AbstractHandlerMethodMapping是处理HandlerMethod的HandlerMapping，其中有一个实现了是我们常用的
它就是RequestMappingHandlerMapping
我们直接看到RequestMappingHandlerMapping的类图
这里大部分接口我们在spring源码分析的时候已经解释过了，这里解释一下那些没有分析过的接口的作用
- EmbeddedValueResolverAware 在bean进行初始化时设置StringValueResolver，这个StringValueResolver是一个占位符解析器
- ApplicationObjectSupport 实现了ApplicationContextAware，额外提供了获取MessageSource（用于国际化）的方法
- HandlerMapping 获取handler和能够用于拦截找到的handler的拦截器，然后组成HandlerExecutionChain
几个实现类的分析
- AbstractHandlerMapping
public abstract class AbstractHandlerMapping extends WebApplicationObjectSupport
implements HandlerMapping, Ordered {
private int order = Integer.MAX_VALUE; // default: same as non-Ordered
private Object defaultHandler;
//构建urlPathHelper
private UrlPathHelper urlPathHelper = new UrlPathHelper();
//AntPathMatcher，这个类我们在分析spring源码的时候进行分析过
private PathMatcher pathMatcher = new AntPathMatcher();
private final List<Object> interceptors = new ArrayList<Object>();
private final List<HandlerInterceptor> adaptedInterceptors = new ArrayList<HandlerInterceptor>();
//默认跨域处理器
private CorsProcessor corsProcessor = new DefaultCorsProcessor();
//基于url的跨域配置源
private final UrlBasedCorsConfigurationSource corsConfigSource = new UrlBasedCorsConfigurationSource();
。。。。。。
}
public final HandlerExecutionChain getHandler(PortletRequest request) throws Exception {
//抽象方法，有子类实现
Object handler = getHandlerInternal(request);
//如果没有获取到，尝试使用默认的handler，一般不设置
if (handler == null) {
handler = getDefaultHandler();
}
if (handler == null) {
return null;
}
// Bean name or resolved handler?
//如果是字符串类型，那么从容器中获取
if (handler instanceof String) {
String handlerName = (String) handler;
handler = getApplicationContext().getBean(handlerName);
}
//将获取到的handler和拦截器构建成HandlerExecutionChain
return getHandlerExecutionChain(handler, request);
}
- AbstractHandlerMethodMapping 这个抽象类实现了InitializingBean接口，让我们来看看它的afterPropertiesSet做了什么
//这个方法被子类RequestMappingHandlerMapping覆盖
public void org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet() {
//构建配置
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());
super.afterPropertiesSet();
}
public void AbstractHandlerMethodMapping.afterPropertiesSet() {
initHandlerMethods();
}
//初始化HandlerMethod
protected void initHandlerMethods() {
if (logger.isDebugEnabled()) {
logger.debug("Looking for request mappings in application context: " + getApplicationContext());
}
//从容器中获取所有beanName，detectHandlerMethodsInAncestorContexts表示是否需要获取父容器的beanName
//默认是false，所以一般我们配置的Controller都是在SpringMVC加载配置文件中
String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ?
BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :
getApplicationContext().getBeanNamesForType(Object.class));
for (String beanName : beanNames) {
//是否以scopedTarget.为前缀，这个scopedTarget.表示范围对象代理，比如request，session等这些scope的对象
//如果我们要把短生命周期的注册到长生命周期的对象中，就应当使用代理，否则就变成和长生命周期的对象一样长的寿命
//这里不考虑这类被代理过的Controller
if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) {
Class<?> beanType = null;
try {
//获取beanName对应bean的类型
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);
}
}
//判断当前类是否是需要的handler，isHandler方法被子类RequestMappingHandlerMapping实现
//其判断逻辑就一行代码
//((AnnotationUtils.findAnnotation(beanType, Controller.class) != null) ||
//(AnnotationUtils.findAnnotation(beanType, RequestMapping.class) != null))
//类是否被@Controller和@RequestMapping两个注解标注
if (beanType != null && isHandler(beanType)) {
//装配HanderMethod
detectHandlerMethods(beanName);
}
}
}
//获取到handlerMethod的后置处理方法，为空方法。
handlerMethodsInitialized(getHandlerMethods());
}
装配HanderMethod
protected void detectHandlerMethods(final Object handler) {
//获取对应handler的类型
Class<?> handlerType = (handler instanceof String ?
