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SpringMvc RequestMappingHandlerMapping

伊甸之恋 2019-02-01 11:01 68 查看

 RequestMappingHandlerMapping是SpringMvc中一个比较核心的类,查看下它的类结构图:  

          

InitializingBean是个很神奇的接口,在Spring每个容器的bean构造方法、属性设置之后,会先调用InitializingBean接口的afterPropertiesSet方法;

RequestMappingHandlerMapping的afterPropertiesSet方法: 初始化了config对象,以及调用父类AbstractHandlerMethodMapping的afterPropertiesSet,父类方法afterPropertiesSet 逻辑是 initHandlerMethods,这也是SpringMvc初始化寻找Controller以及映射加载的核心逻辑; 

@Override
public void afterPropertiesSet() {
this.config = new RequestMappingInfo.BuilderConfiguration();
this.config.setPathHelper(getUrlPathHelper());
this.config.setPathMatcher(getPathMatcher());
this.config.setSuffixPatternMatch(this.useSuffixPatternMatch);
this.config.setTrailingSlashMatch(this.useTrailingSlashMatch);
this.config.setRegisteredSuffixPatternMatch(this.useRegisteredSuffixPatternMatch);
this.config.setContentNegotiationManager(getContentNegotiationManager());
     // 初始化config对象,主要属性就是pathMatcher; 以及调用父类 afterPropertiesSet 方法,这是SpringMvc映射关系加载的核心;
super.afterPropertiesSet();
}

 

AbstractHandlerMethodMapping 的 initHandlerMethods代码:

protected void initHandlerMethods() {
if (logger.isDebugEnabled()) {
logger.debug("Looking for request mappings in application context: " + getApplicationContext());
}
String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ?
BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :
getApplicationContext().getBeanNamesForType(Object.class));   
      // detectHandlerMethodsInAncestorContexts 默认为false,代表不会检测SpringMvc父容器中的bean的映射关系                                                 for (String beanName : beanNames) {                     
//遍历容器中的beanName, 代理的对象跳过,获取当前bean的类型,调用isHandler判断是否是处理器(handler\controller) if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) { Class<?> beanType = null; try { beanType = getApplicationContext().getType(beanName); } catch (Throwable ex) { // An unresolvable bean type, probably from a lazy bean - let's ignore it. if (logger.isDebugEnabled()) { logger.debug("Could not resolve target class for bean with name '" + beanName + "'", ex); } } if (beanType != null && isHandler(beanType)) { //isHandler方法判断是否是controller,判断逻辑下面有; detectHandlerMethods(beanName);  //加载Controller和请求映射关系 } } } handlerMethodsInitialized(getHandlerMethods()); // 该方法是个空实现 }

 

isHandler方法: 判断当前bean的class属性,标注了Controller或者RequestMapping注解,就会去加载Controller和请求映射关系,如果不是handler,迭代下一个bean对象;

protected boolean isHandler(Class<?> beanType) {
return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) ||
AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class));
}

 

 

detectHandlerMethods方法:

protected void detectHandlerMethods(final Object handler) {
Class<?> handlerType = (handler instanceof String ?
getApplicationContext().getType((String) handler) : handler.getClass());//之前传入handler为string类型,此处去容器获取handler的class
final Class<?> userType = ClassUtils.getUserClass(handlerType); //处理class为CGLIB生成class,如果是CGLIB的获取父类class

Map<Method, T> methods = MethodIntrospector.selectMethods(userType,
new MethodIntrospector.MetadataLookup<T>() {
@Override
public T inspect(Method method) {
return getMappingForMethod(method, userType);
}
});

if (logger.isDebugEnabled()) {
logger.debug(methods.size() + " request handler methods found on " + userType + ": " + methods);
}
for (Map.Entry<Method, T> entry : methods.entrySet()) {
Method invocableMethod = AopUtils.selectInvocableMethod(entry.getKey(), userType);
T mapping = entry.getValue();
registerHandlerMethod(handler, invocableMethod, mapping);
}
}

 

 

MethodIntrospector.selectMethods(..)方法是个很全面的解析方法:注释写得很详细,☆方法处,metadataLookup.inspect方法,往上看,调用的就是getMappingForMethod方法获取RequestMappingInfo对象;
public static <T> Map<Method, T> selectMethods(Class<?> targetType, final MetadataLookup<T> metadataLookup) {
final Map<Method, T> methodMap = new LinkedHashMap<Method, T>();
Set<Class<?>> handlerTypes = new LinkedHashSet<Class<?>>();
Class<?> specificHandlerType = null;

if (!Proxy.isProxyClass(targetType)) {        
//handler class不是JDK代理生成的,加入到handlerTypes集合,specificHandlerType为当前handler class handlerTypes.add(targetType); specificHandlerType = targetType; } handlerTypes.addAll(Arrays.asList(targetType.getInterfaces())); /
/handler class实现的接口加入到handlerTypes for (Class<?> currentHandlerType : handlerTypes) { final Class<?> targetClass = (specificHandlerType != null ? specificHandlerType : currentHandlerType); ReflectionUtils.doWithMethods(currentHandlerType, new ReflectionUtils.MethodCallback() {
//该工具类方法,遍历了该currentHandlerType本类中所有的方法 // 调用的是 getDeclaredMethods(),然后遍历method数组,调用doWith回调处理method方法 public void doWith(Method method) { Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass); T result = metadataLookup.inspect(specificMethod);              
// ☆ 核心!!! 这里处理了方法以及类上的映射关系,并且返回泛型T,实际类型是RequesMappingInfo if (result != null) { Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(specificMethod); if (bridgedMethod == specificMethod || metadataLookup.inspect(bridgedMethod) == null) { methodMap.put(specificMethod, result); } } } }, ReflectionUtils.USER_DECLARED_METHODS);  
// ReflectionUtils.USER_DECLARED_METHODS是个methodFilter,作用是过滤方法是用户定义、且非桥接类型的方法; } return methodMap; }

