检测 Spring Boot 应用程序时的类路径问题答案

【问题标题】：Classpath problems while Instrumenting Springboot application检测 Spring Boot 应用程序时的类路径问题
【发布时间】：2020-05-30 22:08:14
【问题描述】：

我有一个 springboot 应用程序，我正在尝试使用 bytebuddy 进行检测。我遇到了我无法理解的类路径问题。

首先，以下是这方面的其他文献：

https://github.com/raphw/byte-buddy/issues/473

https://github.com/raphw/byte-buddy/issues/87

Unable to instrument apache httpclient using javaagent for spring boot uber jar application

https://github.com/raphw/byte-buddy/issues/109

https://github.com/raphw/byte-buddy/issues/473

https://github.com/raphw/byte-buddy/issues/489

https://github.com/spring-projects/spring-boot/issues/4868

https://github.com/alibaba/transmittable-thread-local/issues/161

问题是 Spring-boot 将应用程序捆绑到一个 uber-jar 中，其中包含其他 jars

这里需要注意的是，如果我使用 IntelliJ 运行应用程序，它不会使用 uber-jar，而是通过带有一堆 jar 作为类路径参数的主类运行。

由于这种差异，当通过 uber-jar(java -jar target/demo-0.0.1-SNAPSHOT.jar) 运行时，代理运行时某些类不可用。这些类在应用程序主时是可加载的，因为 spring-boot 使用它自己的类加载器，它是在某个时间创建的 b/w 代理和应用程序主方法。

我将在下面描述不同时间点的行为：

代理 PreMain 时

Thread.currentThread().getContextClassLoader() = Launcher$AppClassLoader
Agent.class.classLoader = Launcher$AppClassLoader
Class.forName("org.springframework.web.servlet.HandlerAdapter") => ClassNotFoundException
Class.forName("javax.servlet.http.HttpServletRequest") => ClassNotFoundException

spring 和 javax 类都没有加载，因为它们不是直接在类路径中，根据 App Classloader。它是内罐的一部分，类似于app.jar!/BOOT-INF/lib/some.jar App Classloader 将无法加载此内容。

在应用程序类主时

Thread.currentThread().getContextClassLoader() =org.springframework.boot.loader.LaunchedURLClassLoader
DemoApplication.class.classloader = same as above
Class.forName("org.springframework.web.servlet.HandlerAdapter") => loads successfully
同样适用于 javax 类，加载成功。

加载后Class.forName("javax.servlet.http.HttpServletRequest").classLoader也是LaunchedURLClassLoader。

`builder.visit`调用时（bytebuddy修改类定义时）

代码：

我有两个类，SpringBootInterceptor（包含拦截方法）和SpringBootInterceptorOne（包含进入和退出方法）

  @Override
  public AgentBuilder intercept(AgentBuilder agentBuilder) {
    return agentBuilder
      .type(isSubTypeOf(HandlerAdapter.class))
      .transform((builder, typeDescription, classLoader, module) ->
        builder.visit(Advice.to(SpringBootInterceptorOne.class, SpringBootInterceptorOne.class).on(named("handle").and(isMethod())))
      );
  }

函数intercept() 在主路径中被调用。

函数visit 在实际尝试加载类型时被调用。那时 bytebuddy 会拦截这些方法并修改字节码。

在此代码的当前版本中，函数intercept() 抛出ClassNotFoundException 并且不会发生拦截。

Caused by: java.lang.NoClassDefFoundError: org/springframework/web/servlet/HandlerAdapter

所以，我尝试将代码更改为以下内容：

  @Override
  public AgentBuilder intercept(AgentBuilder agentBuilder) {
    return agentBuilder
//      .type(isSubTypeOf(HandlerAdapter.class))
      .type(not(isInterface())
        .and(safeHasSuperType(named("org.springframework.web.servlet.HandlerAdapter"))))
      .transform((builder, typeDescription, classLoader, module) ->
        builder.visit(Advice.to(SpringBootInterceptorOne.class, SpringBootInterceptorOne.class).on(named("handle").and(isMethod())))
      );
  }

