如何在ByteBuddy转换器中识别生成类并跳过Spring包装类

我们在JavaAgent中使用ByteBuddy实现了如下转换器，但希望跳过Spring生成的动态包装类这类动态生成的类型。推测这类类的class.getProtectionDomain().getCodeSource()会返回null，但不知道如何在ByteBuddy中实现该检查：

new AgentBuilder.Default()
                .type(TypeMatchers.create(Configuration.getInstance()))
                .transform((builder, typeDescription, classLoader, module, protectionDomain) -> {

                    try {
                        AnnotationDescription digmaMarkerAnnotationDescription = getDigmaMarkerAnnotationDescription();
                        return builder
                                .visit(new MemberAttributeExtension.ForMethod()
                                                                                    .annotateMethod(digmaMarkerAnnotationDescription)
                                        .on(MethodMatchers.create(typeDescription, Configuration.getInstance())));
                    } catch (Throwable e) {
                        Log.error("got exception in bytebuddy transformer", e);
                        return builder;
                    }

                }).installOn(inst);

解决方案 #

ByteBuddy的AgentBuilder支持通过filter()方法添加类过滤逻辑，你可以直接利用转换器参数中的protectionDomain完成CodeSource检查，同时也可以结合动态生成类的其他特征增强过滤效果。

1. 基础实现：检查CodeSource是否为null

在type()匹配阶段之后添加filter()，跳过CodeSource为null的类：

new AgentBuilder.Default()
        .type(TypeMatchers.create(Configuration.getInstance()))
        // 过滤掉CodeSource为null的动态生成类
        .filter((typeDescription, classLoader, module, protectionDomain) -> {
            if (protectionDomain == null) {
                return false;
            }
            return protectionDomain.getCodeSource() != null;
        })
        .transform((builder, typeDescription, classLoader, module, protectionDomain) -> {
            try {
                AnnotationDescription digmaMarkerAnnotationDescription = getDigmaMarkerAnnotationDescription();
                return builder
                        .visit(new MemberAttributeExtension.ForMethod()
                                        .annotateMethod(digmaMarkerAnnotationDescription)
                                .on(MethodMatchers.create(typeDescription, Configuration.getInstance())));
            } catch (Throwable e) {
                Log.error("got exception in bytebuddy transformer", e);
                return builder;
            }
        }).installOn(inst);

2. 增强过滤：结合Spring动态类特征

除了CodeSource检查，还可以通过类名特征、接口实现情况精准识别Spring生成的代理类：

new AgentBuilder.Default()
        .type(TypeMatchers.create(Configuration.getInstance()))
        .filter((typeDescription, classLoader, module, protectionDomain) -> {
            // 跳过CodeSource为null的类
            if (protectionDomain != null && protectionDomain.getCodeSource() == null) {
                return false;
            }
            String className = typeDescription.getTypeName();
            // 跳过Spring CGLIB生成的增强类和FastClass
            if (className.contains("$$EnhancerBySpringCGLIB$$") || className.contains("$$FastClassBySpringCGLIB$$")) {
                return false;
            }
            // 跳过实现Spring CGLIB Factory接口的类
            return !typeDescription.isAssignableTo(org.springframework.cglib.proxy.Factory.class);
        })
        .transform((builder, typeDescription, classLoader, module, protectionDomain) -> {
            try {
                AnnotationDescription digmaMarkerAnnotationDescription = getDigmaMarkerAnnotationDescription();
                return builder
                        .visit(new MemberAttributeExtension.ForMethod()
                                        .annotateMethod(digmaMarkerAnnotationDescription)
                                .on(MethodMatchers.create(typeDescription, Configuration.getInstance())));
            } catch (Throwable e) {
                Log.error("got exception in bytebuddy transformer", e);
                return builder;
            }
        }).installOn(inst);

内容的提问来源于stack exchange，提问作者Shin938