类增强之---记录方法出入参

package com.deer.agent;
import com.deer.agent.sandbox.AgentClazzTransformer;
import java.lang.instrument.Instrumentation;
import java.util.Arrays;
public class AgentMain {
    public static void premain(String agentArgs, Instrumentation inst) {
        System.out.println("premain");
    }
    public static void agentmain(String agentArgs, Instrumentation inst){
        System.out.println("load agent...");
        Class[] clazzList = inst.getAllLoadedClasses();
        Arrays.stream(clazzList).forEach(clazz->{
            if(clazz.getName().startsWith("com.deer.base.service.impl")){
                //
                try {
                    inst.addTransformer(new AgentClazzTransformer(), true);
                    inst.retransformClasses(clazz);
                }catch (Exception e){
                    //
                }
            }
        });
    }
}

package com.deer.agent.sandbox;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;
public class AgentClazzTransformer implements ClassFileTransformer {
    @Override
    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
        ClassReader cr = new ClassReader(classfileBuffer);
        ClassWriter cw = new ClassWriter(cr,ClassWriter.COMPUTE_MAXS);
        TraceClassVisitor traceClassVisitor = new TraceClassVisitor(cw);
        cr.accept(traceClassVisitor,ClassReader.EXPAND_FRAMES);
        return cw.toByteArray();
    }
}

package com.deer.agent.sandbox;
import org.objectweb.asm.*;
import org.objectweb.asm.commons.AdviceAdapter;
public class TraceClassVisitor extends ClassVisitor implements Opcodes {
    private String clazzName;
    private String methodName;
    public TraceClassVisitor(ClassVisitor classVisitor) {
        super(ASM7, classVisitor);
    }
    private static int[] computeLvtSlotIndices(boolean isStatic, Type[] paramTypes) {
        int[] lvtIndex = new int[paramTypes.length];
        int nextIndex = isStatic ? 0 : 1;
        for (int i = 0; i < paramTypes.length; ++i) {
            lvtIndex[i] = nextIndex;
            if (isWideType(paramTypes[i])) {
                nextIndex += 2;
            } else {
                ++nextIndex;
            }
        }
        return lvtIndex;
    }
    private static boolean isWideType(Type aType) {
        return aType == Type.LONG_TYPE || aType == Type.DOUBLE_TYPE;
    }
    private static boolean isStatic(int access) {
        return (access & 8) > 0;
    }
    @Override
    public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
        super.visit(version, access, name, signature, superName, interfaces);
        clazzName = name;
    }
    @Override
    public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
        MethodVisitor mv = cv.visitMethod(access, name, descriptor, signature, exceptions);
        //跳过java原生相关的类
        if (!clazzName.startsWith("com/deer/base")) {
            return mv;
        }
        mv = new AdviceAdapter(ASM7, mv, access, name, descriptor) {
            private  Type[] methodArgs;
            private   String[] parameterNames;
            private   int[] lvtSlotIndex;
            @Override
            protected void onMethodEnter() {
                //记录关键参数
                methodName = name;
                this.methodArgs = Type.getArgumentTypes(descriptor);
                this.parameterNames = new String[this.methodArgs.length];
                this.lvtSlotIndex =computeLvtSlotIndices(isStatic(access),this.methodArgs);
                super.onMethodEnter();
            }
            @Override
            protected void onMethodExit(int opcode) {
                if (methodName .equals("<init>") || methodName.equals("<clinit>")){
                    return;
                }
                if (opcode == RETURN) {
                    push((Type) null);
                } else if (opcode == LRETURN || opcode == DRETURN) {
                    dup2();
                    box(Type.getReturnType(methodDesc));
                } else {
                    dup();
                    box(Type.getReturnType(methodDesc));
                }
                Type objectType = Type.getObjectType("java/lang/Object");
                push(lvtSlotIndex.length);
                newArray(objectType);
                for (int j = 0; j < lvtSlotIndex.length; j++) {
                    int index = lvtSlotIndex[j];
                    Type type = methodArgs[j];
                    dup();
                    push(j);
                    mv.visitVarInsn(ALOAD, index);
                    box(type);
                    arrayStore(objectType);
                }
                visitLdcInsn(clazzName);
                visitLdcInsn(methodName);
                mv.visitMethodInsn(INVOKESTATIC, "com/deer/agent/sandbox/Sender", "send", "(Ljava/lang/Object;[Ljava/lang/Object;Ljava/lang/String;Ljava/lang/String;)V", false);
            }
            @Override
            public void visitLocalVariable(String name, String descriptor, String signature, Label start, Label end, int index) {
                for (int i=0;i<this.lvtSlotIndex.length;i++){
                    if(this.lvtSlotIndex[i] == index){
                        this.parameterNames[i]=name;
                    }
                }
            }
        };
        return mv;
    }
}