我正在编写一个简单的函数，用于通过从BeanPostProcessor创建代理来记录@Metric注释的方法的性能：
Metric.java
@Retention(RUNTIME)
@Target({METHOD, ANNOTATION_TYPE})
public @interface Metric {}
MetricMethodBeanPostProcessor.java
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.util.ClassUtils;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Collectors;
public class MetricMethodBeanPostProcessor implements BeanPostProcessor{
private static final Logger log = LoggerFactory.getLogger(MetricMethodBeanPostProcessor.class);
private final Map<String, Class<?>> originalMetricClasses = new HashMap<>();
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
Class<?> originalMetricClass = bean.getClass();
for (Method method : originalMetricClass.getMethods()) {
if (method.isAnnotationPresent(Metric.class)) {
originalMetricClasses.put(beanName, originalMetricClass);
break;
}
}
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
Class<?> originalBeanClass = originalMetricClasses.get(beanName);
if (originalBeanClass != null) {
return Proxy.newProxyInstance(originalBeanClass.getClassLoader(), ClassUtils.getAllInterfacesForClass(originalBeanClass), (proxy, method, args) -> {
if (originalBeanClass.getMethod(method.getName(), method.getParameterTypes()).isAnnotationPresent(Metric.class)) {
commons.utils.Metric metric = new commons.utils.Metric();
metric.start();
try {
return method.invoke(proxy, args);
} finally {
metric.finish();
log.debug("{}: {}", prettyMethodName(method), metric.getElapsedTime());
}
}
return method.invoke(proxy, args);
});
}
return bean;
}
private String prettyMethodName(Method method) {
return new StringBuilder(method.getDeclaringClass().getSimpleName())
.append(".")
.append(method.getName())
.append("(")
.append(Arrays.stream(method.getParameterTypes())
.map(Class::getSimpleName)
.collect(Collectors.joining(", ")))
.append(")").toString();
}
}
当我尝试使用时，在包含@Metric的bean的自动装配期间出现错误：
15.11.2017 11:23:55 [WARN ] support.XmlWebApplicationContext - Exception encountered during context initialization - cancelling refresh attempt
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'tokenAuthController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private abac.authentication.tokenauth.service.TokenAuthService abac.authentication.controllers.TokenAuthController.tokenService; nested exception is java.lang.IllegalArgumentException: Can not set abac.authentication.tokenauth.service.TokenAuthService field abac.authentication.controllers.TokenAuthController.tokenService to com.sun.proxy.$Proxy106
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1210)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:755)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:664)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:630)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:678)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:549)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:490)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
at javax.servlet.GenericServlet.init(GenericServlet.java:244)
at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:626)
at org.eclipse.jetty.servlet.ServletHolder.initialize(ServletHolder.java:405)
at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:875)
at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:346)
at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1380)
at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1342)
at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:772)
at org.eclipse.jetty.servlet.ServletContextHandler.doStart(ServletContextHandler.java:259)
at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:518)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:114)
at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132)
at org.eclipse.jetty.server.Server.start(Server.java:405)
at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106)
at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
at org.eclipse.jetty.server.Server.doStart(Server.java:372)
at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
at org.hc.jp.WebServer.start(WebServer.java:62)
at org.hc.jp.Main.start(Main.java:42)
at org.hc.jp.Main.main(Main.java:30)
at abac.Main.main(Main.java:5)
在启动bean的过程中查看了调试中的BeanPostProcessors列表，发现MetricMethodBeanPostProcessor在中间某处花费了。
我得出的结论是，创建的代理会覆盖原始类及其所有注释，并且所有后续后处理器都不再看到必要的注释。
因此问题：如何正确编写BeanPostProcessor以进行日志记录，以便不会中断？
P.S。谷歌没有帮助
P.P.S不会使用AOP，因为以降低性能的方式测量性能并不好
答案 0 :(得分：0)
）
首先，正如M. Deinum所说的那样，性能代价为Proxy == AOP
当我运行代码时
***************************申请失败
说明
bean'xxxxxxx'无法注入 'com.spring.demo.demo.tasks.xxxxxx'因为它是JDK动态代理 实现：
动作：
考虑将bean注入其接口之一或强制使用 通过设置proxyTargetClass = true来使用基于CGLib的代理 @EnableAsync和/或@EnableCaching。
转换为基于CGLib的代理，我能够运行并执行指标拦截。
<dependency> <groupId>cglib</groupId> <artifactId>cglib</artifactId> <version>3.2.4</version> </dependency>
private Object createMetricProxy(Class<?> theOriginalBeanClass) {
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(theOriginalBeanClass);
enhancer.setCallback((MethodInterceptor) (obj, method, args, proxy) -> {
if (method.isAnnotationPresent(Metric.class)) {
StopWatch timer = new StopWatch();
timer.start();
try {
return proxy.invokeSuper(obj, args);
} finally {
timer.stop();
myMetricService.addMethodExecution(prettyMethodName(method) ,timer.getTotalTimeMillis());
System.out.println("method = " + prettyMethodName(method) + " , time = " + timer.getTotalTimeMillis());
}
} else {
return proxy.invokeSuper(obj, args);
}
});
return enhancer.create();
}