springMVC源码分析--AbstractHandlerMapping（二）

上一篇博客 springMVC源码分析--HandlerMapping(一)中我们简单的介绍了HandlerMapping，接下来我们介绍一下它的抽象实现类AbstractHandlerMapping

HandlerMapping中定义了方法getHandler（HttpServletRequest request），AbstractHandlerMapping中的实现如下：

//获得一个HandlerExecutionChain@Overridepublic final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {//从实现类中获得HanlderMethodObject handler = getHandlerInternal(request);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);}//获得HandlerExecutionChainHandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);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;}

在getHandler方法中又出现了两个方法getHandlerInternal（request），在子类中实现，目的就是获取要执行的Controller。

//模板方法，用于子类中实现，通过request去查找对应的执行方法HandlerMethodprotected abstract Object getHandlerInternal(HttpServletRequest request) throws Exception;

getHandlerExecutionChain就是创建一个HandlerExecutionChain实例，参数值就是handler和request。

//protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {//如果没有获得则创建一个HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));//获得IP地址及端口后的URL地址String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);//在HandlerExecutionChain中添加拦截器for (HandlerInterceptor interceptor : this.adaptedInterceptors) {if (interceptor instanceof MappedInterceptor) {MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor;//根据lookupPath来获取Interceptorif (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {chain.addInterceptor(mappedInterceptor.getInterceptor());}}else {chain.addInterceptor(interceptor);}}return chain;}

AbstractHandlerMapping提供了设置不同HandlerMapping的执行顺序oder。

//设置不同HandlerMapping实现类的执行顺序public final void setOrder(int order) {  this.order = order;}@Overridepublic final int getOrder() {  return this.order;}

除了以上几个重要的方法外，AbstractHandlerMapping还提供了进行拦截器初始化的一些操作。

//初始化时调用，初始化一些基本信息，这里主要是初始化一些拦截器@Overrideprotected void initApplicationContext() throws BeansException {extendInterceptors(this.interceptors);//添加或修车intercept，现在并没有具体实现detectMappedInterceptors(this.adaptedInterceptors);//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中initInterceptors();}protected void extendInterceptors(List<Object> interceptors) {}//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中protected void detectMappedInterceptors(List<HandlerInterceptor> mappedInterceptors) {mappedInterceptors.addAll(BeanFactoryUtils.beansOfTypeIncludingAncestors(getApplicationContext(), MappedInterceptor.class, true, false).values());}//初始化Interceptor,将interceptors属性里所包含的对象按类型添加到mappedInterceptors或者adaptedInterceptors中。protected void initInterceptors() {if (!this.interceptors.isEmpty()) {for (int i = 0; i < this.interceptors.size(); i++) {Object interceptor = this.interceptors.get(i);if (interceptor == null) {throw new IllegalArgumentException("Entry number " + i + " in interceptors array is null");}this.adaptedInterceptors.add(adaptInterceptor(interceptor));}}}protected HandlerInterceptor adaptInterceptor(Object interceptor) {if (interceptor instanceof HandlerInterceptor) {return (HandlerInterceptor) interceptor;}else if (interceptor instanceof WebRequestInterceptor) {return new WebRequestHandlerInterceptorAdapter((WebRequestInterceptor) interceptor);}else {throw new IllegalArgumentException("Interceptor type not supported: " + interceptor.getClass().getName());}}protected final HandlerInterceptor[] getAdaptedInterceptors() {int count = this.adaptedInterceptors.size();return (count > 0 ? this.adaptedInterceptors.toArray(new HandlerInterceptor[count]) : null);}protected final MappedInterceptor[] getMappedInterceptors() {List<MappedInterceptor> mappedInterceptors = new ArrayList<MappedInterceptor>();for (HandlerInterceptor interceptor : this.adaptedInterceptors) {if (interceptor instanceof MappedInterceptor) {mappedInterceptors.add((MappedInterceptor) interceptor);}}int count = mappedInterceptors.size();return (count > 0 ? mappedInterceptors.toArray(new MappedInterceptor[count]) : null);}

