In a nutshell, a servlet filter lets you intercepts requests and responses on your web application. This article shows you how to register a servlet filter in Spring XML and JavaConfig.

1. Servlet Filter

Review the following custom filter, it will catch any exceptions and redirect to an error page.

package com.mkyong.form.web;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class ErrorHandleFilter implements Filter {
	@Override
	public void destroy() {
		// ...
	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		//
	@Override
	public void doFilter(ServletRequest request, 
               ServletResponse response, FilterChain chain)
		throws IOException, ServletException {
		try {
			chain.doFilter(request, response);
		} catch (Exception ex) {
			request.setAttribute("errorMessage", ex);
			request.getRequestDispatcher("/WEB-INF/views/jsp/error.jsp")
                               .forward(request, response);

2. Spring XML

In Spring MVC + XML configuration, you can register the filters via web.xml

	<filter>
		<filter-name>errorHandlerFilter</filter-name>
		<filter-class>com.mkyong.form.web.ErrorHandleFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>errorHandlerFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>

3. Spring JavaConfig

In Spring MVC + JavaConfig + no web.xml file, you can register the filters via the initializer class.

package com.mkyong.form.config.servlet3;
import javax.servlet.Filter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
import com.mkyong.form.config.SpringRootConfig;
import com.mkyong.form.config.SpringWebConfig;
import com.mkyong.form.web.ErrorHandleFilter;
public class MyWebInitializer extends
		AbstractAnnotationConfigDispatcherServletInitializer {
	//...
	@Override
	protected Filter[] getServletFilters() {
		return new Filter[]{new ErrorHandleFilter()};

References

1. Servlet Filters
2. The Essentials of Filters