这里，基本上是懒加载类。来自 datadog 的辅助函数：

https://github.com/DataDog/dd-trace-java/blob/master/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/ByteBuddyElementMatchers.java

执行此操作后，intercept 函数没有失败，但 visit() 函数行为异常：

java.lang.IllegalStateException: Could not locate class file for my.package.name.SpringBootInterceptorOne
    at net.bytebuddy.dynamic.ClassFileLocator$Resolution$Illegal.resolve(ClassFileLocator.java:118)
    at net.bytebuddy.asm.Advice.to(Advice.java:431)
    at net.bytebuddy.asm.Advice.to(Advice.java:400)
    at net.bytebuddy.asm.Advice.to(Advice.java:375)
    at net.bytebuddy.asm.Advice.to(Advice.java:361)
    at my.package.name.SpringBootInterceptor.lambda$intercept$0(SpringBootInterceptor.java:30)
    at net.bytebuddy.agent.builder.AgentBuilder$Transformer$Compound.transform(AgentBuilder.java:2612)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$Transformation$Simple$Resolution.apply(AgentBuilder.java:10117)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.doTransform(AgentBuilder.java:10494)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.transform(AgentBuilder.java:10457)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.access$1500(AgentBuilder.java:10223)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer$LegacyVmDispatcher.run(AgentBuilder.java:10833)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer$LegacyVmDispatcher.run(AgentBuilder.java:10780)
    at java.security.AccessController.doPrivileged(Native Method)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.transform(AgentBuilder.java:10380)
    at sun.instrument.TransformerManager.transform(TransformerManager.java:188)
    at sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:428)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:757)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:468)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:74)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:369)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:363)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:362)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:419)
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:92)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:352)
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
    at java.lang.Class.getDeclaredMethods(Class.java:1975)
    at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:463)
    at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:358)
    at org.springframework.util.ReflectionUtils.getUniqueDeclaredMethods(ReflectionUtils.java:414)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.lambda$getTypeForFactoryMethod$2(AbstractAutowireCapableBeanFactory.java:743)
    at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1688)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryMethod(AbstractAutowireCapableBeanFactory.java:742)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:681)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:649)
    at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1604)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doGetBeanNamesForType(DefaultListableBeanFactory.java:520)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:491)
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.collectBeanNamesForType(OnBeanCondition.java:230)
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getBeanNamesForType(OnBeanCondition.java:223)
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getBeanNamesForType(OnBeanCondition.java:213)
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchingBeans(OnBeanCondition.java:167)
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchOutcome(OnBeanCondition.java:142)
    at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:47)
    at org.springframework.context.annotation.ConditionEvaluator.shouldSkip(ConditionEvaluator.java:108)
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForBeanMethod(ConfigurationClassBeanDefinitionReader.java:184)
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:144)
    at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:120)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:331)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:236)
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:275)
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:95)
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:706)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:532)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at com.example.demo.DemoApplication.main(DemoApplication.java:10)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:51)
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:52)

此时，

Thread.currentThread().getContextClassLoader() => LaunchedURLClassLoader
SpringBootInterceptor.class.getClassLoader() = null
在调试器窗口中输入 SpringBootInterceptor.class 不会失败，但是
Class.forName("my.package.name.SpringBootInterceptorOne") => NoClassDefFound

接下来，我尝试了以下方法：

  @Override
  public AgentBuilder intercept(AgentBuilder agentBuilder) {
    ClassLoader cl = Thread.currentThread().getContextClassLoader();
    return agentBuilder
//      .type(isSubTypeOf(HandlerAdapter.class))
      .type(not(isInterface())
        .and(safeHasSuperType(named("org.springframework.web.servlet.HandlerAdapter"))))
      .transform((builder, typeDescription, classLoader, module) -> {
          try {
            Class<?> claz = Thread.currentThread().getContextClassLoader().loadClass("my.package.name.SpringBootInterceptorOne");
            return builder.visit(Advice.to(claz, claz,
              new ClassFileLocator.Compound(ClassFileLocator.ForClassLoader.of(cl),
              ClassFileLocator.ForClassLoader.of(Thread.currentThread().getContextClassLoader())
              )).on(named("handle").and(isMethod())));
          } catch (ClassNotFoundException e) {
            e.printStackTrace();
            return builder;
          }
        }
      );
  }

