Dubbo之——改造Dubbo，使其能够兼容Spring 4注解配置
转载请注明出处：http://blog.csdn.net/l1028386804/article/details/70040928
而随着Spring Boot的大热，Java-Base方式配置Spring也变得越来越流行。
Dubbo + Boot的开发模式，也是较为常见的组合方式。
但是，当使用Dubbo在高版本Spring环境中使用注解方式配置时，会因为一些代码版本的原因导致整合出现问题。
- Dubbo原生的注解配置
Dubbo本身就是基于Spring的，而且原生就提供注解配置：
服务提供方配置：
服务提供方注解：
[java] view plain copy
import com.alibaba.dubbo.config.annotation.Service;
@Service(version=”1.0.0”)
public class FooServiceImpl implements FooService {
// ……
}
服务消费方注解：
[java] view plain copy
import com.alibaba.dubbo.config.annotation.Reference;
import org.springframework.stereotype.Component;
@Component
public class BarAction {
@Reference(version="1.0.0")
private FooService fooService;
}
服务消费方配置：
[html] view plain copy
通过官方的例子，就可以看出Dubbo使用xml配置 来开启注解配置，并提供 com.alibaba.dubbo.config.annotation.Service注解进行服务注册，提供com.alibaba.dubbo.config.annotation.Reference注解进行服务注入。
2.实现机制
可以看出，内部机制都是依托于标签。 通过源码分析，Dubbo对于Spring xml解析处理由com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler提供：
DubboNamespaceHandler.java
[java] view plain copy
package com.alibaba.dubbo.config.spring.schema;
import org.springframework.beans.factory.xml.NamespaceHandlerSupport;
import com.alibaba.dubbo.common.Version;
import com.alibaba.dubbo.config.ApplicationConfig;
import com.alibaba.dubbo.config.ConsumerConfig;
import com.alibaba.dubbo.config.ModuleConfig;
import com.alibaba.dubbo.config.MonitorConfig;
import com.alibaba.dubbo.config.ProtocolConfig;
import com.alibaba.dubbo.config.ProviderConfig;
import com.alibaba.dubbo.config.RegistryConfig;
import com.alibaba.dubbo.config.spring.AnnotationBean;
import com.alibaba.dubbo.config.spring.ReferenceBean;
import com.alibaba.dubbo.config.spring.ServiceBean;
/**
- DubboNamespaceHandler
- @author william.liangf
- @export
*/
public class DubboNamespaceHandler extends NamespaceHandlerSupport {
static {
Version.checkDuplicate(DubboNamespaceHandler.class);
}
public void init() {
registerBeanDefinitionParser("application", new DubboBeanDefinitionParser(ApplicationConfig.class, true));
registerBeanDefinitionParser("module", new DubboBeanDefinitionParser(ModuleConfig.class, true));
registerBeanDefinitionParser("registry", new DubboBeanDefinitionParser(RegistryConfig.class, true));
registerBeanDefinitionParser("monitor", new DubboBeanDefinitionParser(MonitorConfig.class, true));
registerBeanDefinitionParser("provider", new DubboBeanDefinitionParser(ProviderConfig.class, true));
registerBeanDefinitionParser("consumer", new DubboBeanDefinitionParser(ConsumerConfig.class, true));
registerBeanDefinitionParser("protocol", new DubboBeanDefinitionParser(ProtocolConfig.class, true));
registerBeanDefinitionParser("service", new DubboBeanDefinitionParser(ServiceBean.class, true));
registerBeanDefinitionParser("reference", new DubboBeanDefinitionParser(ReferenceBean.class, false));
registerBeanDefinitionParser("annotation", new DubboBeanDefinitionParser(AnnotationBean.class, true));
}
}
通过上面的代码可以很直观的发现，标签实际是由com.alibaba.dubbo.config.spring.schema.DubboBeanDefinitionParser解析：
DubboBeanDefinitionParser.java
[java] view plain copy
/**
- AbstractBeanDefinitionParser
- @author william.liangf
- @export
*/
public class DubboBeanDefinitionParser implements BeanDefinitionParser {
private static final Logger logger = LoggerFactory.getLogger(DubboBeanDefinitionParser.class);
private final Class<?> beanClass;
private final boolean required;
public DubboBeanDefinitionParser(Class<?> beanClass, boolean required) {
this.beanClass = beanClass;
this.required = required;
}
public BeanDefinition parse(Element element, ParserContext parserContext) {
return parse(element, parserContext, beanClass, required);
}
@SuppressWarnings("unchecked")
