{"id":10008121,"date":"2023-08-21T11:59:41","date_gmt":"2023-08-21T03:59:41","guid":{"rendered":"https:\/\/blog.itmax.cn\/?p=10008121"},"modified":"2023-08-21T11:59:41","modified_gmt":"2023-08-21T03:59:41","slug":"spring-%e4%b8%ad-primary-%e6%b3%a8%e8%a7%a3%e7%9a%84%e5%8e%9f%e7%90%86%e6%98%af%e4%bb%80%e4%b9%88%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10008121","title":{"rendered":"Spring \u4e2d @Primary \u6ce8\u89e3\u7684\u539f\u7406\u662f\u4ec0\u4e48\uff1f"},"content":{"rendered":"

1. \u95ee\u9898\u5206\u6790<\/h2>\n

\u5f53\u6211\u4eec\u4f7f\u7528 Spring \u7684\u65f6\u5019\uff0c\u6709\u65f6\u5019\u4f1a\u9047\u5230\u4e0b\u9762\u8fd9\u79cd\u60c5\u51b5\u3002<\/p>\n

\u5047\u8bbe\u6211\u6709 A\u3001B \u4e24\u4e2a\u7c7b\uff0c\u5728 A \u4e2d\u6ce8\u5165 B\uff0c\u5982\u4e0b\uff1a<\/p>\n

@Component\npublic class A {\n    @Autowired\n    B b;\n}<\/code><\/pre>\n
\u81f3\u4e8e B\uff0c\u5219\u5728\u914d\u7f6e\u7c7b\u4e2d\u5b58\u5728\u591a\u4e2a\u5b9e\u4f8b\uff1a<\/p>\n
@Configuration\n@ComponentScan\npublic class JavaConfig {\n    @Bean("b1")\n    B b1() {\n        return new B();\n    }\n\n    @Bean("b2")\n    B b2() {\n        return new B();\n    }\n}<\/code><\/pre>\n
\u8fd9\u6837\u7684\u9879\u76ee\u542f\u52a8\u4e4b\u540e\uff0c\u5fc5\u7136\u4f1a\u629b\u51fa\u5982\u4e0b\u5f02\u5e38\uff1a<\/p>\n
\"\"<\/p>\n
\u5f53\u7136\uff0c\u5bf9\u4e8e\u8fd9\u6837\u7684\u95ee\u9898\uff0c\u76f8\u4fe1\u6709\u7ecf\u9a8c\u7684\u540c\u5b66\u90fd\u77e5\u9053\u8be5\u600e\u4e48\u89e3\u51b3\uff1a<\/p>\n
    \n
  1. \u53ef\u4ee5\u4f7f\u7528 @Resource \u6ce8\u89e3\uff0c\u4f7f\u7528\u8be5\u6ce8\u89e3\u65f6\u6307\u5b9a\u5177\u4f53\u7684 Bean \u540d\u79f0\u5373\u53ef\u3002<\/li>\n
  2. \u5728 @Autowired \u6ce8\u89e3\u4e4b\u4e0a\uff0c\u518d\u591a\u52a0\u4e00\u4e2a @Qualifier(“b1”) \u6ce8\u89e3\uff0c\u901a\u8fc7\u8be5\u6ce8\u89e3\u53bb\u6307\u5b9a\u8981\u52a0\u8f7d\u7684 Bean \u540d\u79f0\u3002<\/li>\n<\/ol>\n
    @Component\npublic class A {\n    @Autowired\n    @Qualifier("b1")\n    B b;\n}<\/code><\/pre>\n
      \n
    1. \u5728\u591a\u4e2a B \u5bf9\u8c61\u7684\u67d0\u4e00\u4e2a\u4e4b\u4e0a\uff0c\u6dfb\u52a0 @Primary \u6ce8\u89e3\uff0c\u8868\u793a\u5f53\u5b58\u5728\u91cd\u590d\u7684 B \u5bf9\u8c61\u65f6\uff0c\u4f18\u5148\u4f7f\u7528\u54ea\u4e00\u4e2a\u3002<\/li>\n<\/ol>\n
      @Configuration\n@ComponentScan\npublic class JavaConfig {\n    @Bean("b1")\n    @Primary\n    B b1() {\n        return new B();\n    }\n\n    @Bean("b2")\n    B b2() {\n        return new B();\n    }\n}<\/code><\/pre>\n
      \u9664\u4e86\u8fd9\u4e09\u4e2a\uff0c\u8fd8\u6709\u6ca1\u6709\u5176\u4ed6\u529e\u6cd5\u5462\uff1f\u5fc5\u987b\u6709\uff01\uff01\uff01\u5728 Spring \u4e2d @Qualifier \u6ce8\u89e3\u8fd8\u80fd\u8fd9\u4e48\u7528\uff1f<\/a> \u4e00\u6587\u4e2d\uff0c\u677e\u54e5\u8fd8\u548c\u5927\u5bb6\u6269\u5c55\u4e86 @Qualifier \u6ce8\u89e3\u7684\u5176\u4ed6\u7528\u6cd5\uff0c\u611f\u5174\u8da3\u7684\u5c0f\u4f19\u4f34\u4e0d\u8981\u9519\u8fc7\u54e6\u3002<\/p>\n
