Dubbo原理简述三：启动解析、加载配置信息

太过爱你忘了你带给我的痛 2022-03-26 05:20 192阅读 0赞

<dubbo:registry protocol="zookeeper" address="127.0.0.1:2181"></dubbo:registry>
    	<dubbo:protocol name="dubbo" port="20882"></dubbo:protocol>
    	<dubbo:service interface="com.atguigu.gmall.service.UserService" ref="userServiceImpl01" timeout="1000" version="1.0.0">
    		<dubbo:method name="getUserAddressList" timeout="1000"></dubbo:method>
    	</dubbo:service>
    	<dubbo:monitor protocol="registry"></dubbo:monitor>
    	....
    	....

如上配置文件中的各个标签都对应着Dubbo源码中某个`XxxConfig`（`service`和`reference`标签对应着`XxxBean`）,其对应规则可通过源码得知：

DubboNamespaceHandler.java  
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其中对于配置文件的标签解析，主要体现在此方法上  
：`DubboBeanDefinitionParser.parse(...)`  
源码如下：

public class DubboBeanDefinitionParser implements BeanDefinitionParser { 
        
    
        ......
    
    
        @SuppressWarnings("unchecked")
        private static BeanDefinition parse(Element element, ParserContext parserContext, Class<?> beanClass, boolean required) { 
            RootBeanDefinition beanDefinition = new RootBeanDefinition();
            beanDefinition.setBeanClass(beanClass);
            beanDefinition.setLazyInit(false);
            String id = element.getAttribute("id");
            if ((id == null || id.length() == 0) && required) { 
                String generatedBeanName = element.getAttribute("name");
                if (generatedBeanName == null || generatedBeanName.length() == 0) { 
                    if (ProtocolConfig.class.equals(beanClass)) { 
                        generatedBeanName = "dubbo";
                    } else { 
                        generatedBeanName = element.getAttribute("interface");
                    }
                }
                if (generatedBeanName == null || generatedBeanName.length() == 0) { 
                    generatedBeanName = beanClass.getName();
                }
                id = generatedBeanName; 
                int counter = 2;
                while(parserContext.getRegistry().containsBeanDefinition(id)) { 
                    id = generatedBeanName + (counter ++);
                }
            }
            if (id != null && id.length() > 0) { 
                if (parserContext.getRegistry().containsBeanDefinition(id))  { 
                    throw new IllegalStateException("Duplicate spring bean id " + id);
                }
                parserContext.getRegistry().registerBeanDefinition(id, beanDefinition);
                beanDefinition.getPropertyValues().addPropertyValue("id", id);
            }
            //判断是否匹配 ProtocolConfig
            if (ProtocolConfig.class.equals(beanClass)) { 
                for (String name : parserContext.getRegistry().getBeanDefinitionNames()) { 
                    BeanDefinition definition = parserContext.getRegistry().getBeanDefinition(name);
                    PropertyValue property = definition.getPropertyValues().getPropertyValue("protocol");
                    if (property != null) { 
                        Object value = property.getValue();
                        if (value instanceof ProtocolConfig && id.equals(((ProtocolConfig) value).getName())) { 
                            definition.getPropertyValues().addPropertyValue("protocol", new RuntimeBeanReference(id));
                        }
                    }
                }
                //判断是否匹配 ServiceBean
            } else if (ServiceBean.class.equals(beanClass)) { 
                String className = element.getAttribute("class");
                if(className != null && className.length() > 0) { 
                    RootBeanDefinition classDefinition = new RootBeanDefinition();
                    classDefinition.setBeanClass(ReflectUtils.forName(className));
                    classDefinition.setLazyInit(false);
                    parseProperties(element.getChildNodes(), classDefinition);
                    beanDefinition.getPropertyValues().addPropertyValue("ref", new BeanDefinitionHolder(classDefinition, id + "Impl"));
                }
                //判断是否匹配 ProviderConfig
            } else if (ProviderConfig.class.equals(beanClass)) { 
                parseNested(element, parserContext, ServiceBean.class, true, "service", "provider", id, beanDefinition);
                //判断是否匹配 ConsumerConfig
            } else if (ConsumerConfig.class.equals(beanClass)) { 
                parseNested(element, parserContext, ReferenceBean.class, false, "reference", "consumer", id, beanDefinition);
            }
            Set<String> props = new HashSet<String>();
            ManagedMap parameters = null;
            for (Method setter : beanClass.getMethods()) { 
                String name = setter.getName();
                if (name.length() > 3 && name.startsWith("set")
                        && Modifier.isPublic(setter.getModifiers())
                        && setter.getParameterTypes().length == 1) { 
                    Class<?> type = setter.getParameterTypes()[0];
                    String property = StringUtils.camelToSplitName(name.substring(3, 4).toLowerCase() + name.substring(4), "-");
                    props.add(property);
                    Method getter = null;
                    try { 
                        getter = beanClass.getMethod("get" + name.substring(3), new Class<?>[0]);
                    } catch (NoSuchMethodException e) { 
                        try { 
                            getter = beanClass.getMethod("is" + name.substring(3), new Class<?>[0]);
                        } catch (NoSuchMethodException e2) { 
                        }
                    }
                    if (getter == null 
                            || ! Modifier.isPublic(getter.getModifiers())
                            || ! type.equals(getter.getReturnType())) { 
                        continue;
                    }
                    if ("parameters".equals(property)) { 
                        parameters = parseParameters(element.getChildNodes(), beanDefinition);
                    } else if ("methods".equals(property)) { 
                        parseMethods(id, element.getChildNodes(), beanDefinition, parserContext);
                    } else if ("arguments".equals(property)) { 
                        parseArguments(id, element.getChildNodes(), beanDefinition, parserContext);
                    } else { 
                        String value = element.getAttribute(property);
                        if (value != null) { 
                            value = value.trim();
                            if (value.length() > 0) { 