getApplicationContext().getType((String) handler) : handler.getClass());
final Class<?> userType = ClassUtils.getUserClass(handlerType);
//筛选@RequestMapping注解注释的方法
Map<Method, T> methods = MethodIntrospector.selectMethods(userType,
new MethodIntrospector.MetadataLookup<T>() {
@Override
public T inspect(Method method) {
//获取@RequestMapp注解对应的映射信息，由子类实现
//RequestMappingHandlerMapping返回的是RequestMappingInfo
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()) {
//注册HandlerMethod
registerHandlerMethod(handler, entry.getKey(), entry.getValue());
}
}
- RequestMappingHandlerMapping
筛选HandlerMethod
public static <T> Map<Method, T> org.springframework.core.MethodIntrospector.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;
//判断当前类是否被代理过，如果没有被代理，那么当前类也应当考虑进去
if (!Proxy.isProxyClass(targetType)) {
handlerTypes.add(targetType);
specificHandlerType = targetType;
}
//添加接口
handlerTypes.addAll(Arrays.asList(targetType.getInterfaces()));
for (Class<?> currentHandlerType : handlerTypes) {
//设置目标类，用于获取最具体的方法（比如最终的那个覆盖方法）
final Class<?> targetClass = (specificHandlerType != null ? specificHandlerType : currentHandlerType);
ReflectionUtils.doWithMethods(currentHandlerType, new ReflectionUtils.MethodCallback() {
@Override
public void doWith(Method method) {
//从targetClass获取最具体的方法，比如接口的方法可能被targetClass覆盖
Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);
//(*1*)
T result = metadataLookup.inspect(specificMethod);
if (result != null) {
//获取被桥的方法（被桥的方法才是用户真正的定义的方法，桥方法的解释在spring源码分析的时候已经解释过了）
Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);
//如果被桥方法就是当前具体的方法或者这个被桥的方法就是HandlerMethod方法，那么保存数据
if (bridgedMethod == specificMethod || metadataLookup.inspect(bridgedMethod) == null) {
methodMap.put(specificMethod, result);
}
}
}
//一个类过滤器，过滤掉桥方法和Object类定义的方法
}, ReflectionUtils.USER_DECLARED_METHODS);
}
return methodMap;
}
//(*1*)
protected RequestMappingInfo org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.getMappingForMethod(Method method, Class<?> handlerType) {
//创建方法请求映射信息
RequestMappingInfo info = createRequestMappingInfo(method);
if (info != null) {
//如果类上面也有@RequestMapping注解，那么需要创建类请求映射信息
RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType);
if (typeInfo != null) {
//进行合并
info = typeInfo.combine(info);
}
}
//返回最终映射信息
return info;
}
创建RequestMappingInfo
private RequestMappingInfo org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.createRequestMappingInfo(AnnotatedElement element) {
//获取RequestMapping注解，注意这里获取的RequestMapping注解类型是一个代理对象，主要是因为spring会对元数据进行处理，
//元数据被当成注解的父类，他们的属性会被继承，覆盖，AnnotatedElementUtils在spring源码分析中分析过
RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping注解类型可能.class);
//获取自定义的请求条件，我们可以继承这个RequestMappingHandlerMapping，然后实现这个方法并注册到spring容器中
RequestCondition<?> condition = (element instanceof Class<?> ?
getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element));
//创建RequestMappingInfo
//(*1*)
return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null);
}
//(*1*)
protected RequestMappingInfo createRequestMappingInfo(
RequestMapping requestMapping, RequestCondition<?> customCondition) {
return RequestMappingInfo
//设置路径信息，路径信息如果有${}占位符，会进行替换
.paths(resolveEmbeddedValuesInPatterns(requestMapping.path()))
//设置请求方法
.methods(requestMapping.method())
//请求参数，比如a=10
.params(requestMapping.params())
//设置头部信息
.headers(requestMapping.headers())
//指定能够处理此媒体类型的处理器去处理请求
.consumes(requestMapping.consumes())
//指定请求返回时能够接受的媒体类型
.produces(requestMapping.produces())
//映射名
.mappingName(requestMapping.name())
//设置自定义的请求条件
.customCondition(customCondition)
//配置对象设置
.options(this.config)
//返回RequestMappingInfo对象
.build();
}
在上面的代码中给RequestMappingInfo设置一个配置，下面就是这个配置的类定义
public static class org.springframework.web.servlet.mvc.method.RequestMappingInfo.BuilderConfiguration {
//用户获取url路径的助手类
private UrlPathHelper urlPathHelper;
//路径匹配器
private PathMatcher pathMatcher;
//是否应用尾部的/匹配
private boolean trailingSlashMatch = true;
//是否匹配后缀
private boolean suffixPatternMatch = true;
//注册后缀
private boolean registeredSuffixPatternMatch = false;
//内容协商管理器，用于解析媒体类型，后缀等
private ContentNegotiationManager contentNegotiationManager;
。。。。。。
}
build
public RequestMappingInfo build() {