      \u8fd9\u91cc\u4e09\u4e2a\u65b9\u6cd5\uff0c\u5176\u4e2d @Resource \u662f JSR \u4e2d\u63d0\u4f9b\u7684\u6ce8\u89e3\uff0c\u6211\u8fd9\u91cc\u5148\u4e0d\u5c55\u5f00\uff0c\u677e\u54e5\u540e\u9762\u4e13\u95e8\u518d\u6765\u548c\u5927\u5bb6\u804a @Resource \u6ce8\u89e3\u7684\u6ce8\u5165\u539f\u7406\u3002\u4eca\u5929\u6211\u4e3b\u8981\u662f\u60f3\u548c\u5c0f\u4f19\u4f34\u4eec\u5206\u4eab\u4e00\u4e0b\u540e\u9762\u4e24\u79cd\u65b9\u6848\u7684\u5b9e\u73b0\u539f\u7406\u3002<\/p>\n
      2. \u6e90\u7801\u89e3\u6790<\/h2>\n
      \u672c\u6587\u57fa\u4e8e\u524d\u9762@Autowired \u5230\u5e95\u662f\u600e\u4e48\u628a\u53d8\u91cf\u6ce8\u5165\u8fdb\u6765\u7684\uff1f<\/a>\u4e00\u6587\u5c55\u5f00\uff0c\u6240\u4ee5\u5982\u679c\u8fd8\u6ca1\u770b\u8fc7\u6539\u6587\u7ae0\u7684\u5c0f\u4f19\u4f34\uff0c\u5efa\u8bae\u5148\u53bb\u9605\u8bfb\u4e00\u4e0b\uff0c\u8fd9\u6709\u52a9\u4e8e\u66f4\u597d\u7684\u7406\u89e3\u672c\u6587\u3002<\/p>\n
      2.1 doResolveDependency<\/h3>\n
      \u5728@Autowired \u5230\u5e95\u662f\u600e\u4e48\u628a\u53d8\u91cf\u6ce8\u5165\u8fdb\u6765\u7684\uff1f<\/a>\u7684 3.3 \u5c0f\u8282\u4e2d\uff0c\u6211\u4eec\u63d0\u5230\uff0c\u7ed9 A \u6ce8\u5165 B \u7684\u65f6\u5019\uff0c\u4f1a\u8c03\u7528\u5230 doResolveDependency \u65b9\u6cd5\uff0c\u6211\u4eec\u518d\u6765\u770b\u4e0b\u8be5\u65b9\u6cd5\uff1a<\/p>\n
      DefaultListableBeanFactory#doResolveDependency\uff1a<\/p>\n
      @Nullable\npublic Object doResolveDependency(DependencyDescriptor descriptor, @Nullable String beanName,\n        @Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) throws BeansException {\n        \/\/...\n        Map<String, Object> matchingBeans = findAutowireCandidates(beanName, type, descriptor);\n        if (matchingBeans.isEmpty()) {\n            if (isRequired(descriptor)) {\n                raiseNoMatchingBeanFound(type, descriptor.getResolvableType(), descriptor);\n            }\n            return null;\n        }\n        if (matchingBeans.size() > 1) {\n            autowiredBeanName = determineAutowireCandidate(matchingBeans, descriptor);\n            if (autowiredBeanName == null) {\n                if (isRequired(descriptor) || !indicatesMultipleBeans(type)) {\n                    return descriptor.resolveNotUnique(descriptor.getResolvableType(), matchingBeans);\n                }\n                else {\n                    \/\/ In case of an optional Collection\/Map, silently ignore a non-unique case:\n                    \/\/ possibly it was meant to be an empty collection of multiple regular beans\n                    \/\/ (before 4.3 in particular when we didn't even look for collection beans).\n                    return null;\n                }\n            }\n            instanceCandidate = matchingBeans.get(autowiredBeanName);\n        \/\/...\n}<\/code><\/pre>\n
