java class文件准确的反编译思路

2019-11-11 06:56:32

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1、java Decompiler

这款反编译器叫 “Java Decompiler”, 由 Pavel Kouznetsov开发，目前最新版本为0.2.5. 它由 C++开发，并且官方可以下载 windows、linux和苹果Mac Os三个平台的可执行程序。

官方网站：http://jd.benow.ca/

2、Java 反编译器 JD-GUI

JD-GUI 是一个用 C++ 开发的 Java 反编译工具，由 Pavel Kouznetsov开发，支持Windows、Linux和苹果Mac Os三个平台。而且提供了Eclipse平台下的插件JD-Eclipse。JD-GUI不需要安装，直接点击运行，可以反编译jar,class文件。

官方网站：http://jd.benow.ca/

JD-GUI

主要使用 JD-gui, 因为他可以编译整个文件夹class文件非常方便但是会偶尔地方报错，需要自己分析代码，比如创建一些没有必要的局部变量出错实例如下

  public boolean PReHandle(HttpServletRequest req, HttpServletResponse res, Object h)    throws Exception  {    String servletPath = req.getServletPath().toLowerCase();    boolean isContains = (servletPath.contains("add")) || (servletPath.contains("create"));    boolean pass;    if (isContains) {      String name = this.userService.getStaffNameByStaffId((Long)req.getAttribute("sid"));      boolean pass;      if (StringUtils.isNotBlank(name)) {        pass = true;      } else {        boolean pass = false;        JSON.writeDataToStream(res.getOutputStream(), I18NResult.failure(ErrorType.USERNAM_NONE));      }    } else {      pass = true;    }    return pass;  }}pass 多处创建 调整后如下  public boolean preHandle(HttpServletRequest req, HttpServletResponse res, Object h)/*    */     throws Exception/*    */   {/* 24 */     String servletPath = req.getServletPath().toLowerCase();/* 25 */     boolean isContains = (servletPath.contains("add")) || (servletPath.contains("create"));/*    */     boolean pass;/* 26 */     if (isContains) {/* 27 */       String name = this.userService.getStaffNameByStaffId((Long)req.getAttribute("sid"));/* 28 */       if (StringUtils.isNotBlank(name)) {/* 29 */         pass = true;/*    */       } else {/* 31 */         pass = false;/* 32 */         JSON.writeDataToStream(res.getOutputStream(), I18NResult.failure(ErrorType.USERNAM_NONE));/*    */       }/*    */     } else {/* 35 */       pass = true;/*    */     }/*    */ /* 38 */     return pass;/*    */   }/*    */ }
有时候JD-GUI编译出来的代码莫名其妙，这个时候可以结合
Java Decompiler 编译后的代码综合分析
下面给出一个class 文件的一个函数由 jd-gui编译的函数 （有问题）@RequestMapping({"/getMyProjectTaskList", "/getMeProjectTasks"})/*     */   @ResponseBody/*     */   public Output getMetasks(@RequestParam("projectId") Long projectId, @Sid Long sid) {/*     */     try {/* 141 */       metasks = this.taskService.getMetasks(projectId, sid);/*     */     }/*     */     catch (Exception e)/*     */     {/*     */       List metasks;/* 143 */       throw new RuntimeException(e);/*     */     }/* 147 */     List metasks;/* 146 */     List metaskRess = new ArrayList(metasks.size());/* 147 */     for (Iterator localIterator = metasks.iterator(); localIterator.hasNext(); ) { metask = (MetaskBo)localIterator.next();/* 148 */       MetaskRes metaskVo = new MetaskRes();/*     */ /* 150 */       metaskVo.setTaskId(ObjectUtils.toString(metask.getTaskId()));/* 151 */       metaskVo.setIsLeafTask(ObjectUtils.toString(metask.getIsLeafTask()));/* 152 */       metaskVo.setTaskName(ObjectUtils.toString(metask.getTaskName()));/* 153 */       srt = metask.getStartDateTime();/* 154 */       Date end = metask.getEndDateTime();/* 155 */       metaskVo.setSrtDate(DateUtil.defaultDateToString(srt));/* 156 */       metaskVo.setEndDate(DateUtil.defaultDateToString(end));/* 157 */       metaskVo.setIsFinished(ObjectUtils.toString(metask.getIsFinished()));/* 158 */       metaskVo.setBetween((srt.getTime() <= metask.getCurrentDateTime().longValue()) && (metask.getCurrentDateTime().longValue() <= end.getTime()) ? "1" : "0");/* 159 */       metaskVo.setTaskDesStatus(ObjectUtils.toString(metask.getTaskDesStatus()));/* 