springMVC源码分析--HandlerMethod

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在之前的博客中我们已经接触过HandlerMethod，接下来我们简单介绍一下HandlerMethod，简单来说HandlerMethod包含的信息包括类、方法和参数的一个信息类，通过其两个构造函数我们就可以了解其功能，对应着springMVC的Controller来说就是某个url对应的某个Controller执行的方法。

/** * Create an instance from a bean instance and a method. */public HandlerMethod(Object bean, Method method) {Assert.notNull(bean, "Bean is required");Assert.notNull(method, "Method is required");this.bean = bean;this.beanFactory = null;this.beanType = ClassUtils.getUserClass(bean);this.method = method;this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);this.parameters = initMethodParameters();this.resolvedFromHandlerMethod = null;}

/** * Create an instance from a bean instance, method name, and parameter types. * @throws NoSuchMethodException when the method cannot be found */public HandlerMethod(Object bean, String methodName, Class<?>... parameterTypes) throws NoSuchMethodException {Assert.notNull(bean, "Bean is required");Assert.notNull(methodName, "Method name is required");this.bean = bean;this.beanFactory = null;this.beanType = ClassUtils.getUserClass(bean);this.method = bean.getClass().getMethod(methodName, parameterTypes);this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(this.method);this.parameters = initMethodParameters();this.resolvedFromHandlerMethod = null;}

完整源码如下：

public class HandlerMethod {/** Logger that is available to subclasses */protected final Log logger = LogFactory.getLog(getClass());private final Object bean;private final BeanFactory beanFactory;private final Class<?> beanType;private final Method method;private final Method bridgedMethod;private final MethodParameter[] parameters;private final HandlerMethod resolvedFromHandlerMethod;//创建一个实例，根据bean实例和method方法public HandlerMethod(Object bean, Method method) {Assert.notNull(bean, "Bean is required");Assert.notNull(method, "Method is required");this.bean = bean;this.beanFactory = null;this.beanType = ClassUtils.getUserClass(bean);this.method = method;this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);this.parameters = initMethodParameters();this.resolvedFromHandlerMethod = null;}//根据bean，方法名以及参数类型创建实例public HandlerMethod(Object bean, String methodName, Class<?>... parameterTypes) throws NoSuchMethodException {Assert.notNull(bean, "Bean is required");Assert.notNull(methodName, "Method name is required");this.bean = bean;this.beanFactory = null;this.beanType = ClassUtils.getUserClass(bean);this.method = bean.getClass().getMethod(methodName, parameterTypes);this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(this.method);this.parameters = initMethodParameters();this.resolvedFromHandlerMethod = null;}//根据bean名称，BeanFactory工厂和method方法创建实例public HandlerMethod(String beanName, BeanFactory beanFactory, Method method) {Assert.hasText(beanName, "Bean name is required");Assert.notNull(beanFactory, "BeanFactory is required");Assert.notNull(method, "Method is required");this.bean = beanName;this.beanFactory = beanFactory;this.beanType = ClassUtils.getUserClass(beanFactory.getType(beanName));this.method = method;this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);this.parameters = initMethodParameters();this.resolvedFromHandlerMethod = null;}protected HandlerMethod(HandlerMethod handlerMethod) {Assert.notNull(handlerMethod, "HandlerMethod is required");this.bean = handlerMethod.bean;this.beanFactory = handlerMethod.beanFactory;this.beanType = handlerMethod.beanType;this.method = handlerMethod.method;this.bridgedMethod = handlerMethod.bridgedMethod;this.parameters = handlerMethod.parameters;this.resolvedFromHandlerMethod = handlerMethod.resolvedFromHandlerMethod;}private HandlerMethod(HandlerMethod handlerMethod, Object handler) {Assert.notNull(handlerMethod, "HandlerMethod is required");Assert.notNull(handler, "Handler object is required");this.bean = handler;this.beanFactory = handlerMethod.beanFactory;this.beanType = handlerMethod.beanType;this.method = handlerMethod.method;this.bridgedMethod = handlerMethod.bridgedMethod;this.parameters = handlerMethod.parameters;this.resolvedFromHandlerMethod = handlerMethod;}private MethodParameter[] initMethodParameters() {int count = this.bridgedMethod.getParameterTypes().length;MethodParameter[] result = new MethodParameter[count];for (int i = 0; i < count; i++) {result[i] = new HandlerMethodParameter(i);}return result;}public Object getBean() {return this.bean;}public Method getMethod() {return this.method;}public Class<?> getBeanType() {return this.beanType;}protected Method getBridgedMethod() {return this.bridgedMethod;}public MethodParameter[] getMethodParameters() {return this.parameters;}public HandlerMethod getResolvedFromHandlerMethod() {return this.resolvedFromHandlerMethod;}public MethodParameter getReturnType() {return new HandlerMethodParameter(-1);}public MethodParameter getReturnValueType(Object returnValue) {return new ReturnValueMethodParameter(returnValue);}public boolean isVoid() {return Void.TYPE.equals(getReturnType().getParameterType());}//获取方法上的注解，单个注解，如果没有注解则返回方法本身public <A extends Annotation> A getMethodAnnotation(Class<A> annotationType) {return AnnotatedElementUtils.findMergedAnnotation(this.method, annotationType);}//创建handlerMethodpublic HandlerMethod createWithResolvedBean() {Object handler = this.bean;if (this.bean instanceof String) {String beanName = (String) this.bean;handler = this.beanFactory.getBean(beanName);}return new HandlerMethod(this, handler);}@Overridepublic boolean equals(Object other) {if (this == other) {return true;}if (!(other instanceof HandlerMethod)) {return false;}HandlerMethod otherMethod = (HandlerMethod) other;return (this.bean.equals(otherMethod.bean) && this.method.equals(otherMethod.method));}@Overridepublic int hashCode() {return (this.bean.hashCode() * 31 + this.method.hashCode());}@Overridepublic String toString() {return this.method.toGenericString();}/** * A MethodParameter with HandlerMethod-specific behavior. */protected class HandlerMethodParameter extends SynthesizingMethodParameter {public HandlerMethodParameter(int index) {super(HandlerMethod.this.bridgedMethod, index);}@Overridepublic Class<?> getContainingClass() {return HandlerMethod.this.getBeanType();}@Overridepublic <T extends Annotation> T getMethodAnnotation(Class<T> annotationType) {return HandlerMethod.this.getMethodAnnotation(annotationType);}}/** * A MethodParameter for a HandlerMethod return type based on an actual return value. */private class ReturnValueMethodParameter extends HandlerMethodParameter {private final Object returnValue;public ReturnValueMethodParameter(Object returnValue) {super(-1);this.returnValue = returnValue;}@Overridepublic Class<?> getParameterType() {return (this.returnValue != null ? this.returnValue.getClass() : super.getParameterType());}}}