      \u5728\u8fd9\u4e2a\u65b9\u6cd5\u4e2d\uff0c\u9996\u5148\u8c03\u7528\u4e86 findAutowireCandidates \u65b9\u6cd5\u53bb\u627e\u5230\u6240\u6709\u6ee1\u8db3\u6761\u4ef6\u7684 Class\u3002Map \u4e2d\u7684 key \u5c31\u662f Bean \u7684\u540d\u79f0\uff0cvalue \u5219\u662f\u4e00\u4e2a Class\uff0c\u6b64\u65f6\u8fd8\u6ca1\u6709\u5b9e\u4f8b\u5316\u3002<\/p>\n
      \u5982\u679c\u6211\u4eec\u662f\u901a\u8fc7 @Qualifier \u6ce8\u89e3\u6765\u89e3\u51b3\u95ee\u9898\u7684\uff0c\u90a3\u4e48\u95ee\u9898\u5c31\u5728 findAutowireCandidates \u65b9\u6cd5\u4e2d\u88ab\u89e3\u51b3\u4e86\u3002\u8fd9\u4e2a\u5728\u524d\u9762\u7684\u6587\u7ae0 Spring \u4e2d @Qualifier \u6ce8\u89e3\u8fd8\u80fd\u8fd9\u4e48\u7528\uff1f<\/a> \u4e2d\u5df2\u7ecf\u548c\u5c0f\u4f19\u4f34\u4eec\u804a\u8fc7\u4e86\u3002<\/p>\n
      \u5982\u679c @Qualifier \u6ce8\u89e3\u6ca1\u628a\u95ee\u9898\u89e3\u51b3\u6389\uff0c\u5c31\u4f1a\u5bfc\u81f4\u6700\u7ec8\u67e5\u8be2\u5230\u7684 matchingBeans \u7684\u6570\u91cf\u5927\u4e8e 1\uff0c\u90a3\u4e48\u5c31\u4f1a\u8fdb\u5165\u5230\u63a5\u4e0b\u6765\u7684 if \u73af\u8282\u4e2d\uff0c\u901a\u8fc7 determineAutowireCandidate \u65b9\u6cd5\u8fdb\u4e00\u6b65\u786e\u5b9a\u5230\u5e95\u4f7f\u7528\u54ea\u4e00\u4e2a Bean\uff0c@Primary \u6ce8\u89e3\u7684\u5904\u7406\uff0c\u5c31\u5728\u8be5\u65b9\u6cd5\u4e2d\u5b8c\u6210\u3002<\/p>\n
      2.2 determineAutowireCandidate<\/h3>\n
      DefaultListableBeanFactory#determineAutowireCandidate<\/p>\n
      @Nullable\nprotected String determineAutowireCandidate(Map<String, Object> candidates, DependencyDescriptor descriptor) {\n    Class<?> requiredType = descriptor.getDependencyType();\n    String primaryCandidate = determinePrimaryCandidate(candidates, requiredType);\n    if (primaryCandidate != null) {\n        return primaryCandidate;\n    }\n    String priorityCandidate = determineHighestPriorityCandidate(candidates, requiredType);\n    if (priorityCandidate != null) {\n        return priorityCandidate;\n    }\n    \/\/ Fallback\n    for (Map.Entry<String, Object> entry : candidates.entrySet()) {\n        String candidateName = entry.getKey();\n        Object beanInstance = entry.getValue();\n        if ((beanInstance != null && this.resolvableDependencies.containsValue(beanInstance)) ||\n                matchesBeanName(candidateName, descriptor.getDependencyName())) {\n            return candidateName;\n        }\n    }\n    return null;\n}<\/code><\/pre>\n
      \u8fd9\u4e2a\u65b9\u6cd5\u91cc\u8fb9\u4e00\u5171\u505a\u4e86\u4e09\u79cd\u5c1d\u8bd5\uff1a<\/p>\n
