com.alibaba.nacos.api.utils.StringUtils Maven / Gradle / Ivy
/*
* Copyright 1999-2018 Alibaba Group Holding Ltd.
*
* 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.alibaba.nacos.api.utils;
/**
* StringUtils. copy from apache common-lang3.
*
* @author lin-mt
*/
public class StringUtils {
/**
* The empty String {@code ""}.
*
* @since 2.0
*/
public static final String EMPTY = "";
/**
* Checks if a CharSequence is empty ("") or null.
*
*
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = false
* StringUtils.isEmpty("bob") = false
* StringUtils.isEmpty(" bob ") = false
*
*
* NOTE: This method changed in Lang version 2.0.
* It no longer trims the CharSequence. That functionality is available in isBlank().
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is empty or null
* @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)
*/
public static boolean isEmpty(final CharSequence cs) {
return cs == null || cs.length() == 0;
}
/**
* Checks if a CharSequence is whitespace, empty ("") or null.
*
*
* StringUtils.isBlank(null) = true
* StringUtils.isBlank("") = true
* StringUtils.isBlank(" ") = true
* StringUtils.isBlank("bob") = false
* StringUtils.isBlank(" bob ") = false
*
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is null, empty or whitespace
* @since 2.0
* @since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)
*/
public static boolean isBlank(final CharSequence cs) {
final int strLen;
if (cs == null || (strLen = cs.length()) == 0) {
return true;
}
for (int i = 0; i < strLen; i++) {
if (!Character.isWhitespace(cs.charAt(i))) {
return false;
}
}
return true;
}
// Trim
//-----------------------------------------------------------------------
/**
* Removes control characters (char <= 32) from both
* ends of this String, handling {@code null} by returning {@code null}.
*
* The String is trimmed using {@link String#trim()}.
* Trim removes start and end characters <= 32.
*
*
* StringUtils.trim(null) = null
* StringUtils.trim("") = ""
* StringUtils.trim(" ") = ""
* StringUtils.trim("abc") = "abc"
* StringUtils.trim(" abc ") = "abc"
*
*
* @param str the String to be trimmed, may be null
* @return the trimmed string, {@code null} if null String input
*/
public static String trim(final String str) {
return str == null ? null : str.trim();
}
// Equals
//-----------------------------------------------------------------------
/**
* Compares two CharSequences, returning {@code true} if they represent
* equal sequences of characters.
*
* {@code null}s are handled without exceptions. Two {@code null}
* references are considered to be equal. The comparison is case sensitive.
*
*
* StringUtils.equals(null, null) = true
* StringUtils.equals(null, "abc") = false
* StringUtils.equals("abc", null) = false
* StringUtils.equals("abc", "abc") = true
* StringUtils.equals("abc", "ABC") = false
*
*
* @param cs1 the first CharSequence, may be {@code null}
* @param cs2 the second CharSequence, may be {@code null}
* @return {@code true} if the CharSequences are equal (case-sensitive), or both {@code null}
* @see Object#equals(Object)
* @since 3.0 Changed signature from equals(String, String) to equals(CharSequence, CharSequence)
*/
public static boolean equals(final CharSequence cs1, final CharSequence cs2) {
if (cs1 == cs2) {
return true;
}
if (cs1 == null || cs2 == null) {
return false;
}
if (cs1 instanceof String && cs2 instanceof String) {
return cs1.equals(cs2);
}
return StringUtils.regionMatches(cs1, false, 0, cs2, 0, Math.max(cs1.length(), cs2.length()));
}
/**
* Green implementation of regionMatches.
*
* @param cs the {@code CharSequence} to be processed
* @param ignoreCase whether or not to be case insensitive
* @param thisStart the index to start on the {@code cs} CharSequence
* @param substring the {@code CharSequence} to be looked for
* @param start the index to start on the {@code substring} CharSequence
* @param length character length of the region
* @return whether the region matched
*/
public static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, final int thisStart,
final CharSequence substring, final int start, final int length) {
if (cs instanceof String && substring instanceof String) {
return ((String) cs).regionMatches(ignoreCase, thisStart, (String) substring, start, length);
}
int index1 = thisStart;
int index2 = start;
int tmpLen = length;
while (tmpLen-- > 0) {
final char c1 = cs.charAt(index1++);
final char c2 = substring.charAt(index2++);
if (c1 == c2) {
continue;
}
if (!ignoreCase) {
return false;
}
// The same check as in String.regionMatches():
if (Character.toUpperCase(c1) != Character.toUpperCase(c2) && Character.toLowerCase(c1) != Character
.toLowerCase(c2)) {
return false;
}
}
return true;
}
}