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我正在尝试使用 Bytebuddy 编写一个 javaagent 来拦截 apache httpclient 请求，并且我想将此代理用于 spring boot 应用程序。当我从 Idea 启动我的测试 Spring Boot 应用程序时，代理工作正常（直接运行 main 方法）。但是，当我将应用程序打包到 spring boot uber jar 中并使用 运行它时java -javaagent:myagent.jar -jar myapplication.jar，它会引发以下异常。

onError:org.apache.http.impl.client.AbstractHttpClient
java.lang.NoClassDefFoundError: org/apache/http/HttpHost
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
    at java.lang.Class.getDeclaredMethods(Class.java:1975)
    at net.bytebuddy.description.method.MethodList$ForLoadedType.<init>(MethodList.java:106)
    at net.bytebuddy.description.type.TypeDescription$ForLoadedType.getDeclaredMethods(TypeDescription.java:985)
    at net.bytebuddy.implementation.MethodDelegation$MethodContainer$ForExplicitMethods.ofStatic(MethodDelegation.java:1037)
    at net.bytebuddy.implementation.MethodDelegation.to(MethodDelegation.java:247)
    at net.bytebuddy.implementation.MethodDelegation.to(MethodDelegation.java:226)
    at com.yiji.dtrace.agent.httpclient4.interceptor.HttpClient4Interceptors$1.transform(HttpClient4Interceptors.java:48)
    at net.bytebuddy.agent.builder.AgentBuilder$Transformer$Compound.transform(AgentBuilder.java:457)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$Transformation$Simple$Resolution.apply(AgentBuilder.java:2791)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.transform(AgentBuilder.java:3081)
    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:760)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
    at org.springframework.boot.loader.LaunchedURLClassLoader.doLoadClass(LaunchedURLClassLoader.java:170)
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:142)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
    at org.springframework.boot.loader.LaunchedURLClassLoader.doLoadClass(LaunchedURLClassLoader.java:170)
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:142)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at org.springframework.boot.loader.LaunchedURLClassLoader.doLoadClass(LaunchedURLClassLoader.java:170)
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:142)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at com.yjf.common.net.HttpUtil.<init>(HttpUtil.java:118)
    at com.yjf.common.net.HttpUtil.<init>(HttpUtil.java:81)
    at com.yjf.common.net.HttpUtil.<clinit>(HttpUtil.java:78)
    at com.daidai.dtrace.agent.test.Main.main(Main.java:35)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:53)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: org.apache.http.HttpHost
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 60 more

这是我的代理相关代码。

public class DTraceAgent {

    public static TypeDescription abstractHttpClientDescription() {
        return new TypeDescription.Latent("org.apache.http.impl.client.AbstractHttpClient",
                Modifier.PUBLIC|Modifier.ABSTRACT,
                TypeDescription.OBJECT,
                Arrays.asList(httpClientDescription()));
    }

    public static TypeDescription httpHostDescription() {
        return new TypeDescription.Latent("org.apache.http.HttpHost",
                Modifier.PUBLIC|Modifier.FINAL,
                TypeDescription.OBJECT,
                Arrays.asList(new TypeDescription.ForLoadedType(Cloneable.class),
                        new TypeDescription.ForLoadedType(Serializable.class)));
    }

    public static TypeDescription httpContextDescription() {
        return new TypeDescription.Latent("org.apache.http.protocol.HttpContext",
                getInterfaceModifiers(),
                TypeDescription.OBJECT,
                null);
    }

    public static TypeDescription httpRequestDescription() {
        return new TypeDescription.Latent("org.apache.http.HttpRequest",
                getInterfaceModifiers(),
                httpMessageDescription(),
                null);
    }

    public static void premain(String arguments, Instrumentation instrumentation) {
        new AgentBuilder.Default()
                //.withBinaryLocator(binaryLocatorFor(instrumentation))
                .withListener(DebugListener.getListener())
                .type(is(abstractHttpClientDescription()))
                .transform(new AgentBuilder.Transformer() {
                    public DynamicType.Builder transform(DynamicType.Builder builder,
                                                         TypeDescription typeDescription) {
                        return builder.method(named("execute")
                                .and(takesArguments(httpHostDescription(), httpRequestDescription(), httpContextDescription()))
                                .and(returns(named("org.apache.http.HttpResponse"))))
                                .intercept(MethodDelegation.to(HttpClientInterceptor4dot3Plus.class));
                    }
                }).installOn(instrumentation);
    }
}

