jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/util/TextUtil.java

//
//  ========================================================================
//  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.websocket.common.util;

/**
 * Collection of utility methods for Text content
 */
public final class TextUtil
{
    /**
     * Create a hint of what the text is like.
     * <p>
     * Used by logging and error messages to get a hint of what the text is like.
     * 
     * @param text
     *            the text to abbreviate, quote, and generally give you a hint of what the value is.
     * @return the abbreviated text
     */
    public static String hint(String text)
    {
        if (text == null)
        {
            return "<null>";
        }
        return '"' + maxStringLength(30,text) + '"';
    }

    /**
     * Smash a long string to fit within the max string length, by taking the middle section of the string and replacing them with an ellipsis "..."
     * 
     * <pre>
     * Examples:
     * .maxStringLength( 9, "Eatagramovabits") == "Eat...its"
     * .maxStringLength(10, "Eatagramovabits") == "Eat...bits"
     * .maxStringLength(11, "Eatagramovabits") == "Eata...bits"
     * </pre>
     * 
     * @param max
     *            the maximum size of the string (minimum size supported is 9)
     * @param raw
     *            the raw string to smash
     * @return the ellipsis'd version of the string.
     */
    public static String maxStringLength(int max, String raw)
    {
        int length = raw.length();
        if (length <= max)
        {
            // already short enough
            return raw;
        }

        if (max < 9)
        {
            // minimum supported
            return raw.substring(0,max);
        }

        StringBuilder ret = new StringBuilder();
        int startLen = (int)Math.round((double)max / (double)3);
        ret.append(raw.substring(0,startLen));
        ret.append("...");
        ret.append(raw.substring(length - (max - startLen - 3)));

        return ret.toString();
    }
}