//从配置操作中获取内容协商管理器
ContentNegotiationManager manager = this.options.getContentNegotiationManager();
//创建模式请求条件，虽然可以是通配符的形式，但是我们在实际的SpringMVC的项目中，似乎很少使用
//有通配符的路径，基本上是很具体的路径
PatternsRequestCondition patternsCondition = new PatternsRequestCondition(
this.paths, this.options.getUrlPathHelper(), this.options.getPathMatcher(),
this.options.useSuffixPatternMatch(), this.options.useTrailingSlashMatch(),
this.options.getFileExtensions());
//创建RequestMappingInfo
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);
}
下面是RequestCondition的类层级结构
RequestCondition (org.springframework.web.servlet.mvc.condition)
RequestMappingInfo (org.springframework.web.servlet.mvc.method)
AbstractRequestCondition (org.springframework.web.servlet.mvc.condition)
RequestMethodsRequestCondition (org.springframework.web.servlet.mvc.condition)
ProducesRequestCondition (org.springframework.web.servlet.mvc.condition)
PatternsRequestCondition (org.springframework.web.servlet.mvc.condition)
ParamsRequestCondition (org.springframework.web.servlet.mvc.condition)
RequestConditionHolder (org.springframework.web.servlet.mvc.condition)
ConsumesRequestCondition (org.springframework.web.servlet.mvc.condition)
HeadersRequestCondition (org.springframework.web.servlet.mvc.condition)
CompositeRequestCondition (org.springframework.web.servlet.mvc.condition)
我们随便选其中一个RequestCondition来大致分析下，比如ConsumesRequestCondition，我们直接看到它实现的getMatchingCondition方法
public ConsumesRequestCondition getMatchingCondition(HttpServletRequest request) {
if (isEmpty()) {
return this;
}
//消费媒体类型表达式，用于进行匹配
Set<ConsumeMediaTypeExpression> result = new LinkedHashSet<ConsumeMediaTypeExpression>(expressions);
for (Iterator<ConsumeMediaTypeExpression> iterator = result.iterator(); iterator.hasNext();) {
ConsumeMediaTypeExpression expression = iterator.next();
if (!expression.match(request)) {
//把不匹配的去掉
iterator.remove();
}
}
//返回能够匹配当前request请求的消费请求条件，主要用于后面将要进行最佳匹配RequestMappingInfo的筛选
return (result.isEmpty()) ? null : new ConsumesRequestCondition(result);
}
ConsumeMediaTypeExpression的匹配
public final boolean match(HttpServletRequest request) {
try {
//(*1*)
boolean match = matchMediaType(request);
return (!this.isNegated ? match : !match);
}
catch (HttpMediaTypeException ex) {
return false;
}
}
protected boolean matchMediaType(HttpServletRequest request) throws HttpMediaTypeNotSupportedException {
try {
//解析request中告知的媒体类型
MediaType contentType = StringUtils.hasLength(request.getContentType()) ?
MediaType.parseMediaType(request.getContentType()) :
MediaType.APPLICATION_OCTET_STREAM;
//将程序中设置的媒体类型与请求的媒体类型进行对比
return getMediaType().includes(contentType);
}
catch (InvalidMediaTypeException ex) {
throw new HttpMediaTypeNotSupportedException(
"Can't parse Content-Type [" + request.getContentType() + "]: " + ex.getMessage());
}
}
}
解析request请求中的媒体类型
public static MimeType org.springframework.util.MimeTypeUtils.parseMimeType(String mimeType) {
if (!StringUtils.hasLength(mimeType)) {
throw new InvalidMimeTypeException(mimeType, "'mimeType' must not be empty");
}
//分号分割，比如text/html;charset=utf-8
String[] parts = StringUtils.tokenizeToStringArray(mimeType, ";");
//获取完整的类型
String fullType = parts[0].trim();
// java.net.HttpURLConnection returns a *; q=.2 Accept header
//如果是一个*号，那么设置fulltype为*/*
if (MimeType.WILDCARD_TYPE.equals(fullType)) {
fullType = "*/*";
}
//获取子类型的分割符下标
int subIndex = fullType.indexOf('/');
//无效的媒体类型
if (subIndex == -1) {
throw new InvalidMimeTypeException(mimeType, "does not contain '/'");
}
//媒体类型必须是主类型与子类型进行/分割的
if (subIndex == fullType.length() - 1) {
throw new InvalidMimeTypeException(mimeType, "does not contain subtype after '/'");
}
//获取主类型
String type = fullType.substring(0, subIndex);
//获取子类型
String subtype = fullType.substring(subIndex + 1, fullType.length());
//错误的媒体类型，不能*/html
if (MimeType.WILDCARD_TYPE.equals(type) && !MimeType.WILDCARD_TYPE.equals(subtype)) {
throw new InvalidMimeTypeException(mimeType, "wildcard type is legal only in '*/*' (all mime types)");
}
//解析参数
Map<String, String> parameters = null;
if (parts.length > 1) {
parameters = new LinkedHashMap<String, String>(parts.length - 1);
for (int i = 1; i < parts.length; i++) {