private static BeanDefinition parse(Element element, ParserContext parserContext, Class<?> beanClass, boolean required) {
//略
}
可以看到这个类实现了Spring的org.springframework.beans.factory.xml.BeanDefinitionParser接口，从而完成Spring Bean的解析工作。
而registerBeanDefinitionParser(“annotation”, new DubboBeanDefinitionParser(AnnotationBean.class, true));就是将标签，解析成com.alibaba.dubbo.config.spring.AnnotationBean并注册到Spring中。
3.AnnotationBean分析
先来看看源码：
AnnotationBean.java
[java] view plain copy
package com.alibaba.dubbo.config.spring;
/**
- AnnotationBean
- @author william.liangf
- @export
*/
public class AnnotationBean extends AbstractConfig implements DisposableBean, BeanFactoryPostProcessor, BeanPostProcessor, ApplicationContextAware {
private static final long serialVersionUID = -7582802454287589552L;
private static final Logger logger = LoggerFactory.getLogger(Logger.class);
private String annotationPackage;
private String[] annotationPackages;
private final Set<ServiceConfig<?>> serviceConfigs = new ConcurrentHashSet<ServiceConfig<?>>();
private final ConcurrentMap<String, ReferenceBean<?>> referenceConfigs = new ConcurrentHashMap<String, ReferenceBean<?>>();
public String getPackage() {
return annotationPackage;
}
public void setPackage(String annotationPackage) {
this.annotationPackage = annotationPackage;
this.annotationPackages = (annotationPackage == null || annotationPackage.length() == 0) ? null
: Constants.COMMA_SPLIT_PATTERN.split(annotationPackage);
}
private ApplicationContext applicationContext;
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
throws BeansException {
if (annotationPackage == null || annotationPackage.length() == 0) {
return;
}
if (beanFactory instanceof BeanDefinitionRegistry) {
try {
// init scanner
Class<?> scannerClass = ReflectUtils.forName("org.springframework.context.annotation.ClassPathBeanDefinitionScanner");
Object scanner = scannerClass.getConstructor(new Class<?>[] {BeanDefinitionRegistry.class, boolean.class}).newInstance(new Object[] {(BeanDefinitionRegistry) beanFactory, true});
// add filter
Class<?> filterClass = ReflectUtils.forName("org.springframework.core.type.filter.AnnotationTypeFilter");
Object filter = filterClass.getConstructor(Class.class).newInstance(Service.class);
Method addIncludeFilter = scannerClass.getMethod("addIncludeFilter", ReflectUtils.forName("org.springframework.core.type.filter.TypeFilter"));
addIncludeFilter.invoke(scanner, filter);
// scan packages
String[] packages = Constants.COMMA_SPLIT_PATTERN.split(annotationPackage);
Method scan = scannerClass.getMethod("scan", new Class<?>[]{String[].class});
scan.invoke(scanner, new Object[] {packages});
} catch (Throwable e) {
// spring 2.0
}
}
}
public void destroy() throws Exception {
for (ServiceConfig<?> serviceConfig : serviceConfigs) {
try {
serviceConfig.unexport();
} catch (Throwable e) {
logger.error(e.getMessage(), e);
}
}
for (ReferenceConfig<?> referenceConfig : referenceConfigs.values()) {
try {
referenceConfig.destroy();
} catch (Throwable e) {
logger.error(e.getMessage(), e);
}
}
}
public Object postProcessAfterInitialization(Object bean, String beanName)
throws BeansException {
if (! isMatchPackage(bean)) {
return bean;
}
Service service = bean.getClass().getAnnotation(Service.class);
if (service != null) {
ServiceBean<Object> serviceConfig = new ServiceBean<Object>(service);
if (void.class.equals(service.interfaceClass())
&& "".equals(service.interfaceName())) {
if (bean.getClass().getInterfaces().length > 0) {
serviceConfig.setInterface(bean.getClass().getInterfaces()[0]);
} else {
throw new IllegalStateException("Failed to export remote service class " + bean.getClass().getName() + ", cause: The @Service undefined interfaceClass or interfaceName, and the service class unimplemented any interfaces.");
