@FeignClient注解的接口，用@Autowired可能获取不到实例
背景：
Spring-Boot 2.0.8.RELEASE
Spring-Cloud 2.0.4.RELEASE
OpenFeign 2.0.4.RELEASE
JDK 1.8
启动类：
package com.xxx.tfb;
import java.sql.SQLException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.camunda.bpm.spring.boot.starter.annotation.EnableProcessApplication;
import org.h2.tools.Server;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
import org.springframework.cloud.openfeign.EnableFeignClients;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.FilterType;
import com.xxx.framework.config.SecondDataSourceConfiguration;
import springfox.documentation.swagger2.annotations.EnableSwagger2;
@EnableEurekaClient
@EnableFeignClients(basePackages="com.xxx")
@EnableCircuitBreaker
@EnableProcessApplication
@EnableHystrix
@SpringBootApplication
@EnableSwagger2
@MapperScan(basePackages = { "com.xxx.**.mapper" })
@MapperScan(basePackages = { "com.xxx.**.oramapper" })
@ComponentScan(excludeFilters = {@ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = {SecondDataSourceConfiguration.class})})
@ComponentScan(basePackages = { "com.xxx.framework","com.xxx.workflow",
"com.xxx.tradeengine","com.xxx.component",
"com.xxx.controller", "com.xxx.bizservice",
"com.xxx.rpc","com.xxx.dto.rpc",
"com.xxx.fallbackservice","com.xxx.helper" })
@SuppressWarnings("all")
public class TfbOrBizServiceApplication
{
private static Log log=LogFactory.getLog(TfbOrBizServiceApplication.class);
public static void main(String[] args) {
SpringApplication.run(TfbOrBizServiceApplication.class, args);
}
}
Feign客户端：
package com.xxx.rpc;
import java.util.List;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import com.xxx.dto.tfb.function.UnitBizRequestDto;
import com.xxx.dto.tfb.function.UnitBizResponseDto;
import com.xxx.framework.dto.PaginationDto;
import com.xxx.framework.web.controller.PageRequestDto;
import com.xxx.framework.web.controller.ResponseDto;
@FeignClient(value = "tfb-biz-common-service-app", path="/tfb-biz-common-service-app")
public interface CommonBizRpc {
/**
* 获取交易日期
*/
@RequestMapping(value = "/leftQuery/queryAcctDate", method = RequestMethod.POST)
public ResponseDto queryAcctDate();
}
使用的地方：
package com.xxx.tfb.component.or;
import org.springframework.context.annotation.DependsOn;
import org.springframework.stereotype.Component;
import com.xxx.TradeDto;
import com.xxx.bizenum.tfb.CommonEnum;
import com.xxx.framework.utils.SpringContextUtil;
import com.xxx.rpc.CommonBizRpc;
import com.xxx.tradeengine.dto.DataContext;
import com.xxx.tradeengine.parser.TradeComponent;
@Component
@DependsOn("springContextUtil")
public class OrOpenFxccDataInitComponentImpl implements TradeComponent {
//公共交易服务
CommonBizRpc commonBizRpc = SpringContextUtil.getBean("commonBizRpc");
@Override
public void exec(DataContext dataContext) {
//交易日期
orDto.setTxDt(commonBizRpc.queryAcctDate().getData());
}
}
SpringContextUtil工具类：
@Component
public class SpringContextUtil implements ApplicationContextAware {
private static ApplicationContext applicationContext; // Spring应用上下文环境
/**
* 实现ApplicationContextAware接口的回调方法，设置上下文环境
*
* @param applicationContext @
*/
@Override
public void setApplicationContext(ApplicationContext applicationContext) {
SpringContextUtil.applicationContext = applicationContext;
}
/**
* 获取对象
*
* @param name
* @return Object 一个以所给名字注册的bean的实例 @
*/
@SuppressWarnings("unchecked")
public static T getBean(String name) {
return (T) applicationContext.getBean(name);
}
} 这样的配置，应用启动的时候报错了：
Constructor in com.xxx.tfb.component.or.OrOpenFxccDataInitComponentImpl required a bean named 'commonBizRpc' that could not be found.