//比如charset=utf-8
String parameter = parts[i];
int eqIndex = parameter.indexOf('=');
if (eqIndex != -1) {
String attribute = parameter.substring(0, eqIndex);
String value = parameter.substring(eqIndex + 1, parameter.length());
//比如 charset utf-8
parameters.put(attribute, value);
}
}
}
try {
//创建MimeType
return new MimeType(type, subtype, parameters);
}
catch (UnsupportedCharsetException ex) {
throw new InvalidMimeTypeException(mimeType, "unsupported charset '" + ex.getCharsetName() + "'");
}
catch (IllegalArgumentException ex) {
throw new InvalidMimeTypeException(mimeType, ex.getMessage());
}
}
匹配媒体类型
public boolean org.springframework.util.MimeType.includes(MimeType other) {
if (other == null) {
return false;
}
//如果是*/*，表示匹配所有
if (this.isWildcardType()) {
// */* includes anything
return true;
}
else if (getType().equals(other.getType())) {
//主和子类型都匹配，那么直接返回true
if (getSubtype().equals(other.getSubtype())) {
return true;
}
//是否存在子类型通配符
if (this.isWildcardSubtype()) {
// wildcard with suffix, e.g. application/*+xml
int thisPlusIdx = getSubtype().indexOf('+');
//如果没有+号，也就是 application/*，那么返回true
if (thisPlusIdx == -1) {
return true;
}
else {
// application/*+xml includes application/soap+xml
int otherPlusIdx = other.getSubtype().indexOf('+');
if (otherPlusIdx != -1) {
String thisSubtypeNoSuffix = getSubtype().substring(0, thisPlusIdx);
String thisSubtypeSuffix = getSubtype().substring(thisPlusIdx + 1);
String otherSubtypeSuffix = other.getSubtype().substring(otherPlusIdx + 1);
//如果+号后面的字符串匹配并且+号前面确实是*号，那么表示匹配
if (thisSubtypeSuffix.equals(otherSubtypeSuffix) && WILDCARD_TYPE.equals(thisSubtypeNoSuffix)) {
return true;
}
}
}
}
}
return false;
}
好了，回到获取handlerMethod的逻辑，当 当前类，父类，接口的方法都进行一番检查之后，形成了一个Map<Method, RequestMappingInfo>，接下来就是注册了
protected void org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(Object handler, Method method, T mapping) {
//注册映射
this.mappingRegistry.register(mapping, handler, method);
}
注册映射
public void org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.MappingRegistry.register(T mapping, Object handler, Method method) {
this.readWriteLock.writeLock().lock();
try {
//创建HandlerMethod，一个维护handler，RequestMappingInfo，method，beanFactory，bridgedMethod，parameters
HandlerMethod handlerMethod = createHandlerMethod(handler, method);
//检查是否是唯一的方法映射，RequestMappingInfo -》 handlerMethod
assertUniqueMethodMapping(handlerMethod, mapping);
if (logger.isInfoEnabled()) {
logger.info("Mapped \"" + mapping + "\" onto " + handlerMethod);
}
//一个map《RequestMappingInfo -》 handlerMethod》
this.mappingLookup.put(mapping, handlerMethod);
//获取直接路径，也就是具体路径，没有*号，？号这类通配符的路径
List<String> directUrls = getDirectUrls(mapping);
for (String url : directUrls) {
//map《直接路径，List<RequestMappingInfo>》
this.urlLookup.add(url, mapping);
}
String name = null;
//获取命名策略，这个对象是在创建RequestMappingHandlerMapping时，其父类RequestMappingInfoHandlerMapping的构造器中设置的
//它是RequestMappingInfoHandlerMethodMappingNamingStrategy的实例，当然如果在@RequestMapping注解中
//设置了name就不会再次设置，否则将通过类名的第一个大写字符#方法名组成映射名字
if (getNamingStrategy() != null) {
name = getNamingStrategy().getName(handlerMethod, mapping);
//Map<String, List<HandlerMethod>> nameLookup
addMappingName(name, handlerMethod);
}
//初始化跨域配置
CorsConfiguration corsConfig = initCorsConfiguration(handler, method, mapping);
if (corsConfig != null) {
//map《handlerMethod， 跨域配置》
this.corsLookup.put(handlerMethod, corsConfig);
}
//map《mapping, MappingRegistration》
this.registry.put(mapping, new MappingRegistration<T>(mapping, handlerMethod, directUrls, name));
}
finally {
this.readWriteLock.writeLock().unlock();
}
}
跨域配置
protected CorsConfiguration org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.initCorsConfiguration(Object handler, Method method, RequestMappingInfo mappingInfo) {
//创建HandlerMethod，和前面的创建方式一样
HandlerMethod handlerMethod = createHandlerMethod(handler, method);
//获取类上的@CrossOrigin信息
CrossOrigin typeAnnotation = AnnotatedElementUtils.findMergedAnnotation(handlerMethod.getBeanType(), CrossOrigin.class);
//获取方法上的@CrossOrigin信息
CrossOrigin methodAnnotation = AnnotatedElementUtils.findMergedAnnotation(method, CrossOrigin.class);
if (typeAnnotation == null && methodAnnotation == null) {
