Java URI 方案不是“文件”
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URI scheme is not "file"
提问by Ankur
I get the exception: "URI scheme is not file"
我收到异常：“URI 方案不是文件”
What I am doing is trying to get the name of a file and then save that file (from another server) onto my computer/server from within a servlet.
我正在做的是尝试获取文件的名称，然后从 servlet 中将该文件（从另一台服务器）保存到我的计算机/服务器上。
I have a String called "url", from thereon here is my code:
我有一个名为“url”的字符串，从这里开始是我的代码：
url = Streams.asString(stream); //gets the URL from a form on a webpage
System.out.println("This is the URL: "+url);
URI fileUri = new URI(url);
File fileFromUri = new File(fileUri);
onlyFile = fileFromUri.getName();
URL fileUrl = new URL(url);
InputStream imageStream = fileUrl.openStream();
String fileLoc2 = getServletContext().getRealPath("pics/"+onlyFile);
File newFolder = new File(getServletContext().getRealPath("pics"));
if(!newFolder.exists()){
newFolder.mkdir();
}
IOUtils.copy(imageStream, new FileOutputStream("pics/"+onlyFile));
}
The line causing the error is this one:
导致错误的行是这样的：
File fileFromUri = new File(fileUri);
I have added the rest of the code so you can see what I am trying to do.
我已经添加了其余的代码，所以你可以看到我想要做什么。
采纳答案by David Gelhar
The URI "scheme" is the thing that comes before the ":", for example "http" in "http://stackoverflow.com".
URI“scheme”是“:”之前的内容，例如“http://stackoverflow.com”中的“ http”。
The error message is telling you that new File(fileUri)works only on "file:" URI's (ones referring to a pathname on the current system), not other schemes like "http".
错误消息告诉您new File(fileUri)仅适用于“文件：”URI（指当前系统上的路径名），而不适用于“http”等其他方案。
Basically, the "file:" URI is another way of specifying a pathname to the Fileclass. It is not a magic way of telling Fileto use http to fetch a file from the web.
基本上，“file:”URI 是指定File类路径名的另一种方式。这不是告诉File使用 http 从网络获取文件的神奇方式。
回答by Leni Kirilov
Your assumption to create Filefrom URLis wrong here.
你的假设，建立File由URL是错在这里。
You just don't need to create a Filefrom URL to the file in the Internet, so that you get the file name.
你只是不需要创建一个File从 URL 到 Internet 中的文件，这样你就可以得到文件名。
You can simply do this with parsing the URL like that:
你可以简单地通过解析 URL 来做到这一点：
URL fileUri = new URL("http://local.wasp.uwa.edu.au/~pbourke/miscellaneous/domefisheye/ladybug/fish4.jpg");
int startIndex = fileUri.toString().lastIndexOf('/');
String fileName = fileUri.toString().substring(startIndex + 1);
System.out.println(fileName);
