ratpack.error.internal.ErrorPageRenderer.java Source code

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Here is the source code for ratpack.error.internal.ErrorPageRenderer.java

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/*
 * Copyright 2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ratpack.error.internal;

import com.google.common.collect.ImmutableMap;
import com.google.common.escape.Escaper;
import com.google.common.html.HtmlEscapers;
import com.google.common.io.CharStreams;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.buffer.ByteBufOutputStream;
import io.netty.util.CharsetUtil;
import ratpack.handling.Context;
import ratpack.http.internal.HttpHeaderConstants;

import java.io.*;
import java.util.Map;
import java.util.function.Consumer;

public abstract class ErrorPageRenderer {

    private static final Escaper HTML_ESCAPER = HtmlEscapers.htmlEscaper();

    private String style;

    public ErrorPageRenderer() {
        if (style == null) {
            InputStream resourceAsStream = ErrorPageRenderer.class.getResourceAsStream("error-template-style.css");
            if (resourceAsStream == null) {
                throw new IllegalStateException("Couldn't find style resource");
            }

            InputStreamReader reader = new InputStreamReader(resourceAsStream, CharsetUtil.UTF_8);
            try {
                style = CharStreams.toString(reader);
            } catch (IOException e) {
                throw new IllegalStateException("Could not read style stream", e);
            }
        }

        render();
    }

    protected abstract void render();

    protected void stack(BodyWriter w, String heading, Throwable throwable) {
        if (heading != null) {
            w.println("<div id=\"stack-header\">").println("<div class=\"wrapper\">").print("<h3>").escape(heading)
                    .print("</h3>").println("</div>").println("</div>");
        }
        w.println("<div class=\"wrapper\">").println("<div class=\"stack\">");
        w.print("<pre><code>");
        throwable(w, throwable, false);

        w.println("</pre></code>").println("</div>").println("</div>");
    }

    protected void throwable(BodyWriter w, Throwable throwable, boolean isCause) {
        if (throwable != null) {
            if (isCause) {
                w.escape("Caused by: ");
            }

            w.println(throwable.toString());
            for (StackTraceElement ste : throwable.getStackTrace()) {
                String className = ste.getClassName();
                if (className.startsWith("ratpack") || className.startsWith("io.netty")
                        || className.startsWith("com.google") || className.startsWith("java")
                        || className.startsWith("org.springsource.loaded")) {
                    w.print("<span class='stack-core'>  at ").escape(ste.toString()).println("</span>");
                } else {
                    w.print("  at ").escape(ste.toString()).println("");
                }
            }

            throwable(w, throwable.getCause(), true);
        }
    }

    protected static class BodyWriter {
        private final PrintWriter writer;

        private BodyWriter(PrintWriter writer) {
            this.writer = writer;
        }

        BodyWriter print(String string) {
            writer.print(string);
            return this;
        }

        BodyWriter println(String string) {
            writer.println(string);
            return this;
        }

        BodyWriter escape(String string) {
            return print(HTML_ESCAPER.escape(string));
        }
    }

    protected void messages(BodyWriter writer, String heading, Runnable block) {
        writer.println("<div class=\"wrapper\">").println("<div id=\"messages\">").println("<section>")
                .print("<h2>").escape(heading).println("</h2>");

        block.run();
        writer.println("<p><em>Note: This page will only be visible during development.</em></p>")
                .println("</section>").println("</div>").println("</div>");
    }

    protected void meta(BodyWriter w, Consumer<ImmutableMap.Builder<String, Object>> meta) {
        ImmutableMap.Builder<String, Object> builder = ImmutableMap.builder();
        meta.accept(builder);

        w.println("<table class=\"meta\">");
        for (Map.Entry<String, Object> entry : builder.build().entrySet()) {
            w.print("<tr><th>").escape(entry.getKey()).print("</th><td>").escape(entry.getValue().toString())
                    .println("</td></tr>");
        }
        w.println("</table>");
    }

    protected void render(Context context, String pageTitle, Consumer<? super BodyWriter> body) {
        ByteBuf buffer = context.get(ByteBufAllocator.class).buffer();
        OutputStream out = new ByteBufOutputStream(buffer);
        PrintWriter printWriter = new PrintWriter(new OutputStreamWriter(out, CharsetUtil.UTF_8));
        BodyWriter writer = new BodyWriter(printWriter);

        writer.println("<!DOCTYPE html>").println("<html>").println("<head>").print("  <title>").escape(pageTitle)
                .println("</title>").println("    <style type=\"text/css\">").println(style).println("    </style>")
                .println("</head>").println("<body>").println("  <header>").println("    <div class=\"logo\">")
                .println("      <div class=\"martini\">").println("        <h1>Ratpack</h1>")
                .println("      </div>").println("      <p>Development error page</p>").println("    </div>")
                .println("  </header>");

        body.accept(writer);

        writer.println("<footer>").println("  <a href=\"http://www.ratpack.io\">Ratpack.io</a>")
                .println("</footer>").println("</body>").println("</html>");

        printWriter.close();
        context.getResponse().send(HttpHeaderConstants.HTML_UTF_8, buffer);
    }

}