Java常用工具类封装——String操作工具类
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项目中经常需要用到String的一些操作,结合看到的一些前人的工具类抽取,编写了如下针对String的常用操作的工具类,供大家参考。
/**
* @Copyright © 2017 Sun Info. Tech Ltd. All rights reserved.
*
* @Package: com.util.String
* @author: Hal Sun
* @date: 2017-09-03 10:54:13
*/
package com.util.String;
import java.util.ArrayList;
import java.util.List;
/**
* @ClassName: StringUtil
* @Description: TODO
* @author: Hal Sun
* @date: 2017-09-03 10:54:13
*/
public class StringUtil {
private static final int INDEX_NOT_FOUND = -1;
private static final String EMPTY = "";
/**
* <p>
* The maximum size to which the padding constant(s) can expand.
* </p>
*/
private static final int PAD_LIMIT = 8192;
/**
* 功能:将半角的符号转换成全角符号.(即英文字符转中文字符)
*
* @author jiangshuai
* @param str
* 源字符串
* @return String
* @date 2017年04月24日
*/
public static String changeToFull(String str) {
String source = "1234567890!@#$%^&*()abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_=+\\|[];:'\",<.>/?";
String[] decode = { "1", "2", "3", "4", "5", "6", "7", "8", "9", "0", "!", "@", "#", "$", "%", "︿", "&", "*",
"(", ")", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s",
"t", "u", "v", "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N",
"O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "-", "_", "=", "+", "\", "|", "【", "】", ";",
":", "'", "\"", ",", "〈", "。", "〉", "/", "?" };
String result = "";
for (int i = 0; i < str.length(); i++) {
int pos = source.indexOf(str.charAt(i));
if (pos != -1) {
result += decode[pos];
} else {
result += str.charAt(i);
}
}
return result;
}
/**
* <p>
* 进行tostring操作,如果传入的是null,返回空字符串。
* </p>
*
* <pre>
*
* ObjectUtils.toString(null) = ""
* ObjectUtils.toString("") = ""
* ObjectUtils.toString("bat") = "bat"
* ObjectUtils.toString(Boolean.TRUE) = "true"
* </pre>
*
* @param obj
* 源
* @return String
*/
public static String toString(Object obj) {
return obj == null ? "" : obj.toString();
}
/**
* <p>
* 进行tostring操作,如果传入的是null,返回指定的默认值。
* </p>
*
* <pre>
*
* ObjectUtils.toString(null, null) = null
* ObjectUtils.toString(null, "null") = "null"
* ObjectUtils.toString("", "null") = ""
* ObjectUtils.toString("bat", "null") = "bat"
* ObjectUtils.toString(Boolean.TRUE, "null") = "true"
* </pre>
*
* @param obj
* 源
* @param nullStr
* 如果obj为null时返回这个指定值
* @return String
*/
public static String toString(Object obj, String nullStr) {
return obj == null ? nullStr : obj.toString();
}
/**
* <p>
* 只从源字符串中移除指定开头子字符串.
* </p>
*
* <pre>
*
* StringUtil.removeStart(null, *) = null
* StringUtil.removeStart("", *) = ""
* StringUtil.removeStart(*, null) = *
* StringUtil.removeStart("www.domain.com", "www.") = "domain.com"
* StringUtil.removeStart("domain.com", "www.") = "domain.com"
* StringUtil.removeStart("www.domain.com", "domain") = "www.domain.com"
* StringUtil.removeStart("abc", "") = "abc"
* </pre>
*
* @param str
* 源字符串
* @param remove
* 将要被移除的子字符串
* @return String
*/
public static String removeStart(String str, String remove) {
if (isEmpty(str) || isEmpty(remove)) {
return str;
}
if (str.startsWith(remove)) {
return str.substring(remove.length());
}
return str;
}
/**
* <p>
* 只从源字符串中移除指定结尾的子字符串.
