Java Persistence API – Best Practices and Tips

This JavaOne 2007 session was packed the rim but I soon discovered I should have gone elsewhere. Everything in Java has some type of context and JPA is no different, the speaker was talking about the Persistence Context, blah, blah, Entity Manager, something or other. I found this session a bit hard to follow, a bit too technical and really dry. The slides looked like endless paragraphs from Tolstoy’s The Death of Ivan IIyich. A JPA junkie snapped pictures of the slides so that he can decipher and analyze them at a later time, or so I imagined, with the help of Java non the less.

Here are some general rules that I was able to grasp from this session… You need to manage the relationship of the parent and child object explicitly for each object individually. You should try to use left joins to fetch data in your queries. Using the @Version annotation attribute will help to detect parallel updates to a entity. You should use named queries whenever possible because they are cached by the JPA provider. Use fully qualified names for your queries such as ‘Employee.findByName’ to avoid named collisions. Concatenating strings in an attempt to make dynamic queries is not a best practice because it is open to SQL injection. Use named parameters in queries to avoid SQL injection. Try to avoid native SQL queries so that your application can be more database portable. That said, native queries might be required for vendor specific functionality or stored procedures.

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