return null;
}
//跨域配置，比如设置允许的来源url，方法，请求头，有效时间，凭证
CorsConfiguration config = new CorsConfiguration();
//设置类上的跨域配置
updateCorsConfig(config, typeAnnotation);
//设置方法上的跨域配置（更新操作）
updateCorsConfig(config, methodAnnotation);
//如果没有设置，那么设置默认的，默认的为*，表示允许所有
if (CollectionUtils.isEmpty(config.getAllowedOrigins())) {
config.setAllowedOrigins(Arrays.asList(CrossOrigin.DEFAULT_ORIGINS));
}
if (CollectionUtils.isEmpty(config.getAllowedMethods())) {
for (RequestMethod allowedMethod : mappingInfo.getMethodsCondition().getMethods()) {
config.addAllowedMethod(allowedMethod.name());
}
}
if (CollectionUtils.isEmpty(config.getAllowedHeaders())) {
config.setAllowedHeaders(Arrays.asList(CrossOrigin.DEFAULT_ALLOWED_HEADERS));
}
if (config.getAllowCredentials() == null) {
config.setAllowCredentials(CrossOrigin.DEFAULT_ALLOW_CREDENTIALS);
}
if (config.getMaxAge() == null) {
config.setMaxAge(CrossOrigin.DEFAULT_MAX_AGE);
}
return config;
}
总结一下：RequestMappingHandlerMapping在初始化的时候会获取容器中所有的beanName，然后找到所有被标注了@Controller或者@RequestMapping注解的bean，然后筛选HandlerMethod，也就是被@RequestMapping标注的方法，创建RequestMappingInfo，最后进行注册。
这里有个问题，那就是在bean进行初始化的时候获取所有的bean，哎，这里会发生controller bean的遗漏吗？不会的，我们在springmvc源码分析的前几节的时候可以看到SpringMVC是在所有容器启动之后在onRefresh中进行的，这也解答了，SpringMVC为什么要通过ApplicationContext.getBean(BeanDefinition)进行bean的创建了，而不是直接new。
好了，一切都已经准备就绪，接下来就是寻找handlerMethod了
protected HandlerMethod org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.getHandlerInternal(HttpServletRequest request) throws Exception {
//获取请求路径
String lookupPath = getUrlPathHelper().getLookupPathForRequest(request);
if (logger.isDebugEnabled()) {
logger.debug("Looking up handler method for path " + lookupPath);
}
this.mappingRegistry.acquireReadLock();
try {
//寻找HandlerMethod
HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request);
if (logger.isDebugEnabled()) {
if (handlerMethod != null) {
logger.debug("Returning handler method [" + handlerMethod + "]");
}
else {
logger.debug("Did not find handler method for [" + lookupPath + "]");
}
}
//返回handlerMethod，创建一个新的handlerMethod，防止被修改，如果内部持有的handler是字符串类型，那么会从
//容器中寻找对应
return (handlerMethod != null ? handlerMethod.createWithResolvedBean() : null);
}
finally {
this.mappingRegistry.releaseReadLock();
}
}
lookupHandlerMethod
protected HandlerMethod org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
List<Match> matches = new ArrayList<Match>();
//首先通过精确匹配的方式获取 从urlLookup中获取
List<T> directPathMatches = this.mappingRegistry.getMappingsByUrl(lookupPath);
if (directPathMatches != null) {
//向matches添加能够匹配到的Match对象，Match对象维护着RequestMappingInfo和对应的HandlerMethod
addMatchingMappings(directPathMatches, matches, request);
}
//如果没有获取到，那么进行全对比
if (matches.isEmpty()) {
// No choice but to go through all mappings...
//向matches添加能够匹配到的Match对象，Match对象维护着RequestMappingInfo和对应的HandlerMethod
addMatchingMappings(this.mappingRegistry.getMappings().keySet(), matches, request);
}
//如果找到了，那么还需要选出最适合的
if (!matches.isEmpty()) {
//获取映射比较器
Comparator<Match> comparator = new MatchComparator(getMappingComparator(request));
//进行排序
Collections.sort(matches, comparator);
if (logger.isTraceEnabled()) {
logger.trace("Found " + matches.size() + " matching mapping(s) for [" +
lookupPath + "] : " + matches);
}
//第一个被认为是最佳匹配
Match bestMatch = matches.get(0);
//如果匹配到的个数大于1
if (matches.size() > 1) {
//检查是否为跨域请求，如果是并且是options请求类型，不允许跨域，返回EmptHandler
if (CorsUtils.isPreFlightRequest(request)) {
return PREFLIGHT_AMBIGUOUS_MATCH;
}
Match secondBestMatch = matches.get(1);
//如果第一个和第二个在比较中是相等的，那么出现歧义，抛错
if (comparator.compare(bestMatch, secondBestMatch) == 0) {
Method m1 = bestMatch.handlerMethod.getMethod();
Method m2 = secondBestMatch.handlerMethod.getMethod();
throw new IllegalStateException("Ambiguous handler methods mapped for HTTP path '" +
request.getRequestURL() + "': {" + m1 + ", " + m2 + "}");
}
}
handleMatch(bestMatch.mapping, lookupPath, request);
//获取handlerMethod
return bestMatch.handlerMethod;
}
else {
//木有找到
return handleNoMatch(this.mappingRegistry.getMappings().keySet(), lookupPath, request);
}
}
addMatchingMappings
