英文:
Corrupted APK when downloading in Java but browser download works fine
问题
我正在尝试从服务器下载一个APK文件。通过浏览器下载时，一切正常，文件大小为14MB。但是，当我使用Java下载时，下载的APK文件似乎损坏，因为其大小仅约为189KB。以下是我使用Apache Commons FileUtils进行下载的代码：
URL的格式类似于https://example.com/emm.apk。在浏览器中直接输入此URL可以正常下载APK文件。
URL url = new URL("https://example.com/emm.apk");
File file = new File(UUID.randomUUID().toString() + "-" + FilenameUtils.getName(fileUrl.getPath()));
FileUtils.copyURLToFile(url, file, 50_000, 50_000);
我还尝试了Java内置的文件IO：
URLConnection conn = url.openConnection();
int contentLength = conn.getContentLength();
DataInputStream stream = new DataInputStream(url.openStream());
byte[] buffer = new byte[contentLength];
stream.readFully(buffer);
stream.close();
DataOutputStream fos = new DataOutputStream(new FileOutputStream(file));
fos.write(buffer);
fos.flush();
fos.close();
我只在特定的URL上遇到了这个问题。我无法确定问题出在哪里，因为我无法访问主机服务器。显然，问题出在APK文件的主机方式上。主机APK文件的服务器是否需要特定的配置要求？我遇到了application/vnd.android.package-archive，主机服务器是否需要这个？为什么浏览器（Chrome）可以正常下载，而我的Java代码却不行？
英文:
I am trying to download an APK hosted in a server. When downloading via browser, it works fine. I get 14MB. But when downloading using Java, the APK seems corrupted since APK downloaded is just aroung 189kb. Below is my code when downloading using Apache Commons FileUtils:
URL format is similar to https://example.com/emm.apk. Entering this URL in a browser directly downloads the APK without problem.
URL url = new URL("https://example.com/emm.apk");
File file = new File(UUID.randomUUID().toString() +"-"+ FilenameUtils.getName(fileUrl.getPath()));
FileUtils.copyURLToFile(url, file, 50_000, 50_000);
I also tried Java's built in File IO:
URLConnection conn = url.openConnection();
int contentLength = conn.getContentLength();
DataInputStream stream = new DataInputStream(url.openStream());
byte[] buffer = new byte[contentLength];
stream.readFully(buffer);
stream.close();
DataOutputStream fos = new DataOutputStream(new FileOutputStream(file));
fos.write(buffer);
fos.flush();
fos.close();
I only get this problem for that particular URL. I cannot pinpoint what's wrong since I don't have access with the host server. Clearly the problem is with how the APK is hosted. Is there requirements on how servers hosting APK should be configured? I came across application/vnd.android.package-archive, is this required for host servers? Why does the browser (Chrome) downloads it without problem while my Java code does not?
答案1
得分: 1
似乎APK的主机服务器正在根据User-Agent请求头拦截请求，这就是为什么在浏览器下载时没问题，但在其他方式下载时会出问题。
我尝试手动设置URLConnection的User-Agent，这样下载就正常了。
URLConnection connection = fileUrl.openConnection();
connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36");
InputStream input = connection.getInputStream();
FileUtils.copyInputStreamToFile(input, file);
那个189kb的HTML文件显示请求被拒绝。
英文:
It seems that host server of the APK is blocking requests based on the User-Agent request header that's why browser download is okay but when downloading in different medium, it's not.
I tried manually setting the User-Agent of the URLConnection, and it's downloading properly.
URLConnection connection = fileUrl.openConnection();
connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36");
InputStream input = connection.getInputStream();
FileUtils.copyInputStreamToFile(input, file);
The 189kb is an HTML file saying the request was rejected.
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