用Java下载PDF是否已损坏？

时间：2009-09-04 09:45:42

标签： java pdf url download

我已经阅读了关于How to download and save a file from internet using Java的精彩讨论。但是，如果我执行下一个代码，我会得到一个损坏的PDF。知道为什么吗？

import java.io.*;
import java.net.*;

public class PDFDownload {
    public static String URL = "http://www.nbc.com/Heroes/novels/downloads/";
    public static String FOLDER = "C:/Users/sdelamo/workspace/SandBox/HeroesNovel/";

    public static void main(String[] args) {
        String filename = "Heroes_novel_001.pdf";
        try {
            saveUrl(FOLDER + filename, URL + filename);
        } catch (MalformedURLException e) {
            System.out.println("MalformedURLException");
        } catch (IOException e) {
            System.out.println("IOException");                              
        }                       
    }       



    public static void saveUrl(String filename, String urlString) throws MalformedURLException, IOException {
        BufferedInputStream in = null;
        FileOutputStream fout = null;
        try {
            URL url = new URL(urlString);
            in = new BufferedInputStream(url.openStream());
            fout = new FileOutputStream(filename);

            byte data[] = new byte[1024];
            int count;
            while ((count = in.read(data, 0, 1024)) != -1) {
                fout.write(data, 0, count);
            }
        } finally {
            if (in != null)
                in.close();
            if (fout != null)
                fout.close();
        }
    }
}

以上代码下载html而不是PDF。这是输出：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN"
    "http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>

<meta name="viewport" content="width=240, user-scalable=yes" />
<HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE">
<META HTTP-EQUIV="Expires" CONTENT="-1">
<meta http-equiv="Cache-control" content="no-cache">
<meta http-equiv="Cache-control" content="must-revalidate">
<meta http-equiv="Cache-control" content="max-age=0">
<meta http-equiv="refresh" content="200">

<title>NBC.com: Heroes</title>
<link rel="stylesheet" type="text/css"  href="/style/default.css?sid=8a9212f822e1c675330ec418bc531169" />
<link rel="stylesheet" type="text/css"  href="/style/hro.css?sid=8a9212f822e1c675330ec418bc531169" /> 

</head>
<body>
<center><img src="http://oimg.nbcuni.com/b/ss/nbcunbcnetworkwapbu,nbcuwapsitebu/5/H.8--WAP/4aa0e4cb8b448?vid=8a9212f822e1c675330ec418bc531169&gn=NBC.com Front Door&c2=&c3=Miscellaneous&c4=&c6=m.nbc.com/show/hro&c8=TV Entertainment&c9=NBC Network&c10=&c11= | &c12= | &c25=offdeck&c27=internal&c29=&c44=D=User-Agent&r=" width="5" height="5" border="0" /></center>
<h1 id="fHeader">
<a  href="/?sid=8a9212f822e1c675330ec418bc531169">
<img src="/images/nbc_logo.gif" alt="NBC : logo" border="0" />
</a>
</h1>

<h2>
<a  href="/show/hro?sid=8a9212f822e1c675330ec418bc531169">
<img src="/images/shows/1221684699_Heroes_WAP_166x54.jpg" alt="Heroes : showheader" border="0" />
</a>
</h2>
<div id="tunein_nexton">
    <span id="tunein">Mondays 9/8c</span>
</div><!--end #tunein_nexton-->
<div id="tunein_nexton">
    <!--<span id="tunein">Mondays 8/7c</span>-->

    <p id="nexton"><span class="sectiontitle"></span></p>
</div><!--end #tunein_nexton-->
<div id="featuredcontent">
    <h3>FEATURED CONTENT</h3>
    <table id="featuredItemsTable">

