package coreservlets;
import javax.servlet.*;
import javax.servlet.http.*;
/** Some simple time savers. Note that most are static methods.
*
* Taken from More Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.moreservlets.com/.
* © 2004 Marty Hall; may be freely used or adapted.
*/
public class ServletUtilities {
public static final String DOCTYPE =
"";
public static String headWithTitle(String title) {
return(DOCTYPE + "\n" +
"\n" +
"
" + title + "\n");
}
/** Read a parameter with the specified name and return it.
* Return the designated default value if the parameter
* doesn't exist or has zero length.
*/
public static String getParameter(HttpServletRequest request,
String paramName,
String defaultValue) {
String paramString = request.getParameter(paramName);
if (paramString == null || "".equals(paramString)) {
paramString = defaultValue;
}
return(paramString);
}
/** Read a parameter with the specified name, convert it
* to an int, and return it. Return the designated default
* value if the parameter doesn't exist or if it is an
* illegal integer format.
*/
public static int getIntParameter(HttpServletRequest request,
String paramName,
int defaultValue) {
String paramString = request.getParameter(paramName);
int paramValue;
try {
paramValue = Integer.parseInt(paramString);
} catch(NumberFormatException nfe) { // null or bad format
paramValue = defaultValue;
}
return(paramValue);
}
/** Given an array of Cookies, a name, and a default value,
* this method tries to find the value of the cookie with
* the given name. If there is no cookie matching the name
* in the array, then the default value is returned instead.
*/
public static String getCookieValue(Cookie[] cookies,
String cookieName,
String defaultValue) {
if (cookies != null) {
for(int i=0; i' with
// '>', and (to handle cases that occur inside attribute
// values), all occurrences of double quotes with
// '"' and all occurrences of '&' with '&'.
// Without such filtering, an arbitrary string
// could not safely be inserted in a Web page.
public static String filter(String input) {
StringBuffer filtered = new StringBuffer(input.length());
char c;
for(int i=0; i') {
filtered.append(">");
} else if (c == '"') {
filtered.append(""");
} else if (c == '&') {
filtered.append("&");
} else {
filtered.append(c);
}
}
return(filtered.toString());
}
}