Reddit應用第三次改進版本

REST,Spring
Remote
0
06:00 PM · Dec 01 ,2025

1. 概述

在本文中，我們將繼續推進我們的小型案例研究應用程序，通過實施對現有功能的少量但有用的改進。

2. Better Tables

Let’s start by using the jQuery DataTables plugin to replace the old, basic tables the app was using before.

2.1. Post Repository and Service

First, we’ll add a method to count the scheduled posts of a user – leveraging the Spring Data syntax of course:

public interface PostRepository extends JpaRepository<Post, Long> {
    ...
    Long countByUser(User user);
}

Next, let’s take a quick look at the service layer implementation – retrieving the posts of a user based on pagination parameters:

@Override
public List<SimplePostDto> getPostsList(int page, int size, String sortDir, String sort) {
    PageRequest pageReq = new PageRequest(page, size, Sort.Direction.fromString(sortDir), sort);
    Page<Post> posts = postRepository.findByUser(userService.getCurrentUser(), pageReq);
    return constructDataAccordingToUserTimezone(posts.getContent());
}

We’re converting the dates based on the timezone of the user:

private List<SimplePostDto> constructDataAccordingToUserTimezone(List<Post> posts) {
    String timeZone = userService.getCurrentUser().getPreference().getTimezone();
    return posts.stream().map(post -> new SimplePostDto(
      post, convertToUserTomeZone(post.getSubmissionDate(), timeZone)))
      .collect(Collectors.toList());
}
private String convertToUserTomeZone(Date date, String timeZone) { 
    dateFormat.setTimeZone(TimeZone.getTimeZone(timeZone)); 
    return dateFormat.format(date); 
}

2.2. The API With Pagination

Next, we’re going to publish this operation with full pagination and sorting, via the API:

@RequestMapping(method = RequestMethod.GET)
@ResponseBody
public List<SimplePost> getScheduledPosts(
  @RequestParam(value = "page", required = false, defaultValue = "0") int page, 
  @RequestParam(value = "size", required = false, defaultValue = "10") int size,
  @RequestParam(value = "sortDir", required = false, defaultValue = "asc") String sortDir, 
  @RequestParam(value = "sort", required = false, defaultValue = "title") String sort, 
  HttpServletResponse response) {
    response.addHeader("PAGING_INFO", 
      scheduledPostService.generatePagingInfo(page, size).toString());
    return scheduledPostService.getPostsList(page, size, sortDir, sort);
}

Note how we’re using a custom header to pass the pagination info to the client. There are other, slightly more standard ways to do this – ways we might explore later.

This implementation however is simply enough – we have a simple method to generate paging information:

public PagingInfo generatePagingInfo(int page, int size) {
    long total = postRepository.countByUser(userService.getCurrentUser());
    return new PagingInfo(page, size, total);
}

And the PagingInfo itself:

public class PagingInfo {
    private long totalNoRecords;
    private int totalNoPages;
    private String uriToNextPage;
    private String uriToPrevPage;

    public PagingInfo(int page, int size, long totalNoRecords) {
        this.totalNoRecords = totalNoRecords;
        this.totalNoPages = Math.round(totalNoRecords / size);
        if (page > 0) {
            this.uriToPrevPage = "page=" + (page - 1) + "&size=" + size;
        }
        if (page < this.totalNoPages) {
            this.uriToNextPage = "page=" + (page + 1) + "&size=" + size;
        }
    }
}

2.3. Front End

Finally, the simple front-end will use a custom JS method to interact with the API and handle the jQuery DataTable parameters:

<table>
<thead><tr>
<th>Post title</th><th>Submission Date</th><th>Status</th>
<th>Resubmit Attempts left</th><th>Actions</th>
</tr></thead>   
</table>