}
}
if (applicationContext != null) {
serviceConfig.setApplicationContext(applicationContext);
if (service.registry() != null && service.registry().length > 0) {
List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
for (String registryId : service.registry()) {
if (registryId != null && registryId.length() > 0) {
registryConfigs.add((RegistryConfig)applicationContext.getBean(registryId, RegistryConfig.class));
}
}
serviceConfig.setRegistries(registryConfigs);
}
if (service.provider() != null && service.provider().length() > 0) {
serviceConfig.setProvider((ProviderConfig)applicationContext.getBean(service.provider(),ProviderConfig.class));
}
if (service.monitor() != null && service.monitor().length() > 0) {
serviceConfig.setMonitor((MonitorConfig)applicationContext.getBean(service.monitor(), MonitorConfig.class));
}
if (service.application() != null && service.application().length() > 0) {
serviceConfig.setApplication((ApplicationConfig)applicationContext.getBean(service.application(), ApplicationConfig.class));
}
if (service.module() != null && service.module().length() > 0) {
serviceConfig.setModule((ModuleConfig)applicationContext.getBean(service.module(), ModuleConfig.class));
}
if (service.provider() != null && service.provider().length() > 0) {
serviceConfig.setProvider((ProviderConfig)applicationContext.getBean(service.provider(), ProviderConfig.class));
} else {
}
if (service.protocol() != null && service.protocol().length > 0) {
List<ProtocolConfig> protocolConfigs = new ArrayList<ProtocolConfig>();
for (String protocolId : service.registry()) {
if (protocolId != null && protocolId.length() > 0) {
protocolConfigs.add((ProtocolConfig)applicationContext.getBean(protocolId, ProtocolConfig.class));
}
}
serviceConfig.setProtocols(protocolConfigs);
}
try {
serviceConfig.afterPropertiesSet();
} catch (RuntimeException e) {
throw (RuntimeException) e;
} catch (Exception e) {
throw new IllegalStateException(e.getMessage(), e);
}
}
serviceConfig.setRef(bean);
serviceConfigs.add(serviceConfig);
serviceConfig.export();
}
return bean;
}
public Object postProcessBeforeInitialization(Object bean, String beanName)
throws BeansException {
if (! isMatchPackage(bean)) {
return bean;
}
Method[] methods = bean.getClass().getMethods();
for (Method method : methods) {
String name = method.getName();
if (name.length() > 3 && name.startsWith("set")
&& method.getParameterTypes().length == 1
&& Modifier.isPublic(method.getModifiers())
&& ! Modifier.isStatic(method.getModifiers())) {
try {
Reference reference = method.getAnnotation(Reference.class);
if (reference != null) {
Object value = refer(reference, method.getParameterTypes()[0]);
if (value != null) {
method.invoke(bean, new Object[] { });
}
}
} catch (Throwable e) {
logger.error("Failed to init remote service reference at method " + name + " in class " + bean.getClass().getName() + ", cause: " + e.getMessage(), e);
}
}
}
Field[] fields = bean.getClass().getDeclaredFields();
for (Field field : fields) {
try {
if (! field.isAccessible()) {
field.setAccessible(true);
}
Reference reference = field.getAnnotation(Reference.class);
if (reference != null) {
Object value = refer(reference, field.getType());
if (value != null) {
field.set(bean, value);
}
}
} catch (Throwable e) {
logger.error("Failed to init remote service reference at filed " + field.getName() + " in class " + bean.getClass().getName() + ", cause: " + e.getMessage(), e);
}
}
return bean;
}
private Object refer(Reference reference, Class<?> referenceClass) { //method.getParameterTypes()[0]
String interfaceName;
if (! "".equals(reference.interfaceName())) {
interfaceName = reference.interfaceName();
