Java tutorial
/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright (c) 1997-2017 Oracle and/or its affiliates. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can * obtain a copy of the License at * https://oss.oracle.com/licenses/CDDL+GPL-1.1 * or LICENSE.txt. See the License for the specific * language governing permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at LICENSE.txt. * * GPL Classpath Exception: * Oracle designates this particular file as subject to the "Classpath" * exception as provided by Oracle in the GPL Version 2 section of the License * file that accompanied this code. * * Modifications: * If applicable, add the following below the License Header, with the fields * enclosed by brackets [] replaced by your own identifying information: * "Portions Copyright [year] [name of copyright owner]" * * Contributor(s): * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. */ package javax.activation; import java.util.Hashtable; import java.util.Enumeration; import java.util.Locale; /** * A parameter list of a MimeType * as defined in RFC 2045 and 2046. The Primary type of the * object must already be stripped off. * * @see javax.activation.MimeType */ public class MimeTypeParameterList { private Hashtable parameters; /** * A string that holds all the special chars. */ private static final String TSPECIALS = "()<>@,;:/[]?=\\\""; /** * Default constructor. */ public MimeTypeParameterList() { parameters = new Hashtable(); } /** * Constructs a new MimeTypeParameterList with the passed in data. * * @param parameterList an RFC 2045, 2046 compliant parameter list. * @exception MimeTypeParseException if the MIME type can't be parsed */ public MimeTypeParameterList(String parameterList) throws MimeTypeParseException { parameters = new Hashtable(); // now parse rawdata parse(parameterList); } /** * A routine for parsing the parameter list out of a String. * * @param parameterList an RFC 2045, 2046 compliant parameter list. * @exception MimeTypeParseException if the MIME type can't be parsed */ protected void parse(String parameterList) throws MimeTypeParseException { if (parameterList == null) return; int length = parameterList.length(); if (length <= 0) return; int i; char c; for (i = skipWhiteSpace(parameterList, 0); i < length && (c = parameterList.charAt(i)) == ';'; i = skipWhiteSpace(parameterList, i)) { int lastIndex; String name; String value; // eat the ';' i++; // now parse the parameter name // skip whitespace i = skipWhiteSpace(parameterList, i); // tolerate trailing semicolon, even though it violates the spec if (i >= length) return; // find the end of the token char run lastIndex = i; while ((i < length) && isTokenChar(parameterList.charAt(i))) i++; name = parameterList.substring(lastIndex, i).toLowerCase(Locale.ENGLISH); // now parse the '=' that separates the name from the value i = skipWhiteSpace(parameterList, i); if (i >= length || parameterList.charAt(i) != '=') throw new MimeTypeParseException( "Couldn't find the '=' that separates a " + "parameter name from its value."); // eat it and parse the parameter value i++; i = skipWhiteSpace(parameterList, i); if (i >= length) throw new MimeTypeParseException("Couldn't find a value for parameter named " + name); // now find out whether or not we have a quoted value c = parameterList.charAt(i); if (c == '"') { // yup it's quoted so eat it and capture the quoted string i++; if (i >= length) throw new MimeTypeParseException("Encountered unterminated quoted parameter value."); lastIndex = i; // find the next unescaped quote while (i < length) { c = parameterList.charAt(i); if (c == '"') break; if (c == '\\') { // found an escape sequence // so skip this and the // next character i++; } i++; } if (c != '"') throw new MimeTypeParseException("Encountered unterminated quoted parameter value."); value = unquote(parameterList.substring(lastIndex, i)); // eat the quote i++; } else if (isTokenChar(c)) { // nope it's an ordinary token so it // ends with a non-token char lastIndex = i; while (i < length && isTokenChar(parameterList.charAt(i))) i++; value = parameterList.substring(lastIndex, i); } else { // it ain't a value throw new MimeTypeParseException("Unexpected character encountered at index " + i); } // now put the data into the hashtable parameters.put(name, value); } if (i < length) { throw new MimeTypeParseException("More characters encountered in input than expected."); } } /** * Return the number of name-value pairs in this list. * * @return the number of parameters */ public int size() { return parameters.size(); } /** * Determine whether or not this list is empty. * * @return true if there are no parameters */ public boolean isEmpty() { return parameters.isEmpty(); } /** * Retrieve the value associated with the given name, or null if there * is no current association. * * @param name the parameter name * @return the parameter's value */ public String get(String name) { return (String) parameters.get(name.trim().toLowerCase(Locale.ENGLISH)); } /** * Set the value to be associated with the given name, replacing * any previous association. * * @param name the parameter name * @param value the parameter's value */ public void set(String name, String value) { parameters.put(name.trim().toLowerCase(Locale.ENGLISH), value); } /** * Remove any value associated with the given name. * * @param name the parameter name */ public void remove(String name) { parameters.remove(name.trim().toLowerCase(Locale.ENGLISH)); } /** * Retrieve an enumeration of all the names in this list. * * @return an enumeration of all parameter names */ public Enumeration getNames() { return parameters.keys(); } /** * Return a string representation of this object. */ public String toString() { StringBuffer buffer = new StringBuffer(); buffer.ensureCapacity(parameters.size() * 16); // heuristic: 8 characters per field Enumeration keys = parameters.keys(); while (keys.hasMoreElements()) { String key = (String) keys.nextElement(); buffer.append("; "); buffer.append(key); buffer.append('='); buffer.append(quote((String) parameters.get(key))); } return buffer.toString(); } // below here be scary parsing related things /** * Determine whether or not a given character belongs to a legal token. */ private static boolean isTokenChar(char c) { return ((c > 040) && (c < 0177)) && (TSPECIALS.indexOf(c) < 0); } /** * return the index of the first non white space character in * rawdata at or after index i. */ private static int skipWhiteSpace(String rawdata, int i) { int length = rawdata.length(); while ((i < length) && Character.isWhitespace(rawdata.charAt(i))) i++; return i; } /** * A routine that knows how and when to quote and escape the given value. */ private static String quote(String value) { boolean needsQuotes = false; // check to see if we actually have to quote this thing int length = value.length(); for (int i = 0; (i < length) && !needsQuotes; i++) { needsQuotes = !isTokenChar(value.charAt(i)); } if (needsQuotes) { StringBuffer buffer = new StringBuffer(); buffer.ensureCapacity((int) (length * 1.5)); // add the initial quote buffer.append('"'); // add the properly escaped text for (int i = 0; i < length; ++i) { char c = value.charAt(i); if ((c == '\\') || (c == '"')) buffer.append('\\'); buffer.append(c); } // add the closing quote buffer.append('"'); return buffer.toString(); } else { return value; } } /** * A routine that knows how to strip the quotes and * escape sequences from the given value. */ private static String unquote(String value) { int valueLength = value.length(); StringBuffer buffer = new StringBuffer(); buffer.ensureCapacity(valueLength); boolean escaped = false; for (int i = 0; i < valueLength; ++i) { char currentChar = value.charAt(i); if (!escaped && (currentChar != '\\')) { buffer.append(currentChar); } else if (escaped) { buffer.append(currentChar); escaped = false; } else { escaped = true; } } return buffer.toString(); } }