private void org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.addMatchingMappings(Collection<T> mappings, List<Match> matches, HttpServletRequest request) {
//循环RequestMappingInfo集合
for (T mapping : mappings) {
//获取匹配的RequestMappingInfo
//(*1*)
T match = getMatchingMapping(mapping, request);
if (match != null) {
//包装成Match，添加到matches集合中
matches.add(new Match(match, this.mappingRegistry.getMappings().get(mapping)));
}
}
}
//(*1*)
protected RequestMappingInfo org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping.getMatchingMapping(RequestMappingInfo info, HttpServletRequest request) {
//(*2*)
return info.getMatchingCondition(request);
}
//(*2*)
public RequestMappingInfo org.springframework.web.servlet.mvc.method.RequestMappingInfo.getMatchingCondition(HttpServletRequest request) {
//匹配请求方法，和我们在上面分析的ConsumesRequestCondition差不多，就是把匹配的方法重新包装返回回来
//，如果注解中没有配置此项，返回其本身（一个空的condition）
RequestMethodsRequestCondition methods = this.methodsCondition.getMatchingCondition(request);
//匹配请求参数，把能匹配到的重新构建ParamsRequestCondition返回，如果注解中没有配置此项，返回其本身（一个空的condition）
ParamsRequestCondition params = this.paramsCondition.getMatchingCondition(request);
//匹配请求头，把能匹配的重新构建HeadersRequestCondition返回，如果注解中没有配置此项，返回其本身（一个空的condition）
HeadersRequestCondition headers = this.headersCondition.getMatchingCondition(request);
//匹配请求媒体类型，把能匹配到的重新构建ConsumesRequestCondition返回，如果注解中没有配置此项，返回其本身（一个空的condition）
ConsumesRequestCondition consumes = this.consumesCondition.getMatchingCondition(request);
//匹配返回媒体类型，把能够匹配到的重新构建ProducesRequestCondition返回，如果注解中没有配置此项，返回其本身（一个空的condition）
ProducesRequestCondition produces = this.producesCondition.getMatchingCondition(request);
//如果有一个不匹配，看是不是跨域，如果没有跨域直接返回null，表示没有找到
if (methods == null || params == null || headers == null || consumes == null || produces == null) {
if (CorsUtils.isPreFlightRequest(request)) {
//匹配跨域请求方法，并重新构建RequestMethodsRequestCondition返回
methods = getAccessControlRequestMethodCondition(request);
if (methods == null || params == null) {
return null;
}
}
else {
return null;
}
}
//通配符匹配
PatternsRequestCondition patterns = this.patternsCondition.getMatchingCondition(request);
if (patterns == null) {
return null;
}
//自定义请求条件匹配
RequestConditionHolder custom = this.customConditionHolder.getMatchingCondition(request);
if (custom == null) {
return null;
}
//如果匹配，那么把与当前请求最精确的匹配重新构建成RequestMappingInfo返回
return new RequestMappingInfo(this.name, patterns,
methods, params, headers, consumes, produces, custom.getCondition());
}
这里我们再看下PatternsRequestCondition是如何匹配的
public PatternsRequestCondition getMatchingCondition(HttpServletRequest request) {
//如果没有设置路径匹配，那么直接返回自身
if (this.patterns.isEmpty()) {
return this;
}
//获取请求路径
String lookupPath = this.pathHelper.getLookupPathForRequest(request);
//获取匹配的路径
//(*1*)
List<String> matches = getMatchingPatterns(lookupPath);
//如果不为空，那么重新构建一个与当前request最匹配的PatternsRequestCondition
return matches.isEmpty() ? null :
new PatternsRequestCondition(matches, this.pathHelper, this.pathMatcher, this.useSuffixPatternMatch,
this.useTrailingSlashMatch, this.fileExtensions);
}
//(*1*)
public List<String> getMatchingPatterns(String lookupPath) {
List<String> matches = new ArrayList<String>();
for (String pattern : this.patterns) {
//获取匹配的路径，可能会做些处理，比如添加后缀什么的
//(*2*)
String match = getMatchingPattern(pattern, lookupPath);
if (match != null) {
matches.add(match);
}
}
//进行排序，使用的排序器是AntPatternComparator
Collections.sort(matches, this.pathMatcher.getPatternComparator(lookupPath));
return matches;
}
//(*2*)
private String getMatchingPattern(String pattern, String lookupPath) {
//如果直接相等，那么直接返回，这个路径已经超级具体了
if (pattern.equals(lookupPath)) {
return pattern;
}
//是否允许后缀匹配
if (this.useSuffixPatternMatch) {
//如果有备用后缀和请求路径就有后缀
if (!this.fileExtensions.isEmpty() && lookupPath.indexOf('.') != -1) {
for (String extension : this.fileExtensions) {
//匹配
if (this.pathMatcher.match(pattern + extension, lookupPath)) {
//返回添加了后缀的路径，比如/test/*/abc + .html
return pattern + extension;
}
}
}
else {
//如果@RequestMapping注解定义的路径没有后缀
boolean hasSuffix = pattern.indexOf('.') != -1;
//那么加上.*进行匹配
if (!hasSuffix && this.pathMatcher.match(pattern + ".*", lookupPath)) {
return pattern + ".*";
}
}
}
//直接路径匹配
if (this.pathMatcher.match(pattern, lookupPath)) {
