@EnableBinding({ Source.class })
## @EnableBinding 源码内容
// ...
// 导入Bean
// ****************************************************************
// 1.找到程序入口
// ****************************************************************
// 所以入口在:BindingBeansRegistrar和BinderFactoryConfiguration中
@Import({ BindingBeansRegistrar.class, BinderFactoryConfiguration.class})
// 启用Integration
// 参考Spring Integration文档
@EnableIntegration
public @interface EnableBinding {
Class<?>[] value() default {};
}
package org.springframework.cloud.stream.messaging;
import org.springframework.cloud.stream.annotation.Output;
import org.springframework.messaging.MessageChannel;
public interface Source {
String OUTPUT = "output";
@Output(Source.OUTPUT)
MessageChannel output();
}
public class BindingBeansRegistrar implements ImportBeanDefinitionRegistrar {
@Override
public void registerBeanDefinitions(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
// 2. 获取@EnableBinding({ Source.class })注解上的属性
AnnotationAttributes attrs = AnnotatedElementUtils.getMergedAnnotationAttributes( ClassUtils.resolveClassName(metadata.getClassName(), null), EnableBinding.class);
for (Class<?> type : collectClasses(attrs, metadata.getClassName())) {
// 判断Spring容器中:org.springframework.cloud.stream.messaging.Source
// 是否存在
if (!registry.containsBeanDefinition(type.getName())) { // (!false)
// ***********************************************************
// 4.向Spring容器注册bean
// 4.1 获取@EnableBinding({ Source.class }) 上的Source接口
// 4.2 解析Source上的注解@Output("output")
// 4.3 向Spring中注册Bean信息(name=output,value=org.springframework.cloud.stream.messaging.Source)
// ***********************************************************
// 委托给:BindingBeanDefinitionRegistryUtils进行bean注册
BindingBeanDefinitionRegistryUtils.registerBindingTargetBeanDefinitions(type, type.getName(), registry);
//
BindingBeanDefinitionRegistryUtils.registerBindingTargetsQualifiedBeanDefinitions(ClassUtils.resolveClassName(metadata.getClassName(), null), type, registry);
} //end if
} //end for
}
// 3. 获取@EnableBinding上的value属性
private Class<?>[] collectClasses(AnnotationAttributes attrs, String className) {
EnableBinding enableBinding = AnnotationUtils.synthesizeAnnotation(attrs,
EnableBinding.class, ClassUtils.resolveClassName(className, null));
return enableBinding.value();
} //end collectClasses
}
public abstract class BindingBeanDefinitionRegistryUtils {
// ******************************************************************
// 4. 注册Binding
// ******************************************************************
public static void registerBindingTargetBeanDefinitions(
// org.springframework.cloud.stream.messaging.Source
Class<?> type,
// org.springframework.cloud.stream.messaging.Source
final String bindingTargetInterfaceBeanName,
// bean注册器
final BeanDefinitionRegistry registry) {
ReflectionUtils.doWithMethods(type, method -> {
// 遍历:org.springframework.cloud.stream.messaging.Source
// 类上所有的方法,判断是否存在:@Input注解
Input input = AnnotationUtils.findAnnotation(method, Input.class);
if (input != null) {
String name = getBindingTargetName(input, method);
registerInputBindingTargetBeanDefinition(input.value(), name, bindingTargetInterfaceBeanName,
method.getName(), registry);
} //end if
// ***************************************************************
// 遍历:org.springframework.cloud.stream.messaging.Source
// 类上所有的方法,判断是否存在:@Output注解
// @Output(value="output")
// ***************************************************************
Output output = AnnotationUtils.findAnnotation(method, Output.class);
if (output != null) {
// 获得注解上的value
// output
String name = getBindingTargetName(output, method);
// 注解OutputBindingTargetBeanDefinition
// ***************************************************
// 5.开始向Spring容器中进行Bean注册
// ***************************************************
registerOutputBindingTargetBeanDefinition(output.value(), name, bindingTargetInterfaceBeanName,