Action:
Consider defining a bean named 'commonBizRpc' in your configuration.报错的意思是不存在name为commonBizRpc的实例。已经在@EnableFeignClients(basePackages="com.xxx")配置了basePackages，而且可以确定该@FeignClient已经被扫描到了。
为什么提示找不到呢？
分析下源码：
@EnableFeignClients 注解：
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(FeignClientsRegistrar.class)
public @interface EnableFeignClients {注意上面导入的FeignClientsRegistrar类，该类实现了将@FeignClient注解的接口加入到Spring管理的容器里：
@Override
public void registerBeanDefinitions(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
registerDefaultConfiguration(metadata, registry);
registerFeignClients(metadata, registry);
}
public void registerFeignClients(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
ClassPathScanningCandidateComponentProvider scanner = getScanner();
scanner.setResourceLoader(this.resourceLoader);
Set basePackages;
Map attrs = metadata
.getAnnotationAttributes(EnableFeignClients.class.getName());
AnnotationTypeFilter annotationTypeFilter = new AnnotationTypeFilter(
FeignClient.class);
final Class[] clients = attrs == null ? null
: (Class[]) attrs.get("clients");
if (clients == null || clients.length == 0) {
scanner.addIncludeFilter(annotationTypeFilter);
basePackages = getBasePackages(metadata);
}
else {
final Set clientClasses = new HashSet<>();
basePackages = new HashSet<>();
for (Class clazz : clients) {
basePackages.add(ClassUtils.getPackageName(clazz));
clientClasses.add(clazz.getCanonicalName());
}
AbstractClassTestingTypeFilter filter = new AbstractClassTestingTypeFilter() {
@Override
protected boolean match(ClassMetadata metadata) {
String cleaned = metadata.getClassName().replaceAll("\\$", ".");
return clientClasses.contains(cleaned);
}
};
scanner.addIncludeFilter(
new AllTypeFilter(Arrays.asList(filter, annotationTypeFilter)));
}
for (String basePackage : basePackages) {
Set candidateComponents = scanner
.findCandidateComponents(basePackage);
for (BeanDefinition candidateComponent : candidateComponents) {
if (candidateComponent instanceof AnnotatedBeanDefinition) {
// verify annotated class is an interface
AnnotatedBeanDefinition beanDefinition = (AnnotatedBeanDefinition) candidateComponent;
AnnotationMetadata annotationMetadata = beanDefinition.getMetadata();
Assert.isTrue(annotationMetadata.isInterface(),
"@FeignClient can only be specified on an interface");
Map attributes = annotationMetadata
.getAnnotationAttributes(
FeignClient.class.getCanonicalName());
String name = getClientName(attributes);
registerClientConfiguration(registry, name,
attributes.get("configuration"));
registerFeignClient(registry, annotationMetadata, attributes);
}
}
}
}
private void registerFeignClient(BeanDefinitionRegistry registry,
AnnotationMetadata annotationMetadata, Map attributes) {
String className = annotationMetadata.getClassName();
BeanDefinitionBuilder definition = BeanDefinitionBuilder
.genericBeanDefinition(FeignClientFactoryBean.class);
validate(attributes);
definition.addPropertyValue("url", getUrl(attributes));
definition.addPropertyValue("path", getPath(attributes));
String name = getName(attributes);
definition.addPropertyValue("name", name);
// className为带有包路径的类名
definition.addPropertyValue("type", className);
definition.addPropertyValue("decode404", attributes.get("decode404"));
definition.addPropertyValue("fallback", attributes.get("fallback"));
definition.addPropertyValue("fallbackFactory", attributes.get("fallbackFactory"));
definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
// 默认的别名
// 这里的name是服务方的名称，本示例为注册到Eureka里的服务名
String alias = name + "FeignClient";
AbstractBeanDefinition beanDefinition = definition.getBeanDefinition();
boolean primary = (Boolean)attributes.get("primary"); // has a default, won't be null
beanDefinition.setPrimary(primary);
// 如果注解里加了qualifier，别名就使用qualifier里的名称
String qualifier = getQualifier(attributes);
if (StringUtils.hasText(qualifier)) {
alias = qualifier;
}
BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDefinition, className,
new String[] { alias });
BeanDefinitionReaderUtils.registerBeanDefinition(holder, registry);
} 注意上面的registerFeignClients方法，交给Spring容器管理的实例的name默认是className，即带有包路径的name，本次示例为"com.xxx.rpc.CommonBizRpc"，默认的别名：
// 这里的name是服务方的名称，本示例为注册到Eureka里的服务名，tfb-biz-common-service-appFeignClient
String alias = name + "FeignClient";
// 如果注解里加了qualifier，别名就使用qualifier里的名称
String qualifier = getQualifier(attributes);
if (StringUtils.hasText(qualifier)) {
alias = qualifier;
}
这样在注入的时候，要么使用的name是com.xxx.rpc.CommonBizRpc而不能是CommonBizRpc，或tfb-biz-common-service-appFeignClient（如果该服务注册多个客户端，可能会报错），或使用CommonBizRpc.class
SpringContextUtil.getBean();
@AutoWired也一样
为了方便使用，建议在每个@FeignClient里配置上qualifier，修改后的代码如下：
package com.xxx.rpc;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@FeignClient(value = "tfb-biz-common-service-app", path="/tfb-biz-common-service-app", qualifier="commonBizRpc")
public interface CommonBizRpc {
/**
* 获取交易日期
*/
@RequestMapping(value = "/leftQuery/queryAcctDate", method = RequestMethod.POST)
public ResponseDto queryAcctDate();
}
注意事项：
1.@EnableFeignClients(basePackages="com.xxx") 如果不配置basePackages的话，那么默认只会扫描当前启动类包及其子包的@FeignClient注解
2.@FeignClient里的path最好写上，而且是服务端的contextPath(value = "tfb-biz-common-service-app", path="/tfb-biz-common-service-app", qualifier="commonBizRpc")