NIHVIVO-336 Create StartupStatusDisplayFilter which will forcibly display the StartupStatus if there are warnings or errors.

webapp/src/edu/cornell/mannlib/vitro/webapp/filters/StartupStatusDisplayFilter.java

@@ -0,0 +1,79 @@
+/* $This file is distributed under the terms of the license in /doc/license.txt$ */
+
+package edu.cornell.mannlib.vitro.webapp.filters;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletContext;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+
+import edu.cornell.mannlib.vitro.webapp.startup.StartupStatus;
+import freemarker.cache.WebappTemplateLoader;
+import freemarker.template.Configuration;
+import freemarker.template.Template;
+import freemarker.template.TemplateException;
+
+/**
+ * No matter what URL is requested, check to see whether the StartupStatus
+ * contains errors or warnings. If it does, hijack the request to show the
+ * StartupStatus display page.
+ * 
+ * This only happens once. This filter does nothing after displaying the startup
+ * status page one time.
+ */
+public class StartupStatusDisplayFilter implements Filter {
+	private static final String TEMPLATE_PATH = "/templates/freemarker/body/admin/startupStatus-displayRaw.ftl";
+
+	private ServletContext ctx;
+	private boolean statusAlreadyDisplayed;
+
+	@Override
+	public void init(FilterConfig filterConfig) throws ServletException {
+		ctx = filterConfig.getServletContext();
+		statusAlreadyDisplayed = false;
+	}
+
+	@Override
+	public void destroy() {
+		// nothing to do.
+	}
+
+	@Override
+	public void doFilter(ServletRequest req, ServletResponse resp,
+			FilterChain chain) throws IOException, ServletException {
+		StartupStatus ss = StartupStatus.getBean(ctx);
+		if (ss.allClear() || statusAlreadyDisplayed) {
+			chain.doFilter(req, resp);
+			return;
+		}
+
+		displayStartupStatus(req, resp);
+		statusAlreadyDisplayed = true;
+	}
+
+	private void displayStartupStatus(ServletRequest req, ServletResponse resp)
+			throws IOException, ServletException {
+		Configuration cfg = new Configuration();
+		cfg.setTemplateLoader(new WebappTemplateLoader(ctx));
+		Template tpl = cfg.getTemplate(TEMPLATE_PATH);
+
+		Map<String, Object> bodyMap = new HashMap<String, Object>();
+		bodyMap.put("status", StartupStatus.getBean(ctx));
+
+		try {
+			PrintWriter out = resp.getWriter();
+			tpl.process(bodyMap, out);
+			out.flush();
+		} catch (TemplateException e) {
+			throw new ServletException("Problem with Freemarker Template", e);
+		}
+	}
+}