* </p>
*
* <pre>
*
* StringUtil.removeEnd(null, *) = null
* StringUtil.removeEnd("", *) = ""
* StringUtil.removeEnd(*, null) = *
* StringUtil.removeEnd("www.domain.com", ".com.") = "www.domain.com"
* StringUtil.removeEnd("www.domain.com", ".com") = "www.domain"
* StringUtil.removeEnd("www.domain.com", "domain") = "www.domain.com"
* StringUtil.removeEnd("abc", "") = "abc"
* </pre>
*
* @param str
* 源字符串
* @param remove
* 将要被移除的子字符串
* @return String
*/
public static String removeEnd(String str, String remove) {
if (isEmpty(str) || isEmpty(remove)) {
return str;
}
if (str.endsWith(remove)) {
return str.substring(0, str.length() - remove.length());
}
return str;
}
/**
* <p>
* 将一个字符串重复N次
* </p>
*
* <pre>
*
* StringUtil.repeat(null, 2) = null
* StringUtil.repeat("", 0) = ""
* StringUtil.repeat("", 2) = ""
* StringUtil.repeat("a", 3) = "aaa"
* StringUtil.repeat("ab", 2) = "abab"
* StringUtil.repeat("a", -2) = ""
* </pre>
*
* @param str
* 源字符串
* @param repeat
* 重复的次数
* @return String
*/
public static String repeat(String str, int repeat) {
// Performance tuned for 2.0 (JDK1.4)
if (str == null) {
return null;
}
if (repeat <= 0) {
return EMPTY;
}
int inputLength = str.length();
if (repeat == 1 || inputLength == 0) {
return str;
}
if (inputLength == 1 && repeat <= PAD_LIMIT) {
return repeat(str.charAt(0), repeat);
}
int outputLength = inputLength * repeat;
switch (inputLength) {
case 1:
return repeat(str.charAt(0), repeat);
case 2:
char ch0 = str.charAt(0);
char ch1 = str.charAt(1);
char[] output2 = new char[outputLength];
for (int i = repeat * 2 - 2; i >= 0; i--, i--) {
output2[i] = ch0;
output2[i + 1] = ch1;
}
return new String(output2);
default:
StringBuilder buf = new StringBuilder(outputLength);
for (int i = 0; i < repeat; i++) {
buf.append(str);
}
return buf.toString();
}
}
/**
* <p>
* 将一个字符串重复N次,并且中间加上指定的分隔符
* </p>
*
* <pre>
*
* StringUtil.repeat(null, null, 2) = null
* StringUtil.repeat(null, "x", 2) = null
* StringUtil.repeat("", null, 0) = ""
* StringUtil.repeat("", "", 2) = ""
* StringUtil.repeat("", "x", 3) = "xxx"
* StringUtil.repeat("?", ", ", 3) = "?, ?, ?"
* </pre>
*
* @param str
* 源字符串
* @param separator
* 分隔符
* @param repeat
* 重复次数
* @return String
*/
public static String repeat(String str, String separator, int repeat) {
if (str == null || separator == null) {
return repeat(str, repeat);
} else {
// given that repeat(String, int) is quite optimized, better to rely
// on it than try and splice this into it
String result = repeat(str + separator, repeat);
return removeEnd(result, separator);
}
}
/**
* <p>
* 将某个字符重复N次.
* </p>
*
* @param ch
* 某个字符
* @param repeat
* 重复次数
* @return String
*/
public static String repeat(char ch, int repeat) {
char[] buf = new char[repeat];
for (int i = repeat - 1; i >= 0; i--) {
buf[i] = ch;
}
return new String(buf);
}
/**
* <p>
* 字符串长度达不到指定长度时,在字符串右边补指定的字符.
