Java转化html字符串

public static String toHTMLString(String in)  
{  
   StringBuffer out = new StringBuffer();  
     for(int i = 0; in != null && i < in.length(); i++)  
     {  
             char   c   =   in.charAt(i);  
             if   (c   ==   '\'')  
                     out.append("'");  
             else   if   (c == '\"')  
                     out.append(""");  
             else   if   (c == '<')  
                     out.append("<");  
             else   if   (c == '>')
                     out.append(">");  
             else   if   (c == '&')  
                     out.append("&");  
             else   if   (c == ' ')  
                     out.append(" ");  
             else   if   (c   ==   '\n')  
                     out.append("
");  
             else  
                     out.append(c);  
     }  
     return   out.toString();  
}