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Question

/********************** private mothed start: **************************/        ////写log（此方法本应该synchronized，但synchronized后很多日志并没有记录进LOG，出现丢失，所以就拿掉了）
        private void printLog(String s)
        {
            log.print(DateFormat.getDateTimeInstance().format(new Date())+" ---- ");
            log.print(clientIP+":"+clientPort+" ("+clientName+") ");
            log.print(s);
            log.println(" (ConnectionID:"+ID+")");
            log.flush();
        }
        ////写出错log（此方法本应该synchronized，但synchronized后很多日志并没有记录进LOG，出现丢失，所以就拿掉了）
        private void printErrorLog(String s)
        {
            log.print("ERROR: "+DateFormat.getDateTimeInstance().format(new Date())+" ---- ");
            log.print(clientIP+":"+clientPort+" ("+clientName+") ");
            log.print(s);
            log.println(" (ConnectionID:"+ID+")");
            log.flush();
        }        
        ////读取请求信息，以空行表示结尾("\n\n")
        private String getRequestString() throws IOException
        {
            if (in.ready())
            {
                StringBuffer sb = new StringBuffer(500);
                String str = in.readLine();
                while(str!=null && !str.equals(""))
                {
                    sb.append(str+"\n");
                    str = in.readLine();
                }
                return sb.toString();
            }
            else return null;
        }        /************************* private method end ************************/

Answer 1

/************************* protected method start: *******************/        /**执行GET*/
        protected void doGet()
          throws IOException
        {
            sendFile(getRequestFileName());
        }
        /**验证请求文件路径是否合法（是否超出rootPath范围）
        * @param path 相对路径*/
        protected boolean isAllowAccess(String path) throws IOException
        {
            return getAbsolutePath(path).indexOf(new File(rootPath).getCanonicalPath()) >= 0;
        }
        /**发送文件*/
        protected void sendFile(String fileName)
          throws IOException
        {
            if (!isAllowAccess(fileName))
            {
                //超出rootPath范围，不允许访问
                printLog(getRequestMethod()+" "+fileName+"  failed : 403 Forbidden!"); //写log
                sendError(FORBIDDEN);
            }
            else
            {
                String fileFullPath = getAbsolutePath(fileName);                if (fileName==null || fileName.charAt(0)!='/')  //请求文件名为null或第一个字符不是"/"
                {
                    printLog(getRequestMethod()+" "+fileName+"  failed : 400 Bad Request!"); //写log
                    sendError(BAD_REQUEST);
                }
                //如果fileName以"/"结尾，则列出indexFiles中的文件
                else if (fileName.endsWith("/"))
                {
                    printLog(getRequestMethod()+" "+fileName); //写log                    sendIndexFile(fileName.substring(0, fileName.lastIndexOf('/')));
                }
                else
                {
                    try
                    {
                        fin = new BufferedInputStream(new FileInputStream(fileFullPath));
                        int finLength = fin.available();
                        //如果finLength<0，相当于文件未找到，所以仍旧抛出FileNotFoundException
                        if (finLength < 0)  throw new FileNotFoundException();
                        else
                        {
                            printLog(getRequestMethod()+" "+fileName); //写log
                            out.println("HTTP/1.1 200 OK");
                            out.println("Server: Simple Web Server");
                            out.println("Date: "+DateFormat.getDateTimeInstance().format(new Date()));
                            out.println("Content-Type: "+new File(fileFullPath).toURL().openConnection().getContentType());
                            out.println("Accept-Ranges: bytes");
                            out.println("Content-Length: "+finLength);
                            out.println();
                            int b;
                            while ((b=fin.read()) != -1)  out.write(b);
                        }
                    }
                    catch (FileNotFoundException e)
                    {
                        printLog(getRequestMethod()+" "+fileName+"  failed : 404 Not Found!"); //写log                        //如果allowListFiles为true则列出未找到文件目录下的所有文件
                        if (allowListFiles)  listFiles(fileName.substring(0, fileName.lastIndexOf('/')));
                        else sendError(NOT_FOUND);
                    }
                }
            }
        }
        /**寻找并发送indexFiles列表里的文件
        * @param dir 目录相对路径（结尾没有"/"）*/
        protected void sendIndexFile(String dir) throws IOException
        {
            String index = null;
            //取得dir的绝对路径
            String path = getAbsolutePath(dir);
            //在dir目录下检索第一个存在的index文件            for (int i=0; i<indexFiles.length; i++)
            {
                if (new File(path+File.separator+indexFiles[i]).exists())
                {
                    index = path+File.separator+indexFiles[i];
                    break;
                }
            }            if (index != null)
            {
                try
                {
                    fin = new BufferedInputStream(new FileInputStream(index));
                    int finLength = fin.available();
                    if (finLength >= 0)
                    {
                        printLog(getRequestMethod()+" "+dir+"/"+index.substring(index.lastIndexOf(File.separator)+1)+"  OK : 200"); //写log                        out.println("HTTP/1.1 200 OK");
                        out.println("Server: Simple Web Server");
                        out.println("Date: "+DateFormat.getDateTimeInstance().format(new Date()));
                        out.println("Content-Type: text/html");
                        out.println("Accept-Ranges: bytes");
                        out.println("Content-Length: "+finLength);
                        out.println();
                        int b;
                        while ((b=fin.read()) != -1)  out.write(b);
                    }
                }
                catch (FileNotFoundException e)
                {
                    printLog(getRequestMethod()+" "+dir+"/"+index.substring(index.lastIndexOf(File.separator)+1)+"  failed : 404 Not Found!"); //写log                    //如果allowListFiles为true则列出未找到文件目录下的所有文件
                    if (allowListFiles)  listFiles(dir);
                    else sendError(NOT_FOUND);
                }
            }
        }

