YeLogs.com
知識庫

知識庫 / Spring RSS 訂閱

Reddit應用第三次改進發布

REST,Spring
HongKong
6
04:00 AM · Dec 06 ,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，通過對現有功能的少量但有用的改進來實現小而有用的改進。

2. 更好的表格

讓我們首先使用 jQuery DataTables 插件來替換應用程序之前使用的舊式基本表格。

2.1. 後置存儲與服務

首先，我們將添加一個方法，用於統計用户已安排發佈的數量，當然，我們會利用 Spring Data 的語法：

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

接下來，我們快速看一下 服務層實現——根據分頁參數檢索用户的帖子：

@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());
}

我們正在根據用户的時區轉換日期：

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. 通過 API 實現分頁和排序

接下來，我們將使用 API 對該操作進行發佈，並實現完整的分頁和排序功能。

@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);
}

請注意我們是如何使用自定義標題來將分頁信息傳遞給客户端的。 還有其他一些更標準的方式可以實現這一點，我們稍後可能會探索它們。

不過，這個實現方式已經足夠簡單——我們有一個簡單的生成分頁信息的辦法。

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

以及 本身：

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. 前端

最後，簡單的前端將使用自定義的 JS 方法與 API 交互，並處理 jQuery DataTables 參數：

<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. 通過分頁測試 API

現在 API 已發佈，我們可以編寫 幾個簡單的 API 測試，以確保分頁機制的基本功能正常工作：

@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——當用户的計劃發佈內容被髮送時，用户會收到電子郵件：

3.1. 郵件配置

首先，我們來進行郵件配置：

@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;
}

與必要的屬性一起，以使 SMTP 正常工作：

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

3.2. 計劃帖子發佈時觸發事件

現在，讓我們確保在計劃的帖子成功發佈到 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：

The event implementation is pretty straightforward:

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，我們將簡化重提交選項，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。

我們可以使用帖子得分和投票比例計算總投票數：

  • 得分 = 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(得分 / ((2 * 投票比例) - 1))

首先，我們將修改我們的得分邏輯，以計算並跟蹤總投票數：

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，不再使用。

5. 驗證重提交選項

最後，我們將為用户添加驗證，以處理複雜的重提交選項：

5.1. 計劃發佈服務 (ScheduledPost Service)

以下是簡單的 checkIfValidResubmitOptions() 方法：

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;
}

我們將在安排新帖文時充分利用驗證功能：

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

請注意，如果啓用重試邏輯，則以下字段必須具有非零值：

  • 重試次數
  • 時間間隔
  • 最低得分要求

5.2. 異常處理

最後 – 在出現無效輸入的情況下，InvalidResubmitOptionsException 將被處理在我們的主要錯誤處理邏輯中：

@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. 測試重提交選項

最後，讓我們現在測試我們的重提交選項，我們將測試激活和停用條件：

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，將案例研究應用引向正確的方向——易用性。

Reddit Scheduler 應用的核心理念是允許用户快速在 Reddit 上安排新文章，通過進入應用、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.