az.soak.RemoteElement.java Source code

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Here is the source code for az.soak.RemoteElement.java

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/*******************************************************************************
 * Copyright (c) 2012, Andrzej Zawadzki (azawadzki@gmail.com)
 *  
 * soak 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 2 of the License, or
 * (at your option) any later version.
 *  
 * soak 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 soak; if not, see <http ://www.gnu.org/licenses/>.
 ******************************************************************************/
package az.soak;

import java.io.IOException;

import org.json.simple.JSONValue;

/** RemoteElement is the base class for all elements fetched from SpiderOak server.
 * When working with RemoteElement instances you must strictly follow one rule: in order
 * to access object data other than name and URL, you must call loadData() method first.
 * This paradigm ensures that data is loaded only when needed. If that wouldn't be the
 * case, when iterating over directories you would need to implicitly load all file
 * data killing your application's performance.
 */
abstract class RemoteElement {

    RemoteElement(RemoteElement parent, String name, String urlComponent) {
        mConnectionHandler = (parent != null) ? parent.mConnectionHandler : null;
        mParent = parent;
        mName = name;
        mUrlComponent = urlComponent;
    }

    public void loadData() throws BadLoginException, IOException {
        if (containsLoadableContent() && !isFullyLoaded()) {
            String data = performGet(getUrl());
            initWithData(JSONValue.parse(data));
            mFullyLoaded = true;
        }
    }

    /** Get parent of current element
     * @return Reference to parent element or null in case of top-level elements.
     */
    public RemoteElement getParent() {
        return mParent;
    }

    /** Get URL of current element. The URL can be used to download the element with ConnectionHandler.
     * @return URL of the element.
     */
    public String getUrl() {
        return prepareAbsolutePath(new StringBuilder()).toString();
    }

    /** Get name of the element (e.g. filename, dirname, device name).
     * @return Name of the element.
     */
    public String getName() {
        return mName;
    }

    /** Get ConnectionHandler which is used for fetching the element data.
     * @return ConnectionHandler which is used for fetching the element data.
     */
    public ConnectionHandler getConnectionHandler() {
        return mConnectionHandler;
    }

    /** Assign ConnectionHandler which is used for fetching the element data. This method can be used
     * to change connection handler in case e.g. a file should be downloaded by specialized class.
     * @param connectionHandler ConnectionHandler which is used for fetching the element data. 
     */
    public void setConnectionHandler(ConnectionHandler connectionHandler) {
        mConnectionHandler = connectionHandler;
    }

    /** Check if the element has been fully initialized with loadData() method so that all
     * of its getters can be called. In case the element was not fully loaded, usually only
     * name and URL can be accessed.
     * @return Flag which stated whether all of the element data is fully available or not.
     */
    public boolean isFullyLoaded() {
        return mFullyLoaded;
    }

    /** Method used to initialize the object with data fetched from server. The data is provided
     * in the form of JSON ojectTree.
     * @param objectTree JSON data with which the object should be initialized.
     */
    abstract protected void initWithData(Object objectTree);

    protected boolean containsLoadableContent() {
        return true;
    }

    protected StringBuilder prepareAbsolutePath(StringBuilder builder) {
        if (mParent != null) {
            mParent.prepareAbsolutePath(builder);
        }
        builder.append(mUrlComponent);
        return builder;
    }

    protected String performGet(String address) throws BadLoginException, IOException {
        return performRequest(address, "GET");
    }

    protected String performPost(String address) throws BadLoginException, IOException {
        return performRequest(address, "POST");
    }

    private String performRequest(String address, String method) throws BadLoginException, IOException {
        return mConnectionHandler.performRequest(address, method);
    }

    private RemoteElement mParent;
    private String mUrlComponent;
    private String mName;
    private ConnectionHandler mConnectionHandler;
    private boolean mFullyLoaded;
}