hibernate hibernate-entitymanager 3.3.1.ga org.hibernate hibernate-annotations 3.3.1.GA mysql mysql-connector-java 5.1.17 junit junit 3.8.1 test Test.javapackage com.fancy.test;import java.util.Iterator;import java.util.Set;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.AnnotationConfiguration;import org.hibernate.cfg.Configuration;import com.fancy.po.Company;import com.fancy.po.Employee;/* * - * 文件: Test.java * 作者: fancy * 邮箱: * 时间: 2012-6-10 * 描述: 测试类 * - */public class Test public static void main(String args) /读取hibernate配置,默认读取classpath下的hibernate.cfg.xml Configuration conf = new AnnotationConfiguration(); /构建session工厂 SessionFactory sessionFactory = conf.configure().buildSessionFactory(); /打开session Session session = sessionFactory.openSession(); /开始事务 session.beginTransaction(); / * * * * * * * * * * * * * * * * * * * * * * * * * * * * /test1(session); /测试 1 /test2(session); /测试 2 test3(session); /测试 3 / * * * * * * * * * * * * * * * * * * * * * * * * * * * * /提交事务 session.getTransaction().commit(); /关闭session工厂 sessionFactory.close(); /关闭session session.close(); public static void test1(Session session) Company company = (Company)session.get(Company.class, 1); /发出Company的select语句 Set employee = company.getEmployees(); /不发出Employee的select语句 System.out.println(Company ： + company.getCompanyName(); System.out.println(CountSum： + employee.size(); /Employee初次被使用,发出select语句 Iterator it = employee.iterator(); /Employee不再发出select语句 while(it.hasNext() System.out.println(EmployeeName： + it.next().getEmployeeName(); public static void test2(Session session) Company company = (Company)session.get(Company.class, 2);/发出Company的select语句 Set employee = company.getEmployees(); /不发出Employee的select语句 Iterator it = employee.iterator(); /发出Employee的select语句 Employee e = null; Boolean first = false; while(it.hasNext() e = it.next(); if(!first) System.out.println(EmployeeId： + e.getEmployeeId() + information will be change); e.setEmployeeName(fancy); /更改雇员名字 / session.save(e); /发出Employee的update语句,不发出Company的update语句 session.save(company); /发出Employee的update语句,不发出Company的update语句 first = true; System.out.println(EmployeeName： + e.getEmployeeName(); public static void test3(Session session) Employee employee = (Employee)session.get(Employee.class, 1);/发出Employee的select语句 Company company = (Company)session.get(Company.class, 1);/发出Company的select语句 company.setCompanyName(Oracle); /更改公司名字 / session.save(company);/发出Company的update语句,不发出Employee的update语句 session.save(employee);/发出Company的update语句,不发出Employee的update语句 多对一的话，在many的对象中有一个属性就是one对象，而表结构中就是many表有one表的外键。反过来的话，在one对象里面有many对象的集合（List、Set等都可以）。评论|给力0不给力0 2011-11-21 14:53 zz270564642|五级你问得好奇怪，比如：一个Teacher类,一个Student类Class Teacherprivate int id;private String teacherName;private Set students ;/添加get() and set()。Class Studentprivate int stuId;private String stuName;private int teacherId;/添加get() and set()。你用了Hibernate了吗？保存Teacher对象的时候是会直接