聊聊spring cloud的FeignClientFactoryBean

序

本文主要研究一下spring cloud的FeignClientFactoryBean

FeignClientFactoryBean

spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/FeignClientFactoryBean.java

class FeignClientFactoryBean
        implements FactoryBean<Object>, 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;

    @Override
    public void afterPropertiesSet() throws Exception {
        Assert.hasText(this.contextId, "Context id must be set");
        Assert.hasText(this.name, "Name must be set");
    }

    @Override
    public Object getObject() throws Exception {
        return getTarget();
    }

    @Override
    public Class<?> getObjectType() {
        return this.type;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

    @Override
    public void setApplicationContext(ApplicationContext context) throws BeansException {
        this.applicationContext = context;
    }

    <T> T getTarget() {
        FeignContext context = this.applicationContext.getBean(FeignContext.class);
        Feign.Builder builder = feign(context);

        if (!StringUtils.hasText(this.url)) {
            if (!this.name.startsWith("http")) {
                this.url = "http://" + this.name;
            }
            else {
                this.url = this.name;
            }
            this.url += cleanPath();
            return (T) loadBalance(builder, context,
                    new HardCodedTarget<>(this.type, this.name, this.url));
        }
        if (StringUtils.hasText(this.url) && !this.url.startsWith("http")) {
            this.url = "http://" + this.url;
        }
        String url = this.url + cleanPath();
        Client client = getOptional(context, Client.class);
        if (client != null) {
            if (client instanceof LoadBalancerFeignClient) {
                // not load balancing because we have a url,
                // but ribbon is on the classpath, so unwrap
                client = ((LoadBalancerFeignClient) client).getDelegate();
            }
            builder.client(client);
        }
        Targeter targeter = get(context, Targeter.class);
        return (T) targeter.target(this, builder, context,
                new HardCodedTarget<>(this.type, this.name, url));
    }

    private String cleanPath() {
        String path = this.path.trim();
        if (StringUtils.hasLength(path)) {
            if (!path.startsWith("/")) {
                path = "/" + path;
            }
            if (path.endsWith("/")) {
                path = path.substring(0, path.length() - 1);
            }
        }
        return path;
    }

    //......

}

• FeignClientFactoryBean实现了FactoryBean的getObject、getObjectType、isSingleton方法；实现了InitializingBean的afterPropertiesSet方法；实现了ApplicationContextAware的setApplicationContext方法
• getObject调用的是getTarget方法，它从applicationContext取出FeignContext，然后构造Feign.Builder并设置了logger、encoder、decoder、contract，之后通过configureFeign根据FeignClientProperties来进一步配置Feign.Builder的retryer、errorDecoder、request.Options、requestInterceptors、queryMapEncoder、decode404
• 初步配置完Feign.Builder之后再判断是否需要loadBalance，如果需要则通过loadBalance方法来设置，不需要则在Client是LoadBalancerFeignClient的时候进行unwrap

FeignClientProperties

spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/FeignClientProperties.java

@ConfigurationProperties("feign.client")
public class FeignClientProperties {

    private boolean defaultToProperties = true;

    private String defaultConfig = "default";

    private Map<String, FeignClientConfiguration> config = new HashMap<>();

    public boolean isDefaultToProperties() {
        return this.defaultToProperties;
    }

    public void setDefaultToProperties(boolean defaultToProperties) {
        this.defaultToProperties = defaultToProperties;
    }

    public String getDefaultConfig() {
        return this.defaultConfig;
    }

    public void setDefaultConfig(String defaultConfig) {
        this.defaultConfig = defaultConfig;
    }

    public Map<String, FeignClientConfiguration> getConfig() {
        return this.config;
    }

    public void setConfig(Map<String, FeignClientConfiguration> config) {
        this.config = config;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        FeignClientProperties that = (FeignClientProperties) o;
        return this.defaultToProperties == that.defaultToProperties
                && Objects.equals(this.defaultConfig, that.defaultConfig)
                && Objects.equals(this.config, that.config);
    }

    @Override
    public int hashCode() {
        return Objects.hash(this.defaultToProperties, this.defaultConfig, this.config);
    }