method.getName(), registry);
}// end if
});
}// end registerBindingTargetBeanDefinitions
public static void registerOutputBindingTargetBeanDefinition(
// output
String qualifierValue,
// output
String name,
// org.springframework.cloud.stream.messaging.Source
String bindingTargetInterfaceBeanName,
// output
String bindingTargetInterfaceMethodName,
// bean注册器
BeanDefinitionRegistry registry) {
// *************************************************************
// 委托给:registerBindingTargetBeanDefinition
// *************************************************************
registerBindingTargetBeanDefinition(Output.class, qualifierValue, name, bindingTargetInterfaceBeanName, bindingTargetInterfaceMethodName, registry);
}// end registerOutputBindingTargetBeanDefinition
private static void registerBindingTargetBeanDefinition(
// @Output.class
Class<? extends Annotation> qualifier,
// output
String qualifierValue,
// output
String name,
// org.springframework.cloud.stream.messaging.Source
String bindingTargetInterfaceBeanName,
// output
String bindingTargetInterfaceMethodName,
// bean注册器
BeanDefinitionRegistry registry) {
// 判断bean是否存在(output)
// 看这样纸,是会创建一个bean.对应的@Output(value="output")
if (registry.containsBeanDefinition(name)) { // false
throw new BeanDefinitionStoreException(bindingTargetInterfaceBeanName, name,
"bean definition with this name already exists - " + registry.getBeanDefinition(name));
}
// 创建Bean定义信息
RootBeanDefinition rootBeanDefinition = new RootBeanDefinition();
// 指定使用工厂bean的名称
// org.springframework.cloud.stream.messaging.Source
rootBeanDefinition.setFactoryBeanName(bindingTargetInterfaceBeanName);
// 方法名称
// output
rootBeanDefinition.setUniqueFactoryMethodName(bindingTargetInterfaceMethodName);
// 注册自动注入@Auto....
// qualifier = org.springframework.cloud.stream.annotation.Output
// qualifier = output
rootBeanDefinition.addQualifier(new AutowireCandidateQualifier(qualifier, qualifierValue));
// name = output
registry.registerBeanDefinition(name, rootBeanDefinition);
}// end registerBindingTargetBeanDefinition
// 获得注解上的value属性,如果没有配置value属性,返回的是:方法名称
public static String getBindingTargetName(Annotation annotation, Method method) {
Map<String, Object> attrs = AnnotationUtils.getAnnotationAttributes(annotation, false);
if (attrs.containsKey("value") && StringUtils.hasText((CharSequence) attrs.get("value"))) {
return (String) attrs.get("value");
}
return method.getName();
}// end getBindingTargetName
}
public class BindingBeansRegistrar implements ImportBeanDefinitionRegistrar {
public static void registerBindingTargetsQualifiedBeanDefinitions(
// help.lixin.samples.StreamSourceApplication
Class<?> parent,
// org.springframework.cloud.stream.messaging.Source
Class<?> type,
// bean注册器
final BeanDefinitionRegistry registry) {
// type = org.springframework.cloud.stream.messaging.Source
if (type.isInterface()) { // true
// ****************************************************************
// 创建Bean定义(BindableProxyFactory)
// ****************************************************************
RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(BindableProxyFactory.class);
// 注册依赖置入功能@Auto...
//
rootBeanDefinition.addQualifier(new AutowireCandidateQualifier(Bindings.class, parent));
// 添加构造器:org.springframework.cloud.stream.messaging.Source
rootBeanDefinition.getConstructorArgumentValues().addGenericArgumentValue(type);
// type.name = org.springframework.cloud.stream.messaging.Source
registry.registerBeanDefinition(type.getName(), rootBeanDefinition);
} else {
RootBeanDefinition rootBeanDefinition = new RootBeanDefinition(type);
rootBeanDefinition.addQualifier(new AutowireCandidateQualifier(Bindings.class, parent));
registry.registerBeanDefinition(type.getName(), rootBeanDefinition);
} //end else
}// end registerBindingTargetsQualifiedBeanDefinitions
}