return pattern;
}
//是否使用后缀/匹配，如果@RequestMapping注解定义的路径不是/结尾，那么加上后再匹配
if (this.useTrailingSlashMatch) {
if (!pattern.endsWith("/") && this.pathMatcher.match(pattern + "/", lookupPath)) {
return pattern +"/";
}
}
return null;
}
回到org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.lookupHandlerMethod(String, HttpServletRequest)方法
这个时候我们可能已经找到了候选的HandlerMethod，也可能没有找到
找到和没找到，SpringMVC还有一些后置处理（比如路径变量等），我们先来看下找到后的
protected void org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping.handleMatch(RequestMappingInfo info, String lookupPath, HttpServletRequest request) {
//request.setAttribute(HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE, lookupPath);
//记录查找到当前handlerMethod的请求路径到request中
super.handleMatch(info, lookupPath, request);
//最佳匹配路径
String bestPattern;
//路径变量
Map<String, String> uriVariables;
//解码后的路径变量
Map<String, String> decodedUriVariables;
//获取匹配到的所有pattern路径
Set<String> patterns = info.getPatternsCondition().getPatterns();
if (patterns.isEmpty()) {
//最佳匹配路径当然是request中的uri
bestPattern = lookupPath;
//uri变量为空
uriVariables = Collections.emptyMap();
decodedUriVariables = Collections.emptyMap();
}
else {
//如果patterns不为空，那么第一个被认为是最佳的路径
bestPattern = patterns.iterator().next();
//解析路径变量，比如bestPattern为/test/{a}，lookupPath为/test/520,那么路径变量就是a=520
uriVariables = getPathMatcher().extractUriTemplateVariables(bestPattern, lookupPath);
//对路径变量的值进行url解码
decodedUriVariables = getUrlPathHelper().decodePathVariables(request, uriVariables);
}
//记录最佳的模式路径 HandlerMapping.class.getName() + ".bestMatchingPattern" -》 bestPattern
request.setAttribute(BEST_MATCHING_PATTERN_ATTRIBUTE, bestPattern);
//HandlerMapping.class.getName() + ".uriTemplateVariables" -》 decodedUriVariables
request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, decodedUriVariables);
//是否需要解析矩阵变量。默认是不解析的
if (isMatrixVariableContentAvailable()) {
//解析矩阵参数 比如/test/{a}，然后发来的请求是/test/arg1=0;arg2=1;arg3=2,3,4,5,6
//然后这里的返回值就是a -> {arg1:[0],arg2:[1],arg2:[2,3,4,5,6]}
//如果是这种/test/0;arg2=1;arg3=2,3,4,5,6，也就是第一个参数没有等号
//那么uriVariables原先对应的a=0;arg2=1;arg3=2,3,4,5,6变成了a=0
//然后matrixVars就是{arg2:[1],arg2:[2,3,4,5,6]}
Map<String, MultiValueMap<String, String>> matrixVars = extractMatrixVariables(request, uriVariables);
//HandlerMapping.class.getName() + ".matrixVariables" -》 matrixVars
request.setAttribute(HandlerMapping.MATRIX_VARIABLES_ATTRIBUTE, matrixVars);
}
//设置允许返回的媒体类型
if (!info.getProducesCondition().getProducibleMediaTypes().isEmpty()) {
Set<MediaType> mediaTypes = info.getProducesCondition().getProducibleMediaTypes();
//HandlerMapping.class.getName() + ".producibleMediaTypes" -> mediaTypes
request.setAttribute(PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE, mediaTypes);
}
}
如果没有匹配到handlermethod又是怎么处理的呢？
protected HandlerMethod org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping.handleNoMatch(Set<RequestMappingInfo> requestMappingInfos,
String lookupPath, HttpServletRequest request) throws ServletException {
//存放能匹配到的方法
Set<String> allowedMethods = new LinkedHashSet<String>(4);
//存放能够匹配上的原始RequestMappingInfo
Set<RequestMappingInfo> patternMatches = new HashSet<RequestMappingInfo>();
//存放既能匹配方法，又能匹配路径的RequestMappingInfo
Set<RequestMappingInfo> patternAndMethodMatches = new HashSet<RequestMappingInfo>();
for (RequestMappingInfo info : requestMappingInfos) {
//匹配路径
if (info.getPatternsCondition().getMatchingCondition(request) != null) {
//如果存在匹配当前request的路径子集，那么存到patternMatches集合中
patternMatches.add(info);
if (info.getMethodsCondition().getMatchingCondition(request) != null) {
//如果连方法都能匹配到子集，那么存放到patternAndMethodMatches集合中
patternAndMethodMatches.add(info);
}
else {
//如果方法未匹配到，那么记录当前循环到的RequestMappingInfo支持的方法
for (RequestMethod method : info.getMethodsCondition().getMethods()) {
allowedMethods.add(method.name());
}
}
}
}
//如果路径都不匹配，那说明项目中确实没有定义处理这个请求的handler，返回null
if (patternMatches.isEmpty()) {
return null;
}
//如果路径匹配到了，却没有一个能够接受这个请求方法，那么没得说，项目中已经没有能够处理当前request的请求方法了
//报错吧！
else if (patternAndMethodMatches.isEmpty() && !allowedMethods.isEmpty()) {
throw new HttpRequestMethodNotSupportedException(request.getMethod(), allowedMethods);
}
Set<MediaType> consumableMediaTypes;
