viewmetadataservlet.java

esri的ArcGIS Server超级学习模板程序（for java）

package com.esri.solutions.jitk.common.csw;

import com.esri.solutions.jitk.web.tasks.search.csw.CswSearchTaskBean;

import org.apache.log4j.Logger;

import java.io.IOException;

import javax.faces.FactoryFinder;
import javax.faces.context.FacesContext;
import javax.faces.context.FacesContextFactory;
import javax.faces.lifecycle.Lifecycle;
import javax.faces.lifecycle.LifecycleFactory;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


/**
 * This class handles client requests to view metadata document
 * via HTML or XML by extending {@link HttpServlet}.
 */
@SuppressWarnings("serial")
public class ViewMetadataServlet extends HttpServlet {
    /**
     * {@link Logger} used to log messages for this class.
     */
    private static final Logger LOG = Logger.getLogger(ViewMetadataServlet.class);

    /*
     * (non-Javadoc)
     * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
     */
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {
        ViewMetadataHelper helper = null;
        String metadataGuid = null;
        String catalogId = null;
        String htmlContent = null;
        String outputType = null;
        String taskBeanName = null;
        CswSearchTaskBean taskBean = null;
        String taskBeanInitParamName = "TaskBeanName";
        FacesContext fc = null;

        taskBeanName = getServletConfig().getInitParameter(taskBeanInitParamName);

        if (taskBeanName == null) {
            resp.getWriter()
                .write(generateErrorHtml(
                    "An error has occurred viewing metadata document.  Possible configuration problem."));

            LOG.debug("Missing servlet initialization parameter '" +
                taskBeanInitParamName + "' for servlet: " +
                getServletConfig().getServletName() +
                " - cannot view metadata document");

            resp.getWriter().flush();
            resp.getWriter().close();

            return;
        }

        fc = getFacesContext(req, resp);

        if (!(fc.getApplication().getVariableResolver()
                    .resolveVariable(fc, taskBeanName) instanceof CswSearchTaskBean)) {
            resp.getWriter()
                .write(generateErrorHtml(
                    "An error has occurred viewing metadata document.  Possible configuration problem."));

            LOG.debug("CS/W task bean is not of type '" +
                CswSearchTaskBean.class.getName() +
                "' - cannot view metadata document");

            resp.getWriter().flush();
            resp.getWriter().close();

            return;
        }

        taskBean = (CswSearchTaskBean) fc.getApplication().getVariableResolver()
                                         .resolveVariable(fc, taskBeanName);

        helper = taskBean.getViewMetadataHelper();

        metadataGuid = req.getParameter("guid");
        catalogId = req.getParameter("catalogId");

        if ((req.getParameter("output") == null) ||
                (req.getParameter("output").length() <= 0)) {
            outputType = ViewMetadataHelper.OUTPUT_TYPE_HTML;
        } else if (req.getParameter("output")
                          .equalsIgnoreCase(ViewMetadataHelper.OUTPUT_TYPE_XML)) {
            outputType = ViewMetadataHelper.OUTPUT_TYPE_XML;
        } else {
            outputType = ViewMetadataHelper.OUTPUT_TYPE_HTML;
        }

        // replace the placeholder for with the '&'
        catalogId = catalogId.replace("*/", "&");

        if ((metadataGuid == null) || (metadataGuid.length() <= 0)) {
            LOG.warn("Invalid Metadata GUID");

            htmlContent = generateErrorHtml("Invalid Metadata document GUID.");
        }

        if ((catalogId == null) || (catalogId.length() <= 0)) {
            LOG.warn("Invalid Catalog ID");

            htmlContent = generateErrorHtml("Invalid Catalog Service ID.");
        }

        // if the html content is not null then no error has occurred
        if (htmlContent == null) {
            try {
                htmlContent = helper.generateHtmlForMetadataDoc(metadataGuid,
                        catalogId, outputType);
            } catch (Exception ex) {
                LOG.warn(
                    "An exception occurred viewing metadata document with ID: [" +
                    metadataGuid + "] on catalog service: [" + catalogId + "]",
                    ex);

                htmlContent = generateErrorHtml(
                        "An error has occurred trying to view Metadata document with GUID " +
                        metadataGuid + "on Catalog Service " + catalogId);
            }
        }

        if (htmlContent == null) {
            htmlContent = generateErrorHtml(
                    "An error has occurred trying to view Metadata document with GUID " +
                    metadataGuid + "on Catalog Service " + catalogId);
        }

        resp.getWriter().write(htmlContent);

        resp.getWriter().flush();
        resp.getWriter().close();
    }

    /**
     * Utility method to generate an HTML message that can be
     * sent back to the client.
     *
     * @param message {@link String} message.
     * @return HTML message that can be viewed in a browser.
     */
    private String generateErrorHtml(String message) {
        StringBuilder errorHtml = null;

        errorHtml = new StringBuilder();

        errorHtml.append("<html>");
        errorHtml.append("<head>");
        errorHtml.append("<title>");
        errorHtml.append("Error Viewing Metadata Document");
        errorHtml.append("</title>");
        errorHtml.append("</head>");
        errorHtml.append("<body>");
        errorHtml.append(message);
        errorHtml.append("</body>");
        errorHtml.append("</html>");

        return errorHtml.toString();
    }

    /**
     * Utility method to get the {@link FacesContext} object via
     * the {@link FacesContextFactory#getFacesContext(Object, Object, Object, Lifecycle)}.
     *
     * @param request Reference to the {@link HttpServletRequest} needed for getting the
     *                 {@link FacesContext}.
     * @param response Reference to the {@link HttpServletResponse} needed for getting the
     *                 {@link FacesContext}.
     * @return {@link FacesContext} reference.
     */
    private FacesContext getFacesContext(HttpServletRequest request,
        HttpServletResponse response) {
        FacesContext facesContext = FacesContext.getCurrentInstance();

        if (facesContext == null) {
            FacesContextFactory contextFactory = (FacesContextFactory) FactoryFinder.getFactory(FactoryFinder.FACES_CONTEXT_FACTORY);
            LifecycleFactory lifecycleFactory = (LifecycleFactory) FactoryFinder.getFactory(FactoryFinder.LIFECYCLE_FACTORY);
            Lifecycle lifecycle = lifecycleFactory.getLifecycle(LifecycleFactory.DEFAULT_LIFECYCLE);

            facesContext = contextFactory.getFacesContext(getServletContext(),
                    request, response, lifecycle);
        }

        return facesContext;
    }
}