* </p>
*
* <pre>
*
* StringUtil.rightPad(null, *, *) = null
* StringUtil.rightPad("", 3, 'z') = "zzz"
* StringUtil.rightPad("bat", 3, 'z') = "bat"
* StringUtil.rightPad("bat", 5, 'z') = "batzz"
* StringUtil.rightPad("bat", 1, 'z') = "bat"
* StringUtil.rightPad("bat", -1, 'z') = "bat"
* </pre>
*
* @param str
* 源字符串
* @param size
* 指定的长度
* @param padChar
* 进行补充的字符
* @return String
*/
public static String rightPad(String str, int size, char padChar) {
if (str == null) {
return null;
}
int pads = size - str.length();
if (pads <= 0) {
return str; // returns original String when possible
}
if (pads > PAD_LIMIT) {
return rightPad(str, size, String.valueOf(padChar));
}
return str.concat(repeat(padChar, pads));
}
/**
* <p>
* 扩大字符串长度,从左边补充指定字符
* </p>
*
* <pre>
*
* StringUtil.rightPad(null, *, *) = null
* StringUtil.rightPad("", 3, "z") = "zzz"
* StringUtil.rightPad("bat", 3, "yz") = "bat"
* StringUtil.rightPad("bat", 5, "yz") = "batyz"
* StringUtil.rightPad("bat", 8, "yz") = "batyzyzy"
* StringUtil.rightPad("bat", 1, "yz") = "bat"
* StringUtil.rightPad("bat", -1, "yz") = "bat"
* StringUtil.rightPad("bat", 5, null) = "bat "
* StringUtil.rightPad("bat", 5, "") = "bat "
* </pre>
*
* @param str
* 源字符串
* @param size
* 扩大后的长度
* @param padStr
* 在右边补充的字符串
* @return String
*/
public static String rightPad(String str, int size, String padStr) {
if (str == null) {
return null;
}
if (isEmpty(padStr)) {
padStr = " ";
}
int padLen = padStr.length();
int strLen = str.length();
int pads = size - strLen;
if (pads <= 0) {
return str; // returns original String when possible
}
if (padLen == 1 && pads <= PAD_LIMIT) {
return rightPad(str, size, padStr.charAt(0));
}
if (pads == padLen) {
return str.concat(padStr);
} else if (pads < padLen) {
return str.concat(padStr.substring(0, pads));
} else {
char[] padding = new char[pads];
char[] padChars = padStr.toCharArray();
for (int i = 0; i < pads; i++) {
padding[i] = padChars[i % padLen];
}
return str.concat(new String(padding));
}
}
/**
* <p>
* 检查字符串是否全部为小写.
* </p>
*
* <pre>
*
* StringUtil.isAllLowerCase(null) = false
* StringUtil.isAllLowerCase("") = false
* StringUtil.isAllLowerCase(" ") = false
* StringUtil.isAllLowerCase("abc") = true
* StringUtil.isAllLowerCase("abC") = false
* </pre>
*
* @param cs
* 源字符串
* @return String
*/
public static boolean isAllLowerCase(String cs) {
if (cs == null || isEmpty(cs)) {
return false;
}
int sz = cs.length();
for (int i = 0; i < sz; i++) {
if (Character.isLowerCase(cs.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* <p>
* 检查是否都是大写.
* </p>
*
* <pre>
*
* StringUtil.isAllUpperCase(null) = false
* StringUtil.isAllUpperCase("") = false
* StringUtil.isAllUpperCase(" ") = false
* StringUtil.isAllUpperCase("ABC") = true
* StringUtil.isAllUpperCase("aBC") = false
* </pre>
*
* @param cs
* 源字符串
* @return String
*/
public static boolean isAllUpperCase(String cs) {
if (cs == null || StringUtil.isEmpty(cs)) {
return false;
}
int sz = cs.length();
for (int i = 0; i < sz; i++) {
if (Character.isUpperCase(cs.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* <p>
* 反转字符串.
