Servlet filters

[albinjoseph]

Servlet filters

Servlet filters are used for modifying the request or response before it is processed by the request / response processor. Servlet filters are pre processors for a request and post processor for a response.

Creating a servlet filter involves three steps.

1. Create a sub class of javax.servlet.Filter

[java]
public class MyFilter extends Filter {

}
[/java]

2. Override the doFilter method.

[java]
public void doFilter (ServletRequest request, ServletResponse response, FilterChain chain)
throws java.io.IOException, javax.servlet.ServletException {
System.out.println("My filter ....");
}
[/java]
3. Configure the servlet filter in web.xml using filter tag

[xml]
<filter>
<filter-name>
MyFilter
</filter-name>
<filter-class>
MyFilter
</filter-class>
</filter>

<filter-mapping>
<filter-name>MyFilter</filter-name>
<url-pattern>/*</url-pattern>
<filter-mapping>

[/xml]