        \n
      1. \u7b2c\u4e00\u4e2a\u5c1d\u8bd5\u5c31\u662f\u8c03\u7528 determinePrimaryCandidate \u65b9\u6cd5\u53bb\u786e\u5b9a\u6700\u4f73\u5019\u9009 Bean\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u672c\u8d28\u4e0a\u5c31\u662f\u901a\u8fc7 @Primary \u6ce8\u89e3\u627e\u5230\u6700\u4f73 BeanName\u3002<\/li>\n
      2. \u5982\u679c\u7b2c\u4e00\u6b65\u6ca1\u6709\u627e\u5230\u6700\u4f73 BeanName\uff0c\u90a3\u4e48\u63a5\u4e0b\u6765\u4f1a\u8c03\u7528 determineHighestPriorityCandidate \u65b9\u6cd5\u53bb\u67e5\u627e\u6700\u4f73 Bean\uff0c\u8be5\u65b9\u6cd5\u672c\u8d28\u4e0a\u662f\u901a\u8fc7\u67e5\u627e JSR-330 \u4e2d\u7684 @Priority \u6ce8\u89e3\uff0c\u6765\u786e\u5b9a Bean \u7684\u4f18\u5148\u7ea7\u3002<\/li>\n
      3. \u5982\u679c\u524d\u4e24\u6b65\u90fd\u6ca1\u627e\u5230\u5408\u9002\u7684 BeanName\uff0c\u90a3\u4e48\u63a5\u4e0b\u6765\u8fd9\u4e2a for \u5faa\u73af\u5219\u662f\u901a\u8fc7 Bean \u7684\u540d\u79f0\u8fdb\u884c\u5339\u914d\u4e86\uff0c\u5373 A \u7c7b\u4e2d\u53d8\u91cf\u7684\u540d\u79f0\u548c\u76ee\u6807 Bean \u7684\u540d\u79f0\u662f\u5426\u5339\u914d\uff0c\u5982\u679c\u80fd\u5339\u914d\u4e0a\uff0c\u90a3\u4e5f\u53ef\u4ee5\u3002\u8fd9\u4e5f\u5c31\u662f\u6211\u4e48\u5e38\u8bf4\u7684 @Autowired \u6ce8\u89e3\u5148\u6309\u7167\u7c7b\u578b\u53bb\u5339\u914d\uff0c\u5982\u679c\u7c7b\u578b\u5339\u914d\u4e0d\u4e0a\uff0c\u5c31\u4f1a\u6309\u7167\u540d\u79f0\u53bb\u5339\u914d\u3002<\/li>\n<\/ol>\n
        \u4e0a\u9762\u5927\u81f4\u4ecb\u7ecd\u4e86\u8fd9\u4e2a\u65b9\u6cd5\u7684\u6267\u884c\u601d\u8def\uff0c\u63a5\u4e0b\u6765\u6211\u4eec\u5c31\u6765\u770b\u4e00\u4e0b\u6267\u884c\u7ec6\u8282\u3002<\/p>\n
        2.2.1 determinePrimaryCandidate<\/h4>\n
        @Nullable\nprotected String determinePrimaryCandidate(Map<String, Object> candidates, Class<?> requiredType) {\n    String primaryBeanName = null;\n    for (Map.Entry<String, Object> entry : candidates.entrySet()) {\n        String candidateBeanName = entry.getKey();\n        Object beanInstance = entry.getValue();\n        if (isPrimary(candidateBeanName, beanInstance)) {\n            if (primaryBeanName != null) {\n                boolean candidateLocal = containsBeanDefinition(candidateBeanName);\n                boolean primaryLocal = containsBeanDefinition(primaryBeanName);\n                if (candidateLocal && primaryLocal) {\n                    throw new NoUniqueBeanDefinitionException(requiredType, candidates.size(),\n                            "more than one 'primary' bean found among candidates: " + candidates.keySet());\n                }\n                else if (candidateLocal) {\n                    primaryBeanName = candidateBeanName;\n                }\n            }\n            else {\n                primaryBeanName = candidateBeanName;\n            }\n        }\n    }\n    return primaryBeanName;\n}\nprotected boolean isPrimary(String beanName, Object beanInstance) {\n    String transformedBeanName = transformedBeanName(beanName);\n    if (containsBeanDefinition(transformedBeanName)) {\n        return getMergedLocalBeanDefinition(transformedBeanName).isPrimary();\n    }\n    return (getParentBeanFactory() instanceof DefaultListableBeanFactory parent &&\n            parent.isPrimary(transformedBeanName, beanInstance));\n}<\/code><\/pre>\n
        \u6211\u4eec\u6765\u770b\u4e0b\u8fd9\u4e2a\u65b9\u6cd5\u7684\u6267\u884c\u903b\u8f91\u3002<\/p>\n
        \u53c2\u6570 candidates \u4e2d\u4fdd\u5b58\u4e86\u6240\u6709\u7b26\u5408\u6761\u4ef6\u7684 BeanDefinition\uff0c\u53c2\u6570 key \u5c31\u662f Bean \u7684\u540d\u79f0\uff0cValue \u5219\u662f\u5bf9\u5e94\u7684 BeanDefinition\u3002\u73b0\u5728\u5c31\u53bb\u904d\u5386 candidates\uff0c\u5728\u904d\u5386\u7684\u65f6\u5019\uff0c\u8c03\u7528 isPrimary \u65b9\u6cd5\u53bb\u5224\u65ad\u8fd9\u4e2a BeanDefinition \u4e0a\u662f\u5426\u542b\u6709 @Primary \u6ce8\u89e3\uff0cisPrimary \u65b9\u6cd5\u7684\u903b\u8f91\u6bd4\u8f83\u7b80\u5355\uff0c\u6211\u5c31\u4e0d\u5570\u55e6\u4e86\uff0c\u8be5\u65b9\u6cd5\u4e2d\u6d89\u53ca\u5230 getMergedLocalBeanDefinition \u65b9\u6cd5\u53bb\u7236\u5bb9\u5668\u4e2d\u67e5\u627e\u4e24\u4e2a\u7ec6\u8282\uff0c\u8fd9\u4e2a\u677e\u54e5\u5728\u4e4b\u524d\u7684\u6587\u7ae0\u4e2d\u4e5f\u90fd\u548c\u5927\u5bb6\u804a\u8fc7\u4e86\uff08Spring BeanDefinition\uff1a\u7236\u5b50\u5173\u7cfb\u89e3\u5bc6<\/a>\u3001Spring \u4e2d\u7684\u7236\u5b50\u5bb9\u5668\u662f\u548b\u56de\u4e8b\uff1f<\/a>\uff09\u3002<\/p>\n
        \u5728\u67e5\u627e\u7684\u8fc7\u7a0b\u4e2d\uff0c\u5982\u679c\u6709\u6ee1\u8db3\u6761\u4ef6\u7684 BeanName\uff0c\u5219\u8d4b\u503c\u7ed9 primaryBeanName \u53d8\u91cf\u7136\u540e\u8fd4\u56de\uff0c\u5982\u679c\u5b58\u5728\u591a\u4e2a\u6ee1\u8db3\u6761\u4ef6\u7684 BeanName\uff0c\u90a3\u5c31\u629b\u51fa NoUniqueBeanDefinitionException \u5f02\u5e38\u3002<\/p>\n
        2.2.2 determineHighestPriorityCandidate<\/h4>\n
        \u8981\u7406\u89e3 determineHighestPriorityCandidate \u65b9\u6cd5\uff0c\u5f97\u5148\u4e86\u89e3 @Priority \u6ce8\u89e3\u7684\u7528\u6cd5\u3002\u8003\u8651\u5230\u6709\u7684\u5c0f\u4f19\u4f34\u53ef\u80fd\u8fd8\u4e0d\u719f\u6089 @Priority \u6ce8\u89e3\uff0c\u6211\u8fd9\u91cc\u4e5f\u8ddf\u5927\u5bb6\u7a0d\u5fae\u8bf4\u4e24\u53e5\u3002<\/p>\n
        @Priority \u6ce8\u89e3\u4f5c\u7528\u6709\u70b9\u7c7b\u4f3c\u4e8e @Order\uff0c\u53ef\u4ee5\u7528\u6765\u6307\u5b9a\u4e00\u4e2a Bean \u7684\u4f18\u5148\u7ea7\uff0c\u8fd9\u662f JSR \u4e2d\u63d0\u4f9b\u7684\u6ce8\u89e3\uff0c\u6240\u4ee5\u5982\u679c\u60f3\u4f7f\u7528\u8fd9\u4e2a\u6ce8\u89e3\uff0c\u9700\u8981\u5148\u6dfb\u52a0\u4f9d\u8d56\uff1a<\/p>\n
