Java 为什么JVM为同一个类发送多个JVMTI类加载事件？

我启用了JVMTI类加载事件，这些事件应该在第一次加载类时生成。我希望每个加载的类都能准确地获得此事件一次，但对于某些类，它似乎会生成多次，例如，我得到两次此事件：

ClassLoad: Ljava/util/concurrent/ThreadFactory; loaded by thread 1
ClassLoad: Ljava/util/concurrent/ThreadFactory; loaded by thread 1

在

systemDictionary.cpp

中，我发现发生了三次

JvmtiExport:：post_class_load

，我认为这是负责执行回调的代码（如果有）。他们在

SystemDictionary:：解析\u实例\u类\u或\u null

SystemDictionary:：解析流

SystemDictionary:：define\u instance\u class

但我还不了解整个流程，因此不清楚为什么我会多次获得该活动

---

我能做些什么来防止这种情况发生，或者我需要自己处理，并调整代码以忽略同一类的多个事件吗？

可以看到两次事件。这意味着类解析在不同类装入器的上下文中发生两次。首先，它由引导类装入器解析，然后由系统类装入器-

sun.misc.Launcher.AppClassLoader

解析

来自的实用程序将阐明此类事件发生时的情况

考虑一个简单的例子：

public class Test {

    public void setThreadFactory(ThreadFactory factory) {
    }

    public static void main(String[] args) {
    }
}

当启动器查找

publicstaticvoidmain（）

时，它会为公共方法创建

Method

对象，这会导致解析此类方法签名中的所有类

第一个ClassLoad事件：

Class loaded: java/util/concurrent/ThreadFactory
  - ClassLoad(_jvmtiEnv*, JNIEnv_*, _jobject*, _jclass*) + 0x69
  - JvmtiExport::post_class_load(JavaThread*, Klass*) + 0x15b
  - SystemDictionary::define_instance_class(instanceKlassHandle, Thread*) + 0x3cc
  - SystemDictionary::find_or_define_instance_class(Symbol*, Handle, instanceKlassHandle, Thread*) + 0x35d
  - SystemDictionary::load_instance_class(Symbol*, Handle, Thread*) + 0x20c
  - SystemDictionary::resolve_instance_class_or_null(Symbol*, Handle, Handle, Thread*) + 0x78c
  - JVM_FindClassFromBootLoader + 0x22b
  - Java_java_lang_ClassLoader_findBootstrapClass + 0x9b
  * java/lang/ClassLoader.findBootstrapClass @ -1
  * java/lang/ClassLoader.findBootstrapClassOrNull @ 12
  * java/lang/ClassLoader.loadClass @ 48
  * java/lang/ClassLoader.loadClass @ 38
  * sun/misc/Launcher$AppClassLoader.loadClass @ 81
  * java/lang/ClassLoader.loadClass @ 3
  * java/lang/Class.getDeclaredMethods0 @ -1
  * java/lang/Class.privateGetDeclaredMethods @ 37
  * java/lang/Class.privateGetMethodRecursive @ 2
  * java/lang/Class.getMethod0 @ 16
  * java/lang/Class.getMethod @ 13
  * sun/launcher/LauncherHelper.validateMainClass @ 12
  * sun/launcher/LauncherHelper.checkAndLoadMain @ 214

第二条：

Class loaded: java/util/concurrent/ThreadFactory
  - ClassLoad(_jvmtiEnv*, JNIEnv_*, _jobject*, _jclass*) + 0x69
  - JvmtiExport::post_class_load(JavaThread*, Klass*) + 0x15b
  - SystemDictionary::resolve_instance_class_or_null(Symbol*, Handle, Handle, Thread*) + 0x87c
  - SystemDictionary::resolve_or_fail(Symbol*, Handle, Handle, bool, Thread*) + 0x33
  - get_mirror_from_signature(methodHandle, SignatureStream*, Thread*) + 0xc6
  - Reflection::get_parameter_types(methodHandle, int, oopDesc**, Thread*) + 0x18e
  - Reflection::new_method(methodHandle, bool, bool, Thread*) + 0xfc
  - get_class_declared_methods_helper(JNIEnv_*, _jclass*, unsigned char, bool, Klass*, Thread*) + 0x479
  - JVM_GetClassDeclaredMethods + 0xcb
  * java/lang/Class.getDeclaredMethods0 @ -1
  * java/lang/Class.privateGetDeclaredMethods @ 37
  * java/lang/Class.privateGetMethodRecursive @ 2
  * java/lang/Class.getMethod0 @ 16
  * java/lang/Class.getMethod @ 13
  * sun/launcher/LauncherHelper.validateMainClass @ 12
  * sun/launcher/LauncherHelper.checkAndLoadMain @ 214