I'm currently developing a Java EE web framework and I would want to know how I could route my URL's... I want support HMVC feature! URL's will follow this rule:
/module_name/controller_name/action_name, where:
module_name: path separated by slashes... Ex.: Submodule "Y" of Module "X": /X/Y
controller_name: name of controller with no special chars
action_name: name of action with no special chars
I would like map /module_name/controller_name/ to a specific servlet controller! Action part is a public method on that class! :)
How I could do this? Using filters? I want an example, if possible!
i see 3 ways: filter, basic servlet(all requests via main servlet) or "servlet-mapping"
filter
This example rewrite url
http://example.org/<int value>
to
http://example.org/user?id=<int value>
i.e
http://example.org/1234 -> http://example.org/user?id=1234
- determinate filter in web.xml
<filter>
<filter-name>Router</filter-name>
<filter-class>org.example.Router</filter-class>
<init-param>
<param-name>param1</param-name>
<param-value>valueOfparam1</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>Router</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
in init-param section you can specify route rules
filter class
public class Router implements javax.servlet.Filter {
private static final Pattern REWRITE_PATTERN = Pattern.compile("(^[1-9]\\d*)$");
@Override
public void destroy() {
}
@Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain fc) throws IOException, ServletException {
//this method calling before controller(servlet), every request
HttpServletRequest request = (HttpServletRequest) req;
String url = request.getRequestURL().toString();
String number = url.substring(url.lastIndexOf("/")).replace("/", "");
Matcher m = REWRITE_PATTERN.matcher(number);
if(m.find()) {
RequestDispatcher dispatcher = request.getRequestDispatcher("user?id=" + m.group(1));
dispatcher.forward(req, res);
} else {
fc.doFilter(req, res);
}
}
@Override
public void init(FilterConfig fc) throws ServletException {
//here you may read params from web.xml
}}
basic sevlet
public class BasicServlet extends HttpServlet {
//route rules here, and rewrite
}
servlet-mapping
<servlet-mapping>
<servlet-name>UserServlet</servlet-name>
<uri-mapping>/user/*</uri-mapping>
</servlet-mapping>
<servlet-mapping>
<servlet-name>PostServlet</servlet-name>
<uri-mapping>/post/*</uri-mapping>
</servlet-mapping>
- filter - more flexible and not require serious modify working code
- basic servlet - flexible, require change you code
- servlet mapping - simply, not flexible(for specific route rules)