    /**
     * Feign client configuration.
     */
    public static class FeignClientConfiguration {

        private Logger.Level loggerLevel;

        private Integer connectTimeout;

        private Integer readTimeout;

        private Class<Retryer> retryer;

        private Class<ErrorDecoder> errorDecoder;

        private List<Class<RequestInterceptor>> requestInterceptors;

        private Boolean decode404;

        private Class<Decoder> decoder;

        private Class<Encoder> encoder;

        private Class<Contract> contract;

        public Logger.Level getLoggerLevel() {
            return this.loggerLevel;
        }

        public void setLoggerLevel(Logger.Level loggerLevel) {
            this.loggerLevel = loggerLevel;
        }

        public Integer getConnectTimeout() {
            return this.connectTimeout;
        }

        public void setConnectTimeout(Integer connectTimeout) {
            this.connectTimeout = connectTimeout;
        }

        public Integer getReadTimeout() {
            return this.readTimeout;
        }

        public void setReadTimeout(Integer readTimeout) {
            this.readTimeout = readTimeout;
        }

        public Class<Retryer> getRetryer() {
            return this.retryer;
        }

        public void setRetryer(Class<Retryer> retryer) {
            this.retryer = retryer;
        }

        public Class<ErrorDecoder> getErrorDecoder() {
            return this.errorDecoder;
        }

        public void setErrorDecoder(Class<ErrorDecoder> errorDecoder) {
            this.errorDecoder = errorDecoder;
        }

        public List<Class<RequestInterceptor>> getRequestInterceptors() {
            return this.requestInterceptors;
        }

        public void setRequestInterceptors(
                List<Class<RequestInterceptor>> requestInterceptors) {
            this.requestInterceptors = requestInterceptors;
        }

        public Boolean getDecode404() {
            return this.decode404;
        }

        public void setDecode404(Boolean decode404) {
            this.decode404 = decode404;
        }

        public Class<Decoder> getDecoder() {
            return this.decoder;
        }

        public void setDecoder(Class<Decoder> decoder) {
            this.decoder = decoder;
        }

        public Class<Encoder> getEncoder() {
            return this.encoder;
        }

        public void setEncoder(Class<Encoder> encoder) {
            this.encoder = encoder;
        }

        public Class<Contract> getContract() {
            return this.contract;
        }

        public void setContract(Class<Contract> contract) {
            this.contract = contract;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }
            FeignClientConfiguration that = (FeignClientConfiguration) o;
            return this.loggerLevel == that.loggerLevel
                    && Objects.equals(this.connectTimeout, that.connectTimeout)
                    && Objects.equals(this.readTimeout, that.readTimeout)
                    && Objects.equals(this.retryer, that.retryer)
                    && Objects.equals(this.errorDecoder, that.errorDecoder)
                    && Objects.equals(this.requestInterceptors, that.requestInterceptors)
                    && Objects.equals(this.decode404, that.decode404)
                    && Objects.equals(this.encoder, that.encoder)
                    && Objects.equals(this.decoder, that.decoder)
                    && Objects.equals(this.contract, that.contract);
        }

        @Override
        public int hashCode() {
            return Objects.hash(this.loggerLevel, this.connectTimeout, this.readTimeout,
                    this.retryer, this.errorDecoder, this.requestInterceptors,
                    this.decode404, this.encoder, this.decoder, this.contract);
        }

    }

}

• FeignClientProperties有个Map结构的config，key是feign client的名称，默认是default，value是FeignClientConfiguration；FeignClientConfiguration包含了loggerLevel、connectTimeout、readTimeout、retryer、errorDecoder、requestInterceptors、decode404、decoder、encoder、contract属性

小结

• FeignClientFactoryBean实现了FactoryBean的getObject、getObjectType、isSingleton方法；实现了InitializingBean的afterPropertiesSet方法；实现了ApplicationContextAware的setApplicationContext方法
• getObject调用的是getTarget方法，它从applicationContext取出FeignContext，然后构造Feign.Builder并设置了logger、encoder、decoder、contract，之后通过configureFeign根据FeignClientProperties来进一步配置Feign.Builder的retryer、errorDecoder、request.Options、requestInterceptors、queryMapEncoder、decode404
• 初步配置完Feign.Builder之后再判断是否需要loadBalance，如果需要则通过loadBalance方法来设置，不需要则在Client是LoadBalancerFeignClient的时候进行unwrap

doc

• FeignClientFactoryBean