StringUtils.java

/*
 * Copyright 2017 NAVER Corp.
 *
 * 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.navercorp.pinpoint.common.util;


import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.StringTokenizer;

public class StringUtils {

    private static final int DEFAULT_ABBREVIATE_MAX_WIDTH = 64;

    private static final String NULL_STRING = "null";

    public StringUtils() {
        throw new AssertionError();
    }

    public static String defaultString(final String str, final String defaultStr) {
        return str == null ? defaultStr : str;
    }

    public static boolean isEmpty(final String string) {
        return string == null || string.isEmpty();
    }

    public static boolean isNotEmpty(final String string) {
        return string != null && string.length() > 0;
    }

    public static String toString(final Object object) {
        if (object == null) {
            return NULL_STRING;
        }
        return object.toString();
    }


    public static String abbreviate(final String str) {
        return abbreviate(str, DEFAULT_ABBREVIATE_MAX_WIDTH);
    }


    public static String abbreviate(final String str, final int maxWidth) {
        if (str == null) {
            return NULL_STRING;
        }
        if (maxWidth < 0) {
            throw new IllegalArgumentException("negative maxWidth:" + maxWidth);
        }
        if (str.length() > maxWidth) {
            StringBuilder buffer = new StringBuilder(maxWidth + 10);
            buffer.append(str, 0, maxWidth);
            appendAbbreviateMessage(buffer, str.length());
            return buffer.toString();
        } else {
            return str;
        }
    }

    public static void appendAbbreviate(final StringBuilder builder, final String str, final int maxWidth) {
        if (str == null) {
            return;
        }
        if (maxWidth < 0) {
            return;
        }
        if (str.length() > maxWidth) {
            builder.append(str, 0, maxWidth);
            appendAbbreviateMessage(builder, str.length());
        } else {
            builder.append(str);
        }
    }

    private static void appendAbbreviateMessage(final StringBuilder buffer, final int strLength) {
        buffer.append("...(");
        buffer.append(strLength);
        buffer.append(')');
    }


    /**
     * Copy Spring Framework StringUtils
     *
     * <p>Tokenize the given String into a String array via a StringTokenizer.
     * Trims tokens and omits empty tokens.
     * <p>The given delimiters string is supposed to consist of any number of
     * delimiter characters. Each of those characters can be used to separate
     * tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using {@code delimitedListToStringArray}
     * @param str the String to tokenize
     * @param delimiters the delimiter characters, assembled as String
     * (each of those characters is individually considered as delimiter).
     * @return List of the tokens
     * @see java.util.StringTokenizer
     * @see String#trim()
     */
    public static List<String> tokenizeToStringList(final String str, final String delimiters) {
        return tokenizeToStringList(str, delimiters, true, true);
    }


    /**
     * Spring Framework StringUtils
     *
     * <p>Tokenize the given String into a String array via a StringTokenizer.
     * Trims tokens and omits empty tokens.
     * <p>The given delimiters string is supposed to consist of any number of
     * delimiter characters. Each of those characters can be used to separate
     * tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using {@code delimitedListToStringArray}
     * @param str the String to tokenize
     * @param delimiters the delimiter characters, assembled as String
     * (each of those characters is individually considered as delimiter).
     * @return List of the tokens
     * @see java.util.StringTokenizer
     * @see String#trim()
     */
    public static List<String> tokenizeToStringList(final String str, final String delimiters, final boolean trimTokens, final boolean ignoreEmptyTokens) {

        if (isEmpty(str)) {
            return Collections.emptyList();
        }
        StringTokenizer st = new StringTokenizer(str, delimiters);
        List<String> tokens = new ArrayList<String>();
        while (st.hasMoreTokens()) {
            String token = st.nextToken();
            if (trimTokens) {
                token = token.trim();
            }
            if (!ignoreEmptyTokens || token.length() > 0) {
                tokens.add(token);
            }
        }
        return tokens;
    }
}