160 */       metaskVo.setTaskStatus(ObjectUtils.toString(metask.getTaskStatus()));/* 161 */       metaskVo.setRemindTime(ObjectUtils.toString(metask.getRemindTime()));/* 162 */       metaskVo.setWatcherSid(ObjectUtils.toString(metask.getWatcherSid()));/* 163 */       metaskVo.setAuditorSid(ObjectUtils.toString(metask.getAuditorSid()));/*     */ /* 165 */       metaskRess.add(metaskVo);/*     */     }/* 169 */     Date srt;/* 168 */     List taskInfos = this.taskProgressService.calcTaskProgress(projectId);/* 169 */     for (MetaskBo metask = taskInfos.iterator(); metask.hasNext(); ) { taskInfo = (TaskInfo)metask.next();/* 170 */       for (MetaskRes metaskRes : metaskRess)/* 171 */         if (taskInfo.getTaskId().toString().equals(metaskRes.getTaskId())) {/* 172 */           metaskRes.setPlanProgress(ObjectUtils.toString(Float.valueOf(taskInfo.getPlanProgress())));/* 173 */           float undoneProgress = taskInfo.getPlanProgress() - taskInfo.getProgress();/* 174 */           metaskRes.setUndoneProgress(ObjectUtils.toString(Float.valueOf(undoneProgress < 0.0F ? 0.0F : undoneProgress)));/* 175 */           metaskRes.setActualProgress(ObjectUtils.toString(Float.valueOf(taskInfo.getProgress())));/* 176 */           break;/*     */         }/*     */     }/*     */     TaskInfo taskInfo;/* 181 */     return Result.success(metaskRess);/*     */   }由dj java Decompiler工具分析出来的结果(也有问题)  @RequestMapping(value={"/getMyProjectTaskList", "/getMeProjectTasks"})    @ResponseBody    public Output getMetasks(@RequestParam(value="projectId") Long projectId, @Sid Long sid)    {        List metasks;        try        {            metasks = taskService.getMetasks(projectId, sid);        }        catch(Exception e)        {            throw new RuntimeException(e);        }        List metaskRess = new ArrayList(metasks.size());        MetaskRes metaskVo;        for(Iterator iterator = metasks.iterator(); iterator.hasNext(); metaskRess.add(metaskVo))        {            MetaskBo metask = (MetaskBo)iterator.next();            metaskVo = new MetaskRes();            metaskVo.setTaskId(ObjectUtils.toString(metask.getTaskId()));            metaskVo.setIsLeafTask(ObjectUtils.toString(metask.getIsLeafTask()));            metaskVo.setTaskName(ObjectUtils.toString(metask.getTaskName()));            Date srt = metask.getStartDateTime();            Date end = metask.getEndDateTime();            metaskVo.setSrtDate(DateUtil.defaultDateToString(srt));            metaskVo.setEndDate(DateUtil.defaultDateToString(end));            metaskVo.setIsFinished(ObjectUtils.toString(metask.getIsFinished()));            metaskVo.setBetween(srt.getTime() > metask.getCurrentDateTime().longValue() || metask.getCurrentDateTime().longValue() > end.getTime() ? "0" : "1");            metaskVo.setTaskDesStatus(ObjectUtils.toString(metask.getTaskDesStatus()));            metaskVo.setTaskStatus(ObjectUtils.toString(metask.getTaskStatus()));            metaskVo.setRemindTime(ObjectUtils.toString(metask.getRemindTime()));            metaskVo.setWatcherSid(ObjectUtils.toString(metask.getWatcherSid()));            metaskVo.setAuditorSid(ObjectUtils.toString(metask.getAuditorSid()));        }        List taskInfos = taskProgressService.calcTaskProgress(projectId);        Iterator iterator1 = taskInfos.iterator();label0:        do        {            if(!iterator1.hasNext())                break;            TaskInfo taskInfo = (TaskInfo)iterator1.next();            Iterator iterator2 = metaskRess.iterator();            MetaskRes metaskRes;            do            {                if(!iterator2.hasNext())                    