 

RequestMappingHandlerMapping 的 getMappingForMethod 方法:先分析方法上的映射关系,再分析类所在方法上的映射关系,然后结合处理;

下面一点点记录我查看这个方法的发现;

protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
RequestMappingInfo info = createRequestMappingInfo(method);        
// 解析类上RequestMapping注解 if (info != null) { RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType);// 解析方法上@RequestMapping注解 if (typeInfo != null) { info = typeInfo.combine(info); //方法上RequestMapping注解不为空,就需要结合分析 } } return info; }

 

createRequestMappingInfo 方法:

private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
    //调用Spring注解工具类AnnotatedElementUtils获取方法上注解 RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class); RequestCondition<?> condition = (element instanceof Class<?> ? getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element)); 
    //RequestMappingHandlerMapping两个方法都是返回null,空实现 return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null); }

 

具体的RequestMappingInfo的构造采用建造者模式还是其他模式的?

protected RequestMappingInfo createRequestMappingInfo(
RequestMapping requestMapping, RequestCondition<?> customCondition) {  //customCondition一般都为null
  return RequestMappingInfo
.paths(resolveEmbeddedValuesInPatterns(requestMapping.path()))// @RequestMapping(path={....}) 将path属性设置上去
.methods(requestMapping.method())     // @RequestMapping(method={....}) 将method属性设置上去
.params(requestMapping.params())        // @RequestMapping(method={....}) 将method属性设置上去
.headers(requestMapping.headers())     // @RequestMapping(headers={....}) 将headers属性设置上去
.consumes(requestMapping.consumes())   // @RequestMapping(consumes={....}) 将consumes属性设置上去
.produces(requestMapping.produces())   // @RequestMapping(produces={....}) 将produces属性设置上去
.mappingName(requestMapping.name())    // @RequestMapping(name={....}) 将name属性设置上去   
.customCondition(customCondition)
.options(this.config)
.build();
}

 

 这里只分析一个开头、一个结尾这样;

RequestMappingInfo 的 paths 方法:

public static Builder paths(String... paths) { // paths是@RequestMapping的path属性,字符串数组,这里用可变参数来接收,效果一样     
      return new DefaultBuilder(paths); }

 

 Builder接口所有方法都返回Builder对象,DefaultBuilder持有一堆属性,可以看到都是@ReuqestMapping的属性;

paths方法就将注解的path属性注入到DefaultBuilder中,其他方法methods、params、headers、consumes、produces、mappingName、customCondition都是这个套路;

而 options注入的config属性 ,最开始 afterPropertiesSet 里 ,this.config = new RequestMappingInfo.BuilderConfiguration();

就是将RequestMappingHandleMapping中的config作为DefaultBuilder的options注入; 最后就是build方法。

                           

DefaultBuilder 的 build方法:

public RequestMappingInfo build() {
ContentNegotiationManager manager = this.options.getContentNegotiationManager();
       // PatternsRequestCondition构造的主要属性就是paths,代表了映射的路径,不以/开头会添加 / 这个开头
PatternsRequestCondition patternsCondition = new PatternsRequestCondition(
this.paths, this.options.getUrlPathHelper(), this.options.getPathMatcher(),
this.options.useSuffixPatternMatch(), this.options.useTrailingSlashMatch(),
this.options.getFileExtensions());

return new RequestMappingInfo(this.mappingName, patternsCondition,
new RequestMethodsRequestCondition(methods),
new ParamsRequestCondition(this.params),
new HeadersRequestCondition(this.headers),
new ConsumesRequestCondition(this.consumes, this.headers),
new ProducesRequestCondition(this.produces, this.headers, manager),
this.customCondition);                                                   // customCondition通常为null
}

 

build方法返回 RequestMappingInfo,其中构造入参都是XXXRequestCondition这种,他们都实现了RequestCondition接口;

private PatternsRequestCondition(Collection<String> patterns, UrlPathHelper urlPathHelper,
PathMatcher pathMatcher, boolean useSuffixPatternMatch, boolean useTrailingSlashMatch,
List<String> fileExtensions) {
    //这里就是 prependLeadingSlash 会判断 @RequestMapping注解的 path属性,不是以 /开头会添加 /
this.patterns = Collections.unmodifiableSet(prependLeadingSlash(patterns));   
     this.pathHelper = (urlPathHelper != null ? urlPathHelper : new UrlPathHelper()); this.pathMatcher = (pathMatcher != null ? pathMatcher : new AntPathMatcher()); this.useSuffixPatternMatch = useSuffixPatternMatch; this.useTrailingSlashMatch = useTrailingSlashMatch; if (fileExtensions != null) { for (String fileExtension : fileExtensions) { if (fileExtension.charAt(0) != '.') { fileExtension = "." + fileExtension; } this.fileExtensions.add(fileExtension); } } }

 

private static Set<String> prependLeadingSlash(Collection<String> patterns) {
if (patterns == null) {
return Collections.emptySet();
}
Set<String> result = new LinkedHashSet<String>(patterns.size());
for (String pattern : patterns) {
if (StringUtils.hasLength(pattern) && !pattern.startsWith("/")) {   //URL不以 /开头就会自动添加 /
pattern = "/" + pattern;
}
result.add(pattern);
}
return result;
}

 

