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.StringUtils; import org.jtalks.jcommune.model.entity.*; import org.jtalks.jcommune.service.*; import org.jtalks.jcommune.plugin.api.exceptions.NotFoundException; import org.jtalks.jcommune.service.dto.EntityToDtoConverter; import org.jtalks.jcommune.service.nontransactional.BBCodeService; import org.jtalks.jcommune.service.nontransactional.LocationService; import org.jtalks.jcommune.plugin.api.web.dto.PostDto; import org.jtalks.jcommune.plugin.api.web.dto.PostDraftDto; import org.jtalks.jcommune.plugin.api.web.dto.TopicDto; import org.jtalks.jcommune.plugin.api.web.dto.json.JsonResponse; import org.jtalks.jcommune.plugin.api.web.dto.json.JsonResponseStatus; import org.jtalks.jcommune.plugin.api.web.util.BreadcrumbBuilder; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.propertyeditors.StringTrimmerEditor; import org.springframework.data.domain.Page; import org.springframework.retry.RetryCallback; import org.springframework.retry.RetryContext; import org.springframework.retry.support.RetryTemplate; import org.springframework.stereotype.Controller; import org.springframework.validation.BindingResult; import org.springframework.web.bind.WebDataBinder; import org.springframework.web.bind.annotation.*; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.mvc.support.RedirectAttributes; import org.springframework.web.util.WebUtils; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; import javax.validation.Valid; /** * Controller for post-related actions * * @author Pavel Vervenko * @author Osadchuck Eugeny * @author Kravchenko Vitaliy * @author Kirill Afonin * @author Alexandre Teterin * @author Evgeniy Naumenko * @author Andrey Ivanov */ @Controller public class PostController { public static final String TOPIC_ID = "topicId"; public static final String POST_ID = "postId"; public static final String POST_DTO = "postDto"; public static final String TOPIC_TITLE = "topicTitle"; public static final String BREADCRUMB_LIST = "breadcrumbList"; private static final Logger LOGGER = LoggerFactory.getLogger(PostController.class); private PostService postService; private LastReadPostService lastReadPostService; private BreadcrumbBuilder breadcrumbBuilder; private TopicFetchService topicFetchService; private TopicModificationService topicModificationService; private BBCodeService bbCodeService; private UserService userService; private LocationService locationService; private EntityToDtoConverter converter; private RetryTemplate retryTemplate; /** * This method turns the trim binder on. Trim binder * removes leading and trailing spaces from the submitted fields. * So, it ensures, that all validations will be applied to * trimmed field values only. * * @param binder Binder object to be injected */ @InitBinder public void initBinder(WebDataBinder binder) { binder.registerCustomEditor(String.class, new StringTrimmerEditor(true)); } /** * @param postService {@link PostService} instance to be injected * @param breadcrumbBuilder the object which provides actions on {@link BreadcrumbBuilder} entity * @param topicFetchService to retrieve topics from a database * @param topicModificationService to update topics with new posts * @param bbCodeService to create valid quotes * @param lastReadPostService not to track user posts as updates for himself * @param userService to get the current user information * @param converter instance of {@link EntityToDtoConverter} needed to * obtain link to the topic * @param retryTemplate retry mechanism */ @Autowired public PostController(PostService postService, BreadcrumbBuilder breadcrumbBuilder, TopicFetchService topicFetchService, TopicModificationService topicModificationService, BBCodeService bbCodeService, LastReadPostService lastReadPostService, UserService userService, LocationService locationService, EntityToDtoConverter converter, RetryTemplate retryTemplate) { this.postService = postService; this.breadcrumbBuilder = breadcrumbBuilder; this.topicFetchService = topicFetchService; this.topicModificationService = topicModificationService; this.bbCodeService = bbCodeService; this.lastReadPostService = lastReadPostService; this.userService = userService; this.locationService = locationService; this.converter = converter; this.retryTemplate = retryTemplate; } /** * Delete post by given id * * @param postId post * @return redirect to post next to deleted one. Redirects to previous post in case if it's last post in topic. * @throws NotFoundException when post was not found */ @RequestMapping(method = RequestMethod.DELETE, value = "/posts/{postId}") public ModelAndView delete(@PathVariable(POST_ID) final Long postId) throws NotFoundException { final Post post = this.postService.get(postId); Post nextPost = post.getTopic().getNeighborPost(post); retryTemplate.execute(new RetryCallback<Object, NotFoundException>() { @Override public Object doWithRetry(RetryContext context) throws NotFoundException { Post post = postService.get(postId); postService.deletePost(post); return null; } }); return new ModelAndView("redirect:/posts/" + nextPost.getId()); } /** * Edit post page filled with data from post with given id * * @param postId post id * @return redirect to post form page * @throws NotFoundException when topic or post not found */ @RequestMapping(value = "/posts/{postId}/edit", method = RequestMethod.GET) public ModelAndView