PDF創建在指定位置不起作用

Question

我想從我的數據庫中的blob字段創建pdf。如果我沒有指定文件位置，它工作得很好：pdf生成並可讀。但是如果我指定一個文件位置，我會得到一個nullpointerexception。

文件位置位於屬性文件中。

/** 
* Deze methode zoekt een pdf in de database op pdfnaam 
* 
* @param name, de naam van de pdf 
* @return maakt de pdf aan 
*/ 
public void retrievePdf(int iddocument) { 
    Properties prop = new Properties(); 
    String fileLocation = new String(""); 
    FileOutputStream fos = null; 

    try { 
     // load a properties file 
     prop.load(new FileInputStream("props/config.properties")); 

     // get the property value and use it 
     fileLocation = prop.getProperty("FileLocation"); 

     // verwijderen 
     System.out.println(fileLocation); 

    } catch (IOException ex) { 
     ex.printStackTrace(); 
    } 

    try { 
     c = MySqlDAOFactory.getInstance().getConnection(); 

     String sql = "select * from pdf where iddocument=?"; 
     prest = c.prepareStatement(sql); 
     prest.setInt(1, iddocument); 
     rs = prest.executeQuery(); 

     while (rs.next()) { 
      // create file with the filename from 
      // the db in the dir fileLocation 
      File file = new File(fileLocation, rs.getString("pdfname")); 
      //get the blob from the db 
      Blob blob = rs.getBlob("pdffile"); 
      InputStream is = blob.getBinaryStream(); 
      try { 
       fos = new FileOutputStream(file); 
      } catch (FileNotFoundException e) { 
       // ... 
      } 
      byte [] buffer = new byte[(int)blob.length()]; 
      int length = -1; 
      try { 
       while((length = is.read(buffer)) != -1) { 
        try { 
         fos.write(buffer, 0, length); 
        } catch (IOException e) { 
         // ... 
        } 
        try { 
         fos.flush(); 
         fos.close(); 
        } catch (IOException e) { 
         // ... 
        } 
       } 
      } catch (IOException e) { 
       // ... 
      } 

      return; 
     } 
    } catch (SQLException e) { 
     // ... 
    } finally { 
     MySqlConnectionFactory.getInstance().closeResultSet(rs); 
     MySqlConnectionFactory.getInstance().closeStatement(prest); 
     MySqlConnectionFactory.getInstance().closeConnection(c); 
    } 
} 

在propertyfile寫的是：FileLocation=reports

誰能給一個建議，爲什麼它好好嘗試工作？

Answer 1

解決：

我改變了與目錄文件的制定和它的伎倆：

File file = new File(fileLocation + File.separator + rs.getString("pdfname")); 
        file.getParentFile().mkdirs();