最新的dubbo 2.6.2版本中@Service註解的parameters配置BUG和解決方案
阿新 • • 發佈：2019-02-14
在描述這個BUG之前，我想先說一個需求場景，假設我們有一個DemoService介面:
public interface DemoService {
String sayHello(String name);
String sayHello2(String name);
}我們想單獨設定這兩個方法的超時時間，該如何設定呢？
當然我們可以在consumer端通過@Reference註解的parameters註解實現（PS：基於XML的配置可以配置MethodConfig元素，but基於註解的配置沒有單獨設定某個method的配置，只能曲線救國，我們只要清楚一點就是所有的配置都會作為url引數的一部分就OK了，所以我們可以通過配置註解的parameters引數來往url上附加額外引數來達到相同的目的）:
@RestController public class DemoConsumerController { @Reference( version = "${demo.service.version}", application = "${dubbo.application.id}", registry = "${dubbo.registry.id}", parameters = {"sayHello.timeout", "3000", "sayHello2.timeout", "5000"} ) private DemoService demoService; @RequestMapping("/sayHello") public String sayHello(@RequestParam String name) throws ExecutionException, InterruptedException { return demoService.sayHello(name); } @RequestMapping("/sayHello2") public String sayHello2(@RequestParam String name) throws ExecutionException, InterruptedException { return demoService.sayHello2(name); } }
這裡我們將sayHello.timeout設定了3000毫秒，sayHello2.timeout設定了5000毫秒。執行程式，沒有啥毛病。
但是dubbo官方推薦做法是儘量在provider端多做配置，比如timeout這種配置，應該在服務提供者端配置，而不是在消費者端配置，因為提供者更清楚他提供的方法大致會花費多長時間。（雖然按照dubbo的配置覆蓋規則，在consumer端的配置會覆蓋provider端的配置）。
好吧，那我們還是按官方的建議來調整這個配置，把timeout配置到@Service註解上去:
@Service( version = "${demo.service.version}", application = "${dubbo.application.id}", protocol = "${dubbo.protocol.id}", registry = "${dubbo.registry.id}" , parameters = {"sayHello.timeout", "3100", "sayHello2.timeout", "5000"} ) public class DefaultDemoService implements DemoService { @Override public String sayHello(String name) { System.out.println("get request"); try { Thread.sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); } return "sayHello Hello, " + name + " (from Spring Boot)"; } @Override public String sayHello2(String name) { try { Thread.sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); } return "sayHello2 Hello, " + name + " (from Spring Boot)"; } }
啟動程式你會發現竟然報錯了：
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ServiceBean:defaultDemoService:com.kingnet.blockdata.service.DemoService:${demo.service.version}': Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'java.lang.String[]' to required type 'java.util.Map' for property 'parameters'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String[]' to required type 'java.util.Map' for property 'parameters': no matching editors or conversion strategy found
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:589) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:503) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$97/1279271200.getObject(Unknown Source) ~[na:na]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:760) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:137) [spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at com.kingnet.blockdata.DubboProviderDemo.main(DubboProviderDemo.java:20) [classes/:na]
Caused by: org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'java.lang.String[]' to required type 'java.util.Map' for property 'parameters'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String[]' to required type 'java.util.Map' for property 'parameters': no matching editors or conversion strategy found
at org.springframework.beans.AbstractNestablePropertyAccessor.convertIfNecessary(AbstractNestablePropertyAccessor.java:590) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.AbstractNestablePropertyAccessor.convertForProperty(AbstractNestablePropertyAccessor.java:604) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:219) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1660) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1616) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1363) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:580) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
