jpaflushinterceptor.java

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package org.springframework.samples.petclinic.jpa;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.orm.jpa.SharedEntityManagerCreator;

/**
 * 供完成基于JPA的集成测试使用，保证在目标方法调用结束后立即调用.flush()方法，
 * 从而保证测试结果的正确性.
 * <li>使得目标DAO方法不用显式调用flush()，从而不会为了“测试”而测试，并不会对应用有任何影响。
 * <li>对于其他ORM引擎，可以提供类似的拦截器
 * 
 * @author worldheart
 *
 */
public class JpaFlushInterceptor implements MethodInterceptor {
	
    protected static final Log log = LogFactory.getLog(JpaFlushInterceptor.class);

	private EntityManager em;
	
	public void setEmf(EntityManagerFactory emf) {
		//获得当前活动事务征集的EntityManager
		this.em = SharedEntityManagerCreator.createSharedEntityManager(emf);
	}
	
    public Object invoke(MethodInvocation invocation) throws Throwable {    	
        Object object = invocation.proceed();
        
        //在调用DAO方法或其他事务性方法后，立即调用.flush()
        em.flush();
                
        log.info("returned from...." + invocation.getClass());        
        return object;
    }

}