  回到RequestMappingInfo的构造方法,将@RequestMapping的所有属性都以 RequestCondition的实现类 形式保存到  RequestMappingInfo对象中;

接口RequestCondition定义了三个方法,1.combine:一般用来 方法级别@RequestMapping与类级别@RequestMapping结合,返回新的(通常是RequestMappingInfo);   

2.getMatchingCondition:检查request对象是否满足条件,返回一个新的满足条件的RequestMappingInfo实例(T泛型用都是RequestMappingInfo);

 3.compareTo  用来多个匹配的情况排序挑选最合适的 

public interface RequestCondition<T> {

T combine(T other);

T getMatchingCondition(HttpServletRequest request);

int compareTo(T other, HttpServletRequest request);

}

 

至此 回到 RequestMappingHandlerMapping 的 getMappingForMethod方法 ,第一个方法级别的createRequestMappingInfo方法分析完毕,下面两行解析了标注在 类上的 注解,并且返回 RequestMappingInfo对象,

第188行就是类上标注了@RequestMapping注解,和方法上同样标注@RequestMapping结合处理的步骤:调用类上的RequestMappingInfo的combine方法

               

查看RequestMappingInfo对象的combine方法:

public RequestMappingInfo combine(RequestMappingInfo other) {
    // RequestMapping的name属性的处理方法,一般name属性很少写,处理方式:两个都不为空就返回this.name#other.name;有一个为空 就返回另外一个name   String name = combineNames(other);  
    //下面逻辑A分析 调用AntPathMatcher的combine方法,将类上URL和方法上URL组合并放入新PatternsRequestCondition     PatternsRequestCondition patterns = this.patternsCondition.combine(other.patternsCondition);
    //下面逻辑B分析,并且接下来的methods、params、headers等等实现方式大体一致 RequestMethodsRequestCondition methods = this.methodsCondition.combine(other.methodsCondition); ParamsRequestCondition params = this.paramsCondition.combine(other.paramsCondition); HeadersRequestCondition headers = this.headersCondition.combine(other.headersCondition);
    //!!comsume和produce判断逻辑不是相加,方法上的该属性优先级高于类级别上的 ConsumesRequestCondition consumes = this.consumesCondition.combine(other.consumesCondition); ProducesRequestCondition produces = this.producesCondition.combine(other.producesCondition); RequestConditionHolder custom = this.customConditionHolder.combine(other.customConditionHolder); return new RequestMappingInfo(name, patterns,//返回一个新的RequestMappingInfo对象,其中所有RequestCondition都是新创建的对象 methods, params, headers, consumes, produces, custom.getCondition()); }

 

逻辑A: PatternsRequestCondition 之前介绍过,其属性patterns 就是@RequestMapping的path / value 属性的集合,且判断 path是否以  / 开头,如果不是会自动补全  / 开头;

其实现了RequestCondition接口,查看其combine方法

public PatternsRequestCondition combine(PatternsRequestCondition other) {
          // result作为新的请求路径集合 Set<String> result = new LinkedHashSet<String>();   
          //类上注解@RequestMapping path不为空,方法上注解注解@RequestMapping path不为空      
            //此处的AntPathMatcher就是RequestMappingHandlerMapping对象里的antPathMatcher对象
            //@RequestMapping path属性是集合类型的,这类似笛卡尔积形式 调用AntPathMatcher的combine方式,进行URL组合 加入到result
    if (!this.patterns.isEmpty() && !other.patterns.isEmpty()) { for (String pattern1 : this.patterns) {            
        for (String pattern2 : other.patterns) {         result.add(this.pathMatcher.combine(pattern1, pattern2)); } } }
    //已经说明有一方为空了,只要判断另外一方是否为空,不为空直接加入Set<String> else if (!this.patterns.isEmpty()) {     result.addAll(this.patterns); } else if (!other.patterns.isEmpty()) { result.addAll(other.patterns); } else { result.add(""); } /返回了一个新的PatternsRequestCondition对象,patterns属性就是当前方法的请求路径 return new PatternsRequestCondition(result, this.pathHelper, this.pathMatcher, this.useSuffixPatternMatch, this.useTrailingSlashMatch, this.fileExtensions); / }

 

 

逻辑A-1:AntPathMatcher对象如何对请求路径进行结合combine? 

  类上path  方法上path 结合后path
null null  
/hotels null /hotels
null /hotels /hotels
/hotels /bookings /hotels/bookings
/hotels bookings /hotels/bookings
/hotels/* /bookings /hotels/bookings
/hotels/** /bookings /hotels/**/bookings
/hotels {hotel} /hotels/{hotel}
/hotels/* {hotel} /hotels/{hotel}
/hotels/** {hotel} /hotels/**/{hotel}
/*.html hotels.html /hotels.html
/*.html /hotels /hotels.html
/*.html /*.txt IllegalArgumentException

 

 逻辑B:RequestMethodsRequestCondition 的 combine 方法,方法上注解@RequestMapping的method加入到类上注解的method属性里,然后返回一个全新的RequestMethodsRequestCondition,持有新的method集合;

public RequestMethodsRequestCondition combine(RequestMethodsRequestCondition other) {
Set<RequestMethod> set = new LinkedHashSet<RequestMethod>(this.methods);
set.addAll(other.methods);
return new RequestMethodsRequestCondition(set);
}

 

 getMappingForMethod方法调用结束,返回结合后的RequestMappingInfo对象; 回到MethodIntrospector.selectMethods方法,第19行就是调用的getMappingForMethod方法,返回RequestMappingInfo对象result,result不为空之后,

会筛选不是桥接方法,存入methodMap这个Map对象,key-type是Method,value-type是RequestMappingInfo类型;

