stringescapeutils.java

来自「JAVA 文章管理系统源码」· Java 代码 · 共 553 行 · 第 1/2 页

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.commons.lang;

import java.io.IOException;
import java.io.Writer;

import org.apache.commons.lang.exception.NestableRuntimeException;

/**
 * <p>Escapes and unescapes <code>String</code>s for
 * Java, Java Script, HTML, XML, and SQL.</p>
 *
 * @author Apache Jakarta Turbine
 * @author GenerationJavaCore library
 * @author Purple Technology
 * @author <a href="mailto:[e-mail]">Henri Yandell</a>
 * @author <a href="mailto:[e-mail]">Alexander Day Chaffee</a>
 * @author <a href="mailto:[e-mail]">Antony Riley</a>
 * @author Helge Tesgaard
 * @author <a href="[e-mail]">Sean Brown</a>
 * @author <a href="mailto:[e-mail]">Gary Gregory</a>
 * @author Phil Steitz
 * @author Pete Gieser
 * @since 2.0
 * @version $Id: StringEscapeUtils.java,v 1.25 2003/08/18 02:22:23 bayard Exp $
 */
public class StringEscapeUtils {

    /**
     * <p><code>StringEscapeUtils</code> instances should NOT be constructed in
     * standard programming.</p>
     *
     * <p>Instead, the class should be used as:
     * <pre>StringEscapeUtils.escapeJava("foo");</pre></p>
     *
     * <p>This constructor is public to permit tools that require a JavaBean
     * instance to operate.</p>
     */
    public StringEscapeUtils() {
    }

    // Java and JavaScript
    //--------------------------------------------------------------------------
    /**
     * <p>Escapes the characters in a <code>String</code> using Java String rules.</p>
     *
     * <p>Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.) </p>
     *
     * <p>So a tab becomes the characters <code>'\\'</code> and
     * <code>'t'</code>.</p>
     *
     * <p>The only difference between Java strings and JavaScript strings
     * is that in JavaScript, a single quote must be escaped.</p>
     *
     * <p>Example:
     * <pre>
     * input string: He didn't say, "Stop!"
     * output string: He didn't say, \"Stop!\"
     * </pre>
     * </p>
     *
     * @param str  String to escape values in, may be null
     * @return String with escaped values, <code>null</code> if null string input
     */
    public static String escapeJava(String str) {
        return escapeJavaStyleString(str, false);
    }

    /**
     * <p>Escapes the characters in a <code>String</code> using Java String rules to
     * a <code>Writer</code>.</p>
     * 
     * <p>A <code>null</code> string input has no effect.</p>
     * 
     * @see #escapeJava(java.lang.String)
     * @param out  Writer to write escaped string into
     * @param str  String to escape values in, may be null
     * @throws IllegalArgumentException if the Writer is <code>null</code>
     * @throws IOException if error occurs on undelying Writer
     */
    public static void escapeJava(Writer out, String str) throws IOException {
        escapeJavaStyleString(out, str, false);
    }

    /**
     * <p>Escapes the characters in a <code>String</code> using JavaScript String rules.</p>
     * <p>Escapes any values it finds into their JavaScript String form.
     * Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.) </p>
     *
     * <p>So a tab becomes the characters <code>'\\'</code> and
     * <code>'t'</code>.</p>
     *
     * <p>The only difference between Java strings and JavaScript strings
     * is that in JavaScript, a single quote must be escaped.</p>
     *
     * <p>Example:
     * <pre>
     * input string: He didn't say, "Stop!"
     * output string: He didn\'t say, \"Stop!\"
     * </pre>
     * </p>
     *
     * @param str  String to escape values in, may be null
     * @return String with escaped values, <code>null</code> if null string input
     */
    public static String escapeJavaScript(String str) {
        return escapeJavaStyleString(str, true);
    }

    /**
     * <p>Escapes the characters in a <code>String</code> using JavaScript String rules
     * to a <code>Writer</code>.</p>
     * 
     * <p>A <code>null</code> string input has no effect.</p>
     * 
     * @see #escapeJavaScript(java.lang.String)
     * @param out  Writer to write escaped string into
     * @param str  String to escape values in, may be null
     * @throws IllegalArgumentException if the Writer is <code>null</code>
     * @throws IOException if error occurs on undelying Writer
     **/
    public static void escapeJavaScript(Writer out, String str) throws IOException {
        escapeJavaStyleString(out, str, true);
    }

    private static String escapeJavaStyleString(String str, boolean escapeSingleQuotes) {
        if (str == null) {
            return null;
        }
        try {
            StringPrintWriter writer = new StringPrintWriter(str.length() * 2);
            escapeJavaStyleString(writer, str, escapeSingleQuotes);
            return writer.getString();
        } catch (IOException ioe) {
            // this should never ever happen while writing to a StringWriter
            ioe.printStackTrace();
            return null;
        }
    }

    private static void escapeJavaStyleString(Writer out, String str, boolean escapeSingleQuote) throws IOException {
        if (out == null) {
            throw new IllegalArgumentException("The Writer must not be null");
        }
        if (str == null) {
            return;
        }
        int sz;
        sz = str.length();
        for (int i = 0; i < sz; i++) {
            char ch = str.charAt(i);

            // handle unicode
            if (ch > 0xfff) {
                out.write("\\u" + hex(ch));
            } else if (ch > 0xff) {
                out.write("\\u0" + hex(ch));
            } else if (ch > 0x7f) {
                out.write("\\u00" + hex(ch));
            } else if (ch < 32) {
                switch (ch) {
                    case '\b':
                        out.write('\\');
                        out.write('b');
                        break;
                    case '\n':
                        out.write('\\');
                        out.write('n');
                        break;
                    case '\t':
                        out.write('\\');
                        out.write('t');
                        break;
                    case '\f':
                        out.write('\\');
                        out.write('f');
                        break;
                    case '\r':
                        out.write('\\');
                        out.write('r');
                        break;
                    default :
                        if (ch > 0xf) {
                            out.write("\\u00" + hex(ch));
                        } else {
                            out.write("\\u000" + hex(ch));
                        }
                        break;
                }
            } else {
                switch (ch) {
                    case '\'':
                        if (escapeSingleQuote) out.write('\\');
                        out.write('\'');
                        break;
                    case '"':
                        out.write('\\');
                        out.write('"');
                        break;
                    case '\\':
                        out.write('\\');
                        out.write('\\');
                        break;
                    default :
                        out.write(ch);
                        break;
                }
            }
        }
    }

    /**
     * <p>Returns an upper case hexadecimal <code>String</code> for the given
     * character.</p>
     * 
     * @param ch The character to convert.
     * @return An upper case hexadecimal <code>String</code>
     */
    private static String hex(char ch) {
        return Integer.toHexString(ch).toUpperCase();
    }

    /**
     * <p>Unescapes any Java literals found in the <code>String</code>.
     * For example, it will turn a sequence of <code>'\'</code> and