Http java文件下载问题

问题描述

尝试使用apache httpclient库下载文件，并且导致文件小于原始文件（大约32-32kb，正常文件大小为92-93）时出现问题，并且无法在pdf查看器中正常打开。
有人可以解释一下为什么会发生这种情况吗？ （使用firefox下载此文件有时可能导致文件被完全下载，有时被部分下载）

这里是我通过URL下载文件的代码

  URL url = new URL（pathtofile）; 
 final URLConnection connection = url.openConnection（）; 
 
 final InputStream is = connection.getInputStream（）; 
 FileOutputStream fos = new FileOutputStream（C：//result1.pdf）; 
 
 byte buffer [] = new byte [1024]; 
 int bytesRead; 
 while（（bytesRead = is.read（buffer））> = 0）{
 fos.write（buffer，0，bytesRead）; 
} 
 fos.flush（）; 
 fos.close（）; 
 is.close（）; 
  

尝试使用HttpClient apache库下载此文件，结果相同。

UPDATED：使用网络工具监控流量我发现通过Firefox和应用程序接收文件之间的区别。

使用Firefox首先HttpPayloadLine是：

HTTPPayloadLine：83 Td
/ F2 5.80476 Tf
（A：\040Asinis\04017.12.10\04008：32\040laboratorij）Tj
100 Tz
1 1 1 rg
/ F1 5.80476 Tf
0 0 0 rg
104.4856 0 Td
< 0145> Tj
1 1 1 rg
0 0 0 rg
3.62799 0.72565 Td
/ F2 5.80476 Tf
（\040）Tj
1 1 1 rg
0.83137 0.81569 0.78431 RG
ET
51

应用程序首先HttpPayload是

HTTPPayloadLine：CWgC，ú&ÿ3@ί¯¯×××תªªªªªªªªª$ $ $ $ $ $ b¤Ãðð'È/CÈAø¯ªÍübA«1ÿÅç«VɬZòYóóy7»ÇH.o²e< qZna3l±°¥þ6ñþ[2YÚ1ì³Eë-ÓÊÏ$ y：tÎà！[ËÅS¤¿É ¢è，þ|ºs¨¢¢ÝÝ〜〜ÒÒÒ;;;ÒÒÒÒÒÒÒÒøøøøøøøøø>>>>>>>>>>>>>>>> b


此测量是通过Microsoft网络监视器进行的。

最近更新毕竟，这是一个服务器问题，确定文件下载成功

解决方案

尝试更改为

  while（（bytesRead = in.read（buffer））！= -1）{
 byte [] tmp = ArrayUtils.subarray（buffer，0，bytesRead）; 
 FO s.write（tmp）; 
} 
  

你螨获得0个字节，但是并不意味着它的完成。还只写你收到的字节不是缓冲区。

Trying to download file with apache httpclient library and have a problem with resulting file being smaller than the original (approximately 32-32kb, when normal file size is 92-93) and cannot be opened normally in pdf viewer.Can someone explain me why this can be happening ? (Using firefox to download this file can sometimes lead to file being downloaded fully and sometimes being downloaded partly)

Here is code I was using to download file via URL

    URL url = new URL("pathtofile");
    final URLConnection connection = url.openConnection();

    final InputStream is = connection.getInputStream();
    FileOutputStream fos = new FileOutputStream("C://result1.pdf");

    byte buffer[] = new byte[1024];
    int bytesRead;
    while ((bytesRead = is.read(buffer)) >= 0) {
        fos.write(buffer, 0, bytesRead);
    }
    fos.flush();
    fos.close();
    is.close();

P.S. Was trying to download this file using HttpClient apache library, same result.

UPDATED: Monitoring traffic with network tool I found the difference between receiving file via Firefox and application.

With Firefox first HttpPayloadLine was :

HTTPPayloadLine: 83 Td/F2 5.80476 Tf(A:\040Asinis\04017.12.10\04008:32\040laboratorij) Tj100 Tz1 1 1 rg/F1 5.80476 Tf0 0 0 rg104.4856 0 Td<0145> Tj1 1 1 rg0 0 0 rg3.62799 0.72565 Td/F2 5.80476 Tf(\040) Tj1 1 1 rg0.83137 0.81569 0.78431 RGET51

With application first HttpPayload was

HTTPPayloadLine: CWgC,ú&ÿ3@Î"ݯV¨®~×>×)\ªleÚlµï½ci¤Ãðð'È/CÈAø¯ª ÍübA«1Ãÿ Åç«VɬZòYóóy7»ÇH.o²e<qZna3l±°¥þ6ñþ[2YÚ1ì³Eë-ÓÊÏ$y:tÎà![ËÅS¤¿É¡¢è,þ|ºs¨)@¢Qâ¯ÝF~}oµÒ>¦ OAxz³äÒ.ß9æÃZ¤ùÒ¨*«øUή+4×

This measurements was taken via Microsoft Network Monitor

LAST UPDATE It was a server problem after all, after they fixed that files are downloaded successful

解决方案

Try changing to

while ((bytesRead = in.read(buffer)) != -1) {
 byte[] tmp = ArrayUtils.subarray(buffer, 0, bytesRead);
 fos.write(tmp);
}

you mite get 0 bytes back but that does not mean its finished.Also write only bytes that you received not buffer.

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