一个Java的字符串常用类

package com.tienway.util;
import java.util.ArrayList;
public class StringUtil
{

public static String ContextType1ToType2(String Type1Context)
{
if (Type1Context== null || Type1Context.length() == 0)
{
return "";
}
char[] c = Type1Context.toCharArray();
StringBuffer sb = new StringBuffer();
for (int i = 0; i < c.length; i++)
{
switch (c[i])
{
case '>':
sb.append(">");
break;
case '<':
sb.append("<");
break;
case ' ':
sb.append(" ");
break;
case '"':
sb.append(""");
break;
case '&':
sb.append("&");
break;
case '\n':
sb.append("<br>");
break;
default:
try
{
sb.append(c[i]);
} catch (Exception ex)
{
}
}
}
return sb.toString();
}

public static boolean isLetter(char c)
{
int k = 0x80;
return c / k == 0 ? true : false;
}

public static int length(String s)
{
char[] c = s.toCharArray();
int len = 0;
for (int i = 0; i < c.length; i++)
{
len++;
if (!isLetter(c[i]))
{
len++;
}
}
return len;
}

public static String replaceAll(String strin, String regex,
String replacement)
{
StringBuffer sb = new StringBuffer();
int rbegin = 0;
int rend = strin.indexOf(regex);
int rlen = regex.length();
while (rend >= 0)
{
sb.append(strin.su