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SpringBoot自定义类加载器

news 来源：原创 2024/9/20 9:11:09

讲解如何获取springBoot classLoader和如何往spring boot classLoader 添加包

获取spring boot classLoader

 /*** SpringBoot打包模式下是SpringBoot的类加载器* @return*/public static ClassLoader genClassLoader(){if (!SystemInfo.INSTANCE.isStandalone()) {return null;}AgentLogger.info("[SF Agent] Use springboot classloader.");try {// 检测是否SpringBoot打包方式Class launcherClass = Class.forName(STANDALONE_CLASS);if (launcherClass != null) {String jarfilePath = ClassUtils.getClassFilePath(launcherClass);if (null == jarfilePath) {return null;}// 获取Manifest，并且获取Main-Class，可能是JarLauncher或者是WarLauncherClass jarFileArchiveClass = Class.forName("org.springframework.boot.loader.archive.JarFileArchive");Object jarFileArchiveObj = jarFileArchiveClass.getDeclaredConstructor(File.class).newInstance(new File(jarfilePath));Method manifestMethod = jarFileArchiveClass.getDeclaredMethod("getManifest");Manifest manifest = (Manifest)manifestMethod.invoke(jarFileArchiveObj);String mainClass = manifest.getMainAttributes().getValue("Main-Class");// 反射调用Launcer，获取可以加载SpringBoot依赖的类加载器Class launcher = Class.forName(mainClass);Map<String, Method> methods = getClassLoadderMethod(launcher);Method classLoaderMethod = methods.get("classLoader");Method archivesMethod = methods.get("archive");if (null == classLoaderMethod || null == archivesMethod) {AgentLogger.error("No class loader found.");return null;}archivesMethod.setAccessible(true);classLoaderMethod.setAccessible(true);Object launcherObj = launcher.getDeclaredConstructor().newInstance();Object classPathArchives = archivesMethod.invoke(launcherObj);return (ClassLoader)classLoaderMethod.invoke(launcherObj, classPathArchives);}} catch (Exception e) {}return null;}

通过字节码增强往spring boot classLoader 添加包

public abstract class AbstractEnhanceModel {public abstract byte[] enhance(String className, byte[] source);}

import enhance.AbstractEnhanceModel;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;public class SpringBootEnhance extends AbstractEnhanceModel {public static final SpringBootEnhance INSTANCE = new SpringBootEnhance();private SpringBootEnhance(){}@Overridepublic byte[] enhance(String className, byte[] source) {ClassWriter classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS);ClassReader classReader = new ClassReader(source);AgentJarEnhance agentInitEnhance = new AgentJarEnhance(classWriter);classReader.accept(agentInitEnhance, ClassReader.SKIP_DEBUG);return classWriter.toByteArray();}
}

