hibernate annotion多对多关系示例

实体之间是多对多的关系，如图：


错误的实体代码如下

JAVA 代码:

@ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
   @JoinTable(name = "product_packagetype:packageTypes:products")
   private java.util.Listimplambition.forxxx.model.PackageType> packageTypes;
   /** 
    * @generated 
    */
   @ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
   @JoinTable(name = "product_productcolor:productColors:products")
   private java.util.Listimplambition.forxxx.model.ProductColor> productColors;
   /** 
    * @generated 
    */
   @ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
   @JoinTable(name = "product_attach:attachs:products")
   private java.util.Listimplambition.forxxx.model.Attach> attachs;
 
 

这样的代码本身不能正常运行，报错 cannot simultaneously fetch multiple bags。
改成FetchType.LAZY后，报错 WARN [main] 2009-05-10 16:46:18,655 - SQL Error: 1064, SQLState: 42000
ERROR [main] 2009-05-10 16:46:18,655 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ':packageTypes:products packagetyp0_ left outer join PackageType packagetyp1_ on ' at line 1



最后只能修改为：
Product实体

JAVA 代码:

/** 
    * @generated 
    */
   @ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.LAZY)
   //@JoinTable(name = "product_packagetype:packageTypes:products")
   @JoinTable(name = "product_packagetype", joinColumns = { @JoinColumn(name = "packageTypes") }, inverseJoinColumns = { @JoinColumn(name = "products") }) 
   private java.util.Listimplambition.forxxx.model.PackageType> packageTypes;
   /** 
    * @generated 
    */
   @ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.LAZY)
   //@JoinTable(name = "product_productcolor:productColors:products")
   @JoinTable(name = "product_productcolor", joinColumns = { @JoinColumn(name = "productColors") }, inverseJoinColumns = { @JoinColumn(name = "products") })
   private java.util.Listimplambition.forxxx.model.ProductColor> productColors;
   /** 
    * @generated 
    */
   @ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.LAZY)
   //@JoinTable(name = "product_attach:attachs:products")
   @JoinTable(name = "product_attach", joinColumns = { @JoinColumn(name = "attachs") }, inverseJoinColumns = { @JoinColumn(name = "products") })
   private java.util.Listimplambition.forxxx.model.Attach> attachs;

其他关联实体只列出一个示例，代码如下（注释掉的为studio生成的代码）

JAVA 代码:

/** 
    * @generated 
    */
   //@ManyToMany(cascade = CascadeType.PERSIST, fetch = FetchType.EAGER)
   @ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE }, fetch = FetchType.LAZY, mappedBy="attachs")
   private java.util.Listimplambition.forxxx.model.Product> products;