I took this instance from "Core Servlets and JavaServer Pages" book by Marty Hall and Larry Brown.This is my text book at the moment.
Here is some code:
The main problem is html-tags.. If you try to print out "a<b" (a less than b) - you will not see any text after < symbol. But the method filter() can replace "<" symbol with
"<" (predefined letters combination):/** <b - as a html tag:
if (a<b) {
doThis();
} else {
doThat();
}
*/
public static String filter(String input) {
StringBuilder filtered = new StringBuilder(input.length());
char c;
for(int i=0; i<input.length(); i++) {
c = input.charAt(i);
if (c == '<') {
filtered.append("<");
} else if (c == '>') {
filtered.append(">");
} else if (c == '"') {
filtered.append(""");
} else if (c == '&') {
filtered.append("&");
} else {
filtered.append(c);
}
}
return(filtered.toString());
} JSP code:
<%--
Document : index
Created on : 20-Mar-2013, 18:55:39
Author : Alex
--%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>HTML Converter</title>
</head>
<body>
<div style="width:500px;float:left;display:inline-block;
background:#fbdce1;border:5px solid #fa6e6e;padding:10px;">
<form name="Frm1" action="convert" method="POST">
<TEXTAREA NAME="txt" ROWS=10 COLS=50 WRAP="SOFT" style ="max-width:490px;"></TEXTAREA><BR />
<input type="submit" value="Convert" name="SubmitBtn" />
</form>
</div>
</body>
</html> Here is a servlet code (processRequest() method of a servlet) where everything is happening. This code wos converted by filter() methid:
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
String txt = request.getParameter("txt");
txt = myServUtil.replaceIfMissing(txt, "<NOT FOUND ANY TEXT>");
txt = myServUtil.filter(txt);
String title = "HTML filtering result";
String body = "<div style=\"width:500px;float:left;display:inline-block;\n" +
"background:#fbdce1;border:5px solid #fa6e6e;padding:10px;\">" +
"<form name=\"Frm1\" action=\"convert\" method=\"POST\">" +
"<TEXTAREA NAME=\"txt\" ROWS=10 COLS=50 WRAP=\"SOFT\" style =\"max-width:490px;\">\n\n"+ txt + "\n</TEXTAREA><br />" +
"</form>" + "<br />" +"Try again: " +
"<input type=\"submit\" value=\"Convert\" name=\"SubmitBtn\" />" +
"</div>";
String html = myServUtil.getHTML(title, body);
out.println(html);
} catch(Exception ex) {
ex.printStackTrace(out);
}
finally {
out.close();
}
}If you try to convert ("filter") an empty text you receive such a output:
<!DOCTYPE html>
<html>
<head>
<title>HTML filtering result</title>
</head>
<body>
<div style="width:500px;float:left;display:inline-block;
background:#fbdce1;border:5px solid #fa6e6e;padding:10px;"><form name="Frm1" action="convert" method="POST"><TEXTAREA NAME="txt" ROWS=10 COLS=50 WRAP="SOFT" style ="max-width:490px;">
<NOT FOUND ANY TEXT>
</TEXTAREA><br /></form><br />Try again: <input type="submit" value="Convert" name="SubmitBtn" /></div>
</body>
</html>
P.s. I used CSS style only for decoration.
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