Escapes the characters in a String using JavaScript String rules. - Java Scripting

Java examples for Scripting:Javascript

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Description

Escapes the characters in a String using JavaScript String rules.

Demo Code

/*//from  w ww .  j a  va 2s  .  co m
 * Copyright 2005 Joe Walker
 *
 * 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.java2s;

import java.util.Locale;

public class Main {
    /**
     * <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, &quot;Stop!&quot;
     * output string: He didn\'t say, \&quot;Stop!\&quot;
     * </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) {
        if (str == null) {
            return null;
        }

        StringBuffer writer = new StringBuffer(str.length() * 2);

        int sz = str.length();
        for (int i = 0; i < sz; i++) {
            char ch = str.charAt(i);

            // handle unicode
            if (ch > 0xfff) {
                writer.append("\\u");
                writer.append(hex(ch));
            } else if (ch > 0xff) {
                writer.append("\\u0");
                writer.append(hex(ch));
            } else if (ch > 0x7f) {
                writer.append("\\u00");
                writer.append(hex(ch));
            } else if (ch < 32) {
                switch (ch) {
                case '\b':
                    writer.append('\\');
                    writer.append('b');
                    break;
                case '\n':
                    writer.append('\\');
                    writer.append('n');
                    break;
                case '\t':
                    writer.append('\\');
                    writer.append('t');
                    break;
                case '\f':
                    writer.append('\\');
                    writer.append('f');
                    break;
                case '\r':
                    writer.append('\\');
                    writer.append('r');
                    break;
                default:
                    if (ch > 0xf) {
                        writer.append("\\u00");
                        writer.append(hex(ch));
                    } else {
                        writer.append("\\u000");
                        writer.append(hex(ch));
                    }
                    break;
                }
            } else {
                switch (ch) {
                case '\'':
                    // If we wanted to escape for Java strings then we would
                    // not need this next line.
                    writer.append('\\');
                    writer.append('\'');
                    break;
                case '"':
                    writer.append('\\');
                    writer.append('"');
                    break;
                case '\\':
                    writer.append('\\');
                    writer.append('\\');
                    break;
                default:
                    writer.append(ch);
                    break;
                }
            }
        }

        return writer.toString();
    }

    /**
     * <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(Locale.ENGLISH);
    }
}

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