au.com.iglooit.shar.servlet.FileServlet.java Source code

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Here is the source code for au.com.iglooit.shar.servlet.FileServlet.java

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/*
 * Copyright (c) 2012 Google Inc.
 *
 * 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 au.com.iglooit.shar.servlet;

import au.com.iglooit.shar.model.vo.ClientFile;
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.ByteArrayContent;
import com.google.api.client.http.GenericUrl;
import com.google.api.client.http.HttpResponse;
import com.google.api.client.repackaged.org.apache.commons.codec.binary.Base64;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.model.File;
import org.apache.commons.lang.StringUtils;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Scanner;
import java.util.UUID;

/**
 * Servlet providing a small API for the DrEdit JavaScript client to use in
 * manipulating files.  Each operation (GET, POST, PUT) issues requests to the
 * Google Drive API.
 *
 * @author vicfryzel@google.com (Vic Fryzel)
 */
@SuppressWarnings("serial")
public class FileServlet extends DrEditServlet {
    /**
     * Given a {@code file_id} URI parameter, return a JSON representation
     * of the given file.
     */
    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        Drive service = getDriveService(getCredential(req, resp));
        String fileId = req.getParameter("file_id");

        if (fileId == null) {
            sendError(resp, 400, "The `file_id` URI parameter must be specified.");
            return;
        }

        File file = null;
        try {
            file = service.files().get(fileId).execute();
        } catch (GoogleJsonResponseException e) {
            if (e.getStatusCode() == 401) {
                // The user has revoked our token or it is otherwise bad.
                // Delete the local copy so that their next page load will recover.
                deleteCredential(req, resp);
                sendGoogleJsonResponseError(resp, e);
                return;
            }
        }

        if (file != null) {
            String content = downloadFileContent(service, file);
            if (content == null) {
                content = "";
            }
            sendJson(resp, new ClientFile(file, content));
        } else {
            sendError(resp, 404, "File not found");
        }
    }

    /**
     * Create a new file given a JSON representation, and return the JSON
     * representation of the created file.
     */
    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.setHeader("Access-Control-Allow-Origin", "*");
        Drive service = getDriveService(getDefaultCredential(req, resp));
        ClientFile clientFile = new ClientFile(req.getReader());
        File file = clientFile.toFile();

        byte[] imageData = Base64.decodeBase64(clientFile.content);
        ByteArrayContent byteArrayContent = new ByteArrayContent(clientFile.mimeType, imageData);

        if (!clientFile.content.equals("")) {
            if (StringUtils.isBlank(file.getId())) {
                file = service.files().insert(file, byteArrayContent).execute();
            } else {
                file = service.files().update(file.getId(), file, byteArrayContent).execute();
            }
        } else {
            if (StringUtils.isBlank(file.getId())) {
                file = service.files().insert(file).execute();
            } else {
                file = service.files().update(file.getId(), file).execute();
            }
        }
        sendJson(resp, file.getId());
    }

    /**
     * Update a file given a JSON representation, and return the JSON
     * representation of the created file.
     */
    @Override
    public void doPut(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        boolean newRevision = req.getParameter("newRevision").equals(Boolean.TRUE);
        Drive service = getDriveService(getDefaultCredential(req, resp));
        ClientFile clientFile = new ClientFile(req.getReader());
        File file = clientFile.toFile();
        // If there is content we update the given file
        if (clientFile.content != null) {
            file = service.files()
                    .update(clientFile.resourceId, file,
                            ByteArrayContent.fromString(clientFile.mimeType, clientFile.content))
                    .setNewRevision(newRevision).execute();
        } else { // If there is no content we patch the metadata only
            file = service.files().patch(clientFile.resourceId, file).setNewRevision(newRevision).execute();
        }
        sendJson(resp, file.getId());
    }

    /**
     * Download the content of the given file.
     *
     * @param service Drive service to use for downloading.
     * @param file    File metadata object whose content to download.
     * @return String representation of file content.  String is returned here
     *         because this app is setup for text/plain files.
     * @throws java.io.IOException Thrown if the request fails for whatever reason.
     */
    private String downloadFileContent(Drive service, File file) throws IOException {
        GenericUrl url = new GenericUrl(file.getDownloadUrl());
        HttpResponse response = service.getRequestFactory().buildGetRequest(url).execute();
        try {
            return new Scanner(response.getContent()).useDelimiter("\\A").next();
        } catch (java.util.NoSuchElementException e) {
            return "";
        }
    }

    @Override
    protected void doOptions(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // pre-flight request processing
        resp.setHeader("Access-Control-Allow-Origin", "*");
        resp.setHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
        resp.setHeader("Access-Control-Allow-Headers", "Content-Type");
    }

}