} else if (! void.class.equals(reference.interfaceClass())) {
interfaceName = reference.interfaceClass().getName();
} else if (referenceClass.isInterface()) {
interfaceName = referenceClass.getName();
} else {
throw new IllegalStateException("The @Reference undefined interfaceClass or interfaceName, and the property type " + referenceClass.getName() + " is not a interface.");
}
String key = reference.group() + "/" + interfaceName + ":" + reference.version();
ReferenceBean<?> referenceConfig = referenceConfigs.get(key);
if (referenceConfig == null) {
referenceConfig = new ReferenceBean<Object>(reference);
if (void.class.equals(reference.interfaceClass())
&& "".equals(reference.interfaceName())
&& referenceClass.isInterface()) {
referenceConfig.setInterface(referenceClass);
}
if (applicationContext != null) {
referenceConfig.setApplicationContext(applicationContext);
if (reference.registry() != null && reference.registry().length > 0) {
List<RegistryConfig> registryConfigs = new ArrayList<RegistryConfig>();
for (String registryId : reference.registry()) {
if (registryId != null && registryId.length() > 0) {
registryConfigs.add((RegistryConfig)applicationContext.getBean(registryId, RegistryConfig.class));
}
}
referenceConfig.setRegistries(registryConfigs);
}
if (reference.consumer() != null && reference.consumer().length() > 0) {
referenceConfig.setConsumer((ConsumerConfig)applicationContext.getBean(reference.consumer(), ConsumerConfig.class));
}
if (reference.monitor() != null && reference.monitor().length() > 0) {
referenceConfig.setMonitor((MonitorConfig)applicationContext.getBean(reference.monitor(), MonitorConfig.class));
}
if (reference.application() != null && reference.application().length() > 0) {
referenceConfig.setApplication((ApplicationConfig)applicationContext.getBean(reference.application(), ApplicationConfig.class));
}
if (reference.module() != null && reference.module().length() > 0) {
referenceConfig.setModule((ModuleConfig)applicationContext.getBean(reference.module(), ModuleConfig.class));
}
if (reference.consumer() != null && reference.consumer().length() > 0) {
referenceConfig.setConsumer((ConsumerConfig)applicationContext.getBean(reference.consumer(), ConsumerConfig.class));
}
try {
referenceConfig.afterPropertiesSet();
} catch (RuntimeException e) {
throw (RuntimeException) e;
} catch (Exception e) {
throw new IllegalStateException(e.getMessage(), e);
}
}
referenceConfigs.putIfAbsent(key, referenceConfig);
referenceConfig = referenceConfigs.get(key);
}
return referenceConfig.get();
}
private boolean isMatchPackage(Object bean) {
if (annotationPackages == null || annotationPackages.length == 0) {
return true;
}
String beanClassName = bean.getClass().getName();
for (String pkg : annotationPackages) {
if (beanClassName.startsWith(pkg)) {
return true;
}
}
return false;
}
}
这个AnnotationBean实现了几个Spring生命周期接口，从而完成Dubbo整合Spring 的操作。
org.springframework.beans.factory.config.BeanFactoryPostProcessor
先来看看Spring文档中的介绍：
[plain] view plain copy
BeanFactoryPostProcessor operates on the bean configuration metadata; that is, the Spring IoC container allows a BeanFactoryPostProcessor to read the configuration metadata and potentially change it before the container instantiates any beans other than BeanFactoryPostProcessors.
BeanFactoryPostProcessor可以用于在Spring IoC容器实例化Bean之前，对Spring Bean配置信息进行一些操作
通过Spring文档，可以清楚这个接口的功能，那再来看看Dubbo的AnnotationBean是如何实现这个接口的：
[java] view plain copy
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
throws BeansException {
if (annotationPackage == null || annotationPackage.length() == 0) {
return;
}
if (beanFactory instanceof BeanDefinitionRegistry) {
try {
// init scanner
Class
