StringUtil.java

package com.wisedu.scc.love.utils;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * String Utils
 */
public class StringUtil {

	/**
	 * is null or its length is 0 or it is made by space
	 */
	public static boolean isBlank(String str) {
		return (str == null || str.trim().length() == 0);
	}

	/**
	 * is null or its length is 0
	 */
	public static boolean isEmpty(String str) {
		return (str == null || str.length() == 0);
	}

	/**
	 * compare two string
	 */
	public static boolean isEquals(String actual, String expected) {
		return ObjectUtil.isEquals(actual, expected);
	}

	/**
	 * null string to empty string
	 */
	public static String nullStrToEmpty(String str) {
		return (str == null ? "" : str);
	}

	/**
	 * capitalize first letter
	 */
	public static String capitalizeFirstLetter(String str) {
		if (isEmpty(str)) {
			return str;
		}

		char c = str.charAt(0);
		return (!Character.isLetter(c) || Character.isUpperCase(c)) ? str
				: new StringBuilder(str.length())
						.append(Character.toUpperCase(c))
						.append(str.substring(1)).toString();
	}

	/**
	 * encoded in utf-8
	 */
	public static String utf8Encode(String str) {
		if (!isEmpty(str) && str.getBytes().length != str.length()) {
			try {
				return URLEncoder.encode(str, "UTF-8");
			} catch (UnsupportedEncodingException e) {
				throw new RuntimeException(
						"UnsupportedEncodingException occurred. ", e);
			}
		}
		return str;
	}

	/**
	 * encoded in utf-8, if exception, return defultReturn
	 */
	public static String utf8Encode(String str, String defultReturn) {
		if (!isEmpty(str) && str.getBytes().length != str.length()) {
			try {
				return URLEncoder.encode(str, "UTF-8");
			} catch (UnsupportedEncodingException e) {
				return defultReturn;
			}
		}
		return str;
	}

	/**
	 * get innerHtml from href
	 */
	public static String getHrefInnerHtml(String href) {
		if (isEmpty(href)) {
			return "";
		}
		String hrefReg = ".*<[\\s]*a[\\s]*.*>(.+?)<[\\s]*/a[\\s]*>.*";
		Pattern hrefPattern = Pattern
				.compile(hrefReg, Pattern.CASE_INSENSITIVE);
		Matcher hrefMatcher = hrefPattern.matcher(href);
		if (hrefMatcher.matches()) {
			return hrefMatcher.group(1);
		}
		return href;
	}

    /**
     * process special char in html
     */
	public static String htmlEscapeCharsToString(String source) {
		return isEmpty(source) ? source : source
				.replaceAll("<", "<").replaceAll(">", ">")
				.replaceAll("&", "&").replaceAll(""", "\"");
	}

	/**
	 * transform half width char to full width char
	 */
	public static String fullWidthToHalfWidth(String s) {
		if (isEmpty(s)) {
			return s;
		}
		char[] source = s.toCharArray();
		for (int i = 0; i < source.length; i++) {
			if (source[i] == 12288) {
				source[i] = ' ';
				// } else if (source[i] == 12290) {
				// source[i] = '.';
			} else if (source[i] >= 65281 && source[i] <= 65374) {
				source[i] = (char) (source[i] - 65248);
			} else {
				source[i] = source[i];
			}
		}
		return new String(source);
	}

	/**
	 * transform full width char to half width char
	 */
	public static String halfWidthToFullWidth(String s) {
		if (isEmpty(s)) {
			return s;
		}
		char[] source = s.toCharArray();
		for (int i = 0; i < source.length; i++) {
			if (source[i] == ' ') {
				source[i] = (char) 12288;
			} else if (source[i] >= 33 && source[i] <= 126) {
				source[i] = (char) (source[i] + 65248);
			} else {
				source[i] = source[i];
			}
		}
		return new String(source);
	}

	/**
	 * 一个散列方法,改变一个字符串(如URL)到一个散列适合使用作为一个磁盘文件名。
	 */
	public static String hashKeyForDisk(String key) {
		String cacheKey;
		try {
			final MessageDigest mDigest = MessageDigest.getInstance("MD5");
			mDigest.update(key.getBytes());
			cacheKey = bytesToHexString(mDigest.digest());
		} catch (NoSuchAlgorithmException e) {
			cacheKey = String.valueOf(key.hashCode());
		}
		return cacheKey;
	}

	/**
	 * count(返回字符串的长度；统计方法，一个汉字或中文字符计2，一个字母或英语标点符号计1)
	 */
	public static int count(String str) {
		int singelC = 0, doubleC = 0;
		String s = "[^\\x00-\\xff]";
		Pattern pattern = Pattern.compile(s);
		Matcher ma = pattern.matcher(str);

		while (ma.find()) {
			doubleC++;
		}
		singelC = str.length() - doubleC;
		if (singelC % 2 != 0) {
			doubleC += (singelC + 1) / 2;
		} else {
			doubleC += singelC / 2;
		}

		return doubleC;
	}

    /**
     * 字节转HEX
     * @param bytes
     * @return
     */
    private static String bytesToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < bytes.length; i++) {
            String hex = Integer.toHexString(0xFF & bytes[i]);
            if (hex.length() == 1) {
                sb.append('0');
            }
            sb.append(hex);
        }
        return sb.toString();
    }

}