@WebFilter

@WebFilter

This section contains detailed description of @WebFilter annotation and its implementation with sample code.

Servlet filters are added in the Servlet 2.3. The main task of the Filters is to intercept and modify  server's requests and response. Prior to Servlet 3.0, you need to register filter using deployment descriptor(web.xml). You can do this as follows :

<filter>
	<filter-name>MyFilter</filter-name>
	<filter-class>
		net.roseindia.filters.MyFilter
	</filter-class>
	<init-param>
		<param-name>param1</param-name>
		<param-value>roseindia</param-value>
	</init-param>
</filter>
<filter-mapping>
	<filter-name>MyFilter</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>

The annotation @WebFilter, added in Servlet 3.0, is used to register a filter in web application. The attributes of the annotation @WebFilter are given below :

The tools and technology used in the example is given below :

• Eclipse Helios 3.6.1
  
  
• Tomcat 7
  
  
• jdk1.6.0_18
  

EXAMPLE

In the below example, you will learn how to register the filter using  @WebFilter :

package roseindia;

import java.io.IOException;
import java.util.Date;

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.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.http.HttpServletRequest;

@WebFilter(filterName = "filteranno", urlPatterns = "/*",
 initParams = { @WebInitParam(name = "param1", value = "RoseIndia") })
public class WebFilterAnnotation implements Filter {
	public void doFilter(ServletRequest req, ServletResponse res,
		FilterChain chain) throws IOException, ServletException {
		
		HttpServletRequest request = (HttpServletRequest) req;
		
		// Get the IP address of client machine.
		String ipAddress = request.getRemoteAddr();
		
		// Log the IP address and current timestamp.
		System.out.println("IP " + ipAddress + ", Time "
		+ new Date().toString());
		
		chain.doFilter(req, res);
		}
		
		public void init(FilterConfig config) throws ServletException {
		
		// Get init parameter
		String testParam = config.getInitParameter("param1");
		
		// Print the init parameter
		System.out.println("Init Param Name : " + testParam);
		}
		
		public void destroy() {
		// add code to release any resource
	}
}

OUTPUT

After your application starts executing by Server, any request made will display the message like this on console :

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