如何测量从URL下载的PDF的大小

Question

我从URL下载PDF并将其保存到本地驱动器。

下载代码工作正常，问题是当我尝试测量文件的大小时，它始终声称它是52字节。我很困惑...你能检查一下我的代码，告诉我我是否错过了一些东西？

try { 
       link = new URL("http://www.annualreports.co.uk/HostedData/AnnualReports/PDF/LSE_" + entry[0] + "_2015.pdf"); 
       // http://www.annualreports.co.uk/HostedData/AnnualReports/PDF/LSE_BT_2015.pdf 

       InputStream in = new BufferedInputStream(link.openStream()); 
       ByteArrayOutputStream out = new ByteArrayOutputStream(); 

       byte[] buf = new byte[1024]; 
       int n = 0; 
       while (-1!=(n=in.read(buf))) 
       { 
        out.write(buf, 0, n); 
       } 
       out.close(); 
       in.close(); 
       byte[] response = out.toByteArray(); 

       FileOutputStream fos = new FileOutputStream(fileName); 
       fos.write(response); 
       fos.close(); 

      } catch (Exception e) { 
       System.out.println("Couldn't retrieve : " + entry[1] + " " + year); 
      } 

      int bytes = fileName.length(); 
      System.out.println(bytes); 

Answer 1

这里。只需简单地尝试一下。

URL url = new URL("http://www.annualreports.co.uk/HostedData/AnnualReports/PDF/LSE_" + entry[0] + "_2015.pdf"); 
HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
conn.addRequestProperty("User-Agent", "Mozilla/4.76"); 
int size = conn.getContentLength(); 

     if (size < 0) { 
      System.out.println("File not found"); 
     } else { 
      System.out.println("File size in Bytes: " + size); 
     }