如何在java中找到上傳文件的擴展名？

Question

我有以下代碼來上傳文件，當我使用file.getNeme時，它顯示了具有tmp擴展名的臨時文件名，我怎麼才能找到實際上傳文件的擴展名？ ，我上傳的文件被稱爲test.jpg

import java.io.File; 
import org.apache.commons.io.FileUtils; 

public class FileUploder { 

    private File file; 

    public File getFile() { 
     return file; 
    } 

    public void setFile(File file) { 
     this.file = file; 
    } 
    ...... 

    System.out.println("file:" +file.getName()); 
    try { 
     File fileToCreate = new File(filePath,name); 
     FileUtils.copyFile(file, fileToCreate); 
    } catch (IOException ex) { 
     ex.printStackTrace(); 
    } 

    ...... 

電流輸出類似於>>>file:upload__1a6d32_13d0eda6d49__7fdf_00000012.tmp

Answer 1

你不應該使用file.getName()

http://struts.apache.org/release/2.0.x/docs/file-upload.html#FileUpload-BasicUsage

setX(File file) 
    The file that contains the content of the uploaded file. This is a temporary file and file.getName() will not return the original name of the file 

相反，創建另一個設置器setFileName(String fileName)應該這樣做。

Answer 2

private String getImageFileExtendtion (FileItem item) { 
     String formatName = "png"; 
     String fileName = item.getName(); 
     if (fileName != null && fileName.length() >0) { 
      int index = -1; 
      for (int i = fileName.length()-1 ; i >=0; i --) { 
       if (fileName.charAt(i)=='.') { 
        index = i; 
        break; 
       } 
      } 
      if (index >=0 && index < fileName.length() -1) { 
       formatName = fileName.substring(index+1); 
      } 
     } 
     return formatName ; 
    }