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/*
* Copyright 2013-2023 the original author or authors.
*
* 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
*
* https://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.cloud.nacos.utils;
/**
* StringUtils. copy from apache common-lang3.
*
* @author theonefx
*/
public final class StringUtils {
/**
* The empty String {@code ""}.
*
* @since 2.0
*/
public static final String EMPTY = "";
/**
* Represents a failed index search.
* @since 2.1
*/
public static final int INDEX_NOT_FOUND = -1;
private StringUtils() {
}
/**
*
* 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 not empty ("") and not null.
*
*
*
* StringUtils.isNotEmpty(null) = false
* StringUtils.isNotEmpty("") = false
* StringUtils.isNotEmpty(" ") = true
* StringUtils.isNotEmpty("bob") = true
* StringUtils.isNotEmpty(" bob ") = true
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is not empty and not null
* @since 3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)
*/
public static boolean isNotEmpty(final CharSequence cs) {
return !isEmpty(cs);
}
/**
*
* 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
*/
public static boolean isBlank(final CharSequence cs) {
if (cs == null || cs.length() == 0) {
return true;
}
int strLen = cs.length();
for (int i = 0; i < strLen; i++) {
if (!Character.isWhitespace(cs.charAt(i))) {
return false;
}
}
return true;
}
/**
*
* Checks if a CharSequence is not empty (""), not null and not whitespace only.
*
*
*
* Whitespace is defined by {@link Character#isWhitespace(char)}.
*
*
*
* StringUtils.isNotBlank(null) = false
* StringUtils.isNotBlank("") = false
* StringUtils.isNotBlank(" ") = false
* StringUtils.isNotBlank("bob") = true
* StringUtils.isNotBlank(" bob ") = true
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is not empty and not null and not
* whitespace only
* @since 2.0
* @since 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)
*/
public static boolean isNotBlank(final CharSequence cs) {
return !isBlank(cs);
}
// 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)
*/
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;
}
/**
*
* Gets the substring after the first occurrence of a separator. The separator is not
* returned.
*
*
*
* A null string input will return null. An empty ("")
* string input will return the empty string. A null separator will
* return the empty string if the input string is not null.
*
*
*
* If nothing is found, the empty string is returned.
*
*
*
* StringUtils.substringAfter(null, *) = null
* StringUtils.substringAfter("", *) = ""
* StringUtils.substringAfter(*, null) = ""
* StringUtils.substringAfter("abc", "a") = "bc"
* StringUtils.substringAfter("abcba", "b") = "cba"
* StringUtils.substringAfter("abc", "c") = ""
* StringUtils.substringAfter("abc", "d") = ""
* StringUtils.substringAfter("abc", "") = "abc"
*
* @param str the String to get a substring from, may be null
* @param separator the String to search for, may be null
* @return the substring after the first occurrence of the separator,
* null if null String input
* @since 2.0
*/
public static String substringAfter(String str, String separator) {
if (isEmpty(str)) {
return str;
}
if (separator == null) {
return EMPTY;
}
int pos = str.indexOf(separator);
if (pos == INDEX_NOT_FOUND) {
return EMPTY;
}
return str.substring(pos + separator.length());
}
// Substring between
// -----------------------------------------------------------------------
/**
*
* Gets the String that is nested in between two instances of the same String.
*
*
*
* A null input String returns null. A null tag
* returns null.
*
*
*
* StringUtils.substringBetween(null, *) = null
* StringUtils.substringBetween("", "") = ""
* StringUtils.substringBetween("", "tag") = null
* StringUtils.substringBetween("tagabctag", null) = null
* StringUtils.substringBetween("tagabctag", "") = ""
* StringUtils.substringBetween("tagabctag", "tag") = "abc"
*
* @param str the String containing the substring, may be null
* @param tag the String before and after the substring, may be null
* @return the substring, null if no match
* @since 2.0
*/
public static String substringBetween(String str, String tag) {
return substringBetween(str, tag, tag);
}
/**
*
* Gets the String that is nested in between two Strings. Only the first match is
* returned.
*
*
*
* A null input String returns null. A null
* open/close returns null (no match). An empty ("") open and close
* returns an empty string.
*
*
*
* StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
* StringUtils.substringBetween(null, *, *) = null
* StringUtils.substringBetween(*, null, *) = null
* StringUtils.substringBetween(*, *, null) = null
* StringUtils.substringBetween("", "", "") = ""
* StringUtils.substringBetween("", "", "]") = null
* StringUtils.substringBetween("", "[", "]") = null
* StringUtils.substringBetween("yabcz", "", "") = ""
* StringUtils.substringBetween("yabcz", "y", "z") = "abc"
* StringUtils.substringBetween("yabczyabcz", "y", "z") = "abc"
*
* @param str the String containing the substring, may be null
* @param open the String before the substring, may be null
* @param close the String after the substring, may be null
* @return the substring, null if no match
* @since 2.0
*/
public static String substringBetween(String str, String open, String close) {
if (str == null || open == null || close == null) {
return null;
}
int start = str.indexOf(open);
if (start != INDEX_NOT_FOUND) {
int end = str.indexOf(close, start + open.length());
if (end != INDEX_NOT_FOUND) {
return str.substring(start + open.length(), end);
}
}
return null;
}
}
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