org.javacc.mojo.UrlUtils Maven / Gradle / Ivy
package org.javacc.mojo;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
/**
* Assists in handling of URLs.
*
* @author Benjamin Bentmann
* @version $Id$
*/
class UrlUtils
{
/**
* The UTF-8 character set, used to decode octets in URLs.
*/
private static final Charset UTF8 = Charset.forName( "UTF-8" );
/**
* The protocol prefix for "jar:" URLs.
*/
private static final String JAR = "jar:";
/**
* The protocol prefix for "file:" URLs.
*/
private static final String FILE = "file:";
/**
* The protocol prefix for "jar:file:" URLs.
*/
private static final String JAR_FILE = JAR + FILE;
/**
* Gets the absolute filesystem path to the class path root for the specified resource. The root is either a JAR
* file or a directory with loose class files. If the URL does not use a supported protocol, an exception will be
* thrown.
*
* @param url The URL to the resource, may be null.
* @param resource The name of the resource, must not be null.
* @return The absolute filesystem path to the class path root of the resource or null if the input
* URL was null.
*/
public static File getResourceRoot( URL url, String resource )
{
String path = null;
if ( url != null )
{
String spec = url.toExternalForm();
if ( ( JAR_FILE ).regionMatches( true, 0, spec, 0, JAR_FILE.length() ) )
{
URL jar;
try
{
jar = new URL( spec.substring( JAR.length(), spec.lastIndexOf( "!/" ) ) );
}
catch ( MalformedURLException e )
{
throw new IllegalArgumentException( "Invalid JAR URL: " + url + ", " + e.getMessage() );
}
path = decodeUrl( jar.getPath() );
}
else if ( FILE.regionMatches( true, 0, spec, 0, FILE.length() ) )
{
path = decodeUrl( url.getPath() );
path = path.substring( 0, path.length() - resource.length() );
}
else
{
throw new IllegalArgumentException( "Invalid class path URL: " + url );
}
}
return ( path != null ) ? new File( path ) : null;
}
/**
* Decodes the specified URL as per RFC 3986, i.e. transforms percent-encoded octets to characters by decoding with
* the UTF-8 character set. This function is primarily intended for usage with {@link java.net.URL} which
* unfortunately does not enforce proper URLs. As such, this method will leniently accept invalid characters or
* malformed percent-encoded octets and simply pass them literally through to the result string. Except for rare
* edge cases, this will make unencoded URLs pass through unaltered.
*
* @param url The URL to decode, may be null.
* @return The decoded URL or null if the input was null.
*/
public static String decodeUrl( String url )
{
String decoded = url;
if ( url != null && url.indexOf( '%' ) >= 0 )
{
int n = url.length();
StringBuffer buffer = new StringBuffer();
ByteBuffer bytes = ByteBuffer.allocate( n );
for ( int i = 0; i < n; )
{
if ( url.charAt( i ) == '%' )
{
try
{
do
{
byte octet = (byte) Integer.parseInt( url.substring( i + 1, i + 3 ), 16 );
bytes.put( octet );
i += 3;
}
while ( i < n && url.charAt( i ) == '%' );
continue;
}
catch ( RuntimeException e )
{
// malformed percent-encoded octet, fall through and append characters literally
}
finally
{
if ( bytes.position() > 0 )
{
bytes.flip();
buffer.append( UTF8.decode( bytes ).toString() );
bytes.clear();
}
}
}
buffer.append( url.charAt( i++ ) );
}
decoded = buffer.toString();
}
return decoded;
}
}