stringutils.java

《j2ee开发全程实录》随书源码

package com.cownew.ctk.common;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.Properties;

import com.cownew.ctk.common.stringSep.ParserException;
import com.cownew.ctk.common.stringSep.StringSeparator;

public class StringUtils
{
	private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5',
			'6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

	/**
	 * 将byte[]转换为字符串(采用表驱动方式)
	 * @param is
	 * @return
	 */
	public static String byteArrayToString(byte[] is)
	{
		int i = is.length;
		char[] chars = new char[i * 2];
		int j = 0;
		int k = 0;
		while (j < i)
		{
			int p = is[j++];
			chars[k++] = HEX_DIGITS[p >>> 4 & 0xf];
			chars[k++] = HEX_DIGITS[p & 0xf];
		}
		return new String(chars);
	}

	/**
	 * 字符串是否为空
	 * @param string
	 * @return
	 */
	public static final boolean isEmpty(String string)
	{
		return string == null || string.trim().length() == 0;
	}
	
	/**
	 * StringBuffer是否为空
	 * @param string
	 * @return
	 */
	public static final boolean isEmpty(StringBuffer sb)
	{		
		return sb == null || sb.toString().trim().length() == 0;
	}

	/**
	 * 得到Throwable栈的字符串格式
	 * @param throwable
	 * @return
	 */
	public static String stackToString(Throwable throwable)
	{
		StringWriter stringwriter = new StringWriter();
		throwable.printStackTrace(new PrintWriter(stringwriter));
		return stringwriter.toString();

	}

	/**
	 * 使字符串的第一项为大写
	 * @param string
	 * @return
	 */
	public static String firstUpperCase(String string)
	{
		if (isEmpty(string))
			return string;
		String first = string.substring(0, 1).toUpperCase();
		if (string.length() == 1)
			return first;
		return first + string.substring(1, string.length());
	}

	/**
	 * 使字符串的第一项为小写
	 * @param string
	 * @return
	 */
	public static String firstLowerCase(String string)
	{
		if (isEmpty(string))
			return string;
		String first = string.substring(0, 1).toLowerCase();
		if (string.length() == 1)
			return first;
		return first + string.substring(1, string.length());
	}

	/**
	 * 给字符串加双引号
	 * @param string
	 * @return
	 */
	public static String doubleQuoted(String string)
	{
		if (isEmpty(string))
			return string;
		return "\"" + string + "\"";
	}

	/**
	 * 给字符串加单引号
	 * @param string
	 * @return
	 */
	public static String singleQuoted(String string)
	{
		if (isEmpty(string))
			return string;
		return "'" + string + "'";
	}

	/**
	 * 得到Properties的字符串表示
	 * @param prop
	 * @return
	 */
	public static String propertiesToString(Properties prop)
	{
		List strList = new ArrayList(prop.size());
		Enumeration keyEnum = prop.keys();
		while(keyEnum.hasMoreElements())
		{
			String key = keyEnum.nextElement().toString();
			String property = prop.getProperty(key);
			String item = StringSeparator.pack(new String[]{key,property});
			strList.add(item);
		}
		return StringSeparator.pack(strList);
	}
	
	/**
	 * 从Properties的字符串表示转化回Properties
	 * @param value
	 * @return
	 * @throws ParserException 
	 */
	public static Properties stringToProperties(String value)
			throws ParserException
	{
		//value有可能为空(当所有配置项都为空的时候),所以要把null转化成空字符串，否则后边会报空指针错误
		if(value==null)
		{
			value = "";
		}
		Properties props = new Properties();
		String[] items = StringSeparator.unPackAsArray(value);
		for(int i=0,n=items.length;i<n;i++)
		{
			String[] keyValue = StringSeparator.unPackAsArray(items[i]);
			props.setProperty(keyValue[0], keyValue[1]);
		}
		return props;
	}
}