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package com.penglecode.common.util;
/**
* 字符串工具类
*
* @author pengpeng
* @date 2014年7月19日 上午9:48:56
* @version 1.0
*/
public class StringUtils {
public static final String DEFAULT_EMPTY_STRING = "";
public static final String DEFAULT_NULL_STRING = "null";
/**
* 判断字符串是否为空值(null, "", " ", "null")
*
*
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = true
* StringUtils.isEmpty("null") = true
*
*
* @param str
* @return
*/
public static boolean isEmpty(String str) {
return str == null || DEFAULT_EMPTY_STRING.equals(str.trim()) || DEFAULT_NULL_STRING.equals(str.trim());
}
/**
* 判断字符串是否有长度(不为null或"")
*
*
* StringUtils.hasLength(null) = false
* StringUtils.hasLength("") = false
* StringUtils.hasLength(" ") = true
* StringUtils.hasLength(" abc ") = true
*
*
* @param str
* @return
*/
public static boolean hasLength(String str) {
return str == null ? false : str.length() > 0;
}
/**
* Null-safe 调用String.trim()方法
*
*
* StringUtils.trim(null) = null
* StringUtils.trim("") = ""
* StringUtils.trim(" ") = ""
* StringUtils.trim("abc") = "abc"
* StringUtils.trim(" abc ") = "abc"
*
*
* @param str
* @return
*/
public static String trim(String str) {
return str == null ? null : str.trim();
}
/**
* Null-safe 调用String.trim()方法
*
*
* StringUtils.trim(null) = null
* StringUtils.trim("") = ""
* StringUtils.trim(" ") = ""
* StringUtils.trim(" abc ") = "abc"
* StringUtils.trim(" a b c ") = "abc"
*
*
* @param str
* @return
*/
public static String trimAll(String str) {
return str == null ? null : str.trim().replace(" ", "");
}
/**
* 对字符串trim操作,当字符串为空值(null、""、" "、"null")时转换为null
*
*
* StringUtils.trimToNull(null) = null
* StringUtils.trimToNull("") = null
* StringUtils.trimToNull("null") = null
* StringUtils.trimToNull(" ") = null
* StringUtils.trimToNull("abc") = "abc"
* StringUtils.trimToNull(" abc ") = "abc"
*
*
* @param str
* @return
*/
public static String trimToNull(String str) {
String ts = trim(str);
return isEmpty(ts) ? null : ts;
}
/**
* 对字符串trim操作,当字符串为空值(null、""、" "、"null")时转换为""
*
*
* StringUtils.trimToEmpty(null) = ""
* StringUtils.trimToEmpty("") = ""
* StringUtils.trimToEmpty("null") = ""
* StringUtils.trimToEmpty(" ") = ""
* StringUtils.trimToEmpty("abc") = "abc"
* StringUtils.trimToEmpty(" abc ") = "abc"
*
*
* @param str
* @return
*/
public static String trimToEmpty(String str) {
return str == null ? DEFAULT_EMPTY_STRING : str.trim();
}
/**
* 如果字符串为null则将其转换为""
*
*
* StringUtils.defaultIfNull(null) = ""
* StringUtils.defaultIfNull("") = ""
* StringUtils.defaultIfNull(" ") = " "
* StringUtils.defaultIfNull("abc") = "abc"
*
*
* @param str
* @return
*/
public static String defaultIfNull(String str) {
return defaultIfNull(str, DEFAULT_EMPTY_STRING);
}
/**
* 如果字符串为null则将其转换为defaultValue
*
*
* StringUtils.defaultIfNull(null, "abc") = "abc"
* StringUtils.defaultIfNull("", "abc") = ""
* StringUtils.defaultIfNull(" ", "abc") = " "
* StringUtils.defaultIfNull("abc", "abc") = "abc"
*
*
* @param str
* @param defaultValue
* @return
*/
public static String defaultIfNull(String str, String defaultValue) {
return str == null ? defaultValue : str;
}
/**
* 如果字符串为null则将其转换为""
*
*
* StringUtils.defaultIfEmpty(null) = ""
* StringUtils.defaultIfEmpty("") = ""
* StringUtils.defaultIfEmpty(" ") = " "
* StringUtils.defaultIfEmpty("abc") = "abc"
