package com.whyc.util;
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import javassist.*;
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import javassist.bytecode.*;
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import javassist.compiler.CompileError;
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import javassist.compiler.Javac;
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import java.io.File;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* 字节码操作工具类
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*
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* @author perry
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*/
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public class ClassUtils {
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/**
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* 清空方法
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*
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* @param pool javassist的ClassPool
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* @param classname 要修改的class全名
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* @return 返回方法体的字节
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*/
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public static byte[] rewriteAllMethods(ClassPool pool, String classname) {
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String name = null;
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try {
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CtClass cc = pool.getCtClass(classname);
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CtMethod[] methods = cc.getDeclaredMethods();
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for (CtMethod m : methods) {
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name = m.getName();
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//不是构造方法，在当前类，不是父lei
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if (!m.getName().contains("<") && m.getLongName().startsWith(cc.getName())) {
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//m.setBody(null);//清空方法体
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CodeAttribute ca = m.getMethodInfo().getCodeAttribute();
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//接口的ca就是null,方法体本来就是空的就是-79
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if (ca != null && ca.getCodeLength() != 1 && ca.getCode()[0] != -79) {
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ClassUtils.setBodyKeepParamInfos(m, null, true);
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if ("void".equalsIgnoreCase(m.getReturnType().getName()) && m.getLongName().endsWith(".main(java.lang.String[])") && m.getMethodInfo().getAccessFlags() == 9) {
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m.insertBefore("System.out.println(\"\\nStartup failed, invalid password.\\n\");");
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}
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}
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}
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}
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return cc.toBytecode();
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} catch (Exception e) {
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throw new RuntimeException("[" + classname + "(" + name + ")]" + e.getMessage());
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}
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}
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/**
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* 修改方法体，并且保留参数信息
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*
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* @param m javassist的方法
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* @param src java代码
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* @param rebuild 是否重新构建
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* @throws CannotCompileException 编译异常
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*/
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public static void setBodyKeepParamInfos(CtMethod m, String src, boolean rebuild) throws CannotCompileException {
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CtClass cc = m.getDeclaringClass();
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if (cc.isFrozen()) {
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throw new RuntimeException(cc.getName() + " class is frozen");
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}
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CodeAttribute ca = m.getMethodInfo().getCodeAttribute();
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if (ca == null) {
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throw new CannotCompileException("no method body");
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} else {
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CodeIterator iterator = ca.iterator();
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Javac jv = new Javac(cc);
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try {
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int nvars = jv.recordParams(m.getParameterTypes(), Modifier.isStatic(m.getModifiers()));
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jv.recordParamNames(ca, nvars);
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jv.recordLocalVariables(ca, 0);
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jv.recordReturnType(Descriptor.getReturnType(m.getMethodInfo().getDescriptor(), cc.getClassPool()), false);
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//jv.compileStmnt(src);
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//Bytecode b = jv.getBytecode();
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Bytecode b = jv.compileBody(m, src);
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int stack = b.getMaxStack();
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int locals = b.getMaxLocals();
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if (stack > ca.getMaxStack()) {
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ca.setMaxStack(stack);
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}
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if (locals > ca.getMaxLocals()) {
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ca.setMaxLocals(locals);
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}
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int pos = iterator.insertEx(b.get());
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iterator.insert(b.getExceptionTable(), pos);
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if (rebuild) {
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m.getMethodInfo().rebuildStackMapIf6(cc.getClassPool(), cc.getClassFile2());
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}
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} catch (NotFoundException var12) {
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throw new CannotCompileException(var12);
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} catch (CompileError var13) {
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throw new CannotCompileException(var13);
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} catch (BadBytecode var14) {
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throw new CannotCompileException(var14);
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}
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}
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}
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/**
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* 加载jar包路径
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*
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* @param pool javassist的ClassPool
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* @param paths lib路径，
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*/
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public static void loadClassPath(ClassPool pool, List<String> paths) {
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for (String path : paths) {
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loadClassPath(pool, new File(path));
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}
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}
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/**
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* 加载jar包路径
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*
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* @param pool javassist的ClassPool
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* @param dir lib路径或jar文件
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*/
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public static void loadClassPath(ClassPool pool, File dir) {
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if (dir == null || !dir.exists()) {
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return;
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}
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if (dir.isDirectory()) {
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List<File> jars = new ArrayList<>();
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IoUtils.listFile(jars, dir, ".jar");
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for (File jar : jars) {
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try {
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pool.insertClassPath(jar.getAbsolutePath());
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} catch (NotFoundException e) {
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//ignore
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}
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}
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} else if (dir.getName().endsWith(".jar")) {
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try {
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pool.insertClassPath(dir.getAbsolutePath());
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} catch (NotFoundException e) {
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//ignore
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}
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}
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}
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/**
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* 给方法插入代码并返回bytecode的字节数组
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*
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* @param classMethod 类名#方法名
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* @param javaCode 代码
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* @param line 行数
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* @param libDir classpath
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* @param thisJar 本项目的jar路径
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* @return 修改后的字节数组
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* @throws Exception Exception
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*/
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public static byte[] insertCode(String classMethod, String javaCode, int line, File libDir, File thisJar) throws Exception {
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String className = classMethod.split("#")[0];
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String methodName = classMethod.split("#")[1];
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ClassPool pool = ClassPool.getDefault();
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loadClassPath(pool, libDir);
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if (thisJar != null && thisJar.exists()) {
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loadClassPath(pool, thisJar);
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}
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byte[] bytes;
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CtClass cc = pool.getCtClass(className);
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if (methodName.startsWith("<") && methodName.contains(">")) {
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methodName = methodName.replace("<", "").replace(">", "");
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CtConstructor[] ms = cc.getConstructors();
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for (CtConstructor mt : ms) {
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if (mt.getLongName().endsWith(methodName)) {
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mt.insertAt(line, javaCode);
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}
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}
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} else {
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CtMethod mt = cc.getDeclaredMethod(methodName);
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mt.insertAt(line, javaCode);
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}
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bytes = cc.toBytecode();
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return bytes;
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}
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}
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