fix classloader

Author: shichanglin5

arex-agent-bootstrap/src/main/java/io/arex/agent/bootstrap/util/JarUtils.java

@@ -1,24 +1,23 @@
 package io.arex.agent.bootstrap.util;
 
-import io.arex.agent.bootstrap.constants.ConfigConstants;
-
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.net.URL;
-import java.net.URLClassLoader;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
+import java.util.function.BiConsumer;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 
 public class JarUtils {
     private static Method addURL;
     private static final File TMP_FILE = new File(AccessController.doPrivileged((PrivilegedAction<String>) () -> System.getProperty("java.io.tmpdir")));
     private static final String AREX_TEMP_DIR = TMP_FILE.getAbsolutePath() + File.separator + "arex";
+    public static BiConsumer<ClassLoader, File> addJarToSystemClassLoader = (classLoader, file) -> {
+    };
 
     static {
         try {
@@ -28,10 +27,11 @@ public class JarUtils {
             System.err.println("Failed to get addURL method from URLClassLoader");
         }
     }
+
     public static File extractNestedJar(JarFile file, JarEntry entry, String entryName) throws IOException {
         File outputFile = createFile(AREX_TEMP_DIR + File.separator + entryName);
-        try(InputStream inputStream = file.getInputStream(entry);
-            FileOutputStream outputStream = new FileOutputStream(outputFile)) {
+        try (InputStream inputStream = file.getInputStream(entry);
+             FileOutputStream outputStream = new FileOutputStream(outputFile)) {
             byte[] buffer = new byte[1024];
             int length;
             while ((length = inputStream.read(buffer)) > 0) {
@@ -54,44 +54,20 @@ private static File createFile(String path) throws IOException {
     }
 
     /**
-     * tomcat jdk <= 8, classLoader is ParallelWebappClassLoader, ClassLoader.getSystemClassLoader() is Launcher$AppClassLoader
-     * jdk > 8, classLoader is ParallelWebappClassLoader, ClassLoader.getSystemClassLoader() is ClassLoaders$AppClassLoader
+     * Java Instrumentation.appendToSystemClassLoaderSearch() method is compatible across JDK versions, including JDK 8 through JDK 17. Here’s a detailed breakdown of its compatibility:
+     * 1. JDK 8 Compatibility
+     * •	The appendToSystemClassLoaderSearch() method was introduced as part of the Java Instrumentation API in JDK 6. This means it is fully available and compatible with JDK 8.
+     * •	It allows you to append JARs to the system class loader’s search path, ensuring that classes within those JARs can be loaded by the system class loader.
+     * 2. JDK 9+ (including JDK 17) Compatibility
+     * •	With JDK 9, the module system (Project Jigsaw) was introduced, which brought significant changes to class loading and the organization of Java’s internal APIs.
+     * •	Despite these changes, appendToSystemClassLoaderSearch() remains compatible and continues to work as expected in JDK 9 and later, including JDK 17. It can still be used to add JARs to the classpath of the system class loader.
      */
     public static void appendToClassLoaderSearch(ClassLoader classLoader, File jarFile) {
         try {
-            if (classLoader instanceof URLClassLoader) {
-                addURL.invoke(classLoader, jarFile.toURI().toURL());
-            }
-
-            /*
-             * Due to Java 8 vs java 9+ incompatibility issues
-             * See https://stackoverflow.com/questions/46694600/java-9-compatability-issue-with-classloader-getsystemclassloader/51584718
-             */
-            ClassLoader urlClassLoader = ClassLoader.getSystemClassLoader();
-            if (!(urlClassLoader instanceof URLClassLoader)) {
-                try (URLClassLoader tempClassLoader = new URLClassLoader(new URL[] {jarFile.toURI().toURL()}, urlClassLoader)) {
-                    addURL.invoke(tempClassLoader, jarFile.toURI().toURL());
-                }
-            } else {
-                addURL.invoke(urlClassLoader, jarFile.toURI().toURL());
-            }
-            appendToAppClassLoaderSearch(classLoader, jarFile);
+            addJarToSystemClassLoader.accept(classLoader, jarFile);
         } catch (Exception e) {
             System.err.printf("appendToClassLoaderSearch failed, classLoader: %s, jarFile: %s%n",
                     classLoader.getClass().getName(), jarFile.getAbsolutePath());
         }
     }
-
-    /**
-     * append jar jdk.internal.loader.ClassLoaders.AppClassLoader
-     * if java version >= 11 need add jvm option:--add-opens=java.base/jdk.internal.loader=ALL-UNNAMED
-     */
-    private static void appendToAppClassLoaderSearch(ClassLoader classLoader, File jarFile) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
-        Class<? extends ClassLoader> loaderClass = classLoader.getClass();
-        if (JdkUtils.isJdk11OrHigher() && ConfigConstants.APP_CLASSLOADER_NAME.equalsIgnoreCase(loaderClass.getName())) {
-            Method classPathMethod = loaderClass.getDeclaredMethod("appendToClassPathForInstrumentation", String.class);
-            classPathMethod.setAccessible(true);
-            classPathMethod.invoke(classLoader, jarFile.getPath());
-        }
-    }
 }

arex-agent/src/main/java/io/arex/agent/ArexAgent.java

@@ -40,6 +40,13 @@ private static void init(Instrumentation inst, String agentArgs) {
              */
             installBootstrapJar(inst);
             AgentInitializer.initialize(inst, getJarFile(ArexAgent.class), agentArgs, ArexAgent.class.getClassLoader());
+            io.arex.agent.bootstrap.util.JarUtils.addJarToSystemClassLoader = (classLoader, file) -> {
+                try {
+                    inst.appendToSystemClassLoaderSearch(new JarFile(file, false));
+                } catch (Exception e) {
+                    System.out.printf("%s [AREX] Agent add jar to system classloader error, stacktrace: %s%n", getCurrentTime(), e);
+                }
+            };
         } catch (Exception ex) {
             System.out.printf("%s [AREX] Agent initialize error, stacktrace: %s%n", getCurrentTime(), ex);
         }