Spring的@Service逻辑与构建器模式（Builder Pattern）

huangapple
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英文:

Spring @Service logic with Builder Pattern

问题

我已经在Spring Boot应用程序中使用构建器模式实现了服务逻辑，代码如下：

  1. @Service
  2. public class EmailServiceImpl implements NotificationService{
  4.     private Map<String, Object> emailTemplateContext;
  5.     private List<String> recipients;
  6.     private String templateName;
  7.     private String subjectName;
  8.     private List<String> ccRecipients;
  10.     public EmailServiceImpl() {
  11.     }
  13.     private EmailServiceImpl(String templateName, String subjectName, List<String> recipients,
  14.             List<String> ccRecipients,
  15.             Map<String, Object> emailTemplateContext) {
  16.         this.emailTemplateContext = emailTemplateContext;
  17.         this.recipients = recipients;
  18.         this.templateName = templateName;
  19.         this.subjectName = subjectName;
  20.         this.ccRecipients = ccRecipients;
  21.     }
  22.     
  23.     public static class EmailBuilder {
  25.         private Map<String, Object> emailTemplateContext = new HashMap<String, Object>();
  26.         private List<String> recipients;
  27.         private String templateName;
  28.         private String subjectName;
  29.         private List<String> ccRecipients;
  31.         public EmailBuilder withTemplateName(String templateName) {
  32.             this.templateName = templateName;
  33.             return this;
  34.         }
  36.         public EmailBuilder withSubjectName(String subjectName) {
  37.             this.subjectName = subjectName;
  38.             return this;
  39.         }
  41.         public EmailBuilder withTemplateContextValues(String key, String value) {
  42.             this.emailTemplateContext.put(key, value);
  43.             return this;
  44.         }
  45.         
  46.         public EmailBuilder withTemplateContextValues(String key, List<String> value) {
  47.             this.emailTemplateContext.put(key, value);
  48.             return this;
  49.         }
  51.         public EmailBuilder withRecipients(List<String> recipients) {
  52.             this.recipients = recipients;
  53.             return this;
  54.         }
  56.         public EmailBuilder withCCRecipients(List<String> ccRecipients) {
  57.             this.ccRecipients = ccRecipients;
  58.             return this;
  59.         }
  61.         public EmailServiceImpl build() {
  62.             return new EmailServiceImpl(templateName, subjectName, recipients, ccRecipients, emailTemplateContext);
  63.         }
  64.     }
  65.     
  66.     public void send() {
  67.      // 实现电子邮件发送逻辑
  68.     }
  69. }

然后，它将被注入到另一个类中，类似于以下方式：

  1. public class EmailSender {
  2.     private EmailBuilder emailBuilder;
  3.     
  4.     EmailSender(EmailBuilder emailBuilder) {
  5.         this.emailBuilder = emailBuilder;
  6.     }
  7.     
  8.     public void sendEmail() {
  9.         this.emailBuilder
  10.             .withRecipients(executionRunBO.getEmailRecipients().stream().map(email -> email.getEmail())
  11.                     .collect(Collectors.toList()))
  12.             .withSubjectName("Reports Draft ").withTemplateName("/emails/reports.ftlh")
  13.             .withTemplateContextValues("userName", "TestUser").build().send();
  14.     }
  15. }

关于使用构建器模式和Spring的一些问题：

  1. 由于@Service注释的构造函数是私有的，Spring框架无法初始化该bean类。为了避免获得初始化异常，我将构造函数设置为了public，但这不是构建器模式的正确使用方式。如何正确地在Spring框架中实现构建器模式？

  2. 如何在服务类之外调用EmailServiceImpl类的EmailBuilder？在我的示例中，我已将EmailBuilder作为构造函数参数注入，然后Spring框架抛出以下错误：

    1. required a bean of type '...EmailServiceImpl$EmailBuilder' that could not be found.

请帮我澄清这些问题。

英文:

I have implemented service logic using builder pattern like below in a Spring boot application.

  1.  @Service
  2. public class EmailServiceImpl implements NotificationService{
  3. private Map&lt;String, Object&gt; emailTemplateContext;;
  4. private List&lt;String&gt; recipients;
  5. private String templateName;
  6. private String subjectName;
  7. private List&lt;String&gt; ccRecipients;
  8. public EmailServiceImpl() {
  9. }
  10. private EmailServiceImpl(String templateName, String subjectName, List&lt;String&gt; recipients,
  11. List&lt;String&gt; ccRecipients,
  12. Map&lt;String, Object&gt; emailTemplateContext) {
  13. this.emailTemplateContext = emailTemplateContext;
  14. this.recipients = recipients;
  15. this.templateName = templateName;
  16. this.subjectName = subjectName;
  17. this.ccRecipients = ccRecipients;
  18. }
  19. public static class EmailBuilder {
  20. private Map&lt;String, Object&gt; emailTemplateContext = new HashMap&lt;String, Object&gt;();
  21. private List&lt;String&gt; recipients;
  22. private String templateName;
  23. private String subjectName;
  24. private List&lt;String&gt; ccRecipients;
  25. public EmailBuilder withTemplateName(String templateName) {
  26. this.templateName = templateName;
  27. return this;
  28. }
  29. public EmailBuilder withSubjectName(String subjectName) {
  30. this.subjectName = subjectName;
  31. return this;
  32. }
  33. public EmailBuilder withTemplateContextValues(String key, String value) {
  34. this.emailTemplateContext.put(key, value);
  35. return this;
  36. }
  37. public EmailBuilder withTemplateContextValues(String key,List&lt; String&gt; value) {
  38. this.emailTemplateContext.put(key, value);
  39. return this;
  40. }
  41. public EmailBuilder withRecipients(List&lt;String&gt; recipients) {
  42. this.recipients = recipients;
  43. return this;
  44. }
  45. public EmailBuilder withCCRecipients(List&lt;String&gt; ccRecipients) {
  46. this.ccRecipients = ccRecipients;
  47. return this;
  48. }
  49. public EmailServiceImpl build() {
  50. return new EmailServiceImpl(templateName, subjectName, recipients, ccRecipients, emailTemplateContext);
  51. }
  52. }
  53. public void send() {
  54. // implement email send logic
  55. }
  56. }

