java添加增量号到文件之前存在

Question

我需要在文件之前添加一个增量编号,我知道如何解决这个问题以及如何在最后添加数字但我需要知道如何每次都输入数字

看看这个例如了解我C:\ MyFiles\File.pdf存在所以尝试C:\ MyFiles\File1.pdf和下次C:\ MyFiles\File2.pdf

不知道怎么得到最后一次增量

并且plz看到我的代码我只能增加一次

    int indexOfDot = fName.indexOf(".");
    //if theres a dot, start one character before it, otherwise,
    //start at the end of the string
    int startIndex = indexOfDot > -1 ? indexOfDot - 1 : fName.length() - 1;
    if(indexOfDot > -1)
         fileNameSuffix = fName.substring(indexOfDot, fName.length());
    //search backward on the name to see if it already
    //has a number and count the digits
    StringBuffer digits = new StringBuffer();
    char character = 0;
    for (int i = startIndex; i >= 0; i--)
    {
         character = fName.charAt(i);
         if (Character.isDigit(character))
         {
              digits.append(character);
         }
    }
    if (digits.length() > 0)
    {
          //There where already digits in the filename.
          //Create a number from the digits and add 1
          Integer newNumber =new Integer(Integer.parseInt(digits.toString()) + 1);
          //Then append that to the actual filename
          String actualFileName = fName.substring(0, startIndex + 1 - digits.length());
          rtnNewFileName = actualFileName + newNumber.toString() + fileNameSuffix;
    }else
    {
          //There where no digits in the filename
          //Append 1 to the actual filename
          String actualFileName = fName.substring(0, startIndex - digits.length());
          rtnNewFileName = actualFileName + "1" + fileNameSuffix;
   }

   file.setFileName(rtnNewFileName);

   out.println("<li>File Uploaded <br/>Form field : uploadfile"+"<BR> Uploaded file : "+file.getFileName()+" ("+file.getFileSize()+" bytes)"+"<BR> Content Type : "+file.getContentType());

    //Uses the bean now to store specified by jsp:setProperty at the top.
    upBean.store(mrequest, "uploadfile");

Answer 1

您需要第二次将File2.pdf传递给该方法,或者检查生成的文件名是否存在,然后使用新文件名重复该方法

顺便说一下,我使用了正则表达式:

Pattern p = Pattern.compile("(.*?)(\\d+)?(\\..*)?");
do{
    Matcher m = p.matcher(fName);
    if(m.matches()){//group 1 is the prefix, group 2 is the number, group 3 is the suffix
        fName = m.group(1) + (m.group(2)==null?1:(Integer.parseInt(m.group(2)) + 1)) + (m.group(3)==null?"":m.group(3));
    }
}while(new File(fName).exists());//repeat until a new filename is generated

Answer 2

大家好，我找到了答案，您只需在测试后加载的每个新文件之前添加（C0Py0），如果您的文件存在而不是调用方法更改（）；

<％！String reverseIt(String source) { int i, len = source.length(); StringBuffer dest = new StringBuffer(len);

for (i = (len - 1); i >= 0; i--)
  dest.append(source.charAt(i));
return dest.toString();

}

%> <%！字符串改变(String ffName){ String newName,ext,finalName; 字符串 invName，增量；字符串copyf=null；串测试；整数i=0；整数j=0；整数增量；整数k=j+4；

newName=ffName.substring(0,ffName.length()-4); ext = ffName.substring(ffName.length()-3,ffName.length());

  invName=reverseIt(newName);

                                while(k != invName.length()){

                                 if( invName.substring(j,k).equals("yP0C")){
                                                              copyf=invName.substring(0,j);
                                                              k=invName.length()-1;

                                                                        }
                                 else{
                                     j++;
                                     k++;
                                    }

                                                             }
increment=reverseIt(copyf);
//System.out.println(increment);
incr=Integer.parseInt(increment);
incr+=1;
newName=newName.substring(0,newName.length()-(j-1));
increment=String.valueOf(incr);
finalName=newName+increment+"."+ext;

返回最终名称；
}

%>

我希望这能帮助别人