public class HttpClientInterceptor4dot3Plus {

    public static CloseableHttpResponse doExecute(
            @SuperCall Callable<CloseableHttpResponse> client, @Argument(1)HttpRequest request
            ) throws Exception {
        StringBuilder builder = new StringBuilder(1024);
        if (request != null && request.getRequestLine() != null) {
            RequestLine requestLine = request.getRequestLine();
            builder.append(requestLine.getMethod()).append(" ").append(requestLine.getUri());
        }
        try (TraceScope scope = Trace.startSpanForEntry(builder.toString())) {
            Trace.spanType(Span.SPAN_TYPE_HTTP);
            try {
                return client.call();
            } catch (Exception e) {
                Trace.exception(e);
                throw e;
            }
        }
    }
}

public class DebugListener {
    public static AgentBuilder.Listener getListener() {
        return new AgentBuilder.Listener() {
            @Override
            public void onTransformation(TypeDescription typeDescription, DynamicType dynamicType) {
                System.err.println("onTransformation:" + typeDescription.getCanonicalName());
                try {
                    dynamicType.saveIn(new File("generated_classes"));
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onIgnored(TypeDescription typeDescription) {
                //System.err.println("onIgored:" + typeDescription.getCanonicalName());
            }

            @Override
            public void onError(String typeName, Throwable throwable) {
                System.err.println("onError:" + typeName);
                throwable.printStackTrace();
            }

            @Override
            public void onComplete(String typeName) {
                //System.err.println("onComplete:" + typeName);
            }
        };
    }
}

我认为这个问题是由 spring boot uber jar 引导应用程序的方式引起的。Spring boot 提供了一个专用的类加载器，名为 LaunchedURLClassLoader，用于从 uber jar 加载应用相关的类，而 javaagent jar 是默认加载系统类加载器（如果我的理解是正确的）。因此系统类加载器看不到 apache httpclient lib（包含在 uber jar 中）。

我尝试为 AgentBuilder 提供 BinaryLocator，但没有成功。也许 BinaryLocator 构造不正确。无论如何，一个合适的 BinaryLocator 可能是一个可能的解决方案。

非常感谢任何解决方案或建议。

其他信息可能会有所帮助：
spring-boot 版本 1.3.1.RELEASE byte-buddy 0.7.7，使用 maven-assembly-plugin 的 jar-with-dependencies 描述符 Ref apache httpclient 4.3.2
打包到代理中

4

1 回答 1

1

我通过两个步骤解决了这个问题：

  1. 使用 Spring Boot 的专用ClassLoader于卸载类型：

    public static void premain(String arguments, Instrumentation instrumentation) {
  ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
  ClassFileLocator.Compound compound = new ClassFileLocator.Compound(ClassFileLocator.ForClassLoader.of(classLoader), ClassFileLocator.ForClassLoader.ofClassPath());
  TypeDescription delegator = TypePool.Default.of(compound).describe(delegatorClass).resolve();
  new AgentBuilder.Default()
    //.withBinaryLocator(binaryLocatorFor(instrumentation))
    .withListener(DebugListener.getListener())
    .type(is(abstractHttpClientDescription()))
    .transform(new AgentBuilder.Transformer() {
      @Override
      public DynamicType.Builder transform(DynamicType.Builder builder,
          TypeDescription typeDescription) {
        return builder.method(named("execute")
          .and(takesArguments(httpHostDescription(), httpRequestDescription(), httpContextDescription()))
          .and(returns(named("org.apache.http.HttpResponse"))))
          .intercept(MethodDelegation.to(delegator));
      }
  }).installOn(instrumentation);
}

  2. 将 javaagent jar 打包到 Spring Boot 的uber-jar中，以便委托者类可以引用与被拦截类相关的类。

这个问题在Byte Buddy 的问题跟踪器中有更详细的讨论。

于 2016-01-04T06:23:31.690 回答