Java Json Encode jsonEncode(final String val)

Description

Encode a json string according to the statement:

In JSON only the backslash, double quote and ASCII control characters need to be escaped.

License

Apache License

Parameter

Parameter	Description
val	a parameter

Return

encoded String

Declaration

public static String jsonEncode(final String val) 

Method Source Code

//package com.java2s;
/* ********************************************************************
Licensed to Jasig under one or more contributor license
agreements. See the NOTICE file distributed with this work
for additional information regarding copyright ownership.
Jasig 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://from  www  .  j  a  v  a 2 s  .  co  m
    
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.
*/

public class Main {
    /** Encode a json string according to the statement:
     * <p>In JSON only the backslash, double quote and ASCII control characters
     * need to be escaped. Forward slashes may be escaped
     *
     * <p>I assume we also need to do the whitespace characters
     *
     * @param val
     * @return encoded String
     */
    public static String jsonEncode(final String val) {
        if ((val == null) || (val.length() == 0)) {
            return "\"\"";
        }

        StringBuilder sb = new StringBuilder();

        /* \n    newline
         * \t   tab
         * \b   backspace
         * \f   form feed
         * \r   return
         * \"   "   (double quote)
         * \\   \    (back slash)
         */

        sb.append('"');

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

            switch (ch) {
            case '\n':
                sb.append("\\n");
                break;

            case '\t':
                sb.append("\\t");
                break;

            case '\b':
                sb.append("\\b");
                break;

            case '\f':
                sb.append("\\f");
                break;

            case '\r':
                sb.append("\\r");
                break;

            case '"':
            case '/':
            case '\\':
                sb.append('\\');
                sb.append(ch);
                break;

            case ' ':
                sb.append(" ");
                break;

            default:
                if (Character.isISOControl(ch)) {
                    String str = Integer.toHexString(ch);
                    sb.append("\\u");
                    sb.append("0000".substring(str.length() - 4));
                    sb.append(str);
                } else {
                    sb.append(ch);
                }
            }
        }

        sb.append('"');
        return sb.toString();
    }
}

Related

1. jsonEncodeString(String text)