studio.raptor.ddal.config.io.FileUtils Maven / Gradle / Ivy
/*
* 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.
*/
package studio.raptor.ddal.config.io;
import java.io.File;
import java.net.URL;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
class FileUtils {
/**
* The UTF-8 character set, used to decode octets in URLs.
*/
private static final Charset UTF8 = Charset.forName("UTF-8");
/**
* Convert from a URL to a File.
*
* From version 1.1 this method will decode the URL.
* Syntax such as file:///my%20docs/file.txt will be
* correctly decoded to /my docs/file.txt. Starting with version
* 1.5, this method uses UTF-8 to decode percent-encoded octets to characters.
* Additionally, malformed percent-encoded octets are handled leniently by
* passing them through literally.
*
* @param url the file URL to convert, {@code null} returns {@code null}
* @return the equivalent File object, or {@code null} if the URL's protocol is not
* file
*/
public static File toFile(final URL url) {
if (url == null || !"file".equalsIgnoreCase(url.getProtocol())) {
return null;
} else {
String filename = url.getFile().replace('/', File.separatorChar);
filename = decodeUrl(filename);
return new File(filename);
}
}
/**
* 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 {@code null}.
* @return The decoded URL or {@code null} if the input was {@code null}.
*/
static String decodeUrl(final String url) {
String decoded = url;
if (url != null && url.indexOf('%') >= 0) {
final int n = url.length();
final StringBuilder buffer = new StringBuilder();
final ByteBuffer bytes = ByteBuffer.allocate(n);
for (int i = 0; i < n; ) {
if (url.charAt(i) == '%') {
try {
do {
final 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 (final 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;
}
}