Java tutorial
/** * Copyright (C) 2011 JTalks.org Team * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * This library 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 * Lesser General Public License for more details. * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ package org.jtalks.jcommune.web.controller; import org.apache.commons.lang.time.DateFormatUtils; import org.jtalks.jcommune.service.exceptions.ImageFormatException; import org.jtalks.jcommune.service.exceptions.ImageProcessException; import org.jtalks.jcommune.service.exceptions.ImageSizeException; import org.jtalks.jcommune.plugin.api.web.dto.json.FailJsonResponse; import org.jtalks.jcommune.plugin.api.web.dto.json.JsonResponseReason; import org.jtalks.jcommune.web.util.ImageControllerUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.context.MessageSource; import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.multipart.MultipartFile; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; import java.util.HashMap; import java.util.Locale; import java.util.Map; import java.util.concurrent.TimeUnit; /** * Base class for handling uploaded images and generating preview for them */ public class ImageUploadController { /** We cannot set it to forever since avatars sometimes change, but this is a pretty rare event. */ static long AVATAR_CACHE_AGE_SEC = TimeUnit.DAYS.toSeconds(30); private MessageSource messageSource; static final String WRONG_FORMAT_RESOURCE_MESSAGE = "image.wrong.format"; static final String WRONG_SIZE_RESOURCE_MESSAGE = "image.wrong.size"; static final String COMMON_ERROR_RESOURCE_MESSAGE = "avatar.500.common.error"; protected static final String IF_MODIFIED_SINCE_HEADER = "If-Modified-Since"; static final String HTTP_HEADER_DATETIME_PATTERN = "E, dd MMM yyyy HH:mm:ss z"; private static final Logger LOGGER = LoggerFactory.getLogger(ImageUploadController.class); public ImageUploadController(MessageSource messageSource) { this.messageSource = messageSource; } /** * Handles an exception that is thrown when the image has incorrect size. * * @param e exception * @param locale locale, it's needed for error message localization * @return DTO, that contains information about error, it will be converted to JSON */ @ExceptionHandler(value = ImageSizeException.class) @ResponseBody public FailJsonResponse handleImageSizeException(ImageSizeException e, Locale locale) { Object[] parameters = new Object[] { e.getMaxSize() }; String errorMessage = messageSource.getMessage(WRONG_SIZE_RESOURCE_MESSAGE, parameters, locale); return new FailJsonResponse(JsonResponseReason.VALIDATION, errorMessage); } /** * Handles an exception that is thrown when the image has incorrect format. * * @param e exception * @param locale locale, it's needed for error message localization * @return DTO, that contains information about error, it will be converted to JSON */ @ExceptionHandler(value = ImageFormatException.class) @ResponseBody public FailJsonResponse handleImageFormatException(ImageFormatException e, Locale locale) { Object[] validImageTypes = new Object[] { e.getValidImageTypes() }; String errorMessage = messageSource.getMessage(WRONG_FORMAT_RESOURCE_MESSAGE, validImageTypes, locale); return new FailJsonResponse(JsonResponseReason.VALIDATION, errorMessage); } /** * Handles common exception that can occur when loading an image. * * @param e exception * @param locale locale, it's needed for error message localization * @return DTO, that contains information about error, it will be converted to JSON */ @ExceptionHandler(value = ImageProcessException.class) @ResponseBody public FailJsonResponse handleImageProcessException(ImageProcessException e, Locale locale) { String errorMessage = messageSource.getMessage(COMMON_ERROR_RESOURCE_MESSAGE, null, locale); return new FailJsonResponse(JsonResponseReason.INTERNAL_SERVER_ERROR, errorMessage); } /** * Gets service for resolving messages * * @return service for resolving messages */ public MessageSource getMessageSource() { return messageSource; } /** * Sets up avatar cache related headers. * * @param response - HTTP response object where set headers * @param avatarLastModificationTime - last modification time of avatar */ protected void setupAvatarHeaders(HttpServletResponse response, Date avatarLastModificationTime) { response.setHeader("Pragma", "public"); response.setDateHeader("Expires", System.currentTimeMillis() + AVATAR_CACHE_AGE_SEC * 1000); response.setHeader("Cache-Control", "public"); response.addHeader("Cache-Control", "max-age=" + AVATAR_CACHE_AGE_SEC); String formattedDateLastModified = DateFormatUtils.format(avatarLastModificationTime, HTTP_HEADER_DATETIME_PATTERN, Locale.US); response.setHeader("Last-Modified", formattedDateLastModified); } /** * Check 'If-Modified-Since' header in the request and converts it to * {@link java.util.Date} representation * * @param ifModifiedSinceHeader - value of 'If-Modified-Since' header in * string form * @return If-Modified-Since header or Jan 1, 1970 if it is not set or * can't be parsed */ public Date getIfModifiedSinceDate(String ifModifiedSinceHeader) { Date ifModifiedSinceDate = new Date(0); if (ifModifiedSinceHeader != null) { try { DateFormat dateFormat = new SimpleDateFormat(HTTP_HEADER_DATETIME_PATTERN, Locale.US); ifModifiedSinceDate = dateFormat.parse(ifModifiedSinceHeader); } catch (ParseException e) { LOGGER.error("Failed to parse value of 'If-Modified-Since' header from string form.", e); } } return ifModifiedSinceDate; } /** * Gets uploaded image and generates preview to send back to the client * * @param file file, that contains uploaded image * @param imageControllerUtils object for processing the image * @return generated preview of the uploaded image * @throws IOException * @throws ImageProcessException */ protected ResponseEntity<String> createPreviewOfImage(MultipartFile file, ImageControllerUtils imageControllerUtils) throws IOException, ImageProcessException { HttpHeaders responseHeaders = new HttpHeaders(); responseHeaders.setContentType(MediaType.TEXT_HTML); Map<String, String> responseContent = new HashMap<>(); return imageControllerUtils.prepareResponse(file, responseHeaders, responseContent); } /** * Gets uploaded image and generates preview to send back to the client * * @param imageBytes content of the uploaded image * @param response HTTP response * @param imageControllerUtils object for processing the image * @return generated preview of the uploaded image * @throws ImageProcessException */ protected Map<String, String> createPreviewOfImage(byte[] imageBytes, HttpServletResponse response, ImageControllerUtils imageControllerUtils) throws ImageProcessException { Map<String, String> responseContent = new HashMap<>(); imageControllerUtils.prepareResponse(imageBytes, response, responseContent); return responseContent; } }