Then this will be injected in another class something like below

  1.  public class EmailSender{
  2. private EmailBuilder emailBuilder;
  3. EmailSender(EmailBuilder emailBuilder){
  4. this.emailBuilder=emailBuilder;
  5. }
  6. public void sendEmail(){
  7. this.emailBuilder
  8. .withRecipients(executionRunBO.getEmailRecipients().stream().map(email -&gt; email.getEmail())
  9. .collect(Collectors.toList()))
  10. .withSubjectName(&quot;Reports Draft &quot;).withTemplateName(&quot;/emails/reports.ftlh&quot;)
  11. .withTemplateContextValues(&quot;userName&quot;, &quot;TestUser&quot;).build().send();
  12. }
  13. }

There are few questions related to the Builder pattern with Spring.

  1. Since @service constructor is private Spring framework can not initiate the bean class.To avoid getting initialization exception i have made constructor to public but it is not the builder pattern.So how do i implement builder pattern correctly with Spring framework?

  2. How do i call the EmailServiceImpl class's EmailBuilder outside from the service class? Since in my examples i have injected EmailBuilder as a constructor argument then Spring framework throws that

> required a bean of type '...EmailServiceImpl$EmailBuilder' that could
> not be found.

Please help me to clarify those things.

答案1

得分: 1

你在这里将许多功能混在一起。我会让这个过程更加简化。

我会创建一个dto类Email，而不是一个Spring bean。

  1. public class Email {
  2.     private Map<String, Object> emailTemplateContext;
  3.     private List<String> recipients;
  4.     private String templateName;
  5.     private String subjectName;
  6.     private List<String> ccRecipients;
  8.     private Email(String templateName, String subjectName, List<String> recipients,
  9.                              List<String> ccRecipients,
  10.                              Map<String, Object> emailTemplateContext) {
  11.         this.emailTemplateContext = emailTemplateContext;
  12.         this.recipients = recipients;
  13.         this.templateName = templateName;
  14.         this.subjectName = subjectName;
  15.         this.ccRecipients = ccRecipients;
  16.     }
  18.     public static class EmailBuilder {
  19.         // 你的构建器代码，只需构建Email
  20.     }
  22. }

然后创建一个用于发送电子邮件的服务。

  1. @Service
  2. public class EmailServiceImpl implements NotificationService {
  3.     
  4.     public void sendEmail(Email email) {
  5.         
  6.     }
  8. }

像这样调用它

  1. emailService.sendEmail(new Email.EmailBuilder().build());

没有必要为Email和EmailBuilder创建一个@service。

英文:

You are mixing a lot of functionality together here. I would make this more streamlined.

I would create a dto class Email, not a Spring bean.

  1. public class Email {
  2. private Map&lt;String, Object&gt; emailTemplateContext;
  3. private List&lt;String&gt; recipients;
  4. private String templateName;
  5. private String subjectName;
  6. private List&lt;String&gt; ccRecipients;
  7. private Email(String templateName, String subjectName, List&lt;String&gt; recipients,
  8. List&lt;String&gt; ccRecipients,
  9. Map&lt;String, Object&gt; emailTemplateContext) {
  10. this.emailTemplateContext = emailTemplateContext;
  11. this.recipients = recipients;
  12. this.templateName = templateName;
  13. this.subjectName = subjectName;
  14. this.ccRecipients = ccRecipients;
  15. }
  16. public static class EmailBuilder {
  17. // your builder code, just build the Email 
  18. }
  19. }

And then have a service to send emails.

  1. @Service
  2. public class EmailServiceImpl implements NotificationService {
  3. public void sendEmail(Email email) {
  4. }
  5. }

Call it like this

  1. emailService.sendEmail(new Email.EmailBuilder().build());

There is no need to create a @service from the Email and EmailBuilder.

huangapple
  • 本文由 发表于 2020年8月24日 16:50:50
  • 转载请务必保留本文链接：https://go.coder-hub.com/63557676.html
  • java
  • spring
  • spring-boot
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