hibernate注解方式使我不需要在创建实体类的同时创建*.hbm.xml来映射数据库中对应表格，配置如下代码中所示：
Dept.java
1 package com.entity; 2 3 import java.util.HashSet; 4 import java.util.Set; 5 6 import javax.persistence.CascadeType; 7 import javax.persistence.Column; 8 import javax.persistence.Entity; 9 import javax.persistence.GeneratedValue; 10 import javax.persistence.GenerationType; 11 import javax.persistence.Id; 12 import javax.persistence.OneToMany; 13 import javax.persistence.SequenceGenerator; 14 import javax.persistence.Table; 15 import javax.persistence.Transient; 16 17 @Entity 18 @Table(name="dept") 19 public class Dept implements java.io.Serializable { 20 21 // Fields 22 23 private Integer id; 24 private String name; 25 private String location; 26 private Set<Emp> emps = new HashSet<Emp>(0); 27 28 // Constructors 29 30 /** default constructor */ 31 public Dept() { 32 } 33 34 /** full constructor */ 35 public Dept(String name, String location, Set emps) { 36 this.name = name; 37 this.location = location; 38 this.emps = emps; 39 } 40 41 // Property accessors 42 43 @Id 44 @GeneratedValue(strategy=GenerationType.SEQUENCE,generator="seq_dept") 45 @SequenceGenerator(name="seq_dept",sequenceName="seq_dept_id",allocationSize=20,initialValue=1) 46 public Integer getId() { 47 return this.id; 48 } 49 50 public void setId(Integer id) { 51 this.id = id; 52 } 53 54 @Column(name="name") 55 public String getName() { 56 return this.name; 57 } 58 59 public void setName(String name) { 60 this.name = name; 61 } 62 63 @Transient 64 public String getLocation() { 65 return this.location; 66 } 67 68 public void setLocation(String location) { 69 this.location = location; 70 } 71 72 @OneToMany(mappedBy="dept",cascade=CascadeType.ALL) 73 public Set<Emp> getEmps() { 74 return emps; 75 } 76 77 public void setEmps(Set<Emp> emps) { 78 this.emps = emps; 79 } 80 81 82 }
Emp.java
1 package com.entity; 2 3 import java.util.Date; 4 5 import javax.persistence.Column; 6 import javax.persistence.Entity; 7 import javax.persistence.FetchType; 8 import javax.persistence.GeneratedValue; 9 import javax.persistence.GenerationType; 10 import javax.persistence.Id; 11 import javax.persistence.JoinColumn; 12 import javax.persistence.ManyToOne; 13 import javax.persistence.NamedQuery; 14 import javax.persistence.SequenceGenerator; 15 import javax.persistence.Table; 16 import javax.persistence.Transient; 17 18 @Entity 19 @Table(name="emp") 20 21 public class Emp implements java.io.Serializable { 22 23 24 25 26 private Integer id; 27 private Dept dept; 28 private String name; 29 private String job; 30 private Double salary; 31 32 private Date hiredate; 33 34 // Constructors 35 36 /** default constructor */ 37 public Emp() { 38 } 39 40 /** full constructor */ 41 public Emp(Dept dept, String name, String job, Double salary) { 42 this.dept = dept; 43 this.name = name; 44 this.job = job; 45 this.salary = salary; 46 } 47 48 49 @Id 50 @GeneratedValue(strategy=GenerationType.SEQUENCE,generator="seq_emp") 51 @SequenceGenerator(name="seq_emp",sequenceName="seq_emp_eno",allocationSize=20,initialValue=1) 52 public Integer getId() { 53 return this.id; 54 } 55 56 public void setId(Integer id) { 57 this.id = id; 58 } 59 60 @ManyToOne(fetch=FetchType.LAZY) 61 @JoinColumn(name="dept_id") 62 public Dept getDept() { 63 return this.dept; 64 } 65 66 public void setDept(Dept dept) { 67 this.dept = dept; 68 } 69 70 @Column(name="name") 71 public String getName() { 72 return this.name; 73 } 74 75 public void setName(String name) { 76 this.name = name; 77 } 78 @Transient 79 public String getJob() { 80 return this.job; 81 } 82 83 public void setJob(String job) { 84 this.job = job; 85 } 86 @Transient 87 public Double getSalary() { 88 return this.salary; 89 } 90 91 public void setSalary(Double salary) { 92 this.salary = salary; 93 } 94 @Column(name="hiredate") 95 public Date getHiredate() { 96 return hiredate; 97 } 98 99 public void setHiredate(Date hiredate) { 100 this.hiredate = hiredate; 101 } 102 }
hibernate.cfg.xml中的配置如下：
<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <!-- Generated by MyEclipse Hibernate Tools. --> <hibernate-configuration> <session-factory> <property name="dialect">org.hibernate.dialect.PointbaseDialect</property> <property name="connection.url"> jdbc:oracle:thin:@192.168.40.128:1521:orcl </property> <property name="connection.username">thunder</property> <property name="connection.password">admin</property> <property name="connection.driver_class"> oracle.jdbc.OracleDriver </property> <property name="myeclipse.connection.profile">thunder</property> <property name="show_sql">true</property> <property name="format_sql">true</property> <mapping class="com.entity.Dept"/> <mapping class="com.entity.Emp"/> </session-factory> </hibernate-configuration>
需要注意<mapping>中class属性值的引用方式，这是和引用*.hbm.xml的不同之处。
测试：
public static void main(String[] args) { SessionFactory sf =null; Session session=null; Transaction tx=null; try { //新的获取sf的方式 sf=new AnnotationConfiguration().configure().buildSessionFactory(); //获得session session =sf.openSession(); //获取事务 tx=session.beginTransaction(); Emp emp=new Emp(); emp.setName("神经一枚"); emp.setHiredate(new Date()); session.save(emp); tx.commit(); System.out.println("add ok!"); //根据主键去查询信息，根据many-to-one加载部门信息 Emp emp=(Emp) session.load(Emp.class, new Integer(17)); System.out.println(emp.getName()+" "+emp.getDept().getName()); //通过添加部门的同时把员工添加过去 Emp e1 =new Emp(); e1.setName("思过"); e1.setHiredate(new Date()); Dept d=new Dept(); d.setName("市场部"); d.getEmps().add(e1); e1.setDept(d); session.save(d); tx.commit(); System.out.println("it is successful"); } catch (Exception e) { //tx.rollback(); e.printStackTrace(); }finally{ session.close(); sf.close(); } }
需要注意，获取Session工厂的方法与之前的不一样。
以上就是hibernate逐渐的简单使用。
