SpringMVC源码情操陶冶-AbstractHandlerMapping

初始化操作

initApplicationContext()

ApplicationContextAware#setApplicationContext()

protected void initApplicationContext() throws BeansException {
//供子类扩展添加拦截器，目前spring没有自行实现
extendInterceptors(this.interceptors);
//搜寻springmvc中的MappedInterceptors保存至adaptedInterceptors集合
detectMappedInterceptors(this.adaptedInterceptors);
//将interceptors集合添加至adaptedInterceptors集合中
initInterceptors();
}

springmvc

MappedInterceptor

AbstractHandlerMapping#getHandler()-获取处理链对象

public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
//getHandlerInternal(request)方法为抽象方法，供子类实现
//获取到的handler对象一般为bean/HandlerMethod
Object handler = getHandlerInternal(request);
//上述找不到则使用默认的处理类，没有设定则返回null，则会返回前台404错误
if (handler == null) {
handler = getDefaultHandler();
}
if (handler == null) {
return null;
}
// Bean name or resolved handler?
if (handler instanceof String) {
String handlerName = (String) handler;
handler = getApplicationContext().getBean(handlerName);
}
//创建处理链对象
HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);
//针对cros跨域请求的处理，此处就不分析了
if (CorsUtils.isCorsRequest(request)) {
CorsConfiguration globalConfig = this.corsConfigSource.getCorsConfiguration(request);
CorsConfiguration handlerConfig = getCorsConfiguration(handler, request);
CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig);
executionChain = getCorsHandlerExecutionChain(request, executionChain, config);
}
return executionChain;
}

AbstractHandlerMethodMapping#getHandlerInternal()-针对HandlerMethod的获取

@Controller

@RequestMapping

protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception {
//获取访问的路径，一般类似于request.getServletPath()返回不含contextPath的访问路径
String lookupPath = getUrlPathHelper().getLookupPathForRequest(request);

//获取读锁
this.mappingRegistry.acquireReadLock();
try {
//获取HandlerMethod作为handler对象,这里涉及到路径匹配的优先级
//优先级：精确匹配>最长路径匹配>扩展名匹配
HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request);
//HandlerMethod内部含有bean对象，其实指的是对应的Controller
return (handlerMethod != null ? handlerMethod.createWithResolvedBean() : null);
}
finally {
//释放读锁
this.mappingRegistry.releaseReadLock();
}
}

AbstractUrlHandlerMapping#getHandlerInternal()-针对beanName的获取

protected Object getHandlerInternal(HttpServletRequest request) throws Exception {
String lookupPath = getUrlPathHelper().getLookupPathForRequest(request);
//从handlerMap查找路径对应的beanName
Object handler = lookupHandler(lookupPath, request);
if (handler == null) {
// We need to care for the default handler directly, since we need to
// expose the PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE for it as well.
Object rawHandler = null;
if ("/".equals(lookupPath)) {
rawHandler = getRootHandler();
}
if (rawHandler == null) {
rawHandler = getDefaultHandler();
}
if (rawHandler != null) {
// Bean name or resolved handler?
if (rawHandler instanceof String) {
String handlerName = (String) rawHandler;
rawHandler = getApplicationContext().getBean(handlerName);
}
validateHandler(rawHandler, request);
handler = buildPathExposingHandler(rawHandler, lookupPath, lookupPath, null);
}
}

return handler;
}

AbstractHandlerMapping#getHandlerExecutionChain()-创建处理链对象

//真实处理请求对象
private final Object handler;

//拦截器集合
private HandlerInterceptor[] interceptors;

//拦截器集合
private List<HandlerInterceptor> interceptorList;

//拦截器开始下标，默认正序执行
private int interceptorIndex = -1;

//此处的handler可为HandlerMethod/beanName
protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?
(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));

String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);
for (HandlerInterceptor interceptor : this.adaptedInterceptors) {
if (interceptor instanceof MappedInterceptor) {
MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor;
if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {
chain.addInterceptor(mappedInterceptor.getInterceptor());
}
}
else {
chain.addInterceptor(interceptor);
}
}
return chain;
}

@RequestMapping

HandlerInterceptor

MappedHandlerInterceptor

mvc:interceptor

mvc:resource

小结