该方法selectMethods将Controller / Handler中所有方法都进行判断加载请求映射,返回methodMap对象;

1     public static <T> Map<Method, T> selectMethods(Class<?> targetType, final MetadataLookup<T> metadataLookup) {
2         final Map<Method, T> methodMap = new LinkedHashMap<Method, T>();
3         Set<Class<?>> handlerTypes = new LinkedHashSet<Class<?>>();
4         Class<?> specificHandlerType = null;
5
6         if (!Proxy.isProxyClass(targetType)) {
7             handlerTypes.add(targetType);
8             specificHandlerType = targetType;
9         }
10         handlerTypes.addAll(Arrays.asList(targetType.getInterfaces()));
11
12         for (Class<?> currentHandlerType : handlerTypes) {
13             final Class<?> targetClass = (specificHandlerType != null ? specificHandlerType : currentHandlerType);
14
15             ReflectionUtils.doWithMethods(currentHandlerType, new ReflectionUtils.MethodCallback() {
16                 @Override
17                 public void doWith(Method method) {
18                     Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);
19                     T result = metadataLookup.inspect(specificMethod);
20                     if (result != null) {
21                         Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);
22                         if (bridgedMethod == specificMethod || metadataLookup.inspect(bridgedMethod) == null) {
23                             methodMap.put(specificMethod, result);
24                         }
25                     }
26                 }
27             }, ReflectionUtils.USER_DECLARED_METHODS);
28         }
29
30         return methodMap;
31     }

 

回到最开始的分析detectHandlerMethods方法:methods对象就是上面返回的methodMap,如果日志设置了DEBUG,每遍历一个controller都会输出日志;

1 protected void detectHandlerMethods(final Object handler) {
2         Class<?> handlerType = (handler instanceof String ?
3                 getApplicationContext().getType((String) handler) : handler.getClass());
4         final Class<?> userType = ClassUtils.getUserClass(handlerType);
5
6         Map<Method, T> methods = MethodIntrospector.selectMethods(userType,
7                 new MethodIntrospector.MetadataLookup<T>() {
8                     @Override
9                     public T inspect(Method method) {
10                         return getMappingForMethod(method, userType);
11                     }
12                 });
13
14         if (logger.isDebugEnabled()) {
15             logger.debug(methods.size() + " request handler methods found on " + userType + ": " + methods);
16         }
17         for (Map.Entry<Method, T> entry : methods.entrySet()) {//遍历methods,并且调用registerHandlerMethod注册映射信息
18             Method invocableMethod = AopUtils.selectInvocableMethod(entry.getKey(), userType);
19             T mapping = entry.getValue();
20             registerHandlerMethod(handler, invocableMethod, mapping);
21         }
22     }

 

registerHandlerMethod:总结 :

 

RequestMappingHandlerMapping.mappingRegistry属性

 

  key-type value-type
mappingLookup
RequestMappingInfo HandlerMethod对象
urlLookup
请求路径URL RequestMappingInfo
nameLookup controller name中大写字母#方法名(如UC#test) HandlerMethod对象
registry
RequestMappingInfo
MappingRegistration对象(持有
RequestMappingInfo\HandlerMethod\URL路径\name)

 

protected void registerHandlerMethod(Object handler, Method method, T mapping) {
this.mappingRegistry.register(mapping, handler, method);
} // this对象指RequestMappingHandlerMapping,mapping是RequestMappingInfo对象,handler是controler的name,method是当前@RequestMapping方法

public void register(T mapping, Object handler, Method method) {
this.readWriteLock.writeLock().lock();   //可重入锁 写锁上锁  这里不太明白为什么要上锁
try {
          //创建新的HandlerMethod对象 下面逻辑C 介绍HandlerMethod 逻辑D 分析createHandlerMethod方法 HandlerMethod handlerMethod = createHandlerMethod(handler, method);
          //校验唯一性,一个RequestMappingInfo对应一个Handlermethod,如果根据RequestMappingInfo找到不同的hm 抛出异常 assertUniqueMethodMapping(handlerMethod, mapping); //INFO级别日志 比如Mapped "{[/user/test]}" onto public java.lang.String demo2.UserController.test(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) if (logger.isInfoEnabled()) { logger.info("Mapped \"" + mapping + "\" onto " + handlerMethod); }
           //this指RequestMappingHandlerMapping.MappingRegistry,mappingLookup保存着RequestMappingInfo--HandlerMethod对象 this.mappingLookup.put(mapping, handlerMethod);            //获取 mapping 的PatternsRequestCondition的patterns,也就是拼接的URL路径,并且路径不包含* ?的就加入到集合返回 , List<String> directUrls = getDirectUrls(mapping);
          for (String url : directUrls) {
            //MappingRegistry的urlLookup保存着 url--RequestMappingInfo对象 this.urlLookup.add(url, mapping);   } String name = null; if (getNamingStrategy() != null) {
             //name属性感觉没用,如果@RequestMapping有name属性就是这个属性 如果没有就是 controller名字中的大写字母#方法名字,比如UC#test name = getNamingStrategy().getName(handlerMethod, mapping);
              //MappingRegistry的nameLookup保存着 name--HandlerMethod集合 addMappingName(name, handlerMethod); } CorsConfiguration corsConfig = initCorsConfiguration(handler, method, mapping); if (corsConfig != null) { this.corsLookup.put(handlerMethod, corsConfig); }
     //MappingRegistry的registry保存着RequestMappingInfo--MappingRegistration,MappingRegistration几乎有映射的所有信息 this.registry.put(mapping, new MappingRegistration<T>(mapping, handlerMethod, directUrls, name)); } finally { this.readWriteLock.writeLock().unlock(); //可重入锁 写锁 释放锁 } }