*
*
* @param str
* @return
*/
public static String defaultIfEmpty(String str) {
return defaultIfEmpty(str, DEFAULT_EMPTY_STRING);
}
/**
* 如果字符串为空值(null、""、" ")则将其转换为defaultValue
*
*
* StringUtils.defaultIfEmpty(null, "abc") = "abc"
* StringUtils.defaultIfEmpty("", "abc") = "abc"
* StringUtils.defaultIfEmpty("null", "abc") = "abc"
* StringUtils.defaultIfEmpty(" ", "abc") = "abc"
* StringUtils.defaultIfEmpty("abc", "abc") = "abc"
*
*
* @param str
* @param defaultValue
* @return
*/
public static String defaultIfEmpty(String str, String defaultValue) {
return isEmpty(str) ? defaultValue : str;
}
/**
* 判断两个字符串是否相同
*
*
* 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 str1
* @param str2
* @return
*/
public static boolean equals(String str1, String str2) {
return str1 == null ? str2 == null : str1.equals(str2);
}
/**
* 判断两个字符串不区分大小写比较是否相同
*
*
* StringUtils.equals(null, null) = true
* StringUtils.equals(null, "abc") = false
* StringUtils.equals("abc", null) = false
* StringUtils.equals("abc", "abc") = true
* StringUtils.equals("abc", "ABC") = true
*
*
* @param str1
* @param str2
* @return
*/
public static boolean equalsIgnoreCase(String str1, String str2) {
return str1 == null ? str2 == null : str1.equalsIgnoreCase(str2);
}
/**
* 判断两个字符串trim之后比较是否相同
*
*
* StringUtils.trimEquals(null, null) = true
* StringUtils.trimEquals("", " ") = true
* StringUtils.trimEquals(null, "abc") = false
* StringUtils.trimEquals("abc", null) = false
* StringUtils.trimEquals(" abc ", "abc") = true
* StringUtils.trimEquals("abc", "ABC") = false
*
*
* @param str1
* @param str2
* @return
*/
public static boolean trimEquals(String str1, String str2) {
if(str1 == null || str2 == null){
return str1 == str2;
}
return str1.trim().equals(str2.trim());
}
/**
* 判断两个字符串trim之后不区分大小写比较是否相同
*
*
* StringUtils.trimEquals(null, null) = true
* StringUtils.trimEquals("", " ") = true
* StringUtils.trimEquals(null, "abc") = false
* StringUtils.trimEquals("abc", null) = false
* StringUtils.trimEquals(" abc ", "abc") = true
* StringUtils.trimEquals("abc", "ABC") = true
*
*
* @param str1
* @param str2
* @return
*/
public static boolean trimEqualsIgnoreCase(String str1, String str2) {
if(str1 == null || str2 == null){
return str1 == str2;
}
return str1.trim().equalsIgnoreCase(str2.trim());
}
/**
* 分别从目标字符串中的两端剔除需要剔除的字符串stripChars
*
*
* StringUtils.strip(null, *) = null
* StringUtils.strip("", *) = ""
* StringUtils.strip("abc", null) = "abc"
* StringUtils.strip(" abc", null) = "abc"
* StringUtils.strip("abc ", null) = "abc"
* StringUtils.strip(" abc ", null) = "abc"
* StringUtils.strip(" abcyx", "xyz") = " abc"
*
*
* @param str
* @param stripChars
* @return
*/
public static String strip(String str, String stripChars) {
str = stripStart(str, stripChars);
return stripEnd(str, stripChars);
}
/**
* 从目标字符串中的起始端开始剔除需要剔除的字符串stripChars
*
*
* StringUtils.stripStart(null, *) = null
* StringUtils.stripStart("", *) = ""
* StringUtils.stripStart("abc", "") = "abc"
* StringUtils.stripStart("abc", null) = "abc"
* StringUtils.stripStart(" abc", null) = "abc"
* StringUtils.stripStart("abc ", null) = "abc "
* StringUtils.stripStart(" abc ", null) = "abc "
* StringUtils.stripStart("yxabc ", "xyz") = "abc "
*
*
* @param str
* @param stripChars
* @return
*/
public static String stripStart(String str, String stripChars) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return str;
