https://projects.eclipse.org/projects/ee4j.grizzly/grizzly-websockets-server: Grizzly Bill of Materials (BOM) (Oracle Corporation) 
/*
 * Copyright (c) 2010, 2017 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.grizzly.http.server.util;

import java.io.IOException;
import java.io.Writer;
import org.glassfish.grizzly.http.server.ErrorPageGenerator;
import org.glassfish.grizzly.http.server.Request;
import org.glassfish.grizzly.http.server.Response;
import org.glassfish.grizzly.http.util.HttpStatus;
import org.glassfish.grizzly.http.util.HttpUtils;



Utility class used to generate HTML pages.

Author:Jean-Francois Arcand
/**
 * Utility class used to generate HTML pages.
 *
 * @author Jean-Francois Arcand
 */
public class HtmlHelper{

    private static final int MAX_STACK_ELEMENTS = 10;

    private final static String CSS =
            "div.header {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#003300;font-size:22px;-moz-border-radius-topleft: 10px;border-top-left-radius: 10px;-moz-border-radius-topright: 10px;border-top-right-radius: 10px;padding-left: 5px}" +
            "div.body {font-family:Tahoma,Arial,sans-serif;color:black;background-color:#FFFFCC;font-size:16px;padding-top:10px;padding-bottom:10px;padding-left:10px}" +
            "div.footer {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#666633;font-size:14px;-moz-border-radius-bottomleft: 10px;border-bottom-left-radius: 10px;-moz-border-radius-bottomright: 10px;border-bottom-right-radius: 10px;padding-left: 5px}" +
            "BODY {font-family:Tahoma,Arial,sans-serif;color:black;background-color:white;}" +
            "B {font-family:Tahoma,Arial,sans-serif;color:black;}" +
            "A {color : black;}" +
            "HR {color : #999966;}";

    
Generate and send an error page for the given HTTP response status. Unlike setErrorAndSendErrorPage(Request, Response, ErrorPageGenerator, int, String, String, Throwable), this method doesn't change the Response status code and reason phrase. 
Params:
  • request – 
  • response – 
  • generator – 
  • status – 
  • reasonPhrase – 
  • description – 
  • exception – 
Throws:
/**
     * Generate and send an error page for the given HTTP response status.
     * Unlike {@link #setErrorAndSendErrorPage(org.glassfish.grizzly.http.server.Request, org.glassfish.grizzly.http.server.Response, org.glassfish.grizzly.http.server.ErrorPageGenerator, int, java.lang.String, java.lang.String, java.lang.Throwable)},
     * this method doesn't change the {@link Response} status code and reason phrase.
     * 
     * @param request
     * @param response
     * @param generator
     * @param status
     * @param reasonPhrase
     * @param description
     * @param exception
     * 
     * @throws IOException 
     */
    public static void sendErrorPage(
            final Request request, final Response response,
            final ErrorPageGenerator generator,
            final int status, final String reasonPhrase,
            final String description, final Throwable exception) throws IOException {
        
        if (generator != null && !response.isCommitted() &&
                response.getOutputBuffer().getBufferedDataSize() == 0) {
            final String errorPage = generator.generate(request, status,
                    reasonPhrase, description, exception);
            
            final Writer writer = response.getWriter();
            
            if (errorPage != null) {
                if (!response.getResponse().isContentTypeSet()) {
                    response.setContentType("text/html");
                }
                
                writer.write(errorPage);
            }
            writer.close();
        }
    }
    
    
Generate and send an error page for the given HTTP response status. Unlike setErrorAndSendErrorPage(Request, Response, ErrorPageGenerator, int, String, String, Throwable), this method does change the Response status code and reason phrase. 
Params:
  • request – 
  • response – 
  • generator – 
  • status – 
  • reasonPhrase – 
  • description – 
  • exception – 
Throws:
/**
     * Generate and send an error page for the given HTTP response status.
     * Unlike {@link #setErrorAndSendErrorPage(org.glassfish.grizzly.http.server.Request, org.glassfish.grizzly.http.server.Response, org.glassfish.grizzly.http.server.ErrorPageGenerator, int, java.lang.String, java.lang.String, java.lang.Throwable)},
     * this method does change the {@link Response} status code and reason phrase.
     * 
     * @param request
     * @param response
     * @param generator
     * @param status
     * @param reasonPhrase
     * @param description
     * @param exception
     * 
     * @throws IOException 
     */
    public static void setErrorAndSendErrorPage(
            final Request request, final Response response,
            final ErrorPageGenerator generator,
            final int status, final String reasonPhrase,
            final String description, final Throwable exception) throws IOException {
        
        response.setStatus(status, reasonPhrase);
        
        if (generator != null && !response.isCommitted() &&
                response.getOutputBuffer().getBufferedDataSize() == 0) {
            final String errorPage = generator.generate(request, status,
                    reasonPhrase, description, exception);
            
            final Writer writer = response.getWriter();
            
            if (errorPage != null) {
                if (!response.getResponse().isContentTypeSet()) {
                    response.setContentType("text/html");
                }
                
                writer.write(errorPage);
            }
            writer.close();
        }
    }

    public static void writeTraceMessage(final Request request,
            final Response response) throws IOException {
        response.setStatus(HttpStatus.OK_200);
        response.setContentType("message/http");
        final Writer writer = response.getWriter();
        writer.append(request.getMethod().toString()).append(' ')
                .append(request.getRequest().getRequestURIRef().getOriginalRequestURIBC().toString())
                .append(' ').append(request.getProtocol().getProtocolString())
                .append("\r\n");

        for (String headerName : request.getHeaderNames()) {
            for (String headerValue : request.getHeaders(headerName)) {
                writer.append(headerName).append(": ").append(headerValue).append("\r\n");
            }
        }
    }

