net.pterodactylus.sone.web.ajax.JsonPage.java Source code

Java tutorial

Introduction

Here is the source code for net.pterodactylus.sone.web.ajax.JsonPage.java

Source

/*
 * Sone - JsonPage.java - Copyright  20102013 David Roden
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.pterodactylus.sone.web.ajax;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.URI;
import java.util.logging.Level;
import java.util.logging.Logger;

import net.pterodactylus.sone.data.Sone;
import net.pterodactylus.sone.web.WebInterface;
import net.pterodactylus.sone.web.page.FreenetPage;
import net.pterodactylus.sone.web.page.FreenetRequest;
import net.pterodactylus.util.io.Closer;
import net.pterodactylus.util.logging.Logging;
import net.pterodactylus.util.web.Page;
import net.pterodactylus.util.web.Response;

import com.fasterxml.jackson.databind.ObjectMapper;
import freenet.clients.http.SessionManager.Session;
import freenet.clients.http.ToadletContext;

/**
 * A JSON page is a specialized {@link Page} that will always return a JSON
 * object to the browser, e.g. for use with AJAX or other scripting frameworks.
 *
 * @author <a href="mailto:bombe@pterodactylus.net">David Bombe Roden</a>
 */
public abstract class JsonPage implements FreenetPage {

    /** The logger. */
    private static final Logger logger = Logging.getLogger(JsonPage.class);

    /** The JSON serializer. */
    private static final ObjectMapper objectMapper = new ObjectMapper();

    /** The path of the page. */
    private final String path;

    /** The Sone web interface. */
    protected final WebInterface webInterface;

    /**
     * Creates a new JSON page at the given path.
     *
     * @param path
     *            The path of the page
     * @param webInterface
     *            The Sone web interface
     */
    public JsonPage(String path, WebInterface webInterface) {
        this.path = path;
        this.webInterface = webInterface;
    }

    //
    // ACCESSORS
    //

    /**
     * Returns the current session, creating a new session if there is no
     * current session.
     *
     * @param toadletContenxt
     *            The toadlet context
     * @return The current session, or {@code null} if there is no current
     *         session
     */
    protected Session getCurrentSession(ToadletContext toadletContenxt) {
        return webInterface.getCurrentSession(toadletContenxt);
    }

    /**
     * Returns the current session, creating a new session if there is no
     * current session and {@code create} is {@code true}.
     *
     * @param toadletContenxt
     *            The toadlet context
     * @param create
     *            {@code true} to create a new session if there is no current
     *            session, {@code false} otherwise
     * @return The current session, or {@code null} if there is no current
     *         session
     */
    protected Session getCurrentSession(ToadletContext toadletContenxt, boolean create) {
        return webInterface.getCurrentSession(toadletContenxt, create);
    }

    /**
     * Returns the currently logged in Sone.
     *
     * @param toadletContext
     *            The toadlet context
     * @return The currently logged in Sone, or {@code null} if no Sone is
     *         currently logged in
     */
    protected Sone getCurrentSone(ToadletContext toadletContext) {
        return webInterface.getCurrentSone(toadletContext);
    }

    /**
     * Returns the currently logged in Sone.
     *
     * @param toadletContext
     *            The toadlet context
     * @param create
     *            {@code true} to create a new session if no session exists,
     *            {@code false} to not create a new session
     * @return The currently logged in Sone, or {@code null} if no Sone is
     *         currently logged in
     */
    protected Sone getCurrentSone(ToadletContext toadletContext, boolean create) {
        return webInterface.getCurrentSone(toadletContext, create);
    }

    //
    // METHODS FOR SUBCLASSES TO OVERRIDE
    //

    /**
     * This method is called to create the JSON object that is returned back to
     * the browser.
     *
     * @param request
     *            The request to handle
     * @return The created JSON object
     */
    protected abstract JsonReturnObject createJsonObject(FreenetRequest request);

    /**
     * Returns whether this command needs the form password for authentication
     * and to prevent abuse.
     *
     * @return {@code true} if the form password (given as formPassword?) is
     *         required, {@code false} otherwise
     */
    @SuppressWarnings("static-method")
    protected boolean needsFormPassword() {
        return true;
    }

    /**
     * Returns whether this page requires the user to be logged in.
     *
     * @return {@code true} if the user needs to be logged in to use this page,
     *         {@code false} otherwise
     */
    @SuppressWarnings("static-method")
    protected boolean requiresLogin() {
        return true;
    }

    //
    // PROTECTED METHODS
    //

    /**
     * Creates a success reply.
     *
     * @return A reply signaling success
     */
    protected static JsonReturnObject createSuccessJsonObject() {
        return new JsonReturnObject(true);
    }

    /**
     * Creates an error reply.
     *
     * @param error
     *            The error that has occured
     * @return The JSON object, signalling failure and the error code
     */
    protected static JsonReturnObject createErrorJsonObject(String error) {
        return new JsonErrorReturnObject(error);
    }

    //
    // PAGE METHODS
    //

    /**
     * {@inheritDoc}
     */
    @Override
    public String getPath() {
        return path;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isPrefixPage() {
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Response handleRequest(FreenetRequest request, Response response) throws IOException {
        if (webInterface.getCore().getPreferences().isRequireFullAccess()
                && !request.getToadletContext().isAllowedFullAccess()) {
            return response.setStatusCode(403).setStatusText("Forbidden").setContentType("application/json")
                    .write(objectMapper.writeValueAsString(new JsonErrorReturnObject("auth-required")));
        }
        if (needsFormPassword()) {
            String formPassword = request.getHttpRequest().getParam("formPassword");
            if (!webInterface.getFormPassword().equals(formPassword)) {
                return response.setStatusCode(403).setStatusText("Forbidden").setContentType("application/json")
                        .write(objectMapper.writeValueAsString(new JsonErrorReturnObject("auth-required")));
            }
        }
        if (requiresLogin()) {
            if (getCurrentSone(request.getToadletContext(), false) == null) {
                return response.setStatusCode(403).setStatusText("Forbidden").setContentType("application/json")
                        .write(objectMapper.writeValueAsString(new JsonErrorReturnObject("auth-required")));
            }
        }
        try {
            JsonReturnObject jsonObject = createJsonObject(request);
            return response.setStatusCode(200).setStatusText("OK").setContentType("application/json")
                    .write(objectMapper.writeValueAsString(jsonObject));
        } catch (Exception e1) {
            logger.log(Level.WARNING, "Error executing JSON page!", e1);
            return response.setStatusCode(500).setStatusText(e1.getMessage()).setContentType("text/plain")
                    .write(dumpStackTrace(e1));
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isLinkExcepted(URI link) {
        return false;
    }

    //
    // PRIVATE METHODS
    //

    /**
     * Returns a byte array containing the stack trace of the given throwable.
     *
     * @param t
     *            The throwable whose stack trace to dump into an array
     * @return The array with the stack trace, or an empty array if the stack
     *         trace could not be dumped
     */
    private static byte[] dumpStackTrace(Throwable t) {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        OutputStreamWriter writer = null;
        PrintWriter printWriter = null;
        try {
            writer = new OutputStreamWriter(byteArrayOutputStream, "uTF-8");
            printWriter = new PrintWriter(writer);
            t.printStackTrace(printWriter);
            byteArrayOutputStream.flush();
            return byteArrayOutputStream.toByteArray();
        } catch (IOException ioe1) {
            /* quite not possible. */
            return new byte[0];
        } finally {
            Closer.close(printWriter);
            Closer.close(writer);
            Closer.close(byteArrayOutputStream);
        }
    }

}