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package com.ctc.wstx.util;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.IOException;
import java.net.URL;
import java.net.MalformedURLException;
import com.ctc.wstx.compat.JdkFeatures;
public final class URLUtil
{
private URLUtil() { }
/**
* Method that tries to figure out how to create valid URL from a system
* id, without additional contextual information.
* If we could use URIs this might be easier to do, but they are part
* of JDK 1.4, and preferably code should only require 1.2 (or maybe 1.3)
*/
public static URL urlFromSystemId(String sysId)
throws IOException
{
try {
/* Ok, does it look like a full URL? For one, you need a colon. Also,
* to reduce likelihood of collision with Windows paths, let's only
* accept it if there are 3 preceding other chars...
* Not sure if Mac might be a problem? (it uses ':' as file path
* separator, alas, at least prior to MacOS X)
*/
int ix = sysId.indexOf(':', 0);
/* Also, protocols are generally fairly short, usually 3 or 4
* chars (http, ftp, urn); so let's put upper limit of 8 chars too
*/
if (ix >= 3 && ix <= 8) {
return new URL(sysId);
}
// Ok, let's just assume it's local file reference...
/* 24-May-2006, TSa: Amazingly, this single call does show in
* profiling, for small docs. The problem is that deep down it
* tries to check physical file system, to check if the File
* pointed to is a directory: and that is (relatively speaking)
* a very expensive call. Since in this particular case it
* should never be a dir (and/or doesn't matter), let's just
* implement conversion locally
*/
String absPath = new java.io.File(sysId).getAbsolutePath();
// Need to convert colons/backslashes to regular slashes?
{
char sep = File.separatorChar;
if (sep != '/') {
absPath = absPath.replace(sep, '/');
}
}
if (absPath.length() > 0 && absPath.charAt(0) != '/') {
absPath = "/" + absPath;
}
return new URL("file", "", absPath);
} catch (MalformedURLException e) {
throwIOException(e, sysId);
return null; // never gets here
}
}
public static URL urlFromSystemId(String sysId, URL ctxt)
throws IOException
{
if (ctxt == null) {
return urlFromSystemId(sysId);
}
try {
return new URL(ctxt, sysId);
} catch (MalformedURLException e) {
throwIOException(e, sysId);
return null; // never gets here
}
}
/**
* Method that tries to create and return URL that denotes current
* working directory. Usually used to create a context, when one is
* not explicitly passed.
*/
public static URL urlFromCurrentDir()
throws java.net.MalformedURLException /* an IOException */
{
/* This seems to work; independent of whether there happens to
* be such/file dir or not.
*/
return new File("a").getAbsoluteFile().getParentFile().toURL();
}
/**
* Method that tries to get optimal stream to read from the specified
* URL. Currently it just means creating a simple file stream if the
* URL points to a (local) file.
*/
public static InputStream optimizedStreamFromURL(URL url)
throws IOException
{
if ("file".equals(url.getProtocol())) {
/* As per [WSTX-82], can not do this if the path refers
* to a network drive on windows. This fixes the problem;
* might not be needed on all platforms (NFS?), but should not
* matter a lot: performance penalty of extra wrapping is more
* relevant when accessing local file system.
*/
if (url.getHost() == null) {
return new FileInputStream(url.getPath());
}
}
return url.openStream();
}
/*
///////////////////////////////////////////
// Private helper methods
///////////////////////////////////////////
*/
/**
* Helper method that tries to fully convert strange URL-specific exception
* to more general IO exception. Also, to try to use JDK 1.4 feature without
* creating requirement, uses reflection to try to set the root cause, if
* we are running on JDK1.4
*/
private static void throwIOException(MalformedURLException mex, String sysId)
throws IOException
{
IOException ie = new IOException("[resolving systemId '"+sysId
+"']: "+mex.toString());
JdkFeatures.getInstance().setInitCause(ie, mex);
throw ie;
}
}