    
Returns:A String containing the HTTP response.
/**
     *
     * @return A {@link String} containing the HTTP response.
     */
    public static String getErrorPage(String headerMessage,
            String message, String serverName) {
        return prepareBody(headerMessage, message, serverName);
    }


    public static String getExceptionErrorPage(String headerMessage,
            String message, String serverName, Throwable t) {
        return prepareExceptionBody(headerMessage, message, serverName, t);
    }

    
Prepare the HTTP body containing the error messages.

/**
     * Prepare the HTTP body containing the error messages.
     */
    private static String prepareBody(String headerMessage, String message,
            String serverName) {
        final StringBuilder sb = new StringBuilder();

        sb.append("<html><head><title>");
        sb.append(serverName);
        sb.append("</title>");
        sb.append("<style><!--");
        sb.append(CSS);
        sb.append("--></style> ");
        sb.append("</head><body>");
        sb.append("<div class=\"header\">");
        sb.append(headerMessage);
        sb.append("</div>");
        sb.append("<div class=\"body\">");
        sb.append((message != null) ? message : "<HR size=\"1\" noshade>");
        sb.append("</div>");
        sb.append("<div class=\"footer\">").append(serverName).append("</div>");
        sb.append("</body></html>");
        return sb.toString();
    }


    @SuppressWarnings({"ThrowableResultOfMethodCallIgnored"})
    private static String prepareExceptionBody(String headerMessage,
            String message, String serverName, Throwable t) {

        if (t == null) {
            return prepareBody(headerMessage, message, serverName);
        }
        
        Throwable rootCause = getRootCause(t);

        StackTraceElement[] elements = t.getStackTrace();
        StackTraceElement[] rootCauseElements = null;
        if (rootCause != null) {
            rootCauseElements = rootCause.getStackTrace();
        }
        StringBuilder tBuilder = new StringBuilder();
        formatStackElements(elements, tBuilder);
        StringBuilder rootBuilder = new StringBuilder();
        if (rootCause != null) {
            formatStackElements(rootCauseElements, rootBuilder);
        }
        
        final String exMessage = t.getMessage() != null ?
                HttpUtils.filter(t.getMessage()) : HttpUtils.filter(t.toString());
        
        StringBuilder sb = new StringBuilder();
        sb.append("<html><head><title>");
        sb.append(serverName);
        sb.append("</title>");
        sb.append("<style><!--");
        sb.append(CSS);
        sb.append("--></style> ");
        sb.append("</head><body>");
        sb.append("<div class=\"header\">");
        sb.append(headerMessage);
        sb.append("</div>");
        sb.append("<div class=\"body\">");
        sb.append("<b>").append(exMessage).append("</b>");
        sb.append("<pre>");
        sb.append(tBuilder.toString());
        sb.append("</pre>");
        if (rootCause != null) {
            sb.append("<b>Root Cause: ").append(rootCause.toString()).append("</b>");
            sb.append("<pre>");
            sb.append(rootBuilder.toString());
            sb.append("</pre>");
        }

        sb.append("Please see the log for more detail.");
        sb.append("</div>");
        sb.append("<div class=\"footer\">").append(serverName).append("</div>");
        sb.append("</body></html>");
        return sb.toString();
    }


    private static Throwable getRootCause(Throwable t) {

        Throwable rootCause = null;
        if (t.getCause() != null) {
            rootCause = t.getCause();
            while (rootCause.getCause() != null) {
                rootCause = rootCause.getCause();
            }
        }
        return rootCause;

    }


    private static void formatStackElements(StackTraceElement[] elements, StringBuilder builder) {

        final int maxLines = getMaxStackElementsToDisplay(elements);
        for (int i = 0; i < maxLines; i++) {
            builder.append((i + 1 > 9) ? "    " : "     ").append(i + 1).append(": ").append(elements[i].toString()).append('\n');
        }
        boolean ellipse = elements.length > MAX_STACK_ELEMENTS;
        if (ellipse) {
            builder.append("        ... ").append(elements.length - MAX_STACK_ELEMENTS).append(" more");
        }

    }


    private static int getMaxStackElementsToDisplay(StackTraceElement[] elements) {

        return ((elements.length > MAX_STACK_ELEMENTS) ? MAX_STACK_ELEMENTS : elements.length);
        
    }

}