使用Java从Github下载二进制文件 [英] Download binary file from Github using Java

问题描述

我正在尝试下载此文件（ http://github.com /downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar ）使用以下方法，它似乎不起作用。我收到一个空的/损坏的文件。

  String link =http://github.com/downloads/TheHolyWaffle/ ChampionHelper / ChampionHelper-4.jar; 
 String fileName =ChampionHelper-4.jar; 
 
 URL url = new URL（link）; 
 URLConnection c = url.openConnection（）; 
 c.setRequestProperty（User-Agent，Mozilla / 4.0（兼容; MSIE 6.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; .NET CLR 1.2.30703） ）; 
 
 InputStream输入; 
 input = c.getInputStream（）; 
 byte [] buffer = new byte [4096]; 
 int n = -1; 
 
 OutputStream output = new FileOutputStream（new File（fileName））; 
 while（（n = input.read（buffer））！= -1）{
 if（n> 0）{
 output.write（buffer，0，n）; 
} 
} 
 output.close（）; 
  

但是，我可以从我的保管箱成功下载以下文件（ http://dl.dropbox.com/u/13226123/ChampionHelper-4.jar ）使用相同的方法。

所以Github知道我不是一个试图下载文件的常规用户。我已经尝试更改用户代理，但这也没有帮助。

那么我应该如何使用Java下载我的Github帐户上托管的文件？ / p>

编辑：我尝试使用apache commons-io为此，但我得到相同的效果，一个空/损坏的文件。

解决方案

这个工作：

  public class下载{
 private static boolean isRedirected（Map< String，List< String>> header）{
 for（String hv：header.get（null））{
 if（hv.contains ）
 || hv.contains（302））return true; 
} 
返回false; 
} 
 public static void main（String [] args）throws Throwable 
 {
 String link = 
http://github.com/downloads/TheHolyWaffle/ ChampionHelper /+ 
ChampionHelper-4.jar; 
 String fileName =ChampionHelper-4.jar; 
 URL url = new URL（link）; 
 HttpURLConnection http =（HttpURLConnection）url.openConnection（）; 
地图<字符串，列表<字符串>> header = http.getHeaderFields（）; 
 while（isRedirected（header））{
 link = header.get（Location）.get（0）; 
 url = new URL（link）; 
 http =（HttpURLConnection）url.openConnection（）; 
 header = http.getHeaderFields（）; 
} 
 InputStream input = http.getInputStream（）; 
 byte [] buffer = new byte [4096]; 
 int n = -1; 
 OutputStream output = new FileOutputStream（new File（fileName））; 
 while（（n = input.read（buffer））！= -1）{
 output.write（buffer，0，n）; 
} 
 output.close（）; 
} 
} 
  

I'm trying to download this file (http://github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar) with the following method and it doesn't seem to work. I'm getting an empty/corrupt file.

String link = "http://github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar";
String fileName = "ChampionHelper-4.jar";

URL url = new URL(link);
URLConnection c = url.openConnection();
c.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; .NET CLR 1.2.30703)");

InputStream input;
input = c.getInputStream();
byte[] buffer = new byte[4096];
int n = -1;

OutputStream output = new FileOutputStream(new File(fileName));
while ((n = input.read(buffer)) != -1) {
    if (n > 0) {
        output.write(buffer, 0, n);
    }
}
output.close();

But I can successfully download the following file from my dropbox (http://dl.dropbox.com/u/13226123/ChampionHelper-4.jar) with the same method.

So somehow Github knows that I'm not a regular user trying to download a file. I already tried to change the user agent, but that didn't help either.

So how should I download a file that is hosted on my Github account using Java?

EDIT: I tried to use the apache commons-io for this but I get the same effect, an empty/corrupt file.

解决方案

This one do the work:

public class Download {
   private static boolean isRedirected( Map<String, List<String>> header ) {
      for( String hv : header.get( null )) {
         if(   hv.contains( " 301 " )
            || hv.contains( " 302 " )) return true;
      }
      return false;
   }
   public static void main( String[] args ) throws Throwable
   {
      String link =
         "http://github.com/downloads/TheHolyWaffle/ChampionHelper/" +
         "ChampionHelper-4.jar";
      String            fileName = "ChampionHelper-4.jar";
      URL               url  = new URL( link );
      HttpURLConnection http = (HttpURLConnection)url.openConnection();
      Map< String, List< String >> header = http.getHeaderFields();
      while( isRedirected( header )) {
         link = header.get( "Location" ).get( 0 );
         url    = new URL( link );
         http   = (HttpURLConnection)url.openConnection();
         header = http.getHeaderFields();
      }
      InputStream  input  = http.getInputStream();
      byte[]       buffer = new byte[4096];
      int          n      = -1;
      OutputStream output = new FileOutputStream( new File( fileName ));
      while ((n = input.read(buffer)) != -1) {
         output.write( buffer, 0, n );
      }
      output.close();
   }
}

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