 

逻辑C:HandlerMethod对象 属性有bean,就是controller对象实例;beanFactory当前Spring容器;beanType就是controller的类型;method就是handler method;birdgeMethod是handler method的桥接方法;MethodParameter是handler method的方法参数,handlerMethod一般为null;

  HandlerMethod,作用Spring给出了:一个handler method对象,包含了method以及controller对象,此外提供了便捷方式获取方法入参、返回值、注解等等;

          

 

 逻辑D:createHandlerMethod方法只是调用了HandlerMethod的构造方法,构造方法中对方法入参进行了处理;

1     protected HandlerMethod createHandlerMethod(Object handler, Method method) {
2         HandlerMethod handlerMethod;
3         if (handler instanceof String) {
4             String beanName = (String) handler;
5             handlerMethod = new HandlerMethod(beanName,
6                     getApplicationContext().getAutowireCapableBeanFactory(), method);
7         }
8         else {
9             handlerMethod = new HandlerMethod(handler, method);
10         }
11         return handlerMethod;
12     }
13
14 public HandlerMethod(String beanName, BeanFactory beanFactory, Method method) {
15         Assert.hasText(beanName, "Bean name is required");
16         Assert.notNull(beanFactory, "BeanFactory is required");
17         Assert.notNull(method, "Method is required");
18         this.bean = beanName;            //controller beanName
19         this.beanFactory = beanFactory;      //当前controller所在Spring工厂
20         this.beanType = ClassUtils.getUserClass(beanFactory.getType(beanName));   //获取当前controller类型
21         this.method = method;            //当前handler method
22         this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);  //查找method的桥接方法,没有桥接方法就是返回自身
23         this.parameters = initMethodParameters();   //初始化MethodParameter对象 设置了每个MethodParameter的method、parameterIndex属性 具体方法下图
24         this.resolvedFromHandlerMethod = null;
25     }

                                       

至此,registerHandlerMethod方法分析完毕,detectHandlerMethods方法分析完成,

Spring主要做了哪些工作:将所有请求映射关系保存到上面RequestMappingHandlerMapping的mappingRegistry的相关属性中,详情见上面表格。

 

分析过SpringMvc的请求流程  SpringMvc流程

  篇幅太长,只分析如何找根据请求找到对应的handler?  遍历HandlerMapping对象,调用其getHanlder方法查找controller / handler , RequestMappingHandlerMapping对象的父类AbstractHandlerMapping实现了getHandler方法,方法最开始Object handler = getHandlerInternal(request); 那么我们从AbstractHandlerMapping 的 getHandlerInternal开始记录.

1 protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception {
       // 根据request请求路径以及servlet-mapping得到要请求URL 2 String lookupPath = getUrlPathHelper().getLookupPathForRequest(request); 3 if (logger.isDebugEnabled()) { 4 logger.debug("Looking up handler method for path " + lookupPath); 5 } 6 this.mappingRegistry.acquireReadLock();                        //读锁 上锁    7 try {
           // 这里就是MVC寻找controller匹配的方法! 下面花大篇幅介绍下 8 HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request);
9 if (logger.isDebugEnabled()) { 10 if (handlerMethod != null) { 11 logger.debug("Returning handler method [" + handlerMethod + "]"); 12 } 13 else { 14 logger.debug("Did not find handler method for [" + lookupPath + "]"); 15 } 16 }
          //找到handlerMethod,但bean是controller beanName,用beanFactory getBean替换bean 17 return (handlerMethod != null ? handlerMethod.createWithResolvedBean() : null); 18 } 19 finally { 20 this.mappingRegistry.releaseReadLock(); 21 } 22 }

 lookupHandlerMethod方法:

  逻辑是这样的,先根据请求的URL 从 RequestMappingHandlerMapping的mappingRegistry的urlLookup中尝试寻找RequestMappingInfo;

  寻找大致分为两种情况:一种请求URL清楚,不需要通配符比对,那肯定可以直接找到RequestMappingInfo集合,创建Match对象并且添加到集合里面,然后根据规则对Match集合排序选出最优解;

     第二种情况URL带有通配符,那需要遍历映射关系再重复第一种情况。

1 protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
2         List<Match> matches = new ArrayList<Match>();
        //return this.urlLookup.get(urlPath);调用mappingRegistry的urlLookup根据URL寻找RequestMappingInfo 3      List<T> directPathMatches = this.mappingRegistry.getMappingsByUrl(lookupPath);
4 if (directPathMatches != null) {     
          //遍历找到的RequestMappingInfo集合, 然后寻找匹配的对象并处理添加到matches集合,见 逻辑E 分析     5 addMatchingMappings(directPathMatches, matches, request);
6 } 7 if (matches.isEmpty()) {   //matches为空,有可能是因为通配符匹配的情况需要再次匹配 8 // No choice but to go through all mappings... 9 addMatchingMappings(this.mappingRegistry.getMappings().keySet(), matches, request); 10 } 11 12 if (!matches.isEmpty()) {                                     
          //返回一个MatchComparator对象
          // 持有Comparator属性,并且compare方法是调用了RequestMappingInfo的compareTo 13 Comparator<Match> comparator = new MatchComparator(getMappingComparator(request));         
           //说到底排序还是调用了RequestMappingInfo的compareTo方法, 也存在优先级之分 URL路径>params>headers>comsume>produce>method 排序分析见文章最后 14 Collections.sort(matches, comparator); 15 if (logger.isTraceEnabled()) { 16 logger.trace("Found " + matches.size() + " matching mapping(s) for [" + 17 lookupPath + "] : " + matches); 18 } 19 Match bestMatch = matches.get(0); //找到最优匹配 20 if (matches.size() > 1) { 21 if (CorsUtils.isPreFlightRequest(request)) { 22 return PREFLIGHT_AMBIGUOUS_MATCH; 23 } 24 Match secondBestMatch = matches.get(1); 25 if (comparator.compare(bestMatch, secondBestMatch) == 0) { //存在两个匹配且相等 抛出异常 26 Method m1 = bestMatch.handlerMethod.getMethod(); 27 Method m2 = secondBestMatch.handlerMethod.getMethod(); 28 throw new IllegalStateException("Ambiguous handler methods mapped for HTTP path '" + 29 request.getRequestURL() + "': {" + m1 + ", " + m2 + "}"); 30 } 31 } 32 handleMatch(bestMatch.mapping, lookupPath, request); //解析URL变量,完成设置request属性等工作 33 return bestMatch.handlerMethod;               //返回最优匹配的HandlerMethod对象 34 } 35 else { //没找到handlerMethod 就返回null 36 return handleNoMatch(this.mappingRegistry.getMappings().keySet(), lookupPath, request); 37 } 38 }

