Two, java framework for learning

Two, java framework for learning

• Writing rules entity classes
  • Physical properties of the class are private
  • private attributes using the disclosed set, get, a method of operating
  • It requires a unique entity class has attribute value (id value is generally used)
  • Entity class attribute is not recommended basic data types, corresponding to the basic data types used packaging,
    eight basic data types corresponding packaging
    • int--Integer
    • char--Character
    • Other initial capital letters Example: double - Double
    • Expressed as a fraction of students is 0: int score = 0; but not accurately indicate whether students take the exam.
      If you use the wrapper classes can be: Integer = 0 score 0, Integer = null did not take the exam.
• Hibernate primary key generation strategy
  • Hibernate claim entity class which has a property as a unique value, the corresponding primary key, the master key generation strategy may be different.
  • Hibernate primary key generation strategy has a lot of value
    

• There are many in the class attribute value.
  native: Depending on the database used to select which value to use
  uuid: hibernate help generate uuid
  
• Uuid generation strategy used, the type of entity class id attribute must be a string type.
• (Some specific operation and demonstration slightly)
• Hibernate's cache
  • Hibernate framework provides a lot of optimization ways, its cache optimization is a way
  • Hibernate caching features
    • By default
    • Range is created from session to session close range
    • Stored data must be persistent state data
• Hibernate secondary cache
  • You need to configure
  • Range is sessionFactory
• Hibernate transaction code written specification
  • Code structure
    try {open transaction
    commit the transaction
    } catch () {roll back the transaction
    } finally {
    Close
    }
• Binding Hibernate session
  • Gets the local thread sessio, hibernate core configuration in the configuration file
    
  • SessionFactory inside the method call