UrlEscapers.java
/*
* Copyright (C) 2009 The Guava Authors
*
* Licensed 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 com.google.common.net;
import com.google.common.annotations.GwtCompatible;
import com.google.common.escape.Escaper;
/**
* {@code Escaper} instances suitable for strings to be included in particular sections of URLs.
*
* <p>If the resulting URLs are inserted into an HTML or XML document, they will require additional
* escaping with {@link com.google.common.html.HtmlEscapers} or {@link
* com.google.common.xml.XmlEscapers}.
*
* @author David Beaumont
* @author Chris Povirk
* @since 15.0
*/
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class UrlEscapers {
private UrlEscapers() {}
// For each xxxEscaper() method, please add links to external reference pages
// that are considered authoritative for the behavior of that escaper.
static final String URL_FORM_PARAMETER_OTHER_SAFE_CHARS = "-_.*";
static final String URL_PATH_OTHER_SAFE_CHARS_LACKING_PLUS =
"-._~" // Unreserved characters.
+ "!$'()*,;&=" // The subdelim characters (excluding '+').
+ "@:"; // The gendelim characters permitted in paths.
/**
* Returns an {@link Escaper} instance that escapes strings so they can be safely included in <a
* href="https://goo.gl/MplK6I">URL form parameter names and values</a>. Escaping is performed
* with the UTF-8 character encoding. The caller is responsible for <a
* href="https://goo.gl/9EfkM1">replacing any unpaired carriage return or line feed characters
* with a CR+LF pair</a> on any non-file inputs before escaping them with this escaper.
*
* <p>When escaping a String, the following rules apply:
*
* <ul>
* <li>The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain
* the same.
* <li>The special characters ".", "-", "*", and "_" remain the same.
* <li>The space character " " is converted into a plus sign "+".
* <li>All other characters are converted into one or more bytes using UTF-8 encoding and each
* byte is then represented by the 3-character string "%XY", where "XY" is the two-digit,
* uppercase, hexadecimal representation of the byte value.
* </ul>
*
* <p>This escaper is suitable for escaping parameter names and values even when <a
* href="https://goo.gl/utn6M">using the non-standard semicolon</a>, rather than the ampersand, as
* a parameter delimiter. Nevertheless, we recommend using the ampersand unless you must
* interoperate with systems that require semicolons.
*
* <p><b>Note:</b> Unlike other escapers, URL escapers produce <a
* href="https://url.spec.whatwg.org/#percent-encode">uppercase</a> hexadecimal sequences.
*
*/
public static Escaper urlFormParameterEscaper() {
return URL_FORM_PARAMETER_ESCAPER;
}
private static final Escaper URL_FORM_PARAMETER_ESCAPER =
new PercentEscaper(URL_FORM_PARAMETER_OTHER_SAFE_CHARS, true);
/**
* Returns an {@link Escaper} instance that escapes strings so they can be safely included in <a
* href="https://goo.gl/m2MIf0">URL path segments</a>. The returned escaper escapes all non-ASCII
* characters, even though <a href="https://goo.gl/e7E0In">many of these are accepted in modern
* URLs</a>. (<a href="https://goo.gl/jfVxXW">If the escaper were to leave these characters
* unescaped, they would be escaped by the consumer at parse time, anyway.</a>) Additionally, the
* escaper escapes the slash character ("/"). While slashes are acceptable in URL paths, they are
* considered by the specification to be separators between "path segments." This implies that, if
* you wish for your path to contain slashes, you must escape each segment separately and then
* join them.
*
* <p>When escaping a String, the following rules apply:
*
* <ul>
* <li>The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain
* the same.
* <li>The unreserved characters ".", "-", "~", and "_" remain the same.
* <li>The general delimiters "@" and ":" remain the same.
* <li>The subdelimiters "!", "$", "&", "'", "(", ")", "*", "+", ",", ";", and "=" remain
* the same.
* <li>The space character " " is converted into %20.
* <li>All other characters are converted into one or more bytes using UTF-8 encoding and each
* byte is then represented by the 3-character string "%XY", where "XY" is the two-digit,
* uppercase, hexadecimal representation of the byte value.
* </ul>
*
* <p><b>Note:</b> Unlike other escapers, URL escapers produce <a
* href="https://url.spec.whatwg.org/#percent-encode">uppercase</a> hexadecimal sequences.
*/
public static Escaper urlPathSegmentEscaper() {
return URL_PATH_SEGMENT_ESCAPER;
}
private static final Escaper URL_PATH_SEGMENT_ESCAPER =
new PercentEscaper(URL_PATH_OTHER_SAFE_CHARS_LACKING_PLUS + "+", false);
/**
* Returns an {@link Escaper} instance that escapes strings so they can be safely included in a <a
* href="https://goo.gl/xXEq4p">URL fragment</a>. The returned escaper escapes all non-ASCII
* characters, even though <a href="https://goo.gl/e7E0In">many of these are accepted in modern
* URLs</a>.
*
* <p>When escaping a String, the following rules apply:
*
* <ul>
* <li>The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain
* the same.
* <li>The unreserved characters ".", "-", "~", and "_" remain the same.
* <li>The general delimiters "@" and ":" remain the same.
* <li>The subdelimiters "!", "$", "&", "'", "(", ")", "*", "+", ",", ";", and "=" remain
* the same.
* <li>The space character " " is converted into %20.
* <li>Fragments allow unescaped "/" and "?", so they remain the same.
* <li>All other characters are converted into one or more bytes using UTF-8 encoding and each
* byte is then represented by the 3-character string "%XY", where "XY" is the two-digit,
* uppercase, hexadecimal representation of the byte value.
* </ul>
*
* <p><b>Note:</b> Unlike other escapers, URL escapers produce <a
* href="https://url.spec.whatwg.org/#percent-encode">uppercase</a> hexadecimal sequences.
*/
public static Escaper urlFragmentEscaper() {
return URL_FRAGMENT_ESCAPER;
}
private static final Escaper URL_FRAGMENT_ESCAPER =
new PercentEscaper(URL_PATH_OTHER_SAFE_CHARS_LACKING_PLUS + "+/?", false);
}