Spring Aspect Introduction Example : Spring Aspect « Spring « Java






  1. Java
  2. Spring
  3. Spring Aspect

Spring Aspect Introduction Example

/* Pro Spring By Rob Harrop Jan Machacek ISBN: 1-59059-461-4 Publisher: Apress *//////////////////////////////////////////////////////////////////////////////////////// publicinterface IsModified { publicboolean isModified(); } /////////////////////////////////////////////////////////////////////////////////////// import org.springframework.aop.support.DefaultIntroductionAdvisor; publicclass IsModifiedAdvisor extends DefaultIntroductionAdvisor { public IsModifiedAdvisor() { super(new IsModifiedMixin()); } } /////////////////////////////////////////////////////////////////////////////////////// publicclass TargetBean { private String name; publicvoid setName(String name) { this.name = name; } public String getName() { return name; } } /////////////////////////////////////////////////////////////////////////////////////// import java.lang.reflect.Method; import java.util.HashMap; import java.util.Map; import org.aopalliance.intercept.MethodInvocation; import org.springframework.aop.support.DelegatingIntroductionInterceptor; publicclass IsModifiedMixin extends DelegatingIntroductionInterceptor implements IsModified { privateboolean isModified = false; private Map methodCache = new HashMap(); publicboolean isModified() { return isModified; } public Object invoke(MethodInvocation invocation) throws Throwable { if (!isModified) { if ((invocation.getMethod().getName().startsWith("set")) && (invocation.getArguments().length == 1)) { // invoke the corresponding get method to see // if the value has actually changed  Method getter = getGetter(invocation.getMethod()); if (getter != null) { // modification check is unimportant // for write only methods  Object newVal = invocation.getArguments()[0]; Object oldVal = getter.invoke(invocation.getThis(), null); if((newVal == null) && (oldVal == null)) { isModified = false; } elseif((newVal == null) && (oldVal != null)) { isModified = true; } elseif((newVal != null) && (oldVal == null)) { isModified = true; } else { isModified = (!newVal.equals(oldVal)); } } } } return super.invoke(invocation); } private Method getGetter(Method setter) { Method getter = null; // attempt cache retrieval.  getter = (Method) methodCache.get(setter); if (getter != null) { return getter; } String getterName = setter.getName().replaceFirst("set", "get"); try { getter = setter.getDeclaringClass().getMethod(getterName, null); // cache getter synchronized (methodCache) { methodCache.put(setter, getter); } return getter; } catch (NoSuchMethodException ex) { // must be write only return null; } } } /////////////////////////////////////////////////////////////////////////////////////// import org.springframework.aop.IntroductionAdvisor; import org.springframework.aop.framework.ProxyFactory; publicclass IntroductionExample { publicstaticvoid main(String[] args) { // create the target  TargetBean target = new TargetBean(); target.setName("Name"); // create the advisor  IntroductionAdvisor advisor = new IsModifiedAdvisor(); // create the proxy  ProxyFactory pf = new ProxyFactory(); pf.setTarget(target); pf.addAdvisor(advisor); pf.setOptimize(true); TargetBean proxy = (TargetBean)pf.getProxy(); IsModified proxyInterface = (IsModified)proxy; // test interfaces  System.out.println("Is TargetBean?: " + (proxy instanceof TargetBean)); System.out.println("Is IsModified?: " + (proxy instanceof IsModified)); // test is modified implementation  System.out.println("Has been modified?: " + proxyInterface.isModified()); proxy.setName("Rob Harrop"); System.out.println("Has been modified?: " + proxyInterface.isModified()); proxy.setName("Joe Schmoe"); System.out.println("Has been modified?: " + proxyInterface.isModified()); } }








IntroductionExample.zip( 1,481 k)

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