* </p>
*
* <pre>
*
* StringUtil.reverse(null) = null
* StringUtil.reverse("") = ""
* StringUtil.reverse("bat") = "tab"
* </pre>
*
* @param str
* 源字符串
* @return String
*/
public static String reverse(String str) {
if (str == null) {
return null;
}
return new StringBuilder(str).reverse().toString();
}
/**
* <p>
* 字符串达不到一定长度时在右边补空白.
* </p>
*
* <pre>
*
* StringUtil.rightPad(null, *) = null
* StringUtil.rightPad("", 3) = " "
* StringUtil.rightPad("bat", 3) = "bat"
* StringUtil.rightPad("bat", 5) = "bat "
* StringUtil.rightPad("bat", 1) = "bat"
* StringUtil.rightPad("bat", -1) = "bat"
* </pre>
*
* @param str
* 源字符串
* @param size
* 指定的长度
* @return String
*/
public static String rightPad(String str, int size) {
return rightPad(str, size, ' ');
}
/**
* <p>
* 截取一个字符串的前几个.
* </p>
*
* <pre>
*
* StringUtil.left(null, *) = null
* StringUtil.left(*, -ve) = ""
* StringUtil.left("", *) = ""
* StringUtil.left("abc", 0) = ""
* StringUtil.left("abc", 2) = "ab"
* StringUtil.left("abc", 4) = "abc"
* </pre>
*
* @param str
* 源字符串
* @param len
* 截取的长度
* @return the String
*/
public static String left(String str, int len) {
if (str == null) {
return null;
}
if (len < 0) {
return EMPTY;
}
if (str.length() <= len) {
return str;
}
return str.substring(0, len);
}
/**
* 功能:切换字符串中的所有字母大小写。<br/>
*
* <pre>
*
* StringUtil.swapCase(null) = null
* StringUtil.swapCase("") = ""
* StringUtil.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"
* </pre>
*
*
* @param str
* 源字符串
* @return String
*/
public static String swapCase(String str) {
if (StringUtil.isEmpty(str)) {
return str;
}
char[] buffer = str.toCharArray();
boolean whitespace = true;
for (int i = 0; i < buffer.length; i++) {
char ch = buffer[i];
if (Character.isUpperCase(ch)) {
buffer[i] = Character.toLowerCase(ch);
whitespace = false;
} else if (Character.isTitleCase(ch)) {
buffer[i] = Character.toLowerCase(ch);
whitespace = false;
} else if (Character.isLowerCase(ch)) {
if (whitespace) {
buffer[i] = Character.toTitleCase(ch);
whitespace = false;
} else {
buffer[i] = Character.toUpperCase(ch);
}
} else {
whitespace = Character.isWhitespace(ch);
}
}
return new String(buffer);
}
/**
*
* @Title: convertString
* @Description: 将首字母变成大写
* @param str
* @param beginUp
* @return String
* @throws
*/
private String convertString(String str, Boolean beginUp) {
char[] ch = str.toCharArray();
StringBuffer sbf = new StringBuffer();
for (int i = 0; i < ch.length; i++) {
if (i == 0 && beginUp) {// 如果首字母需大写
sbf.append(charToUpperCase(ch[i]));
} else {
sbf.append(charToLowerCase(ch[i]));
}
}
return sbf.toString();
}
/** 转大写 **/
private char charToUpperCase(char ch) {
if (ch <= 122 && ch >= 97) {
ch -= 32;
}
return ch;
}
/*** 转小写 **/
private char charToLowerCase(char ch) {
if (ch <= 90 && ch >= 65) {
ch += 32;
}
return ch;
}
/**
* 功能:检查这个字符串是不是空字符串。<br/>
* 如果这个字符串为null或者trim后为空字符串则返回true,否则返回false。
*
* @author Hal Sun
* @date 2017年04月24日
* @param chkStr
* 被检查的字符串
* @return boolean
*/
public static boolean isEmpty(String chkStr) {
if (chkStr == null) {
return true;
} else {
return "".equals(chkStr.trim()) ? true : false;
}
}
}
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