@TransactionAttribute(TransactionAttributeType.SUPPORTS) public Product support(int productid)( return em.find(Product.class,productid): @TransactionAttribute(TransactionAttributeType.MANDATORY) //意义④ public void mandatory(){ em persist(new Product("mandatory",(float)52)): 1 @TransactionAttribute(TransactionAttributeType.NEVER) /意义⑤ public Product never(int productid)( return em.find(Product.class,productid) 第5页共7页 第 5 页 共 7 页 @TransactionAttribute(TransactionAttributeType.SUPPORTS) public Product support(int productid) { return em.find(Product.class, productid); } @TransactionAttribute(TransactionAttributeType.MANDATORY) // 意义④_______________________________ public void mandatory() { em.persist(new Product("mandatory", (float)52)); } @TransactionAttribute(TransactionAttributeType.NEVER) // 意义⑤_______________________________ public Product never(int productid) { return em.find(Product.class, productid); } }