SpringHttpRequestPerformanceFilter.java

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package etm.contrib.integration.spring.web;

import etm.contrib.integration.web.HttpRequestPerformanceFilter;
import etm.core.monitor.EtmMonitor;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

import javax.servlet.ServletException;

/**
 * A Servlet Filter that spans performance monitoring around HTTP requests for
 * etm.contrib.integration.spring managed EtmMonitor instances. The filter requires the existence of an Spring
 * WebApplicationContext that was created through a Spring <code>ContextLoaderListener</code> or
 * <code>ContextLoaderServlet</code> (<i>It should be possible to locate the WebApplicationContext with
 * WebApplicationContextUtils.getRequiredWebApplicationContext()</i>).
 * <p/>
 * Usually the filter is able to locate the EtmMonitor automatically, however if you have more than one EtmMonitor
 * instance you need specify the monitor bean name as specified in your etm.contrib.integration.spring configuration. Therefore add the filter
 * init parameter called <code>etmMonitorName</code> holding its name.
 * <p/>
 * Example:
 * <pre>
 * <filter>
 *   <filter-name>requestPerformanceFilter</filter-name>
 *   <filter-class>etm.contrib.integration.etm.contrib.integration.spring.web.SpringHttpRequestPerformanceFilter</filter-class>
 *   <init-param>
 *     <param-name>etmMonitorName</param-name>
 *     <param-value>lala</param-value>
 *   </init-param>
 * </filter>
 * </pre>
 * @author void.fm
 * @version $Revision$
 * @since 1.2.0
 */
public class SpringHttpRequestPerformanceFilter extends HttpRequestPerformanceFilter {

  protected EtmMonitor getEtmMonitor() throws ServletException {
    // retrieve name of EtmMonitor to use. may be null    
    String etmMonitorName = getFilterConfig().getInitParameter(SpringEtmMonitorContextSupport.ETM_MONITOR_PARAMETER_NAME);
    WebApplicationContext ctx = WebApplicationContextUtils.getRequiredWebApplicationContext(getFilterConfig().getServletContext());

    return SpringEtmMonitorContextSupport.locateEtmMonitor(ctx, etmMonitorName);
  }

}