        <dependency>\n    <groupId>jakarta.annotation<\/groupId>\n    <artifactId>jakarta.annotation-api<\/artifactId>\n    <version>2.1.1<\/version>\n<\/dependency><\/code><\/pre>\n
        \u7136\u540e\u5728\u7c7b\u4e0a\u6dfb\u52a0\u8be5\u6ce8\u89e3\uff0c\u50cf\u4e0b\u9762\u8fd9\u6837\uff1a<\/p>\n
        public interface IBService {\n}\n@Component\n@Priority(100)\npublic class BServiceImpl1 implements IBService{\n}\n@Component\n@Priority(101)\npublic class BServiceImpl2 implements IBService{\n}<\/code><\/pre>\n
        @Priority \u6ce8\u89e3\u4e2d\u7684\u6570\u5b57\u8868\u793a\u4f18\u5148\u7ea7\uff0c\u6570\u5b57\u8d8a\u5927\u4f18\u5148\u7ea7\u8d8a\u5c0f\u3002\u5c06\u6765\u5728 A \u4e2d\u6ce8\u5165 IBService \u65f6\uff0c\u5c31\u4f1a\u4f18\u5148\u67e5\u627e\u4f18\u5148\u7ea7\u9ad8\u7684 Bean\u3002\u867d\u7136 @Priority \u6ce8\u89e3\u53ef\u4ee5\u52a0\u5728\u7c7b\u4e0a\uff0c\u4e5f\u53ef\u4ee5\u52a0\u5728\u65b9\u6cd5\u4e0a\uff0c\u4f46\u662f\u5728\u5177\u4f53\u5b9e\u8df5\u4e2d\uff0c\u52a0\u5728\u65b9\u6cd5\u4e0a\u8fd9\u4e2a\u6ce8\u89e3\u5e76\u4e0d\u4f1a\u751f\u6548\uff0c\u53ea\u80fd\u52a0\u5728\u7c7b\u4e0a\u9762\u3002\u81f3\u4e8e\u539f\u56e0\uff0c\u5927\u5bb6\u770b\u5b8c\u63a5\u4e0b\u6765\u7684\u6e90\u7801\u5206\u6790\u5c31\u61c2\u4e86\u3002<\/p>\n
        \u73b0\u5728\u6211\u4eec\u518d\u6765\u770b\u4e0b determineHighestPriorityCandidate \u65b9\u6cd5\uff1a<\/p>\n
        @Nullable\nprotected String determineHighestPriorityCandidate(Map<String, Object> candidates, Class<?> requiredType) {\n    String highestPriorityBeanName = null;\n    Integer highestPriority = null;\n    for (Map.Entry<String, Object> entry : candidates.entrySet()) {\n        String candidateBeanName = entry.getKey();\n        Object beanInstance = entry.getValue();\n        if (beanInstance != null) {\n            Integer candidatePriority = getPriority(beanInstance);\n            if (candidatePriority != null) {\n                if (highestPriorityBeanName != null) {\n                    if (candidatePriority.equals(highestPriority)) {\n                        throw new NoUniqueBeanDefinitionException(requiredType, candidates.size(),\n                                "Multiple beans found with the same priority ('" + highestPriority +\n                                "') among candidates: " + candidates.keySet());\n                    }\n                    else if (candidatePriority < highestPriority) {\n                        highestPriorityBeanName = candidateBeanName;\n                        highestPriority = candidatePriority;\n                    }\n                }\n                else {\n                    highestPriorityBeanName = candidateBeanName;\n                    highestPriority = candidatePriority;\n                }\n            }\n        }\n    }\n    return highestPriorityBeanName;\n}<\/code><\/pre>\n