continue label0;                metaskRes = (MetaskRes)iterator2.next();            } while(!taskInfo.getTaskId().toString().equals(metaskRes.getTaskId()));            metaskRes.setPlanProgress(ObjectUtils.toString(Float.valueOf(taskInfo.getPlanProgress())));            float undoneProgress = taskInfo.getPlanProgress() - taskInfo.getProgress();            metaskRes.setUndoneProgress(ObjectUtils.toString(Float.valueOf(undoneProgress >= 0.0F ? undoneProgress : 0.0F)));            metaskRes.setActualProgress(ObjectUtils.toString(Float.valueOf(taskInfo.getProgress())));        } while(true);        return Result.success(metaskRess);    }结合二者的优点 回避各自缺点最终分析出来的结果/*     */   @RequestMapping({"/getMyProjectTaskList", "/getMeProjectTasks"})/*     */   @ResponseBody/*     */   public Output getMetasks(@RequestParam("projectId") Long projectId, @Sid Long sid) {		      List<MetaskBo> metasks;/*     */     try {/* 141 */       metasks = this.taskService.getMetasks(projectId, sid);/*     */     }/*     */     catch (Exception e)/*     */     {/* 143 */       throw new RuntimeException(e);/*     */     }/* 147 */     /* 146 */     List<MetaskRes> metaskRess = new ArrayList<MetaskRes>(metasks.size());/* 147 */     for (Iterator localIterator = metasks.iterator(); localIterator.hasNext(); ) 			  { 				MetaskBo metask = (MetaskBo)localIterator.next();/* 148 */       MetaskRes metaskVo = new MetaskRes();/*     */ /* 150 */       metaskVo.setTaskId(ObjectUtils.toString(metask.getTaskId()));/* 151 */       metaskVo.setIsLeafTask(ObjectUtils.toString(metask.getIsLeafTask()));/* 152 */       metaskVo.setTaskName(ObjectUtils.toString(metask.getTaskName()));/* 153 */       Date srt = metask.getStartDateTime();/* 154 */       Date end = metask.getEndDateTime();/* 155 */       metaskVo.setSrtDate(DateUtil.defaultDateToString(srt));/* 156 */       metaskVo.setEndDate(DateUtil.defaultDateToString(end));/* 157 */       metaskVo.setIsFinished(ObjectUtils.toString(metask.getIsFinished()));/* 158 */       metaskVo.setBetween((srt.getTime() <= metask.getCurrentDateTime().longValue()) && (metask.getCurrentDateTime().longValue() <= end.getTime()) ? "1" : "0");/* 159 */       metaskVo.setTaskDesStatus(ObjectUtils.toString(metask.getTaskDesStatus()));/* 160 */       metaskVo.setTaskStatus(ObjectUtils.toString(metask.getTaskStatus()));/* 161 */       metaskVo.setRemindTime(ObjectUtils.toString(metask.getRemindTime()));/* 162 */       metaskVo.setWatcherSid(ObjectUtils.toString(metask.getWatcherSid()));/* 163 */       metaskVo.setAuditorSid(ObjectUtils.toString(metask.getAuditorSid()));/*     */ /* 165 */       metaskRess.add(metaskVo);/*     */     }/* 168 */     List<TaskInfo> taskInfos = this.taskProgressService.calcTaskProgress(projectId);/* 169 */     for (Iterator iterator1= taskInfos.iterator(); iterator1.hasNext(); ) {				TaskInfo taskInfo = (TaskInfo)iterator1.next();/* 170 */       for (MetaskRes metaskRes : metaskRess)/* 171 */         if (taskInfo.getTaskId().toString().equals(metaskRes.getTaskId())) {/* 172 */           metaskRes.setPlanProgress(ObjectUtils.toString(Float.valueOf(taskInfo.getPlanProgress())));/* 173 */           float undoneProgress = taskInfo.getPlanProgress() - taskInfo.getProgress();/* 174 */           metaskRes.setUndoneProgress(ObjectUtils.toString(Float.valueOf(undoneProgress < 0.0F ? 0.0F : undoneProgress)));/* 175 */           metaskRes.setActualProgress(ObjectUtils.toString(Float.valueOf(taskInfo.getProgress())));/* 176 */           break;/*     */         }/*     */     }/* 181 */     return Result.success(metaskRess);/*     */   }

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