                                if ("registry".equals(property) && RegistryConfig.NO_AVAILABLE.equalsIgnoreCase(value)) { 
                                    RegistryConfig registryConfig = new RegistryConfig();
                                    registryConfig.setAddress(RegistryConfig.NO_AVAILABLE);
                                    beanDefinition.getPropertyValues().addPropertyValue(property, registryConfig);
                                } else if ("registry".equals(property) && value.indexOf(',') != -1) { 
                                    parseMultiRef("registries", value, beanDefinition, parserContext);
                                } else if ("provider".equals(property) && value.indexOf(',') != -1) { 
                                    parseMultiRef("providers", value, beanDefinition, parserContext);
                                } else if ("protocol".equals(property) && value.indexOf(',') != -1) { 
                                    parseMultiRef("protocols", value, beanDefinition, parserContext);
                                } else { 
                                    Object reference;
                                    if (isPrimitive(type)) { 
                                        if ("async".equals(property) && "false".equals(value)
                                                || "timeout".equals(property) && "0".equals(value)
                                                || "delay".equals(property) && "0".equals(value)
                                                || "version".equals(property) && "0.0.0".equals(value)
                                                || "stat".equals(property) && "-1".equals(value)
                                                || "reliable".equals(property) && "false".equals(value)) { 
                                            // 兼容旧版本xsd中的default值
                                            value = null;
                                        }
                                        reference = value;
                                    } else if ("protocol".equals(property) 
                                            && ExtensionLoader.getExtensionLoader(Protocol.class).hasExtension(value)
                                            && (! parserContext.getRegistry().containsBeanDefinition(value)
                                                    || ! ProtocolConfig.class.getName().equals(parserContext.getRegistry().getBeanDefinition(value).getBeanClassName()))) { 
                                        if ("dubbo:provider".equals(element.getTagName())) { 
                                            logger.warn("Recommended replace <dubbo:provider protocol=\"" + value + "\" ... /> to <dubbo:protocol name=\"" + value + "\" ... />");
                                        }
                                        // 兼容旧版本配置
                                        ProtocolConfig protocol = new ProtocolConfig();
                                        protocol.setName(value);
                                        reference = protocol;
                                    } else if ("monitor".equals(property) 
                                            && (! parserContext.getRegistry().containsBeanDefinition(value)
                                                    || ! MonitorConfig.class.getName().equals(parserContext.getRegistry().getBeanDefinition(value).getBeanClassName()))) { 
                                        // 兼容旧版本配置
                                        reference = convertMonitor(value);
                                    } else if ("onreturn".equals(property)) { 
                                        int index = value.lastIndexOf(".");
                                        String returnRef = value.substring(0, index);
                                        String returnMethod = value.substring(index + 1);
                                        reference = new RuntimeBeanReference(returnRef);
                                        beanDefinition.getPropertyValues().addPropertyValue("onreturnMethod", returnMethod);
                                    } else if ("onthrow".equals(property)) { 
                                        int index = value.lastIndexOf(".");
                                        String throwRef = value.substring(0, index);
                                        String throwMethod = value.substring(index + 1);
                                        reference = new RuntimeBeanReference(throwRef);
                                        beanDefinition.getPropertyValues().addPropertyValue("onthrowMethod", throwMethod);
                                    } else { 
                                        if ("ref".equals(property) && parserContext.getRegistry().containsBeanDefinition(value)) { 
                                            BeanDefinition refBean = parserContext.getRegistry().getBeanDefinition(value);
                                            if (! refBean.isSingleton()) { 
                                                throw new IllegalStateException("The exported service ref " + value + " must be singleton! Please set the " + value + " bean scope to singleton, eg: <bean id=\"" + value+ "\" scope=\"singleton\" ...>");
                                            }
                                        }
                                        reference = new RuntimeBeanReference(value);
                                    }
                                    beanDefinition.getPropertyValues().addPropertyValue(property, reference);
                                }
                            }
                        }
                    }
                }
            }
            NamedNodeMap attributes = element.getAttributes();
            int len = attributes.getLength();
            for (int i = 0; i < len; i++) { 
                Node node = attributes.item(i);
                String name = node.getLocalName();
                if (! props.contains(name)) { 
                    if (parameters == null) { 
                        parameters = new ManagedMap();
                    }
                    String value = node.getNodeValue();
                    parameters.put(name, new TypedStringValue(value, String.class));
                }
            }
            if (parameters != null) { 
                beanDefinition.getPropertyValues().addPropertyValue("parameters", parameters);
            }
            return beanDefinition;
        }
    
        
        ......
    
    }

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