}
int start = 0;
if (stripChars == null) {
while (start != strLen && Character.isWhitespace(str.charAt(start))) {
start++;
}
} else if (stripChars.length() == 0) {
return str;
} else {
while (start != strLen && stripChars.indexOf(str.charAt(start)) != -1) {
start++;
}
}
return str.substring(start);
}
/**
* 从目标字符串中的末端开始剔除需要剔除的字符串stripChars
*
*
* StringUtils.stripEnd(null, *) = null
* StringUtils.stripEnd("", *) = ""
* StringUtils.stripEnd("abc", "") = "abc"
* StringUtils.stripEnd("abc", null) = "abc"
* StringUtils.stripEnd(" abc", null) = " abc"
* StringUtils.stripEnd("abc ", null) = "abc"
* StringUtils.stripEnd(" abc ", null) = " abc"
* StringUtils.stripEnd(" abcyx", "xyz") = " abc"
* StringUtils.stripEnd("120.00", ".0") = "12"
*
*
* @param str
* @param stripChars
* @return
*/
public static String stripEnd(String str, String stripChars) {
int end;
if (str == null || (end = str.length()) == 0) {
return str;
}
if (stripChars == null) {
while (end != 0 && Character.isWhitespace(str.charAt(end - 1))) {
end--;
}
} else if (stripChars.length() == 0) {
return str;
} else {
while (end != 0 && stripChars.indexOf(str.charAt(end - 1)) != -1) {
end--;
}
}
return str.substring(0, end);
}
/**
* 在目标字符串targetStr左边补充字符appendChar,使得目标字符串的总长度达到length
* (注：targetStr为null时返回null)
*
* @param targetStr
* @param appendChar
* @param length
* @return
*/
public static String leftPad(String targetStr, char appendChar, int length) {
if (targetStr == null) {
return null;
}
int len = targetStr.length();
while (len++ < length) {
targetStr = appendChar + targetStr;
}
return targetStr;
}
/**
* 在目标字符串targetStr右边补充字符appendChar,使得目标字符串的总长度达到length
* (注：targetStr为null时返回null)
*
* @param targetStr
* @param appendChar
* @param length
* @return
*/
public static String rightPad(String targetStr, char appendChar, int length) {
if (targetStr == null) {
return null;
}
int len = targetStr.length();
while (len++ < length) {
targetStr += appendChar;
}
return targetStr;
}
/**
* 判断字符串是否全是由字母组成
*
*
* StringUtils.isAlpha(null) = false
* StringUtils.isAlpha("") = false
* StringUtils.isAlpha(" ") = false
* StringUtils.isAlpha("abc") = true
* StringUtils.isAlpha("ab2c") = false
* StringUtils.isAlpha("ab-c") = false
*
*
* @param str
* @return
*/
public static boolean isAlpha(String str) {
if (str == null || str.length() == 0) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if (Character.isLetter(str.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* 判断字符是否由字母或者数字[a-zA-Z0-9]组成
*
* @param str
* @return
*/
public static boolean isAlphanumeric(String str) {
if (str == null || str.length() == 0) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if (Character.isLetterOrDigit(str.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* 判断字符串是否全由数字组成[0-9]
*
* @param str
* @return
*/
public static boolean isNumeric(String str) {
if (str == null || str.length() == 0) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if (Character.isDigit(str.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* 反序返回字符串
*
*
* StringUtils.reverse(null) = null
* StringUtils.reverse("") = ""
* StringUtils.reverse("bat") = "tab"
*
*
* @param str
* @return
*/
public static String reverse(String str) {
if (str == null) {
return null;
}
return new StringBuilder(str).reverse().toString();
}
}