dubbo注册中心占位符无法解析问题(一)
dubbo注册中心占位符无法解析问题
1、背景
最近搞了2个老项目,想把他们融合到一起。这俩项目情况简介如下:
项目一:基于SpringMVC + dubbo,配置读取本地properties文件,少量配置读取apollo
项目二:基于Springboot + dubbo,配置读取apollo
本着就高不就低的原则,顺带就把他们拉平到基于springboot的了,没想到这一番操作引入了一个折腾我2天的坑。
2、现象
项目合到一起后,处理掉各种报错后,启动,控制台迅速打印出错误日志:
Caused by: java.net.UnknownHostException: ${zk.address} at java.net.InetAddress.getAllByName0(InetAddress.java:1280) at java.net.InetAddress.getAllByName(InetAddress.java:1192) at java.net.InetAddress.getAllByName(InetAddress.java:1126) at java.net.InetAddress.getByName(InetAddress.java:1076) at io.netty.util.internal.SocketUtils$8.run(SocketUtils.java:156)
zk.address是写在项目的spring-dubbo-common.xml中,配置内容如下:
<!--?xml version="1.0" encoding="UTF-8"?--><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo" xsi:schemalocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd"> <dubbo:application name="dc-dubbo"> <dubbo:registry address="${zk.address}"> <dubbo:protocol name="dubbo" port="21660" threadpool="fixed" threads="300"></dubbo:protocol></dubbo:registry></dubbo:application></beans>
具体的值是配置在apollo上的。
3、问题排查
3.1、apollo配置问题?
首先想到的是,可能是apollo配置问题。就依次做了如下检查:
检查【src/main/resources/META-INF/app.properties】里面的appId是否和apollo配置中心的一致
检查apollo上的配置,是不是真的有zk.address
检查下【C:\opt\data\ {appId}】目录下的apollo配置缓存,找一下是不是有zk.address的配置
这三点都检查下来,发现配置读取都正常。
3.2、 配置解析问题?
配置都正常,但是占位符却没解析,那么想到解析“模块”出了问题。
解析占位符一般通过Spring的PropertySourcesPlaceholderConfigurer来处理。
在Apollo的源码中,已经注册过PropertySourcesPlaceholderConfigurer这个类了,源码com.ctrip.framework.apollo.spring.spi.DefaultApolloConfigRegistrarHelper摘录如下:
public class DefaultApolloConfigRegistrarHelper implements ApolloConfigRegistrarHelper { @Override public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { AnnotationAttributes attributes = AnnotationAttributes .fromMap(importingClassMetadata.getAnnotationAttributes(EnableApolloConfig.class.getName())); String[] namespaces = attributes.getStringArray("value"); int order = attributes.getNumber("order"); PropertySourcesProcessor.addNamespaces(Lists.newArrayList(namespaces), order); Map<string, object=""> propertySourcesPlaceholderPropertyValues = new HashMap<>(); propertySourcesPlaceholderPropertyValues.put("order", 0); // !! 这里注册了PropertySourcesPlaceholderConfigurer类 !! BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, PropertySourcesPlaceholderConfigurer.class.getName(), PropertySourcesPlaceholderConfigurer.class, propertySourcesPlaceholderPropertyValues); BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, PropertySourcesProcessor.class.getName(), PropertySourcesProcessor.class); BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, ApolloAnnotationProcessor.class.getName(), ApolloAnnotationProcessor.class); BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, SpringValueProcessor.class.getName(), SpringValueProcessor.class); BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, SpringValueDefinitionProcessor.class.getName(), SpringValueDefinitionProcessor.class); BeanRegistrationUtil.registerBeanDefinitionIfNotExists(registry, ApolloJsonValueProcessor.class.getName(), ApolloJsonValueProcessor.class); } @Override public int getOrder() { return Ordered.LOWEST_PRECEDENCE; } }
然后我尝试在PropertySourcesPlaceholderConfigurer里面加断点,看下是不是有进入解析替换配置。
从debug来看,配置解析也正常,能正确解析apollo上的配置。
到这里,我有点纳闷了,已经解析到了,咋还提示报错了呢?难道是dubbo的问题?