总体来看AbstractHandlerMapping提供了抽象方法getHandlerInternal在子类中实现，根据获得的Handler及配置的拦截器Interceptor来生成HandlerExecutionChain。

完整的AbstractHandlerMapping源码如下：

public abstract class AbstractHandlerMapping extends WebApplicationObjectSupportimplements HandlerMapping, Ordered {private int order = Integer.MAX_VALUE;  // default: same as non-Orderedprivate Object defaultHandler;private UrlPathHelper urlPathHelper = new UrlPathHelper();private PathMatcher pathMatcher = new AntPathMatcher();private final List<Object> interceptors = new ArrayList<Object>();private final List<HandlerInterceptor> adaptedInterceptors = new ArrayList<HandlerInterceptor>();private CorsProcessor corsProcessor = new DefaultCorsProcessor();private final UrlBasedCorsConfigurationSource corsConfigSource = new UrlBasedCorsConfigurationSource();//设置不同HandlerMapping实现类的执行顺序public final void setOrder(int order) {  this.order = order;}@Overridepublic final int getOrder() {  return this.order;}public void setDefaultHandler(Object defaultHandler) {this.defaultHandler = defaultHandler;}public Object getDefaultHandler() {return this.defaultHandler;}public void setAlwaysUseFullPath(boolean alwaysUseFullPath) {this.urlPathHelper.setAlwaysUseFullPath(alwaysUseFullPath);this.corsConfigSource.setAlwaysUseFullPath(alwaysUseFullPath);}public void setUrlDecode(boolean urlDecode) {this.urlPathHelper.setUrlDecode(urlDecode);this.corsConfigSource.setUrlDecode(urlDecode);}public void setRemoveSemicolonContent(boolean removeSemicolonContent) {this.urlPathHelper.setRemoveSemicolonContent(removeSemicolonContent);this.corsConfigSource.setRemoveSemicolonContent(removeSemicolonContent);}public void setUrlPathHelper(UrlPathHelper urlPathHelper) {Assert.notNull(urlPathHelper, "UrlPathHelper must not be null");this.urlPathHelper = urlPathHelper;this.corsConfigSource.setUrlPathHelper(urlPathHelper);}public UrlPathHelper getUrlPathHelper() {return urlPathHelper;}public void setPathMatcher(PathMatcher pathMatcher) {Assert.notNull(pathMatcher, "PathMatcher must not be null");this.pathMatcher = pathMatcher;this.corsConfigSource.setPathMatcher(pathMatcher);}public PathMatcher getPathMatcher() {return this.pathMatcher;}public void setInterceptors(Object[] interceptors) {this.interceptors.addAll(Arrays.asList(interceptors));}public void setCorsProcessor(CorsProcessor corsProcessor) {Assert.notNull(corsProcessor, "CorsProcessor must not be null");this.corsProcessor = corsProcessor;}/** * Return the configured {@link CorsProcessor}. */public CorsProcessor getCorsProcessor() {return this.corsProcessor;}public void setCorsConfigurations(Map<String, CorsConfiguration> corsConfigurations) {this.corsConfigSource.setCorsConfigurations(corsConfigurations);}/** * Get the CORS configuration. */public Map<String, CorsConfiguration> getCorsConfigurations() {return this.corsConfigSource.getCorsConfigurations();}//初始化时调用，初始化一些基本信息，这里主要是初始化一些拦截器@Overrideprotected void initApplicationContext() throws BeansException {extendInterceptors(this.interceptors);//添加或修车intercept，现在并没有具体实现detectMappedInterceptors(this.adaptedInterceptors);//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中initInterceptors();}protected void extendInterceptors(List<Object> interceptors) {}//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中protected void detectMappedInterceptors(List<HandlerInterceptor> mappedInterceptors) {mappedInterceptors.addAll(BeanFactoryUtils.beansOfTypeIncludingAncestors(getApplicationContext(), MappedInterceptor.class, true, false).values());}//初始化Interceptor,将interceptors属性里所包含的对象按类型添加到mappedInterceptors或者adaptedInterceptors中。