Dubbo源码分析之一：spring集成之xml
关于dubbo与spring 的集成有俩种方式：xml配置文件，注解。相关代码主要集中在dubbo-config-spring 包中。
xml配置文件方式的处理
spring 在启动时，找到dubbo命名空间的处理类。
META-INF/spring.handlers
内容
http\://code.alibabatech.com/schema/dubbo=com.alibaba.dubbo.config.spring.schema.DubboNamespaceHandler
public class DubboNamespaceHandler extends NamespaceHandlerSupport {
static {
//检查重复
Version.checkDuplicate(DubboNamespaceHandler.class);
}
public void init() {
// 注册xml元素解析器
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));// 注解的方式
}
}
所有元素的解析器都为DubboBeanDefinitionParser ，实现了spring 的 BeanDefinitionParser接口
这里要吐槽一下，所有的解析都在一个方法中，有点乱！
public DubboBeanDefinitionParser(Class<?> beanClass, boolean required) {
this.beanClass = beanClass; //元素对应的配置类
this.required = required; // 是否必须
}
// 最终的解析方法
// element xml元素
// parserContext 解析上下文
// beanClass element对应的Class
// required 是否必须
private static BeanDefinition parse(Element element, ParserContext parserContext, Class<?> beanClass, boolean required) {
// 配置bean定义
RootBeanDefinition beanDefinition = new RootBeanDefinition();
beanDefinition.setBeanClass(beanClass);
beanDefinition.setLazyInit(false); //默认不延迟
String id = element.getAttribute("id");
if ((id == null || id.length() == 0) && required) {
// 确定bean 名称
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); // 如果ID重复
}
parserContext.getRegistry().registerBeanDefinition(id, beanDefinition); // 注入spring
beanDefinition.getPropertyValues().addPropertyValue("id", id);
}
if (ProtocolConfig.class.equals(beanClass)) { //配置 ProtocolConfig
//在spring中 将 protocol 注入所有需要的bean中
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())) {
// 设置protocol属性
definition.getPropertyValues().addPropertyValue("protocol", new RuntimeBeanReference(id));
}
}
}
} else if (ServiceBean.class.equals(beanClass)) {
// 待暴露的服务
String className = element.getAttribute("class");
if(className != null && className.length() > 0) { //如果指定了class
RootBeanDefinition classDefinition = new RootBeanDefinition();
classDefinition.setBeanClass(ReflectUtils.forName(className));
classDefinition.setLazyInit(false);
parseProperties(element.getChildNodes(), classDefinition); //解析服务属性
// 将服务关联到ServiceBean
beanDefinition.getPropertyValues().addPropertyValue("ref", new BeanDefinitionHolder(classDefinition, id + "Impl"));
}
} else if (ProviderConfig.class.equals(beanClass)) { // 处理提供者
parseNested(element, parserContext, ServiceBean.class, true, "service", "provider", id, beanDefinition);
} else if (ConsumerConfig.class.equals(beanClass)) { // 处理消费者
parseNested(element, parserContext, ReferenceBean.class, false, "reference", "consumer", id, beanDefinition);
}
// 设置 对应配置的属性
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];
// setter名处理 （uvwXyz -> uvw-xyz）
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); // 解析parameters
} 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); // 直接在当前节点中获取对应的属性
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) { // 多个registry
parseMultiRef("registries", value, beanDefinition, parserContext);
} else if ("provider".equals(property) && value.indexOf(',') != -1) { // 多个provider属性
parseMultiRef("providers", value, beanDefinition, parserContext);
} else if ("protocol".equals(property) && value.indexOf(',') != -1) { // 多个protocol属性
parseMultiRef("protocols", value, beanDefinition, parserContext);
} else {
Object reference;
if (isPrimitive(type)) { //基本类型
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())) { // 不建议使用dubbo:provider
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);// 处理监控器的配置
} else if ("onreturn".equals(property)) { // 处理返回值的方法
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)) { //处理抛出异常的方法
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()) { //必须单例
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);
}
}
}
}
}
}
// 将节点中的属性，全部设置到beanDefinition中
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;
}