3.3、dubbo自身的问题?
dubbo的配置,最终会封装成对象。上面配置的zk.address是dubbo:registry的配置,最终会封装成RegistryConfig对象。
类似的还有很多,比如:
ApplicationConfig:对应dubbo:application应用配置
ProtocolConfig:对应协议配置
于是,我在RegistryConfig#setAddress方法加了个断点。看看对象构造时,传入的address参数是多少。
看来,这个问题还得往前找原因。
当我继续往下执行的时候,idea提示断点进入了3.2节的org.springframework.context.support.PropertySourcesPlaceholderConfigurer#postProcessBeanFactory处。
也就是说,在Spring解析占位符之前,dubbo的对象(RegistryConfig)就开始创建并初始化了。
3.4、对象创建时机问题
从前面的分析下来,问题原因算是找到了:
在Spring解析占位符之前,dubbo的对象(RegistryConfig)就开始创建初始化了。导致后面引用的都是未替换占位符的RegistryConfig对象。最终,项目启动才报UnknownHostException: ${zk.address} 异常
再次debug走起,断点停留在RegistryConfig#setAddress方法,看下调用栈:
setAddress:118, RegistryConfig (com.alibaba.dubbo.config), RegistryConfig.javainvoke0:-1, NativeMethodAccessorImpl (sun.reflect), NativeMethodAccessorImpl.javainvoke:62, NativeMethodAccessorImpl (sun.reflect), NativeMethodAccessorImpl.javainvoke:43, DelegatingMethodAccessorImpl (sun.reflect), DelegatingMethodAccessorImpl.javainvoke:498, Method (java.lang.reflect), Method.javasetValue:332, BeanWrapperImpl$BeanPropertyHandler (org.springframework.beans), BeanWrapperImpl.javaprocessLocalProperty:458, AbstractNestablePropertyAccessor (org.springframework.beans), AbstractNestablePropertyAccessor.javasetPropertyValue:278, AbstractNestablePropertyAccessor (org.springframework.beans), AbstractNestablePropertyAccessor.javasetPropertyValue:266, AbstractNestablePropertyAccessor (org.springframework.beans), AbstractNestablePropertyAccessor.javasetPropertyValues:97, AbstractPropertyAccessor (org.springframework.beans), AbstractPropertyAccessor.javasetPropertyValues:77, AbstractPropertyAccessor (org.springframework.beans), AbstractPropertyAccessor.javaapplyPropertyValues:1732, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javapopulateBean:1444, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javadoCreateBean:594, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javacreateBean:517, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javalambda$doGetBean$0:323, AbstractBeanFactory (org.springframework.beans.factory.support), AbstractBeanFactory.javagetObject:-1, 1713129148 (org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$195), Unknown SourcegetSingleton:226, DefaultSingletonBeanRegistry (org.springframework.beans.factory.support), DefaultSingletonBeanRegistry.javadoGetBean:321, AbstractBeanFactory (org.springframework.beans.factory.support), AbstractBeanFactory.javagetBean:202, AbstractBeanFactory (org.springframework.beans.factory.support), AbstractBeanFactory.javagetBeansOfType:621, DefaultListableBeanFactory (org.springframework.beans.factory.support), DefaultListableBeanFactory.javagetBeansOfType:1251, AbstractApplicationContext (org.springframework.context.support), AbstractApplicationContext.javabeansOfTypeIncludingAncestors:378, BeanFactoryUtils (org.springframework.beans.factory), BeanFactoryUtils.javaafterPropertiesSet:140, ReferenceBean (com.alibaba.dubbo.config.spring), ReferenceBean.javainvokeInitMethods:1855, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javainitializeBean:1792, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javadoCreateBean:595, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javacreateBean:517, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javalambda$doGetBean$0:323, AbstractBeanFactory (org.springframework.beans.factory.support), AbstractBeanFactory.javagetObject:-1, 1713129148 (org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$195), Unknown