/*
 * (C) 2007-2012 Alibaba Group Holding Limited.
 * 
 * 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.taobao.gecko.core.util;

public class StringUtils {
    /**
     * ¼ì²é×Ö·û´®ÊÇ·ñÎª<code>null</code>»ò¿Õ×Ö·û´®<code>""</code>¡£
     * 
     * <pre>
     * StringUtil.isEmpty(null)      = true
     * StringUtil.isEmpty("")        = true
     * StringUtil.isEmpty(" ")       = false
     * StringUtil.isEmpty("bob")     = false
     * StringUtil.isEmpty("  bob  ") = false
     * </pre>
     * 
     * @param str
     *            Òª¼ì²éµÄ×Ö·û´®
     * 
     * @return Èç¹ûÎª¿Õ, Ôò·µ»Ø<code>true</code>
     */
    public static boolean isEmpty(final String str) {
        return str == null || str.length() == 0;
    }


    /**
     * ¼ì²é×Ö·û´®ÊÇ·ñÊÇ¿Õ°×£º<code>null</code>¡¢¿Õ×Ö·û´®<code>""</code>»òÖ»ÓÐ¿Õ°××Ö·û¡£
     * 
     * <pre>
     * StringUtil.isBlank(null)      = true
     * StringUtil.isBlank("")        = true
     * StringUtil.isBlank(" ")       = true
     * StringUtil.isBlank("bob")     = false
     * StringUtil.isBlank("  bob  ") = false
     * </pre>
     * 
     * @param str
     *            Òª¼ì²éµÄ×Ö·û´®
     * 
     * @return Èç¹ûÎª¿Õ°×, Ôò·µ»Ø<code>true</code>
     */
    public static boolean isBlank(final String str) {
        int length;

        if (str == null || (length = str.length()) == 0) {
            return true;
        }

        for (int i = 0; i < length; i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return false;
            }
        }

        return true;
    }
}