Set<MediaType> producibleMediaTypes;
List<String[]> paramConditions;
//如果有匹配到路径，程序也没有设置能够允许的请求方法，那么从patternMatches寻找不匹配的请求媒体类型
//不匹配的返回媒体类型，不匹配的参数RequestMappingInfo
if (patternAndMethodMatches.isEmpty()) {
consumableMediaTypes = getConsumableMediaTypes(request, patternMatches);
producibleMediaTypes = getProducibleMediaTypes(request, patternMatches);
paramConditions = getRequestParams(request, patternMatches);
}
//从patternAndMethodMatches寻找不匹配的请求媒体类型
//不匹配的返回媒体类型，不匹配的参数RequestMappingInfo
else {
consumableMediaTypes = getConsumableMediaTypes(request, patternAndMethodMatches);
producibleMediaTypes = getProducibleMediaTypes(request, patternAndMethodMatches);
paramConditions = getRequestParams(request, patternAndMethodMatches);
}
//然后确实发现了不匹配的请求类型的RequestMappingInfo
if (!consumableMediaTypes.isEmpty()) {
MediaType contentType = null;
if (StringUtils.hasLength(request.getContentType())) {
try {
contentType = MediaType.parseMediaType(request.getContentType());
}
catch (InvalidMediaTypeException ex) {
throw new HttpMediaTypeNotSupportedException(ex.getMessage());
}
}
//抛出错误，表示你请求的媒体类型，springMVC中定义的handler不支持
throw new HttpMediaTypeNotSupportedException(contentType, new ArrayList<MediaType>(consumableMediaTypes));
}
else if (!producibleMediaTypes.isEmpty()) {
//抛出没有可接受的返回类型
throw new HttpMediaTypeNotAcceptableException(new ArrayList<MediaType>(producibleMediaTypes));
}
else if (!CollectionUtils.isEmpty(paramConditions)) {
//不满足指定的参数类型
throw new UnsatisfiedServletRequestParameterException(paramConditions, request.getParameterMap());
}
else {
//其他的返回null
return null;
}
}
回到AbstractHandlerMapping的getHandler方法
public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
Object handler = getHandlerInternal(request);
if (handler == null) {
//获取默认的handlerMethod
handler = getDefaultHandler();
}
if (handler == null) {
return null;
}
// Bean name or resolved handler?
//如果是字符串类型，那么从容器中寻找
if (handler instanceof String) {
String handlerName = (String) handler;
handler = getApplicationContext().getBean(handlerName);
}
//用拦截器和handlerMethod构建HandlerExecutionChain
HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);
//检查request的请求头中是否存在Origin，如果有表示跨域
if (CorsUtils.isCorsRequest(request)) {
//从当前HandlerMapping中获取全局的跨域请求配置
CorsConfiguration globalConfig = this.corsConfigSource.getCorsConfiguration(request);
//从注册mapping中获取跨域配置
CorsConfiguration handlerConfig = getCorsConfiguration(handler, request);
//合并
CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig);
//额外添加跨域相关的拦截器，用于判断是否允许跨域，不予许就被拦截，并设置禁止访问编码
executionChain = getCorsHandlerExecutionChain(request, executionChain, config);
}
return executionChain;
}
获取拦截器
protected HandlerExecutionChain org.springframework.web.servlet.handler.AbstractHandlerMapping.getHandlerExecutionChain(Object handler, HttpServletRequest request) {
HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?
(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));
String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);
//this.adaptedInterceptors这里面的值是在HandlerMapping初始化设置ApplicationContext时扩展和自动装配的
for (HandlerInterceptor interceptor : this.adaptedInterceptors) {
//判断是否是映射拦截器，如果是，那么需要进行uri匹配，一般我们配置的拦截器会配置在
//SpringMVC的配置文件中，并设置url匹配路径，最后会被包装成这个类型
if (interceptor instanceof MappedInterceptor) {
MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor;
//(*1*)
if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {
chain.addInterceptor(mappedInterceptor.getInterceptor());
}
}
else {
chain.addInterceptor(interceptor);
}
}
return chain;
}
//(*1*)
public boolean matches(String lookupPath, PathMatcher pathMatcher) {
PathMatcher pathMatcherToUse = (this.pathMatcher != null) ? this.pathMatcher : pathMatcher;
//不拦截的路径
if (this.excludePatterns != null) {
for (String pattern : this.excludePatterns) {
//使用的AntPatchMatcher
if (pathMatcherToUse.match(pattern, lookupPath)) {
return false;
}
}
}
if (this.includePatterns == null) {
return true;
}
else {
for (String pattern : this.includePatterns) {
//匹配拦截路径
if (pathMatcherToUse.match(pattern, lookupPath)) {
return true;
}
}
return false;
}
}
自此，我们查找的handlerMethod的任务就结束了，下一节分析一下AbstractUrlHandlerMapping
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