SourcegetSingleton:226, DefaultSingletonBeanRegistry (org.springframework.beans.factory.support), DefaultSingletonBeanRegistry.javadoGetBean:321, AbstractBeanFactory (org.springframework.beans.factory.support), AbstractBeanFactory.javagetTypeForFactoryBean:1646, AbstractBeanFactory (org.springframework.beans.factory.support), AbstractBeanFactory.javagetTypeForFactoryBean:895, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support), AbstractAutowireCapableBeanFactory.javaisTypeMatch:613, AbstractBeanFactory (org.springframework.beans.factory.support), AbstractBeanFactory.javadoGetBeanNamesForType:537, DefaultListableBeanFactory (org.springframework.beans.factory.support), DefaultListableBeanFactory.javagetBeanNamesForType:495, DefaultListableBeanFactory (org.springframework.beans.factory.support), DefaultListableBeanFactory.javagetBeansOfType:617, DefaultListableBeanFactory (org.springframework.beans.factory.support), DefaultListableBeanFactory.javagetBeansOfType:609, DefaultListableBeanFactory (org.springframework.beans.factory.support), DefaultListableBeanFactory.javagetBeansOfType:1243, AbstractApplicationContext (org.springframework.context.support), AbstractApplicationContext.javaprocessPropertyPlaceHolders:367, MapperScannerConfigurer (org.mybatis.spring.mapper), MapperScannerConfigurer.javapostProcessBeanDefinitionRegistry:338, MapperScannerConfigurer (org.mybatis.spring.mapper), MapperScannerConfigurer.javainvokeBeanDefinitionRegistryPostProcessors:280, PostProcessorRegistrationDelegate (org.springframework.context.support), PostProcessorRegistrationDelegate.javainvokeBeanFactoryPostProcessors:126, PostProcessorRegistrationDelegate (org.springframework.context.support), PostProcessorRegistrationDelegate.javainvokeBeanFactoryPostProcessors:707, AbstractApplicationContext (org.springframework.context.support), AbstractApplicationContext.javarefresh:533, AbstractApplicationContext (org.springframework.context.support), AbstractApplicationContext.javarefresh:143, ServletWebServerApplicationContext (org.springframework.boot.web.servlet.context), ServletWebServerApplicationContext.javarefresh:758, SpringApplication (org.springframework.boot), SpringApplication.javarefresh:750, SpringApplication (org.springframework.boot), SpringApplication.javarefreshContext:397, SpringApplication (org.springframework.boot), SpringApplication.javarun:315, SpringApplication (org.springframework.boot), SpringApplication.javamain:36, DcRemoteApplication (com.yc.dc.remote), DcRemoteApplication.java
从调用栈,发现一点奇怪的调用路径:
在org.mybatis.spring.mapper.MapperScannerConfigurer#processPropertyPlaceHolders方法中,调用了applicationContext.getBeansOfType(PropertyResourceConfigurer.class); 从而引发了后面的一些列的对象创建在PropertyResourceConfigurer之前。
public class MapperScannerConfigurer implements BeanDefinitionRegistryPostProcessor, InitializingBean, ApplicationContextAware, BeanNameAware { @Override public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) { if (this.processPropertyPlaceHolders) { // true processPropertyPlaceHolders(); } ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry); scanner.setAddToConfig(this.addToConfig); scanner.setAnnotationClass(this.annotationClass); scanner.setMarkerInterface(this.markerInterface); scanner.setSqlSessionFactory(this.sqlSessionFactory); scanner.setSqlSessionTemplate(this.sqlSessionTemplate); scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName); scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName); scanner.setResourceLoader(this.applicationContext); scanner.setBeanNameGenerator(this.nameGenerator); scanner.setMapperFactoryBeanClass(this.mapperFactoryBeanClass); if (StringUtils.hasText(lazyInitialization)) { scanner.setLazyInitialization(Boolean.valueOf(lazyInitialization)); } scanner.registerFilters(); scanner.scan( StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS)); } private void processPropertyPlaceHolders() { // 这里调 getBeansOfType(PropertyResourceConfigurer.class) Map<string, propertyresourceconfigurer=""> prcs = applicationContext.getBeansOfType(PropertyResourceConfigurer.class); // ...此处省略若干代码... } // ...此处省略若干代码...}
【applicationContext.getBeansOfType(PropertyResourceConfigurer.class);】执行过程中
Spring一路执行到org.springframework.beans.factory.support.DefaultListableBeanFactory#doGetBeanNamesForType,
并在方法内,循环所有beanDefinitionNames,逐一判断beanDefinition是不是PropertyResourceConfigurer类型的(isTypeMatch方法)
判断的时候,就需要从Spring容器中取这个bean,取着取着发现没有,就开始doCeateBean-->invokeInitMethods-->afterPropertiesSet 了。
在创建dubbo消费者的时候,消费者接口被封装成ReferenceBean,在其afterPropertiesSet方法中,依赖RegistryConfig对象,从而依赖注册中心配置的地址。
而这些,都是发生在PropertyResourceConfigurer创建之前。
此处特别说明,我项目里面使用的mybatis-spring是2.0.3版本
4、 解决方法
4.1、方法一
前面分析了,MapperScannerConfigurer对象的boolean属性processPropertyPlaceHolders为true,导致执行了processPropertyPlaceHolders()方法。
那么,据此可以自定义一个MapperScannerConfigurer对象,设置processPropertyPlaceHolders为false。
// 去掉 @MapperScan 注解,通过下面的方式设置MapperScannerConfigurer@Beanpublic MapperScannerConfigurer dsCrmMapperScannerConfigurer() { MapperScannerConfigurer configurer = new MapperScannerConfigurer(); configurer.setProcessPropertyPlaceHolders(false); configurer.setBasePackage("com.yc.dc.mapper"); configurer.setSqlSessionFactoryBeanName("dsCrmSqlSessionFactory"); return configurer; }
通过这种方式试了下,发现果然可行。
为啥可行? 究其原因如下:
MapperScannerConfigurer一般通过MapperScannerRegistrar引入进来。
mybatis-spring 是从2.0.2版本开始,引入MapperScannerConfigurer的时候,设置了processPropertyPlaceHolders值为true。
才会在扫描mapper之前,调了一下 processPropertyPlaceHolders()方法。
// org.mybatis.spring.annotation.MapperScannerRegistrar,mybatis-spring 2.0.2及以上版本void registerBeanDefinitions(AnnotationAttributes annoAttrs, BeanDefinitionRegistry registry, String beanName) { BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(MapperScannerConfigurer.class); builder.addPropertyValue("processPropertyPlaceHolders", true); // 看这里!! Class<!--? extends Annotation--> annotationClass = annoAttrs.getClass("annotationClass"); if (!Annotation.class.equals(annotationClass)) { builder.addPropertyValue("annotationClass", annotationClass); } // .....}// org.mybatis.spring.annotation.MapperScannerRegistrar,mybatis-spring 2.0.1及以下版本void registerBeanDefinitions(AnnotationAttributes annoAttrs, BeanDefinitionRegistry registry) { ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry); // ClassPathMapperScanner里面就没有getBeansOfType(PropertyResourceConfigurer.class) Optional.ofNullable(resourceLoader).ifPresent(scanner::setResourceLoader); Class<!--? extends Annotation--> annotationClass = annoAttrs.getClass("annotationClass"); if (!Annotation.class.equals(annotationClass)) { scanner.setAnnotationClass(annotationClass); } // .....}
4.2、方法二
降低mybatis-spring的版本到 2.0.1 或者 更低版本。
5、 未完待续
到这里,问题就查清楚了,并且解决办法也有了。但真的结束了吗?
木有,合并前的老项目二使用的就是mybatis-spring-2.0.3.jar,但是他没有报【UnknownHostException: ${zk.address}】,也没有自定义MapperScannerConfigurer设置processPropertyPlaceHolders为false
那为什么?
来源https://www.cnblogs.com/yejg1212/p/15427802.html