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Feign中FeignClientFactoryBean的作用是什么

发表于:2025-12-01 作者:千家信息网编辑
千家信息网最后更新 2025年12月01日,今天就跟大家聊聊有关Feign中FeignClientFactoryBean的作用是什么,可能很多人都不太了解,为了让大家更加了解,小编给大家总结了以下内容,希望大家根据这篇文章可以有所收获。图1其属
千家信息网最后更新 2025年12月01日Feign中FeignClientFactoryBean的作用是什么

今天就跟大家聊聊有关Feign中FeignClientFactoryBean的作用是什么,可能很多人都不太了解,为了让大家更加了解,小编给大家总结了以下内容,希望大家根据这篇文章可以有所收获。

图1

其属性如List-1所示,这些属性的值都是在FeignClientsRegistrar中设置的。

List-1

class FeignClientFactoryBean                implements FactoryBean, InitializingBean, ApplicationContextAware {        /***********************************         * WARNING! Nothing in this class should be @Autowired. It causes NPEs because of some         * lifecycle race condition.         ***********************************/        private Class type;        private String name;        private String url;        private String contextId;        private String path;        private boolean decode404;        private ApplicationContext applicationContext;        private Class fallback = void.class;        private Class fallbackFactory = void.class;...

由于实现了FactoryBean接口,我们来看最重要的getObject()方法,如List-2,getTarget方法中首先从Spring上下文中获取FeignContext。FeignContext是在FeignAutoConfiguration中注册到Spring容器中的,如List-3所示,会将spring容器所有的FeignClientSpecification放入到FeignContext中,FeignClientSpecification在Feign源码分析之EnableFeignClients中讲过,即EnableFeignClients的defaultConfiguration。

List-2

@Overridepublic Object getObject() throws Exception {    return getTarget();} T getTarget() {    FeignContext context = this.applicationContext.getBean(FeignContext.class);    Feign.Builder builder = feign(context);...

List-3

public class FeignAutoConfiguration {        @Autowired(required = false)        private List configurations = new ArrayList<>();        @Bean        public HasFeatures feignFeature() {                return HasFeatures.namedFeature("Feign", Feign.class);        }        @Bean        public FeignContext feignContext() {                FeignContext context = new FeignContext();                context.setConfigurations(this.configurations);                return context;        }...

List-2中,得到FeignContext后,调用feign方法,从FeignContext中获取Encoder、Decoder、Contract,其实内部是从spring容器中获取的,得到Feign.Builder。

我们可以实现RequestInterceptor接口,之后交给Spring容器,feign会自动加上这个拦截器,这个的实现也在FeignClientFactoryBean中,在configureUsingConfiguration方法中,如下List-4

List-4

Map requestInterceptors = context.getInstances(this.contextId, RequestInterceptor.class);if (requestInterceptors != null) {    builder.requestInterceptors(requestInterceptors.values());}

List-4中的context.getInstances()方法内部是如何实现的呢。来看下FeignContext的父类NamedContextFactory,List-5中的setConfigurations方法在List-3中调用,在构造FeignContext的时候调用的。

List-5

public void setConfigurations(List configurations) {    for (C client : configurations) {        this.configurations.put(client.getName(), client);    }}

List-6中

  1. getConext方法获取ApplicationContext,之后从该ApplicationContext中获取bean

  2. getConext方法中,如过name对应的ApplicationContext不存在,则调用createContext方法进行创建

  3. AnnotationConfigApplicationContext.register方法把配置类注册到ApplicationContext中,还设置了AnnotationConfigApplicationContext的parent为当前Spring上下文,这样当在AnnotationConfigApplicationContext中获取不到bean时,就会从父ApplicationContext中获取

List-6

public  T getInstance(String name, Class type) {    AnnotationConfigApplicationContext context = getContext(name);    if (BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context,            type).length > 0) {        return context.getBean(type);    }    return null;}protected AnnotationConfigApplicationContext getContext(String name) {    if (!this.contexts.containsKey(name)) {        synchronized (this.contexts) {            if (!this.contexts.containsKey(name)) {                this.contexts.put(name, createContext(name));            }        }    }    return this.contexts.get(name);}protected AnnotationConfigApplicationContext createContext(String name) {    AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();    if (this.configurations.containsKey(name)) {        for (Class configuration : this.configurations.get(name)                .getConfiguration()) {            context.register(configuration);        }    }    for (Map.Entry entry : this.configurations.entrySet()) {        if (entry.getKey().startsWith("default.")) {            for (Class configuration : entry.getValue().getConfiguration()) {                context.register(configuration);            }        }    }    context.register(PropertyPlaceholderAutoConfiguration.class,            this.defaultConfigType);    context.getEnvironment().getPropertySources().addFirst(new MapPropertySource(            this.propertySourceName,            Collections.singletonMap(this.propertyName, name)));    if (this.parent != null) {        // Uses Environment from parent as well as beans        context.setParent(this.parent);        // jdk11 issue        // https://github.com/spring-cloud/spring-cloud-netflix/issues/3101        context.setClassLoader(this.parent.getClassLoader());    }    context.setDisplayName(generateDisplayName(name));    context.refresh();    return context;}

看完上述内容,你们对Feign中FeignClientFactoryBean的作用是什么有进一步的了解吗?如果还想了解更多知识或者相关内容,请关注行业资讯频道,感谢大家的支持。

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