... 15 common frames omitted
Caused by: java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String[]' to required type 'java.util.Map' for property 'parameters': no matching editors or conversion strategy found
at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:299) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.beans.AbstractNestablePropertyAccessor.convertIfNecessary(AbstractNestablePropertyAccessor.java:585) ~[spring-beans-5.0.7.RELEASE.jar:5.0.7.RELEASE]
... 21 common frames omitted原因很明顯，@Service裡面的parameters是String[]型別，但是要對映到ServiceBean的parameters屬性是一個Map<String,String>型別，沒法自動轉換對映上去,所以報了這個錯誤。
那麼如何解決這個問題呢？
我們檢視原始碼發現ServiceBean是通過:
com.alibaba.dubbo.config.spring.beans.factory.annotation.ServiceAnnotationBeanPostProcessor#registerServiceBean
這個BeanPostProcessor註冊進來的，這裡面掃描了所有打了@Service的類，把他們註冊成了ServiceBean。
於是我們就有了曲線救國的方法，我們在定義一個BeanPostProcessor，在ServiceAnnotationBeanPostProcessor之後執行，然後在ServiceBean真正例項化之前轉換一下parameters這個引數為Map<String,String>就好了:
import com.alibaba.dubbo.config.spring.ServiceBean;
import com.alibaba.dubbo.config.spring.convert.converter.StringArrayToMapConverter;
import com.alibaba.dubbo.config.spring.convert.converter.StringArrayToStringConverter;
import org.springframework.beans.BeansException;
import org.springframework.beans.PropertyValue;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
import org.springframework.core.PriorityOrdered;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;
import java.beans.PropertyDescriptor;
import java.util.Map;
/**
* 解決@Service註解配置parameters引數時無法將String[]轉化成Map<String,String>的bug
*
* @author : xiaojun
* @since 13:16 2018/7/23
*/
public class ServiceParameterBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter implements PriorityOrdered {
@Override
public int getOrder() {
return PriorityOrdered.LOWEST_PRECEDENCE;
}
@Override
public PropertyValues postProcessPropertyValues(PropertyValues pvs, PropertyDescriptor[] pds, Object bean, String beanName) throws BeansException {
// pvs.getPropertyValue("parameter")
if (bean instanceof ServiceBean) {
PropertyValue propertyValue = pvs.getPropertyValue("parameters");
ConversionService conversionService = getConversionService();
if (propertyValue != null && propertyValue.getValue() != null && conversionService.canConvert(propertyValue.getValue().getClass(), Map.class)) {
Map parameters = conversionService.convert(propertyValue.getValue(), Map.class);
propertyValue.setConvertedValue(parameters);
}
}
return pvs;
}
private ConversionService getConversionService() {
DefaultConversionService conversionService = new DefaultConversionService();
conversionService.addConverter(new StringArrayToStringConverter());
conversionService.addConverter(new StringArrayToMapConverter());
return conversionService;
}
}細心的讀者可能已經發現了點端倪，為毛@Reference註解裡面的parameters可以正確對映到ReferenceBean的Map<String,String> parameters上來。。。說來也有點坑，這兩個註解Bean的實現方式竟然不統一。但是dubbo提供了一個Converter:
com.alibaba.dubbo.config.spring.convert.converter.StringArrayToMapConverter;我們也用這個converter將原始PropertySource裡面的String[] parameters轉換成Map<String,String> parameters就行了。
這裡還實現了Ordered介面，讓我們的這個BeanPostProcessor的優先順序最低，這樣可以保證在dubbo自己的那個BeanPostProcessor之後執行，才能順利轉換這個屬性。
當然，別忘了註冊bean:
@Bean
ServiceParameterBeanPostProcessor serviceParameterBeanPostProcessor() {
return new ServiceParameterBeanPostProcessor();
}啟動程式檢視一下console的url資訊:
dubbo://192.168.56.1:12345/com.kingnet.blockdata.service.DemoService?anyhost=true&application=dubbo-provider-demo&dubbo=2.6.2&generic=false&interface=com.kingnet.blockdata.service.DemoService&methods=sayHello,sayHello2&pid=9052&revision=1.0.0&sayHello.timeout=3100&sayHello2.timeout=5000&side=provider&status=server×tamp=1532588660430&version=1.0.0
發現parameters的配置資訊成功附加到url的引數裡面了。