        <tr>
            <td><a  href="/show/hro/videos.html?sid=8a9212f822e1c675330ec418bc531169"><img src="/images/hro/nbc_hro_pro_040X921HRO120FLYPSIDE_exp921_20090_543_large.jpg" alt="featured" /></a>
            </td>
            <td>
                <span class="ftitle">Dreams</span>
                <span class="fdesc">Heroes premieres Mon., Sept. 21s...</span>
            </td>
        </tr>
                                        <tr>
            <td><a  href="/show/hro/recaps.html?sid=8a9212f822e1c675330ec418bc531169"><img src="http://origin-www.nbc.com/Heroes/images/episodes/season3/325/hro_325_01.jpg" alt="featured" height="45" width="80"/></a>
            </td>
            <td>
                <span class="ftitle">Recap:</span>
                <span class="fdesc">Season 3 Episode An Invisible Thread</span>
            </td>
        </tr>
                                        <tr>
            <td><a  href="/show/hro/photos.html?sid=8a9212f822e1c675330ec418bc531169"><img src="http://origin-www.nbc.com/app2/img/200x200xS/scet/photos/51/3736/NUP_110031_0323.JPG" alt="featured" height="45" width="80"/></a>
            </td>
            <td class="finfo">
                <span class="ftitle">Photo:</span>
                <span class="fdesc">Heroes "Cast Photos"</span>
            </td>
        </tr>
                    </table>


</div><!--end #featuredcontent-->

<h3>HEROES</h3>
<table class="showNav">
    <tr><td><a  href="/show/hro/about.html?sid=8a9212f822e1c675330ec418bc531169" accesskey="1">About</a></td></tr>
        <tr><td><a  href="/show/hro/videos.html?sid=8a9212f822e1c675330ec418bc531169" accesskey="2">Videos</a></td></tr>
                <tr><td><a  href="/show/hro/recaps.html?sid=8a9212f822e1c675330ec418bc531169" accesskey="3">Episode Recaps</a></td></tr>
                    <tr><td><a  href="/show/hro/photos.html?sid=8a9212f822e1c675330ec418bc531169" accesskey="4">Photos</a></td></tr>
                <tr><td><a  href="/show/hro/community.html?sid=8a9212f822e1c675330ec418bc531169" accesskey="5">Community</a></td></tr>
    <tr><td><a  href="/shows.shtml?sid=8a9212f822e1c675330ec418bc531169" accesskey="6">Shows List</a></td></tr>
</table>
<!-- <a  href="http://www.insightexpress.com/ix/Survey.aspx?id=151580&accessCode=3161643404&sid=8a9212f822e1c675330ec418bc531169" ><img src="/images/mNBCcom_166x54.jpg" border="0"></a> -->



<div class="footer" align="center"><a  href="http://m.nbc.com?sid=8a9212f822e1c675330ec418bc531169"><strong>NBC Mobile Main</strong></a> | <a  href="/terms.shtml?sid=8a9212f822e1c675330ec418bc531169"><strong>Terms of Use</strong></a> | <a  href="/privacy.shtml?sid=8a9212f822e1c675330ec418bc531169"><strong>Privacy</strong></a></div><div class="cpyrt" align="center">&#169; NBC Universal, Inc.</div>

</body>
</html>

知道如何下载PDF吗？

解

连接前设置User-Agent。

URL u = new URL(urlString); 
HttpURLConnection huc =  (HttpURLConnection)  u.openConnection();
huc.setRequestMethod("GET"); 
huc.setRequestProperty("User-Agent", "  Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2 (.NET CLR 3.5.30729)");
huc.connect();          

in = new BufferedInputStream(huc.getInputStream());

5 个答案:

答案 0 :(得分：3)

您是否尝试使用文本编辑器查看下载的文件？

您会看到它包含HTML页面，而不是PDF。可能URL没有指向PDF，或者有一些重定向，标准java.net类默认不支持。

确保网址正确指向PDF。您可以使用Apache HttpClient通过HTTP执行更复杂的操作，包括自动处理HTTP重定向。

注意：您发布的代码无法编译，因为您错误地放置了}。

答案 1 :(得分：1)

检查生成的文件 - 我希望它是一个HTML文件。如果没有引用者或使用JavaScript重定向页面或其他内容，该站点可能会返回错误。您可以使用HttpURLConnection类来检查服务器返回的HTTP标头。

