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huangapple
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英文:

spring bean default Priority

问题

以下是您提供的代码的翻译部分：

  1. import javax.annotation.Priority;
  3. import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  4. import org.springframework.context.annotation.ComponentScan;
  5. import org.springframework.context.annotation.Configuration;
  6. import org.springframework.core.Ordered;
  7. import org.springframework.stereotype.Component;
  9. public class SpringPriorityMain {
  11.     public static void main(String[] args) {
  13.         try (AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(SpringConfig.class)) {
  15.             Bean bean = ctx.getBean(Bean.class);
  17.             System.out.println();
  18.             System.out.println(bean.getName());
  19.             System.out.println();
  21.         }
  22.     }
  24.     public static interface Bean {
  26.         String getName();
  27.     }
  29.     @Component
  30.     // @Priority(0)
  31.     public static class BeanImplBusiness implements Bean {
  33.         @Override
  34.         public String getName() {
  35.             return "Business";
  36.         }
  37.     }
  39.     @Component
  40.     @Priority(Ordered.LOWEST_PRECEDENCE)
  41.     public static class BeanImplTest implements Bean {
  43.         @Override
  44.         public String getName() {
  45.             return "Test";
  46.         }
  47.     }
  49.     @Configuration
  50.     @ComponentScan("ro.catta.spring")
  51.     public static class SpringConfig {
  53.     }
  55. }

Maven项目的POM文件内容如下：

  1. <project xmlns="http://maven.apache.org/POM/4.0.0"
  2.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  3.     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  4.     <modelVersion>4.0.0</modelVersion>
  6.     <groupId>ro.catta.poc</groupId>
  7.     <artifactId>spring-priority</artifactId>
  8.     <version>0.0.1-SNAPSHOT</version>
  10.     <properties>
  11.         <maven.compiler.source>1.8</maven.compiler.source>
  12.         <maven.compiler.target>1.8</maven.compiler.target>
  13.         <mvn.spring.version>4.3.20.RELEASE</mvn.spring.version>
  14.         <!-- <mvn.spring.version>5.2.5.RELEASE</mvn.spring.version> -->
  15.     </properties>
  17.     <dependencies>
  18.         <dependency>
  19.             <groupId>org.springframework</groupId>
  20.             <artifactId>spring-core</artifactId>
  21.             <version>${mvn.spring.version}</version>
  22.         </dependency>
  23.         <dependency>
  24.             <groupId>org.springframework</groupId>
  25.             <artifactId>spring-context</artifactId>
  26.             <version>${mvn.spring.version}</version>
  27.         </dependency>
  28.         <dependency>
  29.             <groupId>org.springframework</groupId>
  30.             <artifactId>spring-beans</artifactId>
  31.             <version>${mvn.spring.version}</version>
  32.         </dependency>
  33.         <dependency>
  34.             <groupId>javax</groupId>
  35.             <artifactId>javaee-api</artifactId>
  36.             <version>7.0</version>
  37.             <scope>provided</scope>
  38.         </dependency>
  39.     </dependencies>
  40. </project>
英文:

In my simplified code sample I have 2 spring beans implementing the same interface (in real life the 2 components reside in different jars). One component (BeanImplBusiness in my sample) must be annotated with only @Component. The second one (BeanImplTest) can have any annotations.

The desired behavior is when both beans are in the classpath, spring to inject the "Business" bean in all places.

I try to achieve this using the javax.annotation.Priority annotation but it doesn't work the way I expect. Let me explain:

  • put @Priority annotation only in "Test" component: spring will inject only the "Test" bean no matter what value I give to @Priority. It looks like the "Business" bean doesn't exists.
  • put @Priority annotation in both beans and the lowest precedence in "Test" bean ( @Priority(Ordered.LOWEST_PRECEDENCE) ) it works perfectly, spring inject the "Business" component.

Spring version is 4.3.20, but I try also with 5.2.5 and I have same results.

So, my question is how can I configure the spring bean to give a default "Priority" on Business bean even if I don't declare it with annotation. Any solution with annotations, xml is good.

Why do I need to specify Priority annotations on both components? Is this a bug?