import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;import static org.objectweb.asm.Opcodes.*;public class AgentJarEnhance extends ClassVisitor {private ClassVisitor cv;public AgentJarEnhance(ClassVisitor classVisitor) {super(ASM4, classVisitor);this.cv = classVisitor;}@Overridepublic MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {// 新版接口转换为旧版接口if ("isPostProcessingClassPathArchives".equals(name)) {return null;}if ("postProcessClassPathArchives".equals(name)) {return null;}if ("genArchive".equals(name)) {return null;}return cv.visitMethod(access, name, descriptor, signature, exceptions);}@Overridepublic void visitEnd(){isPostProcessingClassPathArchives();postProcessClassPathArchives();cv.visitEnd();}private void isPostProcessingClassPathArchives(){MethodVisitor methodVisitor = cv.visitMethod(ACC_PUBLIC, "isPostProcessingClassPathArchives", "()Z", null, null);methodVisitor.visitCode();Label label0 = new Label();methodVisitor.visitLabel(label0);methodVisitor.visitLineNumber(14, label0);methodVisitor.visitInsn(ICONST_1);methodVisitor.visitInsn(IRETURN);Label label1 = new Label();methodVisitor.visitLabel(label1);methodVisitor.visitLocalVariable("this", "Lorg/springframework/boot/loader/JarLauncher;", null, label0, label1, 0);methodVisitor.visitMaxs(1, 1);methodVisitor.visitEnd();}private void postProcessClassPathArchives(){MethodVisitor methodVisitor = cv.visitMethod(ACC_PROTECTED, "postProcessClassPathArchives", "(Ljava/util/List;)V", "(Ljava/util/List<Lorg/springframework/boot/loader/archive/Archive;>;)V", new String[]{"java/lang/Exception"});methodVisitor.visitCode();Label label0 = new Label();methodVisitor.visitLabel(label0);methodVisitor.visitLineNumber(42, label0);methodVisitor.visitVarInsn(ALOAD, 1);methodVisitor.visitInsn(ICONST_0);methodVisitor.visitVarInsn(ALOAD, 0);methodVisitor.visitMethodInsn(INVOKEVIRTUAL, "org/springframework/boot/loader/JarLauncher", "getArchive", "()Lorg/springframework/boot/loader/archive/Archive;", false);methodVisitor.visitMethodInsn(INVOKEINTERFACE, "java/util/List", "add", "(ILjava/lang/Object;)V", true);Label label1 = new Label();methodVisitor.visitLabel(label1);methodVisitor.visitLineNumber(43, label1);// 往classLoader添加jar包methodVisitor.visitMethodInsn(INVOKESTATIC, "agent/config/SupportConfig", "getAll", "()Ljava/util/List;", false);methodVisitor.visitVarInsn(ASTORE, 2);Label label2 = new Label();methodVisitor.visitLabel(label2);methodVisitor.visitLineNumber(44, label2);methodVisitor.visitVarInsn(ALOAD, 2);methodVisitor.visitMethodInsn(INVOKEINTERFACE, "java/util/List", "iterator", "()Ljava/util/Iterator;", true);methodVisitor.visitVarInsn(ASTORE, 3);Label label3 = new Label();methodVisitor.visitLabel(label3);methodVisitor.visitFrame(Opcodes.F_APPEND, 2, new Object[]{"java/util/List", "java/util/Iterator"}, 0, null);methodVisitor.visitVarInsn(ALOAD, 3);methodVisitor.visitMethodInsn(INVOKEINTERFACE, "java/util/Iterator", "hasNext", "()Z", true);Label label4 = new Label();methodVisitor.visitJumpInsn(IFEQ, label4);methodVisitor.visitVarInsn(ALOAD, 3);methodVisitor.visitMethodInsn(INVOKEINTERFACE, "java/util/Iterator", "next", "()Ljava/lang/Object;", true);methodVisitor.visitTypeInsn(CHECKCAST, "java/lang/String");methodVisitor.visitVarInsn(ASTORE, 4);Label label5 = new Label();methodVisitor.visitLabel(label5);methodVisitor.visitLineNumber(45, label5);methodVisitor.visitTypeInsn(NEW, "org/springframework/boot/loader/jar/JarFile");methodVisitor.visitInsn(DUP);methodVisitor.visitTypeInsn(NEW, "java/io/File");methodVisitor.visitInsn(DUP);methodVisitor.visitVarInsn(ALOAD, 4);methodVisitor.visitMethodInsn(INVOKESPECIAL, "java/io/File", "<init>", "(Ljava/lang/String;)V", false);methodVisitor.visitMethodInsn(INVOKESPECIAL, "org/springframework/boot/loader/jar/JarFile", "<init>", "(Ljava/io/File;)V", false);methodVisitor.visitVarInsn(ASTORE, 5);Label label6 = new Label();methodVisitor.visitLabel(label6);methodVisitor.visitLineNumber(46, label6);methodVisitor.visitVarInsn(ALOAD, 1);methodVisitor.visitTypeInsn(NEW, "org/springframework/boot/loader/archive/JarFileArchive");methodVisitor.visitInsn(DUP);methodVisitor.visitVarInsn(ALOAD, 5);methodVisitor.visitMethodInsn(INVOKESPECIAL, "org/springframework/boot/loader/archive/JarFileArchive", "<init>", "(Lorg/springframework/boot/loader/jar/JarFile;)V", false);methodVisitor.visitMethodInsn(INVOKEINTERFACE, "java/util/List", "add", "(Ljava/lang/Object;)Z", true);methodVisitor.visitInsn(POP);Label label7 = new Label();methodVisitor.visitLabel(label7);methodVisitor.visitLineNumber(47, label7);methodVisitor.visitJumpInsn(GOTO, label3);methodVisitor.visitLabel(label4);methodVisitor.visitLineNumber(48, label4);methodVisitor.visitFrame(Opcodes.F_CHOP, 1, null, 0, null);methodVisitor.visitInsn(RETURN);Label label8 = new Label();methodVisitor.visitLabel(label8);methodVisitor.visitLocalVariable("jarFile", "Lorg/springframework/boot/loader/jar/JarFile;", null, label6, label7, 5);methodVisitor.visitLocalVariable("path", "Ljava/lang/String;", null, label5, label7, 4);methodVisitor.visitLocalVariable("this", "Lorg/springframework/boot/loader/JarLauncher;", null, label0, label8, 0);methodVisitor.visitLocalVariable("archives", "Ljava/util/List;", "Ljava/util/List<Lorg/springframework/boot/loader/archive/Archive;>;", label0, label8, 1);methodVisitor.visitLocalVariable("paths", "Ljava/util/List;", "Ljava/util/List<Ljava/lang/String;>;", label2, label8, 2);methodVisitor.visitMaxs(5, 6);methodVisitor.visitEnd();}
}

import java.util.ArrayList;
import java.util.List;public class SupportConfig {private static final String KEY = "Governance.SupportConfig";private static final String SPLIT = ";";public static void add(String support) {String value = System.getProperty(KEY);if (null == value || value.length() < 1) {value = support;}else {value = value + SPLIT + support;}System.setProperty(KEY, value);}public static List<String> getAll(){String value = System.getProperty(KEY);if (null == value || value.length() < 1) {return new ArrayList<>();}List<String> list = new ArrayList<>();String[] values = value.split(SPLIT);for(String row : values) {list.add(row);}return list;}
}