<script>
$(document).ready(function() {
    $('table').dataTable( {
        "processing": true,
        "searching":false,
        "columnDefs": [
            { "name": "title", "targets": 0 },
            { "name": "submissionDate", "targets": 1 },
            { "name": "submissionResponse", "targets": 2 },
            { "name": "noOfAttempts", "targets": 3 } ],
        "columns": [
            { "data": "title" },
            { "data": "submissionDate" },
            { "data": "submissionResponse" },
            { "data": "noOfAttempts" }],
        "serverSide": true,
        "ajax": function(data, callback, settings) {
            $.get('api/scheduledPosts', {
              size: data.length,
              page: (data.start/data.length),
              sortDir: data.order[0].dir,
              sort: data.columns[data.order[0].column].name
              }, function(res,textStatus, request) {
                var pagingInfo = request.getResponseHeader('PAGING_INFO');
                var total = pagingInfo.split(",")[0].split("=")[1];
                callback({recordsTotal: total, recordsFiltered: total,data: res});
              });
          }
    } );
} );
</script>

2.4. API Testing for Paging

With the API now published, we can write a few simple API tests to make sure the basics of the paging mechanism work as expected:

@Test
public void givenMoreThanOnePage_whenGettingUserScheduledPosts_thenNextPageExist() 
  throws ParseException, IOException {
    createPost();
    createPost();
    createPost();

    Response response = givenAuth().
      params("page", 0, "size", 2).get(urlPrefix + "/api/scheduledPosts");

    assertEquals(200, response.statusCode());
    assertTrue(response.as(List.class).size() > 0);

    String pagingInfo = response.getHeader("PAGING_INFO");
    long totalNoRecords = Long.parseLong(pagingInfo.split(",")[0].split("=")[1]);
    String uriToNextPage = pagingInfo.split(",")[2].replace("uriToNextPage=", "").trim();

    assertTrue(totalNoRecords > 2);
    assertEquals(uriToNextPage, "page=1&size=2");
}

@Test
public void givenMoreThanOnePage_whenGettingUserScheduledPostsForSecondPage_thenCorrect() 
  throws ParseException, IOException {
    createPost();
    createPost();
    createPost();

    Response response = givenAuth().
      params("page", 1, "size", 2).get(urlPrefix + "/api/scheduledPosts");

    assertEquals(200, response.statusCode());
    assertTrue(response.as(List.class).size() > 0);

    String pagingInfo = response.getHeader("PAGING_INFO");
    long totalNoRecords = Long.parseLong(pagingInfo.split(",")[0].split("=")[1]);
    String uriToPrevPage = pagingInfo.split(",")[3].replace("uriToPrevPage=", "").trim();

    assertTrue(totalNoRecords > 2);
    assertEquals(uriToPrevPage, "page=0&size=2");
}

3. 電子郵件通知

接下來，我們將構建一個基本的電子郵件通知流程——當用户計劃發佈的帖子被髮送時，他們會收到電子郵件：

3.1. 電子郵件配置

首先，讓我們進行電子郵件配置：

@Bean
public JavaMailSenderImpl javaMailSenderImpl() {
    JavaMailSenderImpl mailSenderImpl = new JavaMailSenderImpl();
    mailSenderImpl.setHost(env.getProperty("smtp.host"));
    mailSenderImpl.setPort(env.getProperty("smtp.port", Integer.class));
    mailSenderImpl.setProtocol(env.getProperty("smtp.protocol"));
    mailSenderImpl.setUsername(env.getProperty("smtp.username"));
    mailSenderImpl.setPassword(env.getProperty("smtp.password"));
    Properties javaMailProps = new Properties();
    javaMailProps.put("mail.smtp.auth", true);
    javaMailProps.put("mail.smtp.starttls.enable", true);
    mailSenderImpl.setJavaMailProperties(javaMailProps);
    return mailSenderImpl;
}

以及用於使 SMTP 正常工作所需的必要屬性：

smtp.host=email-smtp.us-east-1.amazonaws.com
smtp.port=465
smtp.protocol=smtps
smtp.username=example
smtp.password=
[email protected]

3.2. 在發佈帖子時觸發事件

現在，讓我們確保在計劃發佈的帖子成功發佈到 Reddit 時觸發事件：

private void updatePostFromResponse(JsonNode node, Post post) {
    JsonNode errorNode = node.get("json").get("errors").get(0);
    if (errorNode == null) {
        ...
        String email = post.getUser().getPreference().getEmail();
        eventPublisher.publishEvent(new OnPostSubmittedEvent(post, email));
    } 
    ...
}