这会导致拦截器被“安装”。进入和退出方法称为okay。但是将参数转换为正确的类型会导致参数类型出错

exit spring boot
[Ljava.lang.Object;@c83066a
java.lang.NoClassDefFoundError: javax/servlet/http/HttpServletRequest
    at my.package.name.SpringBootInterceptorOne.getEndpoint(SpringBootInterceptorOne.java:36)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1598)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:748)

这里是 SpringBootInterceptorOne 供参考：

  @Advice.OnMethodExit
  static void exit(@Advice.Origin final Executable executable,
                   @Advice.This Object handlerAdapter,
                   @Advice.AllArguments Object[] arguments,
                   @Advice.Enter final TimerContext ctx) {
//      final long duration = ctx.getDuration();
    System.out.println("exit spring boot");
    String e = getEndpoint(arguments);
    System.out.println(e);
  }

  public static String getEndpoint(Object[] arguments) {
    System.out.println(arguments);
    HttpServletRequest request = (HttpServletRequest) arguments[0];
    HandlerMethod  handler = (HandlerMethod) arguments[2];
    return "ad";
  }

更新：

根据答案中提供的建议，我尝试了以下方法：

  @Override
  public AgentBuilder intercept(AgentBuilder agentBuilder) {
    return agentBuilder
//      .type(isSubTypeOf(HandlerAdapter.class))
      .type(not(isInterface())
        .and(safeHasSuperType(named("org.springframework.web.servlet.HandlerAdapter"))))
      .transform(new AgentBuilder.Transformer.ForAdvice()
        .include(SpringBootInterceptorOne.class.getClassLoader())
        .include(getClass().getClassLoader())
        .advice(named("handle"), SpringBootInterceptorOne.class.getName())
      );
  }

它再次抛出错误：

java.lang.NoClassDefFoundError: javax/servlet/http/HttpServletRequest
    at io.signoz.interceptors.http.server.springboot.SpringBootInterceptorOne.getEndpoint(SpringBootInterceptorOne.java:37) ~[na:na]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.3.RELEASE.jar!/:5.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1598) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_242]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_242]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.30.jar!/:9.0.30]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_242]

【问题讨论】：

您是否尝试过您链接的第一个 Github 问题中提到的解决方案，使用Instrumentation::appendToBootSearchPath？
@user991710 是的，我有。这是我的代理做的第一件事。

标签： java spring spring-boot byte-buddy apm

【解决方案1】：

问题是通知类将作为代理的一部分加载到系统类加载器上，而实际的应用程序代码加载到系统类加载器不可见的子类加载器上。如果您在引导加载程序上加载代理，这种情况也不会改变。因此，代理无法加载属于 uber-jar 的 HttpServletRequest 类。

这是代理的典型问题，Byte Buddy 有一个标准的方法来规避它，即使用Transformer.ForAdvice 实例而不是直接使用Advice 类。 Byte Buddy 然后创建一个虚拟类加载器层次结构，考虑由两个类加载器表示的类。

更新：问题是您正在调用在系统类加载器中定义的拦截器，其中相关类不可用。带注释的代码将被内联，但调用的方法不会。如果您将代码复制粘贴到带注释的方法中，则行为与您预期的一样。 Byte Buddy 使用带注释的代码作为模板，并重用 javac 发出的大量信息以保证快速转换。因此，库不能简单地复制方法，而应该将整个方法体提供给 javac。

【讨论】：

恐怕这行不通。更新了问题的详细信息。
@rafael-winterhalter and prongs，我也面临同样的问题。解决这个问题会非常有用。

代理 PreMain 时

在应用程序类主时

builder.visit调用时（bytebuddy修改类定义时）

代码：

`builder.visit`调用时（bytebuddy修改类定义时）