URL url = new URL(
    "http://www.nbc.com/Heroes/novels/downloads/Heroes_novel_001.pdf");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("HEAD");
try {
  for (Map.Entry<String, List<String>> header : conn.getHeaderFields()
      .entrySet()) {
    System.out.println(header.getKey() + "=" + header.getValue());
  }
} finally {
  conn.disconnect();
}

上述代码返回Content-Type text/html。

答案 2 :(得分：1)

对于这种探索，我强烈推荐Jython（或Groovy，或......）。例如：

C:\Users\Vinay>jython
Jython 2.5.0 (Release_2_5_0:6476, Jun 16 2009, 13:33:26)
[Java HotSpot(TM) Client VM (Sun Microsystems Inc.)] on java1.6.0_16
Type "help", "copyright", "credits" or "license" for more information.
>>> s = "http://www.nbc.com/Heroes/novels/downloads/Heroes_novel_001.pdf"
>>> import java.net
>>> import jarray
>>> u = java.net.URL(s)
>>> os = u.openStream()
>>> buffer = jarray.zeros(1024, 'b')
>>> n = os.read(buffer, 0, 1024)
>>> java.lang.String(buffer)

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.1//EN"
    "http://www.w3.org/TR/xhtml-basic/xhtml-basic11.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>

<meta name="viewport" content="width=240, user-scalable=yes" />
<HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE">
<META HTTP-EQUIV="Expires" CONTENT="-1">
<meta http-equiv="Cache-control" content="no-cache">
<meta http-equiv="Cache-control" content="must-revalidate">
<meta http-equiv="Cache-control" content="max-age=0">
 meta http-equiv="refresh" content="200">
<title>NBC.com: Heroes</title>
<link rel="stylesheet" type="text/css"  href="/style/default.css?sid=c67ddc30f79
ec4cc811f6e67e383fed7" />
<link rel="stylesheet" type="text/css"  href="/style/hro.css?sid=c67ddc30f79ec4c
c811f6e67e383fed7" />

</head>
<body>
<center><img src="http://oimg.nbcuni.com/b/ss/nbcunbcnetworkwapbu,nbcuwapsitebu/
5/H.8--WAP/4aa0e7ce2535c?vid=c67ddc30f79ec4cc811f6e67e383fed7&gn=NBC.com Front
>>>

确认您找到了什么，但没有编辑/编译周期来阻碍。只是我的2美分......

至于如何获取数据 - 可能是您必须欺骗User-Agent标头。在Firefox中，相同的网址会返回Content-Type application/pdf和PDF文件。

更新：以下Jython脚本：

import java.net
import jarray

s = "http://www.nbc.com/Heroes/novels/downloads/Heroes_novel_001.pdf"
u = java.net.URL(s)
c = u.openConnection()
c.setRequestProperty("User-Agent", "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.2) Gecko/20090810 Ubuntu/9.10 (karmic) Firefox/3.5.2")
BUFLEN = 4
buffer = jarray.zeros(BUFLEN, 'b')
c.connect()
stream = c.getInputStream()
stream.read(buffer, 0, BUFLEN)
data = java.lang.String(buffer)
print data

打印

  

％PDF

所以网站 正在查看User-Agent标题。

答案 3 :(得分：1)

这与您的其他问题相同。如果它认为你是刮刀，NBC.com不会向你发回PDF：）

同样的技巧会做，

conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.0.13) Gecko/2009073021 Firefox/3.0.13");

答案 4 :(得分：0)

如果设置User-Agent没有解决它。这可能是Cookies的问题。安装简单的浏览器插件（EditThisCookie，用于Chrome的HTTP Spy）并检查请求和放大器。响应标头。抓取那些cookie值并使用相同的HttpURLConnection设置它们。

代码:(扩展到Sergio del Amo发布的解决方案）

URL u = new URL(urlString); 
HttpURLConnection huc =  (HttpURLConnection)  u.openConnection();
huc.setRequestMethod("GET"); 
huc.setRequestProperty("User-Agent", "  Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2 (.NET CLR 3.5.30729)");

String myCookies = "cookie_name_1=cookie_value_1;cokoie_name_2=cookie_value_2";
huc.setRequestProperty("Cookie", myCookies);

huc.connect();          

in = new BufferedInputStream(huc.getInputStream());
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