Add java filters in grails application

Posted By : Deepak Agrawal | 19-Dec-2014

grails

This blog explain how to add web.xml file in grails application to add java filters.

And An example to describe the use of filters.

Steps:

1. First we need to add web.xml file in grails application.

Use grails install-templates command to add web.xml. You can find web.xml in application/src/templates/war folder.

2. now Create filter by implementing javax.servlet.Filter

package com.dcx.secured;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class BrowserAuthenticationFiltor implements Filter {

	@Override
	public void destroy() {

	}

	@Override
	public void doFilter(ServletRequest arg0, ServletResponse arg1,	FilterChain arg2) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest) arg0;
		HttpServletResponse response = (HttpServletResponse) arg1;
		PrintWriter wr=response.getWriter();
		wr.write("Generate response from filter");
		wr.close();
		//uncomment this line if you want to to send request to next resource
		//arg2.doFilter(arg0, arg1);
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {

	}

}

3. Now add BrowserAuthenticationFilter in web.xml file:

Add these lines in web.xml file before DelegatingFilterProxy Filter. So that BrowserAuthenticationFilter will be first filter to execute.

<filter>
	<filter-name>browserAuthenticationFiltor</filter-name>
	<filter-class>com.dcx.secured.BrowserAuthenticationFiltor</filter-class>
</filter>
<filter-mapping>
	<filter-name>browserAuthenticationFiltor</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>

Now you have successfully configured filters in grails application. Similarly we can add servlets or other resource to our web.xml file.

Thanks