 

逻辑E:遍历找到的RequestMappingInfo集合,调用RequestMappingInfo的getMatchCondition进行匹配以获取匹配的RequestMappingInfo对象;寻找到合适的RequestMappingInfo对象之后,创建一个Match对象加入matches集合;

mappingRegistry 的 getMappings方法返回mappingLookup属性,上述表格mappingLookup 存放 RequestMappingInfo--HandlerMethod,根据RequestMappingInfo对象从map中取对象,(逻辑G分析 RequestMappingInfo重写了的hashCode以及equals方法)。 Match对象持有RequestMappingInfo以及HandlerMethod属性;此处方法调用结束matches可能包含多个Match结果;

           

RequestMappingInfo的getMatchingCondition方法

1 public RequestMappingInfo getMatchingCondition(HttpServletRequest request) {
  //如果RequestMappingInfo没有指定methods属性,返回RequestMappingInfo本身,否则方法匹配 2 RequestMethodsRequestCondition methods = this.methodsCondition.getMatchingCondition(request);
        //下面几个匹配逻辑是一样的,匹配了返回自身,没匹配返回null,具体参数作用、如何匹配看吧; 3 ParamsRequestCondition params = this.paramsCondition.getMatchingCondition(request); 4 HeadersRequestCondition headers = this.headersCondition.getMatchingCondition(request); 5 ConsumesRequestCondition consumes = this.consumesCondition.getMatchingCondition(request); 6 ProducesRequestCondition produces = this.producesCondition.getMatchingCondition(request); 7         //有一个条件匹配不上就直接返回null 8 if (methods == null || params == null || headers == null || consumes == null || produces == null) {
9 return null; 10 } 11         //其他匹配上了,最重要的匹配请求URL, 路径匹配作为 逻辑F 分析 12 PatternsRequestCondition patterns = this.patternsCondition.getMatchingCondition(request);
13 if (patterns == null) { 14 return null; 15 } 16 17 RequestConditionHolder custom = this.customConditionHolder.getMatchingCondition(request); 18 if (custom == null) { 19 return null; 20 } 21 22 return new RequestMappingInfo(this.name, patterns,
             //寻找到匹配之后,构造一个新的RequestMappingInfo对象,持有上述匹配之后的结果返回 23 methods, params, headers, consumes, produces, custom.getCondition()); 24 }

 

逻辑F:PatternsRequestCondition匹配

调用PatternsRequestCondition 的 getMatchingPattern 方法进行URL匹配;遍历PatternsRequestCondition的 patterns属性,逐个getMatchingPattern进行比较,匹配上将pattern存入集合,并且使用AntPatternComparator进行排序,排序之后集合加入到一个新的PatternsRequestCondition对象中;

  //pattern就是patterns属性当前迭代的元素,lookupPath就是servlet-mapping下请求URL
1 private String getMatchingPattern(String pattern, String lookupPath) { 2 if (pattern.equals(lookupPath)) {   //两者相等 无疑义直接返回   这种是没有通配符 * ?这种都会很容易匹配到并且返回       3 return pattern; 4 } 5 if (this.useSuffixPatternMatch) { // useSuffixPatternMatch默认为true 6 if (!this.fileExtensions.isEmpty() && lookupPath.indexOf('.') != -1) { // fileExtensions默认为空 7 for (String extension : this.fileExtensions) { 8 if (this.pathMatcher.match(pattern + extension, lookupPath)) { 9 return pattern + extension; 10 } 11 } 12 } 13 else { 14 boolean hasSuffix = pattern.indexOf('.') != -1; //pattern字符串是否有 . 15 if (!hasSuffix && this.pathMatcher.match(pattern + ".*", lookupPath)) { //没有 . 就用AntPathMatcher的match匹配 pattern.* lookupPath 16 return pattern + ".*"; 17 } 18 } 19 } 20 if (this.pathMatcher.match(pattern, lookupPath)) {
      // 用AntPathMatcher的match匹配 pattern lookupPath,匹配上就返回pattern 21 return pattern; 22 } 23 if (this.useTrailingSlashMatch) { 24 if (!pattern.endsWith("/") && this.pathMatcher.match(pattern + "/", lookupPath)) { 25 return pattern +"/"; 26 } 27 } 28 return null; 29 }

 

