在之前的部落格中我們已經接觸過HandlerMethod,接下來我們簡單介紹一下HandlerMethod,簡單來說HandlerMethod包含的資訊包括類、方法和參數的一個資訊類,通過其兩個構造函數我們就可以了解其功能,對應着springMVC的Controller來說就是某個url對應的某個Controller執行的方法。
/**
* 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;
}
完整源碼如下:
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;
//建立一個執行個體,根據bean執行個體和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;
}
//根據bean,方法名以及參數類型建立執行個體
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;
}
//根據bean名稱,BeanFactory工廠和method方法建立執行個體
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());
}
//擷取方法上的注解,單個注解,如果沒有注解則傳回方法本身
public <A extends Annotation> A getMethodAnnotation(Class<A> annotationType) {
return AnnotatedElementUtils.findMergedAnnotation(this.method, annotationType);
}
//建立handlerMethod
public 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);
}
@Override
public 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));
}
@Override
public int hashCode() {
return (this.bean.hashCode() * 31 + this.method.hashCode());
}
@Override
public 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);
}
@Override
public Class<?> getContainingClass() {
return HandlerMethod.this.getBeanType();
}
@Override
public <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;
}
@Override
public Class<?> getParameterType() {
return (this.returnValue != null ? this.returnValue.getClass() : super.getParameterType());
}
}
}