org.apache.tomcat.util.buf.CharsetHolder 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 org.apache.tomcat.util.buf;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
/**
* Represents a character encoding to be used for a request or response.
*
* Historically the Servlet API has used Strings for this information with lazy conversion to Charset. Sometimes the API
* required that an invalid name triggered an exception. Sometimes the invalid name was treated as if it had never been
* set. This resulted in classes storing both the String and, if the name was valid, the Charset with validation and
* conversion logic spread throughout those classes.
*
* This class is an attempt to encapsulate that behaviour.
*/
public class CharsetHolder {
public static final CharsetHolder EMPTY = new CharsetHolder(null, null);
public static CharsetHolder getInstance(String name) {
if (name == null) {
return EMPTY;
}
Charset charset;
try {
charset = B2CConverter.getCharset(name);
} catch (UnsupportedEncodingException e) {
charset = null;
}
return new CharsetHolder(name, charset);
}
public static CharsetHolder getInstance(Charset encoding) {
if (encoding == null) {
return EMPTY;
}
return new CharsetHolder(encoding.name(), encoding);
}
private final String name;
private final Charset charset;
private CharsetHolder(String name, Charset charset) {
this.name = name;
this.charset = charset;
}
public String getName() {
return name;
}
/**
* Returns the Charset, {@code null} if no Charset has been specified, or {@code null} if the holder was created
* using the name of a Charset that the JRE does not recognise.
*
* @return The Charset or {@code null} it is not set or invalid
*/
public Charset getCharset() {
return charset;
}
/**
* Returns the Charset or {@code null} if no Charset has been specified.
*
* @return The validated Charset or {@code null} if is not set
*
* @throws UnsupportedEncodingException if the holder was created using the name of a Charset that the JRE does not
* recognise
*/
public Charset getValidatedCharset() throws UnsupportedEncodingException {
validate();
return charset;
}
/**
* Throws an exception if the instance holds a name that without a matching Charset.
*
* @throws UnsupportedEncodingException if the holder contains a name without a matching Charset
*/
public void validate() throws UnsupportedEncodingException {
if (name != null && charset == null) {
throw new UnsupportedEncodingException(name);
}
}
}