How to Add Header Using Tomcat Filters

We first write a filter to web.xml (before < /web-app> tag)

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

Then MyFilter.java will be like this.

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;


public final class MyFilter implements Filter {


    private FilterConfig filterConfig = null;

    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain)
 throws IOException, ServletException {
      String browserDet = ((HttpServletRequest) request).getHeader("User-Agent").toLowerCase();
      HttpServletResponse hrs = null;
       hrs = (HttpServletResponse)response;
       hrs.setHeader("Cache-Control", "max-age=10000");
       
          }

      chain.doFilter(request, hrs);
    }
    public void destroy() {
    }

    public void init(FilterConfig filterConfig) {
 this.filterConfig = filterConfig;
    }

}

This code will add

Cache-Control max-age=10000
header to the package. You can add different headers for different file types for performance or anything else.