  1. import javax.annotation.Priority;
  3. import org.springframework.context.annotation.AnnotationConfigApplicationContext;
  4. import org.springframework.context.annotation.ComponentScan;
  5. import org.springframework.context.annotation.Configuration;
  6. import org.springframework.core.Ordered;
  7. import org.springframework.stereotype.Component;
  9. public class SpringPriorityMain {
  11.     public static void main(String[] args) {
  13.         try (AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(SpringConfig.class)) {
  15.             Bean bean = ctx.getBean(Bean.class);
  17.             System.out.println();
  18.             System.out.println(bean.getName());
  19.             System.out.println();
  21.         }
  22.     }
  24.     public static interface Bean {
  26.         String getName();
  27.     }
  29.     @Component
  30.     // @Priority(0)
  31.     public static class BeanImplBusiness implements Bean {
  33.         @Override
  34.         public String getName() {
  35.             return &quot;Business&quot;;
  36.         }
  37.     }
  39.     @Component
  40.     @Priority(Ordered.LOWEST_PRECEDENCE)
  41.     public static class BeanImplTest implements Bean {
  43.         @Override
  44.         public String getName() {
  45.             return &quot;Test&quot;;
  46.         }
  47.     }
  49.     @Configuration
  50.     @ComponentScan(&quot;ro.catta.spring&quot;)
  51.     public static class SpringConfig {
  53.     }
  55. }

The sample project is a maven project, here is the pom file to see exactly the dependencies

  1. &lt;project xmlns=&quot;http://maven.apache.org/POM/4.0.0&quot;
  2. 	xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;
  3. 	xsi:schemaLocation=&quot;http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd&quot;&gt;
  4. 	&lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
  6. 	&lt;groupId&gt;ro.catta.poc&lt;/groupId&gt;
  7. 	&lt;artifactId&gt;spring-priority&lt;/artifactId&gt;
  8. 	&lt;version&gt;0.0.1-SNAPSHOT&lt;/version&gt;
  10. 	&lt;properties&gt;
  11.         &lt;maven.compiler.source&gt;1.8&lt;/maven.compiler.source&gt;
  12.         &lt;maven.compiler.target&gt;1.8&lt;/maven.compiler.target&gt;
  13. 		&lt;mvn.spring.version&gt;4.3.20.RELEASE&lt;/mvn.spring.version&gt;
  14. 		&lt;!-- &lt;mvn.spring.version&gt;5.2.5.RELEASE&lt;/mvn.spring.version&gt; --&gt;
  15. 	&lt;/properties&gt;
  17. 	&lt;dependencies&gt;
  18. 		&lt;dependency&gt;
  19. 			&lt;groupId&gt;org.springframework&lt;/groupId&gt;
  20. 			&lt;artifactId&gt;spring-core&lt;/artifactId&gt;
  21. 			&lt;version&gt;${mvn.spring.version}&lt;/version&gt;
  22. 		&lt;/dependency&gt;
  23. 		&lt;dependency&gt;
  24. 			&lt;groupId&gt;org.springframework&lt;/groupId&gt;
  25. 			&lt;artifactId&gt;spring-context&lt;/artifactId&gt;
  26. 			&lt;version&gt;${mvn.spring.version}&lt;/version&gt;
  27. 		&lt;/dependency&gt;
  28. 		&lt;dependency&gt;
  29. 			&lt;groupId&gt;org.springframework&lt;/groupId&gt;
  30. 			&lt;artifactId&gt;spring-beans&lt;/artifactId&gt;
  31. 			&lt;version&gt;${mvn.spring.version}&lt;/version&gt;
  32. 		&lt;/dependency&gt;
  33.         &lt;dependency&gt;
  34.             &lt;groupId&gt;javax&lt;/groupId&gt;
  35.             &lt;artifactId&gt;javaee-api&lt;/artifactId&gt;
  36.             &lt;version&gt;7.0&lt;/version&gt;
  37.             &lt;scope&gt;provided&lt;/scope&gt;
  38.         &lt;/dependency&gt;
  39. 	&lt;/dependencies&gt;
  40. &lt;/project&gt;

huangapple
  • 本文由 发表于 2020年4月5日 16:25:59
  • 转载请务必保留本文链接：https://java.coder-hub.com/61039887.html
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