使用Java从Github下载二进制文件
我正在尝试使用以下方法下载此文件（ http://github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar ），但它似乎不起作用。 我收到一个空/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 (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(); 但我可以使用相同的方法从我的Dropbox（ http://dl.dropbox.com/u/13226123/ChampionHelper-4.jar ）成功下载以下文件。
所以不知何故Github知道我不是一个试图下载文件的普通用户。 我已经尝试更改用户代理，但这也无济于事。
那么我应该如何使用Java下载托管在我的Github帐户上的文件？
编辑：我试图使用apache commons-io，但我得到相同的效果，一个空/损坏的文件。
这个做的工作：
public class Download { private static boolean isRedirected( Map> 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(); } }
当您请求此文件时，看起来GitHub会为您提供多个重定向级别，而此StackOverflow文章指出URLConnection不会自动遵循更改协议的重定向。 以下是我所看到的curl：
第一次请求：
curl -v http://github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar * About to connect() to github.com port 80 (#0) * Trying 207.97.227.239... connected * Connected to github.com (207.97.227.239) port 80 (#0) > GET /downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar HTTP/1.1 > User-Agent: curl/7.21.4 (universal-apple-darwin11.0) libcurl/7.21.4 OpenSSL/0.9.8r zlib/1.2.5 > Host: github.com > Accept: */* > < HTTP/1.1 301 Moved Permanently < Server: nginx < Date: Sun, 18 Nov 2012 15:56:36 GMT < Content-Type: text/html < Content-Length: 178 < Connection: close < Location: https://github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar < 301 Moved Permanently 301 Moved Permanently
nginx * Closing connection #0
这个位置标题的curl：
curl -v https://github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar * About to connect() to github.com port 443 (#0) * Trying 207.97.227.239... connected * Connected to github.com (207.97.227.239) port 443 (#0) * SSLv3, TLS handshake, Client hello (1): * SSLv3, TLS handshake, Server hello (2): * SSLv3, TLS handshake, CERT (11): * SSLv3, TLS handshake, Server finished (14): * SSLv3, TLS handshake, Client key exchange (16): * SSLv3, TLS change cipher, Client hello (1): * SSLv3, TLS handshake, Finished (20): * SSLv3, TLS change cipher, Client hello (1): * SSLv3, TLS handshake, Finished (20): * SSL connection using RC4-SHA * Server certificate: * subject: businessCategory=Private Organization; 1.3.6.1.4.1.311.60.2.1.3=US; 1.3.6.1.4.1.311.60.2.1.2=California; serialNumber=C3268102; C=US; ST=California; L=San Francisco; O=GitHub, Inc.; CN=github.com * start date: 2011-05-27 00:00:00 GMT * expire date: 2013-07-29 12:00:00 GMT * subjectAltName: github.com matched * issuer: C=US; O=DigiCert Inc; OU=www.digicert.com; CN=DigiCert High Assurance EV CA-1 * SSL certificate verify ok. > GET /downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar HTTP/1.1 > User-Agent: curl/7.21.4 (universal-apple-darwin11.0) libcurl/7.21.4 OpenSSL/0.9.8r zlib/1.2.5 > Host: github.com > Accept: */* > < HTTP/1.1 302 Found < Server: nginx < Date: Sun, 18 Nov 2012 15:58:56 GMT < Content-Type: text/html; charset=utf-8 < Connection: keep-alive < Status: 302 Found < Strict-Transport-Security: max-age=2592000 < Cache-Control: no-cache < X-Runtime: 48 < Location: http://cloud.github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar < X-Frame-Options: deny < Content-Length: 149 < * Connection #0 to host github.com left intact * Closing connection #0 * SSLv3, TLS alert, Client hello (1): You are being redirected.
此响应中的位置标头返回实际文件。 您可能希望使用Apache HTTP Client下载它。 您可以将其设置为在GET期间遵循这些301和302重定向。
我找到了解决方案。
显然http://github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar没有直接链接到我的文件。
使用文本编辑器查看生成的jar时，我发现：
You are being redirected.
所以这意味着直接链接如下： http://cloud.github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar ： http://cloud.github.com/downloads/TheHolyWaffle/ChampionHelper/ChampionHelper-4.jar
通过此链接，我可以使用我的方法下载文件，没有任何问题。
我可以使它适用于有问题的链接模板
http://github.com/downloads/Nodeclipse/eclipse-node-ide/CoffeeScriptSet.p2f
不是这个
http://cloud.github.com/downloads/Nodeclipse/eclipse-node-ide/CoffeeScriptSet.p2f
但是以下是对我有用的
https://raw.github.com/Nodeclipse/eclipse-node-ide/master/EclipseNodeIDE-0.2.p2f
获取原始二进制文件的直接下载链接，例如https://github.com/xerial/sqlite-jdbc/blob/master/src/main/resources/org/sqlite/native/Windows/x86_64/sqlitejdbc.dll?raw =复制View Raw链接时为true ：
最后使用以下代码下载文件：
public static void download(String downloadURL) throws IOException { URL website = new URL(downloadURL); String fileName = getFileName(downloadURL); try (InputStream inputStream = website.openStream()) { Files.copy(inputStream, Paths.get(fileName), StandardCopyOption.REPLACE_EXISTING); } } public static String getFileName(String downloadURL) { String baseName = FilenameUtils.getBaseName(downloadURL); String extension = FilenameUtils.getExtension(downloadURL); String fileName = baseName + "." + extension; int questionMarkIndex = fileName.indexOf("?"); if (questionMarkIndex != -1) { fileName = fileName.substring(0, questionMarkIndex); } fileName = fileName.replaceAll("-", ""); return URLDecoder.decode(fileName, "UTF-8"); }
您还需要FilenameUtils类的Apache Commons IO maven依赖项：
commons-io commons-io LATEST