protected void initInterceptors() {if (!this.interceptors.isEmpty()) {for (int i = 0; i < this.interceptors.size(); i++) {Object interceptor = this.interceptors.get(i);if (interceptor == null) {throw new IllegalArgumentException("Entry number " + i + " in interceptors array is null");}this.adaptedInterceptors.add(adaptInterceptor(interceptor));}}}protected HandlerInterceptor adaptInterceptor(Object interceptor) {if (interceptor instanceof HandlerInterceptor) {return (HandlerInterceptor) interceptor;}else if (interceptor instanceof WebRequestInterceptor) {return new WebRequestHandlerInterceptorAdapter((WebRequestInterceptor) interceptor);}else {throw new IllegalArgumentException("Interceptor type not supported: " + interceptor.getClass().getName());}}protected final HandlerInterceptor[] getAdaptedInterceptors() {int count = this.adaptedInterceptors.size();return (count > 0 ? this.adaptedInterceptors.toArray(new HandlerInterceptor[count]) : null);}protected final MappedInterceptor[] getMappedInterceptors() {List<MappedInterceptor> mappedInterceptors = new ArrayList<MappedInterceptor>();for (HandlerInterceptor interceptor : this.adaptedInterceptors) {if (interceptor instanceof MappedInterceptor) {mappedInterceptors.add((MappedInterceptor) interceptor);}}int count = mappedInterceptors.size();return (count > 0 ? mappedInterceptors.toArray(new MappedInterceptor[count]) : null);}//获得一个HandlerExecutionChain@Overridepublic final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {//从实现类中获得HanlderMethodObject handler = getHandlerInternal(request);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);}//获得HandlerExecutionChainHandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);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;}//模板方法，用于子类中实现，通过request去查找对应的执行方法HandlerMethodprotected abstract Object getHandlerInternal(HttpServletRequest request) throws Exception;//protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {//如果没有获得则创建一个HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));//获得IP地址及端口后的URL地址String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);//在HandlerExecutionChain中添加拦截器for (HandlerInterceptor interceptor : this.adaptedInterceptors) {if (interceptor instanceof MappedInterceptor) {MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor;//根据lookupPath来获取Interceptorif (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {chain.addInterceptor(mappedInterceptor.getInterceptor());}}else {chain.addInterceptor(interceptor);}}return chain;}protected CorsConfiguration getCorsConfiguration(Object handler, HttpServletRequest request) {if (handler instanceof HandlerExecutionChain) {handler = ((HandlerExecutionChain) handler).getHandler();}if (handler instanceof CorsConfigurationSource) {return ((CorsConfigurationSource) handler).getCorsConfiguration(request);}return null;}protected HandlerExecutionChain getCorsHandlerExecutionChain(HttpServletRequest request,HandlerExecutionChain chain, CorsConfiguration config) {if (CorsUtils.isPreFlightRequest(request)) {HandlerInterceptor[] interceptors = chain.getInterceptors();chain = new HandlerExecutionChain(new PreFlightHandler(config), interceptors);}else {chain.addInterceptor(new CorsInterceptor(config));}return chain;}private class PreFlightHandler implements HttpRequestHandler {private final CorsConfiguration config;public PreFlightHandler(CorsConfiguration config) {this.config = config;}@Overridepublic void handleRequest(HttpServletRequest request, HttpServletResponse response)throws IOException {corsProcessor.processRequest(this.config, request, response);}}private class CorsInterceptor extends HandlerInterceptorAdapter {private final CorsConfiguration config;public CorsInterceptor(CorsConfiguration config) {this.config = config;}@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response,Object handler) throws Exception {return corsProcessor.processRequest(this.config, request, response);}}}