editPage(@PathVariable(POST_ID) Long postId) throws NotFoundException { Post post = postService.get(postId); return new ModelAndView("topic/editPost").addObject(POST_DTO, PostDto.getDtoFor(post)) .addObject(TOPIC_ID, post.getTopic().getId()).addObject(POST_ID, postId) .addObject(TOPIC_TITLE, post.getTopic().getTitle()) .addObject("breadcrumbList", breadcrumbBuilder.getForumBreadcrumb(post.getTopic())); } /** * Update existing post * * @param postDto Dto populated in form * @param result validation result * @param postId the current postId * @return {@code ModelAndView} object which will be redirect to topic page * if saved successfully or show form with error message * @throws NotFoundException when topic, branch or post not found */ @RequestMapping(value = "/posts/{postId}/edit", method = RequestMethod.POST) public ModelAndView update(@Valid @ModelAttribute PostDto postDto, BindingResult result, @PathVariable(POST_ID) Long postId) throws NotFoundException { Post post = postService.get(postId); if (result.hasErrors()) { return new ModelAndView("topic/editPost").addObject(TOPIC_ID, post.getTopic().getId()) .addObject(POST_ID, postId); } postService.updatePost(post, postDto.getBodyText()); return new ModelAndView("redirect:/posts/" + postId); } /** * Get quote text. * If user select nothing JS will substitute whole post contents here * <p/> * Supports post method to pass large quotations. * * @param postId identifier os the post we're quoting * @param selection text selected by user for the quotation * @throws NotFoundException when topic was not found */ @RequestMapping(method = RequestMethod.POST, value = "/posts/{postId}/quote") @ResponseBody public JsonResponse getQuote(@PathVariable(POST_ID) Long postId, @RequestParam("selection") String selection) throws NotFoundException { Post source = postService.get(postId); String content = StringUtils.defaultString(selection, source.getPostContent()); return new JsonResponse(JsonResponseStatus.SUCCESS, bbCodeService.quote(content, source.getUserCreated())); } /** * Process the reply form. Adds new post to the specified topic and redirects to the * topic view page. * * @param postDto dto that contains data entered in form * @param result validation result * @return redirect to the topic or back to answer pae if validation failed * @throws NotFoundException when topic or branch not found */ @RequestMapping(method = RequestMethod.POST, value = "/topics/{topicId}") // public ModelAndView create(@RequestParam(value = "page", defaultValue = "1", required = false) String page, @PathVariable(TOPIC_ID) Long topicId, @Valid @ModelAttribute final PostDto postDto, BindingResult result, RedirectAttributes attr) throws NotFoundException { postDto.setTopicId(topicId); if (result.hasErrors()) { attr.addFlashAttribute("postDto", postDto); return new ModelAndView("redirect:/topics/error/" + topicId + "?page=" + page); } final Topic topic = topicFetchService.get(topicId); final long branchId = topic.getBranch().getId(); Post newbie = retryTemplate.execute(new RetryCallback<Post, NotFoundException>() { @Override public Post doWithRetry(RetryContext context) throws NotFoundException { return topicModificationService.replyToTopic(postDto.getTopicId(), postDto.getBodyText(), branchId); } }); lastReadPostService.markTopicAsRead(newbie.getTopic()); return new ModelAndView(this.redirectToPageWithPost(newbie.getId())); } /** * Gets validation errors from 'create' methods to redirect them to the view. We need it * to implement POST/redirect/GET pattern, which leads to preventing of repeating POST request * on browser refresh. * * @param page page of the current post * @param topicId ID of a topic * @param postDto Dto with failed validation * @param result validation result * * @return {@code ModelAndView} object which shows form with an error message * @throws NotFoundException when topic, branch or post not found */ @RequestMapping(method = RequestMethod.GET, value = "/topics/error/{topicId}") public ModelAndView errorRedirect(@RequestParam(value = "page", required = false) String page, @PathVariable(TOPIC_ID) Long topicId, @ModelAttribute @Valid PostDto postDto, BindingResult result) throws NotFoundException { JCUser currentUser = userService.getCurrentUser(); Topic topic = topicFetchService.get(topicId); PostDraft draft = topic.getDraftForUser(currentUser); if (draft != null) { // If we create new dto object instead of using already existing // we lose error messages linked with it postDto.fillFrom(draft); } postDto.setTopicId(topicId); Page<Post> postsPage = postService.getPosts(topic, page); return new ModelAndView("topic/postList").addObject("viewList", locationService.getUsersViewing(topic)) .addObject("postsPage", postsPage).addObject("topic", topic).addObject(POST_DTO, postDto) .addObject("subscribed", topic.getSubscribers().contains(currentUser)) .addObject(BREADCRUMB_LIST, breadcrumbBuilder.getForumBreadcrumb(topic)); } /** * Redirects user to the topic view with the appropriate page selected. * Method clients should not wary about paging at all, post id * is enough to be transferred to the proper page. * * If post belongs to plugable topic and appropriated plugin is enabled redirects * to plugable topic view. * * @param postId unique post identifier * @return redirect view to the certain topic page * @throws NotFoundException is the is no post for the identifier given */ @RequestMapping(method = RequestMethod.GET, value = "/posts/{postId}") public String redirectToPageWithPost(@PathVariable Long postId) throws NotFoundException { Post post = postService.get(postId); int page = postService.calculatePageForPost(post); String topicUrl = converter.convertTopicToDto(post.getTopic()).getTopicUrl(); return "redirect:" + topicUrl + "?page=" + page + "#" + postId; } /** * Converts post with bb codes to HTML for client-side * preview in bbEditor * * @param postDto Current post dto * @param result Spring MVC binding result * @return HTML content for post * @throws Exception */ @RequestMapping(method = RequestMethod.POST, value = "/posts/bbToHtml") public ModelAndView preview(@Valid @ModelAttribute PostDto postDto, BindingResult result) throws Exception { return getPreviewModelAndView(result).addObject("content", postDto.getBodyText()); } /** * Converts topic with bb codes to HTML for client-side * preview in bbEditor * * @param topicDto Current topic dto * @param result Spring MVC binding result * @return HTML content for topic * @throws Exception */ @RequestMapping(method = RequestMethod.POST, value = "/topics/bbToHtml") public ModelAndView preview(@Valid @ModelAttribute TopicDto topicDto, BindingResult result) throws Exception { return getPreviewModelAndView(result).addObject("content", topicDto.getBodyText()); } /** * Votes up for post with specified id * * @param postId id of a post to vote up * @param request HttpServletRequest * * @return response in JSON format * * @throws NotFoundException if post with specified id not found */ @RequestMapping(method = RequestMethod.GET, value = "/posts/{postId}/voteup") @ResponseBody public JsonResponse voteUp(@PathVariable Long postId, HttpServletRequest request) throws NotFoundException { PostVote vote = new PostVote(true); voteWithSessionLocking(postId, vote, request); return new JsonResponse(JsonResponseStatus.SUCCESS); } /** * Votes down for post with specified id * * @param postId id of a post to vote down * @param request HttpServletRequest * * @return response in JSON format * * @throws NotFoundException if post with specified id not found */ @RequestMapping(method = RequestMethod.GET, value = "/posts/{postId}/votedown") @ResponseBody public JsonResponse voteDown(@PathVariable Long postId, HttpServletRequest request) throws NotFoundException { PostVote vote = new PostVote(false); voteWithSessionLocking(postId, vote, request); return new JsonResponse(JsonResponseStatus.SUCCESS); } /** * Saves new draft or update if it already exist * * @param postDraftDto post draft dto populated in form * @param result validation result * * @return response in JSON format * * @throws NotFoundException if topic to store draft not exist */ @RequestMapping(value = "/posts/savedraft", method = RequestMethod.POST) @ResponseBody public JsonResponse saveDraft(@Valid @RequestBody PostDraftDto postDraftDto, BindingResult result) throws NotFoundException { if (result.hasErrors()) { return new JsonResponse(JsonResponseStatus.FAIL); } Topic topic = topicFetchService.getTopicSilently(postDraftDto.getTopicId()); PostDraft saved = postService.saveOrUpdateDraft(topic, postDraftDto.getBodyText()); return new JsonResponse(JsonResponseStatus.SUCCESS, saved.getId()); } /** * Deletes draft * * @param draftId id of draft to delete * * @return response in JSON format * * @throws NotFoundException if post with specified id not exist */ @RequestMapping(value = "drafts/{draftId}/delete", method = RequestMethod.GET) @ResponseBody public JsonResponse deleteDraft(@PathVariable Long draftId) throws NotFoundException { postService.deleteDraft(draftId); return new JsonResponse(JsonResponseStatus.SUCCESS); } /** * Prepare ModelAndView for showing preview * * @return prepared ModelAndView for preview */ private ModelAndView getPreviewModelAndView(BindingResult result) { return new ModelAndView("ajax/postPreview").addObject("isInvalid", result.hasFieldErrors("bodyText")) .addObject("errors", result.getFieldErrors("bodyText")); } /** * Performs vote with session locking to prevent handling of concurrent requests from same user * * @param postId id of a post to vote * @param vote {@link PostVote} object * @param request HttpServletRequest * * @throws NotFoundException if post with specified id not found */ private void voteWithSessionLocking(Long postId, PostVote vote, HttpServletRequest request) throws NotFoundException { /** * We should not create session here to prevent possibility of creating multiplier sessions for same user in * concurrent requests */ HttpSession session = request.getSession(false); if (session != null) { Object mutex = WebUtils.getSessionMutex(session); /** * Next operations performed in synchronized block to prevent handling of concurrent requests from same * user. We use session mutex as the lock object. In many cases, the HttpSession reference itself is a safe * mutex as well, since it will always be the same object reference for the same active logical session. * However, this is not guaranteed across different servlet containers; the only 100% safe way is a session * mutex. */ synchronized (mutex) { Post post = postService.get(postId); postService.vote(post, vote); } } else { /** * If <code>HttpSession</code> is <code>null</code> we have no mutex object, so we perform operations * without synchronization */ Post post = postService.get(postId); postService.vote(post, vote); } } }