com.bstek.dorado.web.resolver.ErrorPageResolver.java Source code

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Here is the source code for com.bstek.dorado.web.resolver.ErrorPageResolver.java

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/*
 * This file is part of Dorado 7.x (http://dorado7.bsdn.org).
 * 
 * Copyright (c) 2002-2012 BSTEK Corp. All rights reserved.
 * 
 * This file is dual-licensed under the AGPLv3 (http://www.gnu.org/licenses/agpl-3.0.html) 
 * and BSDN commercial (http://www.bsdn.org/licenses) licenses.
 * 
 * If you are unsure which license is appropriate for your use, please contact the sales department
 * at http://www.bstek.com/contact.
 */

package com.bstek.dorado.web.resolver;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Properties;

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

import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.context.Context;
import org.apache.velocity.runtime.RuntimeConstants;

import com.bstek.dorado.core.Constants;

/**
 * @author Benny Bao (mailto:benny.bao@bstek.com)
 * @since 2011-1-31
 */
public class ErrorPageResolver extends AbstractTextualResolver {
    private static Log logger = LogFactory.getLog(ErrorPageResolver.class);

    public static final String EXCEPTION_ATTRIBUTE = "exception";

    private VelocityEngine velocityEngine;
    private Properties velocityProperties;
    private StringEscapeHelper stringEscapeHelper = new StringEscapeHelper();

    public ErrorPageResolver() {
        setContentType(HttpConstants.CONTENT_TYPE_HTML);
    }

    private VelocityEngine getVelocityEngine() throws Exception {
        if (velocityEngine == null) {
            velocityEngine = new VelocityEngine();

            velocityProperties = new Properties();
            velocityProperties.setProperty(RuntimeConstants.INPUT_ENCODING, Constants.DEFAULT_CHARSET);
            velocityProperties.setProperty(RuntimeConstants.OUTPUT_ENCODING, Constants.DEFAULT_CHARSET);
            velocityProperties.setProperty("file.resource.loader.class",
                    "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");
            velocityEngine.init(velocityProperties);
        }
        return velocityEngine;
    }

    @Override
    public void execute(HttpServletRequest request, HttpServletResponse response) throws Exception {
        try {
            doExcecute(request, response);
        } catch (Throwable t) {
            // ?????
            logger.error(t, t);
        }
    }

    private void doExcecute(HttpServletRequest request, HttpServletResponse response)
            throws Exception, IOException {
        response.setContentType(HttpConstants.CONTENT_TYPE_HTML);
        response.setCharacterEncoding(Constants.DEFAULT_CHARSET);

        Context velocityContext = new VelocityContext();
        Exception e = (Exception) request.getAttribute(EXCEPTION_ATTRIBUTE);
        if (e != null) {
            logger.error(e, e);

            if (e instanceof PageNotFoundException) {
                response.setStatus(HttpServletResponse.SC_NOT_FOUND);
            } else if (e instanceof PageAccessDeniedException) {
                response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            }

            Throwable throwable = e;
            while (throwable.getCause() != null) {
                throwable = throwable.getCause();
            }

            String message = null;
            if (throwable != null) {
                message = throwable.getMessage();
            }
            message = StringUtils.defaultString(message, throwable.getClass().getName());

            velocityContext.put("message", message);
            velocityContext.put(EXCEPTION_ATTRIBUTE, throwable);
        } else {
            velocityContext.put("message", "Can not gain exception information!");
        }
        velocityContext.put("esc", stringEscapeHelper);

        Template template = getVelocityEngine().getTemplate("com/bstek/dorado/web/resolver/ErrorPage.html");

        PrintWriter writer = getWriter(request, response);
        try {
            template.merge(velocityContext, writer);
        } finally {
            writer.flush();
            writer.close();
        }
    }
}