SpringMVC源码解读 - HandlerMapping

1 package org.springframework.web.servlet;
2 public interface HandlerMapping {
3     HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception;
4 
5 }

1 package org.springframework.web.servlet.handler;
2 public abstract class AbstractHandlerMapping extends WebApplicationObjectSupport
3         implements HandlerMapping, Ordered {
4     // ...
5 }

 1     // order赋了最大值,优先级是最小的
 2     private int order = Integer.MAX_VALUE;  // default: same as non-Ordered
 3     // 默认的Handler,这边使用的Obejct,子类实现的时候,使用HandlerMethod,HandlerExecutionChain等
 4     private Object defaultHandler;
 5     // url计算的辅助类
 6     private UrlPathHelper urlPathHelper = new UrlPathHelper();
 7     // 基于ant进行path匹配,解决如/books/{id}场景
 8     private PathMatcher pathMatcher = new AntPathMatcher();
 9     // 拦截器配置:1,HandlerMapping属性设置;2,extendInterceptors设置
10     private final List<Object> interceptors = new ArrayList<Object>();
11     // 从interceptors中解析得到,直接添加给全部handler
12     private final List<HandlerInterceptor> adaptedInterceptors = new ArrayList<HandlerInterceptor>();
13     // 使用前需要跟url进行匹配,匹配通过才会使用
14     private final List<MappedInterceptor> mappedInterceptors = new ArrayList<MappedInterceptor>();

 1     @Override
 2     protected void initApplicationContext() throws BeansException {
 3         extendInterceptors(this.interceptors);
 4         detectMappedInterceptors(this.mappedInterceptors);
 5         initInterceptors();
 6     }
 7 
 8     /**
 9      * 提供给子类扩展拦截器,可惜都没有使用
10      */
11     protected void extendInterceptors(List<Object> interceptors) {
12     }
13 
14     /**
15      * 扫描应用下的MappedInterceptor,并添加到mappedInterceptors
16      */
17     protected void detectMappedInterceptors(List<MappedInterceptor> mappedInterceptors) {
18         mappedInterceptors.addAll(
19                 BeanFactoryUtils.beansOfTypeIncludingAncestors(
20                         getApplicationContext(),MappedInterceptor.class, true, false).values());
21     }
22 
23     /**
24      * 归集MappedInterceptor,并适配HandlerInterceptor和WebRequestInterceptor
25      */
26     protected void initInterceptors() {
27         if (!this.interceptors.isEmpty()) {
28             for (int i = 0; i < this.interceptors.size(); i++) {
29                 Object interceptor = this.interceptors.get(i);
30                 if (interceptor == null) {
31                     throw new IllegalArgumentException("Entry number " + i + " in interceptors array is null");
32                 }
33                 if (interceptor instanceof MappedInterceptor) {
34                     mappedInterceptors.add((MappedInterceptor) interceptor);
35                 }
36                 else {
37                     adaptedInterceptors.add(adaptInterceptor(interceptor));
38                 }
39             }
40         }
41     }
42 
43     protected HandlerInterceptor adaptInterceptor(Object interceptor) {
44         if (interceptor instanceof HandlerInterceptor) {
45             return (HandlerInterceptor) interceptor;
46         }
47         else if (interceptor instanceof WebRequestInterceptor) {
48             return new WebRequestHandlerInterceptorAdapter((WebRequestInterceptor) interceptor);
49         }
50         else {
51             throw new IllegalArgumentException("Interceptor type not supported: " + interceptor.getClass().getName());
52         }
53     }

 1     public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
 2         Object handler = getHandlerInternal(request);
 3         if (handler == null) {
 4             handler = getDefaultHandler();
 5         }
 6         if (handler == null) {
 7             return null;
 8         }
 9         // Bean name or resolved handler?
10         if (handler instanceof String) {
11             String handlerName = (String) handler;
12             handler = getApplicationContext().getBean(handlerName);
13         }
14         return getHandlerExecutionChain(handler, request);
15     }
16 
17     protected abstract Object getHandlerInternal(HttpServletRequest request) throws Exception;

 1     protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
 2         HandlerExecutionChain chain =
 3             (handler instanceof HandlerExecutionChain) ?
 4                 (HandlerExecutionChain) handler : new HandlerExecutionChain(handler);
 5 
 6         chain.addInterceptors(getAdaptedInterceptors());
 7 
 8         String lookupPath = urlPathHelper.getLookupPathForRequest(request);
 9         for (MappedInterceptor mappedInterceptor : mappedInterceptors) {
10             if (mappedInterceptor.matches(lookupPath, pathMatcher)) {
11                 chain.addInterceptor(mappedInterceptor.getInterceptor());
12             }
13         }
14 
15         return chain;
16     }

1     protected void registerHandler(String[] urlPaths, String beanName) throws BeansException, IllegalStateException { }
2 
3     protected void registerHandler(String urlPath, Object handler) throws BeansException, IllegalStateException { }

1 protected Object getHandlerInternal(HttpServletRequest request) throws Exception {}
2 // 根据url查找handler
3 protected Object lookupHandler(String urlPath, HttpServletRequest request) throws Exception {}
4 // 校验handler
5 protected void validateHandler(Object handler, HttpServletRequest request) throws Exception {}
6 // 封装拦截器到HandlerExecutionChain
7 protected Object buildPathExposingHandler(Object rawHandler, String bestMatchingPattern,
8             String pathWithinMapping, Map<String, String> uriTemplateVariables) {}

 1     @Override
 2     public void initApplicationContext() throws ApplicationContextException {
 3         super.initApplicationContext();
 4         detectHandlers();
 5     }
 6 
 7     protected void detectHandlers() throws BeansException {
 8         // ...
 9     }
10 
11 
12     /**
13      * Determine the URLs for the given handler bean.
14      * 钩子而已
15      */
16     protected abstract String[] determineUrlsForHandler(String beanName);

 1     @Override
 2     protected String[] determineUrlsForHandler(String beanName) {
 3         Class beanClass = getApplicationContext().getType(beanName);
 4         if (isEligibleForMapping(beanName, beanClass)) {
 5             return buildUrlsForHandler(beanName, beanClass);
 6         }
 7         else {
 8             return null;
 9         }
10     }
11 
12     protected boolean isEligibleForMapping(String beanName, Class beanClass) {}
13 
14     protected boolean isControllerType(Class beanClass) {}
15 
16     protected abstract String[] buildUrlsForHandler(String beanName, Class beanClass);