CODEWITHSUNDEEP
javaurluriinputstream
M314
M314

Reputation: 955

find protocol corresponding to URI in Java

I have URI object in Java. I want to convert it to InputStream, but the conversion should depend on the protocol. I can make it this way if my URI is http://somepath.com/mysuperfile.xsl:

return myURI.toURL().openConnection().getInputStream();

or this way if my uri is file:///somepath/mysuperfile.xsl:

return new FileInputStream(Paths.get(myURI).toFile());

or maybe even some another way. I can try to check it manually, but do Java have some nice/proper way to check it, maybe using that new java.nio.* package?

Upvotes: 14

Views: 15309

Answers (3)

user719662
user719662

Reputation:

Every URI is defined as consisting of four parts, as follows:

[scheme name] : [hierarchical part] [[ ? query ]] [[ # fragment ]]

If the thing you want is the scheme name (which roughly translates to protocol), just use

switch ( myURI.getScheme() ) {
  case "http":
    return myURI.toURL().openConnection().getInputStream();
  case "ftp":
    // do something   
  case "file":
    return new FileInputStream( Paths.get(myURI).toFile() );
}

http://docs.oracle.com/javase/6/docs/api/java/net/URI.html#getScheme%28%29

or, if you just want to generate an InputStream without differentiating the scheme, simply use

return myURI.toURL().openStream();

or

return myURI.toURL().openConnection().getInputStream();

(as you already did for HTTP protocol/scheme)

Upvotes: 23

Asaph
Asaph

Reputation: 162801

No need to special case file URIs. The same code works for either case. I just tested it with the following little scratch program:

URIReadTest.java

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

public class URIReadTest {
    public static void main(String[] args) throws Exception {
        URI uri = new URI("file:///tmp/test.txt");
        InputStream in = uri.toURL().openConnection().getInputStream();
        // or, more concisely:
        // InputStream in = uri.toURL().openStream();
        int b;
        while((b = in.read()) != -1) {
            System.out.print((char) b);
        }
        in.close();
    }
}

Make a /tmp/test.txt on your system and you'll see the contents of it printed out when you compile and run the above code.

Upvotes: 1

Daan Luttik
Daan Luttik

Reputation: 2855

you can check the characters at the start of the string with the startsWith(String prefix) function, it is www. or http:// use the first method otherwise use the second method.

Upvotes: -1

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