3.3. 事件和監聽器

事件實現相當簡單：

public class OnPostSubmittedEvent extends ApplicationEvent {
    private Post post;
    private String email;

    public OnPostSubmittedEvent(Post post, String email) {
        super(post);
        this.post = post;
        this.email = email;
    }
}

以及監聽器：

@Component
public class SubmissionListner implements ApplicationListener<OnPostSubmittedEvent> {
    @Autowired
    private JavaMailSender mailSender;

    @Autowired
    private Environment env;

    @Override
    public void onApplicationEvent(OnPostSubmittedEvent event) {
        SimpleMailMessage email = constructEmailMessage(event);
        mailSender.send(email);
    }

    private SimpleMailMessage constructEmailMessage(OnPostSubmittedEvent event) {
        String recipientAddress = event.getEmail();
        String subject = "Your scheduled post submitted";
        SimpleMailMessage email = new SimpleMailMessage();
        email.setTo(recipientAddress);
        email.setSubject(subject);
        email.setText(constructMailContent(event.getPost()));
        email.setFrom(env.getProperty("support.email"));
        return email;
    }

    private String constructMailContent(Post post) {
        return "Your post " + post.getTitle() + " is submitted.\n" +
          "http://www.reddit.com/r/" + post.getSubreddit() +
          "/comments/" + post.getRedditID();
    }
}

4. 使用總投票數

接下來，我們將簡化提交選項，不再使用投票比例（由於其難以理解）——現在我們使用總投票數。

我們可以使用帖子分數和投票比例計算總投票數:

  • 分數 = 投票數 - 投降數
  • 總投票數 = 投票數 + 投降數
  • 投票比例 = 投票數/總投票數

因此:

總投票數 = Math.round( 分數 / ((2 * 投票比例) - 1))

首先，我們將修改分數邏輯以計算和跟蹤總投票數:

public PostScores getPostScores(Post post) {
    ...

    float ratio = node.get("upvote_ratio").floatValue();
    postScore.setTotalVotes(Math.round(postScore.getScore() / ((2 * ratio) - 1)));
    
    ...
}

當然，我們還會利用它來檢查帖子是否被認為失敗:

private boolean didPostGoalFail(Post post) {
    PostScores postScores = getPostScores(post);
    int totalVotes = postScores.getTotalVotes();
    ...
    return (((score < post.getMinScoreRequired()) || 
            (totalVotes < post.getMinTotalVotes())) && 
            !((noOfComments > 0) && post.isKeepIfHasComments()));
}

最後，我們當然會移除舊的 ratio 字段的使用。

5. Validate Resubmit Options

Finally, we will help the user by adding some validations to the complex resubmit options:

5.1. ScheduledPost Servicestrongtranslate

Here is the simple checkIfValidResubmitOptions() method:

private boolean checkIfValidResubmitOptions(Post post) {
    if (checkIfAllNonZero(
          post.getNoOfAttempts(), 
          post.getTimeInterval(), 
          post.getMinScoreRequired())) {
        return true;
    } else {
        return false;
    }
}
private boolean checkIfAllNonZero(int... args) {
    for (int tmp : args) {
       if (tmp == 0) {
           return false;
        }
    }
    return true;
}

We’ll make good use of this validation when scheduling a new post:

public Post schedulePost(boolean isSuperUser, Post post, boolean resubmitOptionsActivated) 
  throws ParseException {
    if (resubmitOptionsActivated && !checkIfValidResubmitOptions(post)) {
        throw new InvalidResubmitOptionsException("Invalid Resubmit Options");
    }
    ...        
}

Note that if the resubmit logic is on – the following fields need to have non-zero values:

  • Number of attempts
  • Time interval
  • Minimum score required

5.2. Exception Handling

Finally – in case of invalid input, the InvalidResubmitOptionsException is handled in our main error handling logic:

@ExceptionHandler({ InvalidResubmitOptionsException.class })
public ResponseEntity<Object> handleInvalidResubmitOptions
  (RuntimeException ex, WebRequest request) {
    
    logger.error("400 Status Code", ex);
    String bodyOfResponse = ex.getLocalizedMessage();
    return new ResponseEntity<Object>(
      bodyOfResponse, new HttpHeaders(), HttpStatus.BAD_REQUEST);
}