Answer 2

        /**发送错误*/
        protected void sendError(String errorType)
          throws IOException
        {
            //NOT_FOUND
            if (errorType.equals(NOT_FOUND))
            {
                out.println("HTTP/1.1 404 Not Found");
                out.println("Server: Simple Web Server");
                out.println("Date: "+DateFormat.getDateTimeInstance().format(new Date()));
                out.println("Content-Type: text/html");
                try
                {
                    String errorFile = properties.getProperty(NOT_FOUND);
                    if (errorFile == null)  throw new FileNotFoundException();
                    else
                    {
                        fin = new BufferedInputStream(new FileInputStream(errorFile));
                        int finLength = fin.available();
                        //如果finLength为0，相当于文件未找到，所以仍旧抛出FileNotFoundException
                        if (finLength <= 0)  throw new FileNotFoundException();
                        else
                        {
                            out.println("Accept-Ranges: bytes");
                            out.println("Content-Length: "+finLength);
                            out.println();
                            int b;
                            while ((b=fin.read()) != -1)  out.write(b);
                        }
                    }
                }
                catch (FileNotFoundException e)
                {
                    out.println("Content-Length: "+default_NOT_FOUND.getBytes().length);
                    out.println();
                    out.println(default_NOT_FOUND);
                }
            }
            //BAD_REQUEST
            else if (errorType.equals(BAD_REQUEST))
            {
                out.println("HTTP/1.1 400 Bad Request");
                out.println("Server: Simple Web Server");
                out.println("Date: "+DateFormat.getDateTimeInstance().format(new Date()));
                out.println("Content-Type: text/html");
                try
                {
                    String errorFile = properties.getProperty(BAD_REQUEST);
                    if (errorFile == null)  throw new FileNotFoundException();
                    else
                    {
                        fin = new BufferedInputStream(new FileInputStream(errorFile));
                        int finLength = fin.available();
                        //如果finLength为0，相当于文件未找到，所以仍旧抛出FileNotFoundException
                        if (finLength <= 0)  throw new FileNotFoundException();
                        else
                        {
                            out.println("Accept-Ranges: bytes");
                            out.println("Content-Length: "+finLength);
                            out.println();
                            int b;
                            while ((b=fin.read()) != -1)  out.write(b);
                        }
                    }
                }
                catch (FileNotFoundException e)
                {
                    out.println("Content-Length: "+default_BAD_REQUEST.getBytes().length);
                    out.println();
                    out.println(default_BAD_REQUEST);
                }
            }
            //FORBIDDEN
            else if (errorType.equals(FORBIDDEN))
            {
                out.println("HTTP/1.1 400 Bad Request");
                out.println("Server: Simple Web Server");
                out.println("Date: "+DateFormat.getDateTimeInstance().format(new Date()));
                out.println("Content-Type: text/html");
                try
                {
                    String errorFile = properties.getProperty(FORBIDDEN);
                    if (errorFile == null)  throw new FileNotFoundException();
                    else
                    {
                        fin = new BufferedInputStream(new FileInputStream(errorFile));
                        int finLength = fin.available();
                        //如果finLength为0，相当于文件未找到，所以仍旧抛出FileNotFoundException
                        if (finLength <= 0)  throw new FileNotFoundException();
                        else
                        {
                            out.println("Accept-Ranges: bytes");
                            out.println("Content-Length: "+finLength);
                            out.println();
                            int b;
                            while ((b=fin.read()) != -1)  out.write(b);
                        }
                    }
                }
                catch (FileNotFoundException e)
                {
                    out.println("Content-Length: "+default_FORBIDDEN.getBytes().length);
                    out.println();
                    out.println(default_FORBIDDEN);
                }
            }
        }        /************************* protected method end **********************/