逻辑G:先介绍下为什么要看RequestMappingInfo的hashCode以及equals方法?RequestMappingInfo作为key存储在Map中,肯定需要重写HashCode以及equals方法;

    RequestMappingInfo的hashCode以及equals方法:  比较的时候会先调用hashCode判断值是否相等,相等再比较equals方法,如果相等则认为是同一个对象;

    先来看hashCode方法,将RequestMappingInfo的所有RequestCondition属性按公式求和,这些属性都是AbstractRequestCondition,equals和hashCode方法都调用了getContent方法,而AbstractRequestCondition的各种实现类的getContent方法,比如PatternsRequestCondition实现方式就是返回patterns(URL)集合;比如RequestMethodsRequestCondition实现就是返回methods集合;

RequestMappingInfo
1 public boolean equals(Object other) { 2 if (this == other) { 3 return true; 4 } 5 if (!(other instanceof RequestMappingInfo)) { 6 return false; 7 } 8 RequestMappingInfo otherInfo = (RequestMappingInfo) other; 9 return (this.patternsCondition.equals(otherInfo.patternsCondition) && 10 this.methodsCondition.equals(otherInfo.methodsCondition) && 11 this.paramsCondition.equals(otherInfo.paramsCondition) && 12 this.headersCondition.equals(otherInfo.headersCondition) && 13 this.consumesCondition.equals(otherInfo.consumesCondition) && 14 this.producesCondition.equals(otherInfo.producesCondition) && 15 this.customConditionHolder.equals(otherInfo.customConditionHolder)); 16 } 17 18 @Override 19 public int hashCode() { 20 return (this.patternsCondition.hashCode() * 31 + // primary differentiation 21 this.methodsCondition.hashCode() + this.paramsCondition.hashCode() + 22 this.headersCondition.hashCode() + this.consumesCondition.hashCode() + 23 this.producesCondition.hashCode() + this.customConditionHolder.hashCode()); 24 }

 

AbstractRequestCondition  
1 public boolean equals(Object obj) { 2 if (this == obj) { 3 return true; 4 } 5 if (obj != null && getClass() == obj.getClass()) { 6 AbstractRequestCondition<?> other = (AbstractRequestCondition<?>) obj; 7 return getContent().equals(other.getContent()); 8 } 9 return false; 10 } 11 12 @Override 13 public int hashCode() { 14 return getContent().hashCode(); 15 }

 

 

 分析到上面,getHandlerInternal已经找到了对应的HandlerMethod对象,调用getHandlerExecutionChain封装成HandlerExecutionChain;

1 protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
2         HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?
3                 (HandlerExecutionChain) handler : new HandlerExecutionChain(handler)); 
           // //构造一个HandlerExecutionChain对象,持有handlerMethod 4 5 String lookupPath = this.urlPathHelper.getLookupPathForRequest(request); 6 for (HandlerInterceptor interceptor : this.adaptedInterceptors) {
      //adaptedInterceptors在开启<mvc:annotation-drvien/>之后不为空,多了一个MappedInterceptor拦截器 7 if (interceptor instanceof MappedInterceptor) { 8 MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor; 9 if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) { 10 chain.addInterceptor(mappedInterceptor.getInterceptor());     
      //将ConversionServiceExposingInterceptor添加到HandlerExecutionChain的interceptorList属性中 11 } 12 } 13 else { 14 chain.addInterceptor(interceptor); 15 } 16 } 17 return chain; //返回HandlerExecutionChain对象 18 }

 

Tip1:这个RequestMappingHandlerMapping的MappedInterceptor是从哪里注入的呢?

开启了<mvc:annotation-driven />之后 Spring向容器中注入了这样两个bean的定义,MappedInterceptor,该对象持有ConversionServiceExposingInterceptor对象;

       

容器中有了MappedInterceptor对象,什么时候给RequestMappingHandlerMapping设置的adaptedInterceptors呢?通过打断点分析到,RequestMappingHandlerMapping实现了ApplicationContextAware接口,Spring向其注入ApplicationContext的时候,调用了initApplicationContext方法,不断进入方法最后进入到父类AbstractHandlerMapping的initApplicationContext方法,

1 protected void initApplicationContext() throws BeansException {
2         extendInterceptors(this.interceptors);
3         detectMappedInterceptors(this.adaptedInterceptors);   //此处添加了RequestMappingHandlerMapping的adaptedInterceptors
4         initInterceptors();
5 }
6
7 protected void detectMappedInterceptors(List<HandlerInterceptor> mappedInterceptors) {
       //这里将容器中的MappedInterceptor添加到了RequestMappingHandlerMapping的adaptedInterceptors 8 mappedInterceptors.addAll(                   
9 BeanFactoryUtils.beansOfTypeIncludingAncestors( 10 getApplicationContext(), MappedInterceptor.class, true, false).values()); 11 }

 

至此,如何找到HandlerMethod已经分析完毕;

 

总结

SpringMvc请求寻找规则 : 如果一个请求同时匹配上多个方法,按照如下顺序选择执行哪个方法:

先URL匹配的方法 >>>>>  params满足的方法  >>>>>  headers 满足的方法  >>>>>>consume满足的方法 >>>> produce 满足的方法 >>>> method满足的方法

 

如果一个请求匹配上了多个RequestMappingInfo筛选:

之前介绍过排序是调用 RequestMappingInfo的compareTo进行排序

1 public int compareTo(RequestMappingInfo other, HttpServletRequest request) {
2         int result = this.patternsCondition.compareTo(other.getPatternsCondition(), request);  //优先URL进行匹配
3         if (result != 0) {
4             return result;
5         }
6         result = this.paramsCondition.compareTo(other.getParamsCondition(), request);
7         if (result != 0) {
8             return result;
9         }
10         result = this.headersCondition.compareTo(other.getHeadersCondition(), request);
11         if (result != 0) {
12             return result;
13         }
14         result = this.consumesCondition.compareTo(other.getConsumesCondition(), request);
15         if (result != 0) {
16             return result;
17         }
18         result = this.producesCondition.compareTo(other.getProducesCondition(), request);
19         if (result != 0) {
20             return result;
21         }
22         result = this.methodsCondition.compareTo(other.getMethodsCondition(), request);
23         if (result != 0) {
24             return result;
25         }
26         result = this.customConditionHolder.compareTo(other.customConditionHolder, request);
27         if (result != 0) {
28             return result;
29         }
30         return 0;
31     }

 

 介绍下URL如何排序吧,其他类似; 假设两个URL   /get1  可以被匹配  /get*  以及 /get?

1 public int compareTo(PatternsRequestCondition other, HttpServletRequest request) {
2         String lookupPath = this.pathHelper.getLookupPathForRequest(request);
3         Comparator<String> patternComparator = this.pathMatcher.getPatternComparator(lookupPath);  //获取AntPatternComparator比较器
4         Iterator<String> iterator = this.patterns.iterator();
5         Iterator<String> iteratorOther = other.patterns.iterator();
6         while (iterator.hasNext() && iteratorOther.hasNext()) {
7             int result = patternComparator.compare(iterator.next(), iteratorOther.next());   //URL比较规则在这里
8             if (result != 0) {
9                 return result;
10             }
11         }
12         if (iterator.hasNext()) {
13             return -1;
14         }
15         else if (iteratorOther.hasNext()) {
16             return 1;
17         }
18         else {
19             return 0;
20         }
21     }

 

 URL比较规则:按照请求URL通配符按一定权重计算排序顺序,{个数+*个数+ ** 个数 ;所以 get* 比get?排在前面;

1 public int compare(String pattern1, String pattern2) {      //例子中pattern1为 /get*  pattern2为/get?
2             PatternInfo info1 = new PatternInfo(pattern1);  //具体查看下面构造方法
3             PatternInfo info2 = new PatternInfo(pattern2);
4
5             if (info1.isLeastSpecific() && info2.isLeastSpecific()) {
6                 return 0;
7             }
8             else if (info1.isLeastSpecific()) {
9                 return 1;
10             }
11             else if (info2.isLeastSpecific()) {                     //上面三种情况是 比较 /**的情况
12                 return -1;
13             }
14
15             boolean pattern1EqualsPath = pattern1.equals(path);
16             boolean pattern2EqualsPath = pattern2.equals(path);
17             if (pattern1EqualsPath && pattern2EqualsPath) {
18                 return 0;
19             }
20             else if (pattern1EqualsPath) {
21                 return -1;
22             }
23             else if (pattern2EqualsPath) {                        //这三种情况是比较  pattern1 pattern2存在和请求URL完全匹配的情况
24                 return 1;
25             }
26
27             if (info1.isPrefixPattern() && info2.getDoubleWildcards() == 0) {
28                 return 1;
29             }
30             else if (info2.isPrefixPattern() && info1.getDoubleWildcards() == 0) {   //哪个pattern的 /**多 哪个排在前面
31                 return -1;
32             }
33
34             if (info1.getTotalCount() != info2.getTotalCount()) {
35                 return info1.getTotalCount() - info2.getTotalCount();   //按照权重来排序了   {算1   *算1 **算2  哪个大哪个排前面  /get*权重为1排前面
36             }
37
38             if (info1.getLength() != info2.getLength()) {
39                 return info2.getLength() - info1.getLength();
40             }
41
42             if (info1.getSingleWildcards() < info2.getSingleWildcards()) {
43                 return -1;
44             }
45             else if (info2.getSingleWildcards() < info1.getSingleWildcards()) {
46                 return 1;
47             }
48
49             if (info1.getUriVars() < info2.getUriVars()) {
50                 return -1;
51             }
52             else if (info2.getUriVars() < info1.getUriVars()) {
53                 return 1;
54             }
55
56             return 0;
57         }
58
59 public PatternInfo(String pattern) {
60                 this.pattern = pattern;
61                 if (this.pattern != null) {
62                     initCounters();
63                     this.catchAllPattern = this.pattern.equals("/**");      //代表匹配所有就是pattern为 /**
64                     this.prefixPattern = !this.catchAllPattern && this.pattern.endsWith("/**");
65                 }
66                 if (this.uriVars == 0) {
67                     this.length = (this.pattern != null ? this.pattern.length() : 0);
68                 }
69             }
70
71             protected void initCounters() {
72                 int pos = 0;
73                 while (pos < this.pattern.length()) {
74                     if (this.pattern.charAt(pos) == '{') {   //存在变量 则uriVars自增
75                         this.uriVars++;
76                         pos++;
77                     }
78                     else if (this.pattern.charAt(pos) == '*') {          //解析到*
79                         if (pos + 1 < this.pattern.length() && this.pattern.charAt(pos + 1) == '*') {
80                             this.doubleWildcards++;      // doubleWildcards代表有两个*的
81                             pos += 2;
82                         }
83                         else if (pos > 0 && !this.pattern.substring(pos - 1).equals(".*")) {    //最后一位是* 且倒数第二位不是 *
84                             this.singleWildcards++;     // singleWildcards代表有单个*
85                             pos++;
86                         }
87                         else {
88                             pos++;
89                         }
90                     }
91                     else {
92                         pos++;
93                     }
94                 }
95             }

 

 

 

 

 

 

 

 

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