如何使用escape和unescape函数？

在作b/s程序的时候经常为了汉字编码的问题头疼不已，一直想在偷懒等有人写个java 版的escape/unescape来给我用，昨晚终于忍无可忍了，自己写了一个。没有来得及严密测试，要发现bug了mail给我（stoneat163@163.net)

class EscapeUnescape
{
public static String escape (String src)
{
int i;
char j;
StringBuffer tmp = new StringBuffer();
tmp.ensureCapacity(src.length()*6);

for (i=0;i<src.length() ;i++ )
{

j = src.charAt(i);

if (Character.isDigit(j) || Character.isLowerCase(j) || Character.isUpperCase(j))
tmp.append(j);
else
if (j<256)
{
tmp.append( "%" );
if (j<16)
tmp.append( "0" );
tmp.append( Integer.toString(j,16) );
}
else
{
tmp.append( "%u" );
tmp.append( Integer.toString(j,16) );
}
}
return tmp.toString();
}

public static String unescape (String src)
{
StringBuffer tmp = new StringBuffer();
tmp.ensureCapacity(src.length());
int lastPos=0,pos=0;
char ch;
while (lastPos<src.length())
{
pos = src.indexOf("%",lastPos);
if (pos == lastPos)
{
if (src.charAt(pos+1)=='u')
{
ch = (char)Integer.parseInt(src.substring(pos+2,pos+6),16);
tmp.append(ch);
lastPos = pos+6;
}
else
{
ch = (char)Integer.parseInt(src.substring(pos+1,pos+3),16);
tmp.append(ch);
lastPos = pos+3;
}
}
else
{
if (pos == -1)
{
tmp.append(src.substring(lastPos));
lastPos=src.length();
}
else
{
tmp.append(src.substring(lastPos,pos));
lastPos=pos;
}
}
}
return tmp.toString();
}

public static void main(String[] args)
{
String tmp="~!@#$%^&*()_+|//=-,./?><;'][{}/"";
System.out.println("testing escape : "+tmp);
tmp =escape(tmp);
System.out.println(tmp);
System.out.println("testing unescape :"+tmp);
System.out.println(unescape(tmp));
}
}