package com.moral.andbrickslib.compresshelper;
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/**
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*
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* 字符串相关工具类
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*
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* Author: nanchen
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* Email: liushilin520@foxmail.com
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* Date: 2017-02-19 9:52
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*/
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public class StringUtils {
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private StringUtils() {
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throw new UnsupportedOperationException("u can't instantiate me...");
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}
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/**
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* 判断字符串是否为null或长度为0
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*
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* @param s 待校验字符串
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* @return {@code true}: 空<br> {@code false}: 不为空
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*/
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public static boolean isEmpty(CharSequence s) {
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return s == null || s.length() == 0;
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}
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/**
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* 判断字符串是否为null或全为空格
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*
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* @param s 待校验字符串
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* @return {@code true}: null或全空格<br> {@code false}: 不为null且不全空格
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*/
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public static boolean isSpace(String s) {
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return (s == null || s.trim().length() == 0);
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}
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/**
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* 判断两字符串是否相等
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*
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* @param a 待校验字符串a
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* @param b 待校验字符串b
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* @return {@code true}: 相等<br>{@code false}: 不相等
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*/
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public static boolean equals(CharSequence a, CharSequence b) {
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if (a == b) return true;
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int length;
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if (a != null && b != null && (length = a.length()) == b.length()) {
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if (a instanceof String && b instanceof String) {
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return a.equals(b);
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} else {
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for (int i = 0; i < length; i++) {
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if (a.charAt(i) != b.charAt(i)) return false;
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}
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return true;
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}
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}
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return false;
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}
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/**
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* 判断两字符串忽略大小写是否相等
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*
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* @param a 待校验字符串a
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* @param b 待校验字符串b
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* @return {@code true}: 相等<br>{@code false}: 不相等
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*/
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public static boolean equalsIgnoreCase(String a, String b) {
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return (a == b) || (b != null) && (a.length() == b.length()) && a.regionMatches(true, 0, b, 0, b.length());
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}
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/**
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* null转为长度为0的字符串
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*
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* @param s 待转字符串
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* @return s为null转为长度为0字符串，否则不改变
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*/
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public static String null2Length0(String s) {
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return s == null ? "" : s;
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}
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/**
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* 返回字符串长度
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*
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* @param s 字符串
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* @return null返回0，其他返回自身长度
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*/
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public static int length(CharSequence s) {
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return s == null ? 0 : s.length();
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}
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/**
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* 首字母大写
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*
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* @param s 待转字符串
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* @return 首字母大写字符串
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*/
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public static String upperFirstLetter(String s) {
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if (isEmpty(s) || !Character.isLowerCase(s.charAt(0))) return s;
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return String.valueOf((char) (s.charAt(0) - 32)) + s.substring(1);
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}
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/**
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* 首字母小写
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*
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* @param s 待转字符串
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* @return 首字母小写字符串
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*/
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public static String lowerFirstLetter(String s) {
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if (isEmpty(s) || !Character.isUpperCase(s.charAt(0))) return s;
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return String.valueOf((char) (s.charAt(0) + 32)) + s.substring(1);
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}
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/**
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* 反转字符串
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*
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* @param s 待反转字符串
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* @return 反转字符串
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*/
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public static String reverse(String s) {
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int len = length(s);
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if (len <= 1) return s;
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int mid = len >> 1;
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char[] chars = s.toCharArray();
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char c;
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for (int i = 0; i < mid; ++i) {
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c = chars[i];
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chars[i] = chars[len - i - 1];
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chars[len - i - 1] = c;
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}
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return new String(chars);
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}
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/**
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* 转化为半角字符
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*
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* @param s 待转字符串
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* @return 半角字符串
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*/
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public static String toDBC(String s) {
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if (isEmpty(s)) return s;
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char[] chars = s.toCharArray();
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for (int i = 0, len = chars.length; i < len; i++) {
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if (chars[i] == 12288) {
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chars[i] = ' ';
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} else if (65281 <= chars[i] && chars[i] <= 65374) {
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chars[i] = (char) (chars[i] - 65248);
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} else {
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chars[i] = chars[i];
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}
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}
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return new String(chars);
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}
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/**
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* 转化为全角字符
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*
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* @param s 待转字符串
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* @return 全角字符串
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*/
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public static String toSBC(String s) {
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if (isEmpty(s)) return s;
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char[] chars = s.toCharArray();
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for (int i = 0, len = chars.length; i < len; i++) {
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if (chars[i] == ' ') {
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chars[i] = (char) 12288;
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} else if (33 <= chars[i] && chars[i] <= 126) {
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chars[i] = (char) (chars[i] + 65248);
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} else {
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chars[i] = chars[i];
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}
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}
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return new String(chars);
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}
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}
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