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POUsing Dynamic Proxies to centralize JPA code
 

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    <p>Actually, This is not a question but really I need your opinions in a matter... I put his post here because I know you always active, so please don't consider this a bad question and share me your opinions.</p> <p>I've used Java dynamic proxies to Centralize The code of JPA that I used in a standalone mode, and Here's the dynamic proxy code:</p> <pre><code>package com.forat.service; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.util.logging.Level; import java.util.logging.Logger; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.EntityTransaction; import javax.persistence.Persistence; import com.forat.service.exceptions.DAOException; /** * Example of usage : * &lt;pre&gt; * OnlineFromService onfromService = * (OnlineFromService) DAOProxy.newInstance(new OnlineFormServiceImpl()); * try { * Student s = new Student(); * s.setName("Mohammed"); * s.setNationalNumber("123456"); * onfromService.addStudent(s); * }catch (Exception ex) { * System.out.println(ex.getMessage()); * } *&lt;/pre&gt; * @author mohammed hewedy * */ public class DAOProxy implements InvocationHandler{ private Object object; private Logger logger = Logger.getLogger(this.getClass().getSimpleName()); private DAOProxy(Object object) { this.object = object; } public static Object newInstance(Object object) { return Proxy.newProxyInstance(object.getClass().getClassLoader(), object.getClass().getInterfaces(), new DAOProxy(object)); } @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { EntityManagerFactory emf = null; EntityManager em = null; EntityTransaction et = null; Object result = null; try { emf = Persistence.createEntityManagerFactory(Constants.UNIT_NAME); em = emf.createEntityManager();; Method entityManagerSetter = object.getClass(). getDeclaredMethod(Constants.ENTITY_MANAGER_SETTER_METHOD, EntityManager.class); entityManagerSetter.invoke(object, em); et = em.getTransaction(); et.begin(); result = method.invoke(object, args); et.commit(); return result; }catch (Exception ex) { et.rollback(); Throwable cause = ex.getCause(); logger.log(Level.SEVERE, cause.getMessage()); if (cause instanceof DAOException) throw new DAOException(cause.getMessage(), cause); else throw new RuntimeException(cause.getMessage(), cause); }finally { em.close(); emf.close(); } } } </code></pre> <p>And here's the link that contains more info (<a href="http://m-hewedy.blogspot.com/2010/04/using-dynamic-proxies-to-centralize-jpa.html" rel="nofollow noreferrer">http://m-hewedy.blogspot.com/2010/04/using-dynamic-proxies-to-centralize-jpa.html</a>)</p> <p>So, Please give me your opinions.</p> <p>Thanks.</p>
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    1. COAre you asking if it's a good idea to use dynamic proxies to centralize JPA code? Or are you asking for a constructive critique of your code? Or are you looking for war stories from people who have used a similar approach in the past?
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    2. COOf course I am asking for constructive critique
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