5.3. Test Resubmit Options

Finally, let’s now test our resubmit options – we will test both activating and deactivating conditions:

public class ResubmitOptionsLiveTest extends AbstractLiveTest {
    private static final String date = "2016-01-01 00:00";

    @Test
    public void 
      givenResubmitOptionsDeactivated_whenSchedulingANewPost_thenCreated() 
      throws ParseException, IOException {
        Post post = createPost();

        Response response = withRequestBody(givenAuth(), post)
          .queryParams("resubmitOptionsActivated", false)
          .post(urlPrefix + "/api/scheduledPosts");

        assertEquals(201, response.statusCode());
        Post result = objectMapper.reader().forType(Post.class).readValue(response.asString());
        assertEquals(result.getUrl(), post.getUrl());
    }

    @Test
    public void 
      givenResubmitOptionsActivated_whenSchedulingANewPostWithZeroAttempts_thenInvalid() 
      throws ParseException, IOException {
        Post post = createPost();
        post.setNoOfAttempts(0);
        post.setMinScoreRequired(5);
        post.setTimeInterval(60);

        Response response = withRequestBody(givenAuth(), post)
          .queryParams("resubmitOptionsActivated", true)
          .post(urlPrefix + "/api/scheduledPosts");

        assertEquals(400, response.statusCode());
        assertTrue(response.asString().contains("Invalid Resubmit Options"));
    }

    @Test
    public void 
      givenResubmitOptionsActivated_whenSchedulingANewPostWithZeroMinScore_thenInvalid() 
      throws ParseException, IOException {
        Post post = createPost();
        post.setMinScoreRequired(0);
        post.setNoOfAttempts(3);
        post.setTimeInterval(60);

        Response response = withRequestBody(givenAuth(), post)
          .queryParams"resubmitOptionsActivated", true)
          .post(urlPrefix + "/api/scheduledPosts");

        assertEquals(400, response.statusCode());
        assertTrue(response.asString().contains("Invalid Resubmit Options"));
    }

    @Test
    public void 
      givenResubmitOptionsActivated_whenSchedulingANewPostWithZeroTimeInterval_thenInvalid() 
      throws ParseException, IOException {
        Post post = createPost();
        post.setTimeInterval(0);
        post.setMinScoreRequired(5);
        post.setNoOfAttempts(3);

        Response response = withRequestBody(givenAuth(), post)
          .queryParams("resubmitOptionsActivated", true)
          .post(urlPrefix + "/api/scheduledPosts");

        assertEquals(400, response.statusCode());
        assertTrue(response.asString().contains("Invalid Resubmit Options"));
    }

    @Test
    public void 
      givenResubmitOptionsActivated_whenSchedulingNewPostWithValidResubmitOptions_thenCreated() 
      throws ParseException, IOException {
        Post post = createPost();
        post.setMinScoreRequired(5);
        post.setNoOfAttempts(3);
        post.setTimeInterval(60);

        Response response = withRequestBody(givenAuth(), post)
          .queryParams("resubmitOptionsActivated", true)
          .post(urlPrefix + "/api/scheduledPosts");

        assertEquals(201, response.statusCode());
        Post result = objectMapper.reader().forType(Post.class).readValue(response.asString());
        assertEquals(result.getUrl(), post.getUrl());
    }

    private Post createPost() throws ParseException {
        Post post = new Post();
        post.setTitle(randomAlphabetic(6));
        post.setUrl("test.com");
        post.setSubreddit(randomAlphabetic(6));
        post.setSubmissionDate(dateFormat.parse(date));
        return post;
    }
}

6. 結論

在本篇中，我們進行了多項改進，將案例研究應用程序引向正確的方向——易用性。

Reddit Scheduler應用程序的想法是允許用户快速安排新的文章到Reddit，通過進入應用程序，完成工作並退出。

正在朝着正確的方向發展。

user avatar
0 位用戶收藏了這個故事！
收藏

發佈 評論

Some HTML is okay.