        determineHighestPriorityCandidate \u65b9\u6cd5\u7684\u6574\u4f53\u5904\u7406\u601d\u8def\u8ddf determinePrimaryCandidate \u65b9\u6cd5\u7279\u522b\u50cf\uff0c\u4e0d\u540c\u7684\u662f determinePrimaryCandidate \u65b9\u6cd5\u5904\u7406\u7684\u662f @Primary \u6ce8\u89e3\uff0c\u800c determineHighestPriorityCandidate \u65b9\u6cd5\u5904\u7406\u7684\u662f @Priority \u6ce8\u89e3\u3002<\/p>\n
        determineHighestPriorityCandidate \u65b9\u6cd5\u4e5f\u662f\u904d\u5386 candidates\uff0c\u7136\u540e\u8c03\u7528 getPriority \u65b9\u6cd5\u83b7\u53d6\u5230\u5177\u4f53\u7684\u4f18\u5148\u7ea7\u7684\u503c\u3002\u7136\u540e\u6839\u636e\u8fd9\u4e2a\u5177\u4f53\u7684\u6570\u5b57\u9009\u5b9a\u4e00\u4e2a\u5408\u9002\u7684 beanName \u8fd4\u56de\uff0c\u5982\u679c\u5b58\u5728\u591a\u4e2a\u4f18\u5148\u7ea7\u76f8\u540c\u7684 bean\uff0c\u90a3\u4e48\u5c31\u4f1a\u629b\u51fa NoUniqueBeanDefinitionException \u5f02\u5e38\u3002<\/p>\n
        \u6700\u540e\u518d\u6765\u770b\u4e0b getPriority \u65b9\u6cd5\uff0c\u51e0\u7ecf\u8f97\u8f6c\u4e4b\u540e\uff0c\u8be5\u65b9\u6cd5\u4f1a\u8c03\u7528\u5230 AnnotationAwareOrderComparator#getPriority \u65b9\u6cd5\uff1a<\/p>\n
        @Override\n@Nullable\npublic Integer getPriority(Object obj) {\n    if (obj instanceof Class<?> clazz) {\n        return OrderUtils.getPriority(clazz);\n    }\n    Integer priority = OrderUtils.getPriority(obj.getClass());\n    if (priority == null  && obj instanceof DecoratingProxy decoratingProxy) {\n        return getPriority(decoratingProxy.getDecoratedClass());\n    }\n    return priority;\n}<\/code><\/pre>\n
        \u53ef\u4ee5\u770b\u5230\uff0c\u8fd9\u91cc\u6700\u7ec8\u5c31\u662f\u8c03\u7528 OrderUtils.getPriority \u65b9\u6cd5\u53bb\u67e5\u627e\u53c2\u6570 clazz \u4e0a\u7684 @Priority \u6ce8\u89e3\uff0c\u5e76\u627e\u5230\u6ce8\u89e3\u4e0a\u5bf9\u5e94\u7684\u503c\u8fd4\u56de\u3002OrderUtils.getPriority \u5728\u6267\u884c\u7684\u65f6\u5019\uff0c\u53c2\u6570\u65f6 clazz\uff0c\u5373\u53ea\u4f1a\u67e5\u627e clazz \u4e0a\u7684 \u6ce8\u89e3\uff0c\u5e76\u4e0d\u4f1a\u67e5\u627e\u65b9\u6cd5\u4e0a\u7684\u6ce8\u89e3\uff0c\u56e0\u6b64\u524d\u9762\u6211\u8bf4 @Priority \u6ce8\u89e3\u8981\u52a0\u5728\u7c7b\u4e0a\u624d\u6709\u6548\u3002<\/p>\n
        2.2.3 \u6309\u540d\u79f0\u5339\u914d<\/h4>\n
        \u6700\u540e\u6211\u4eec\u518d\u6765\u770b\u4e0b\u6309\u7167\u540d\u5b57\u53bb\u5339\u914d\u7684\u903b\u8f91\uff1a<\/p>\n
