Hibernate使用注解

基本注解

//entity表示需要实体化的实体类
@Entity 
//实体类所对应的表
@Table(name="t_book")
public class Book {
    //主键
    @Id
    //主键生成策略，auto相当于native
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name="book_id")
    private int id;
    @Column(name="book_name")
    private String name;
    @Column
    private double price;
    //不写@Colum就是默认列名字和属性一致
    private String author;
    private Date pubDate;
/*set/get方法略*/

使用注解后*.hbm.xml不存在了所以在hiberntae.cfg.xml里面mapping改为

<mapping class="cn.siggy.pojo.Book" />

不再是resource

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多对一双向注解

//entity表示需要实体化的实体类
@Entity 
//实体类所对应的表
@Table(name="t_book")
public class Book {
    //主键
    @Id
    //主键生成策略
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name="book_id")
    private int id;
    @Column(name="book_name")
    private String name;
    @Column
    private double price;
    private String author;
    private Date pubDate;
    @ManyToOne(cascade=CascadeType.ALL)
    @JoinColumn(name="category_id")
    private Category catregory;
}

@Entity
@Table
public class Category {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)//oracle比较麻烦，参考网上的例子
    private int id;
    private String name;
    @OneToMany(mappedBy="category")
    private Set<Book>  books=new HashSet<Book>();

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