        \/\/ Fallback\nfor (Map.Entry<String, Object> entry : candidates.entrySet()) {\n    String candidateName = entry.getKey();\n    Object beanInstance = entry.getValue();\n    if ((beanInstance != null && this.resolvableDependencies.containsValue(beanInstance)) ||\n            matchesBeanName(candidateName, descriptor.getDependencyName())) {\n        return candidateName;\n    }\n}\nprotected boolean matchesBeanName(String beanName, @Nullable String candidateName) {\n    return (candidateName != null &&\n            (candidateName.equals(beanName) || ObjectUtils.containsElement(getAliases(beanName), candidateName)));\n}<\/code><\/pre>\n
        \u53ef\u4ee5\u770b\u5230\uff0c\u8fd9\u91cc\u4e5f\u662f\u904d\u5386 candidates \u96c6\u5408\uff0c\u7136\u540e\u8c03\u7528 matchesBeanName \u65b9\u6cd5\uff0c\u5728\u8be5\u65b9\u6cd5\u4e2d\uff0c\u4f1a\u53bb\u5224\u65ad\u5019\u9009\u7684 BeanName \u548c\u9700\u8981\u6ce8\u5165\u7684\u53d8\u91cf\u540d\uff08descriptor.getDependencyName()<\/code>\uff09\u662f\u5426\u76f8\u7b49\uff0c\u5982\u679c\u76f8\u7b49\uff0c\u5c31\u76f4\u63a5\u8fd4\u56de\u5373\u53ef\u3002\u5373\u4e0b\u9762\u8fd9\u79cd\u4ee3\u7801\u4e0d\u9700\u8981\u989d\u5916\u7684\u6ce8\u89e3\u662f\u53ef\u4ee5\u8fd0\u884c\u4e0d\u4f1a\u62a5\u9519\u7684\uff1a<\/p>\n
        @Component\npublic class AService {\n    @Autowired\n    B b1;\n\n}\n@Configuration\n@ComponentScan\npublic class JavaConfig {\n\n    @Bean\n    public B b1() {\n        return new B();\n    }\n\n    @Bean\n    B b2() {\n        return new B();\n    }\n\n}<\/code><\/pre>\n
        3. \u5c0f\u7ed3<\/h2>\n
        \u597d\u5566\uff0c\u7ecf\u8fc7\u4e0a\u9762\u7684\u5206\u6790\uff0c\u73b0\u5728\u5c0f\u4f19\u4f34\u4eec\u660e\u767d\u4e86 @Primary \u6ce8\u89e3\u7684\u5b8c\u6574\u5904\u7406\u903b\u8f91\u4e86\u5427\uff5e\u672c\u6587\u7ed3\u5408@Autowired \u5230\u5e95\u662f\u600e\u4e48\u628a\u53d8\u91cf\u6ce8\u5165\u8fdb\u6765\u7684\uff1f<\/a> \u548c Spring \u4e2d @Qualifier \u6ce8\u89e3\u8fd8\u80fd\u8fd9\u4e48\u7528\uff1f<\/a> \u4e00\u8d77\u98df\u7528\u6548\u679c\u66f4\u597d\u54e6\uff01<\/p>\n
        https:\/\/segmentfault.com\/a\/1190000044133117<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
        1. \u95ee\u9898\u5206\u6790 \u5f53\u6211\u4eec\u4f7f\u7528 Spring \u7684\u65f6\u5019\uff0c\u6709\u65f6\u5019\u4f1a\u9047\u5230\u4e0b\u9762\u8fd9\u79cd\u60c5\u51b5\u3002 \u5047\u8bbe\u6211\u6709 A\u3001B \u4e24\u4e2a\u7c7b\uff0c\u5728 A […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10008121","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008121","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10008121"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10008121\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10008121"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10008121"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10008121"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}