前言
RequestMappingHandlerMapping用于解析@Controller或@RequestMapping以及@RestController、@GetMapping、@PostMapping，将请求路径与请求方法的映射信息放入springmvc的容器中。
一、实例化
1、WebMvcAutoConfiguration
WebMvcAutoConfiguration 中标注了@Bean RequestMappingHandlerMapping ，并且用了@Primary注解，在RequestMappingHandlerMapping 实例化过程中或执行该Bean
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({
Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({
DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {
@Bean
@Primary
@Override
public RequestMappingHandlerMapping requestMappingHandlerMapping(
@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager,
@Qualifier("mvcConversionService") FormattingConversionService conversionService,
@Qualifier("mvcResourceUrlProvider") ResourceUrlProvider resourceUrlProvider) {
// Must be @Primary for MvcUriComponentsBuilder to work
return super.requestMappingHandlerMapping(contentNegotiationManager, conversionService,
resourceUrlProvider);
}
}
3、super.requestMappingHandlerMapping
WebMvcConfigurationSupport.java
//这里也标注了@Bean注解
@Bean
@SuppressWarnings("deprecation")
public RequestMappingHandlerMapping requestMappingHandlerMapping(
@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager,
@Qualifier("mvcConversionService") FormattingConversionService conversionService,
@Qualifier("mvcResourceUrlProvider") ResourceUrlProvider resourceUrlProvider) {
//创建RequestMappingHandlerMapping
RequestMappingHandlerMapping mapping = createRequestMappingHandlerMapping();
//初始化一些属性
mapping.setOrder(0);
mapping.setInterceptors(getInterceptors(conversionService, resourceUrlProvider));
mapping.setContentNegotiationManager(contentNegotiationManager);
mapping.setCorsConfigurations(getCorsConfigurations());
PathMatchConfigurer pathConfig = getPathMatchConfigurer();
if (pathConfig.getPatternParser() != null) {
mapping.setPatternParser(pathConfig.getPatternParser());
}
else {
mapping.setUrlPathHelper(pathConfig.getUrlPathHelperOrDefault());
mapping.setPathMatcher(pathConfig.getPathMatcherOrDefault());
Boolean useSuffixPatternMatch = pathConfig.isUseSuffixPatternMatch();
if (useSuffixPatternMatch != null) {
mapping.setUseSuffixPatternMatch(useSuffixPatternMatch);
}
Boolean useRegisteredSuffixPatternMatch = pathConfig.isUseRegisteredSuffixPatternMatch();
if (useRegisteredSuffixPatternMatch != null) {
mapping.setUseRegisteredSuffixPatternMatch(useRegisteredSuffixPatternMatch);
}
}
Boolean useTrailingSlashMatch = pathConfig.isUseTrailingSlashMatch();
if (useTrailingSlashMatch != null) {
mapping.setUseTrailingSlashMatch(useTrailingSlashMatch);
}
if (pathConfig.getPathPrefixes() != null) {
mapping.setPathPrefixes(pathConfig.getPathPrefixes());
}
return mapping;
}
4、createRequestMappingHandlerMapping( )
WebMvcAutoConfiguration.java
@Override
protected RequestMappingHandlerMapping createRequestMappingHandlerMapping() {
if (this.mvcRegistrations != null) {
RequestMappingHandlerMapping mapping = this.mvcRegistrations.getRequestMappingHandlerMapping();
if (mapping != null) {
return mapping;
}
}
//调用父类方法
return super.createRequestMappingHandlerMapping();
}
WebMvcConfigurationSupport.java
protected RequestMappingHandlerMapping createRequestMappingHandlerMapping() {
//直接new了一个
return new RequestMappingHandlerMapping();
}
二、初始化
RequestMappingHandlerMapping实现了InitializingBean接口，在初始化过程中会调用afterPropertiesSet方法
1、afterPropertiesSet( )
RequestMappingHandlerMapping.java
public void afterPropertiesSet() {
//初始化所有RequestMappingInfo公用的一些属性RequestMappingInfo.BuilderConfiguration
this.config = new RequestMappingInfo.BuilderConfiguration();
this.config.setTrailingSlashMatch(useTrailingSlashMatch());
this.config.setContentNegotiationManager(getContentNegotiationManager());
if (getPatternParser() != null) {
this.config.setPatternParser(getPatternParser());
Assert.isTrue(!this.useSuffixPatternMatch && !this.useRegisteredSuffixPatternMatch,
"Suffix pattern matching not supported with PathPatternParser.");
}
else {
this.config.setSuffixPatternMatch(useSuffixPatternMatch());
this.config.setRegisteredSuffixPatternMatch(useRegisteredSuffixPatternMatch());
this.config.setPathMatcher(getPathMatcher());
}
super.afterPropertiesSet();
}
2、super.afterPropertiesSet()
AbstractHandlerMethodMapping.java
public void afterPropertiesSet() {
//初始化处理器方法
initHandlerMethods();
}
protected void initHandlerMethods() {
//遍历beanFactory中注册的BeanNames
for (String beanName : getCandidateBeanNames()) {
if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) {
//处理bean
processCandidateBean(beanName);
}
}
handlerMethodsInitialized(getHandlerMethods());
}
3、processCandidateBean( )
protected void processCandidateBean(String beanName) {
Class<?> beanType = null;
try {
beanType = obtainApplicationContext().getType(beanName);
}
catch (Throwable ex) {
// An unresolvable bean type, probably from a lazy bean - let's ignore it.
if (logger.isTraceEnabled()) {
logger.trace("Could not resolve type for bean '" + beanName + "'", ex);
}
}
//校验是否是handler
if (beanType != null && isHandler(beanType)) {
//获取处理器的方法
detectHandlerMethods(beanName);
}
isHandler( )
校验是否含有@Controller或@RequestMapping
protected boolean isHandler(Class<?> beanType) {
return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) ||
AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class));
}
4、detectHandlerMethods( )
protected void detectHandlerMethods(Object handler) {
Class<?> handlerType = (handler instanceof String ?
obtainApplicationContext().getType((String) handler) : handler.getClass());
if (handlerType != null) {
//类可能被代理，获取用户自定义的类
Class<?> userType = ClassUtils.getUserClass(handlerType);
Map<Method, T> methods = MethodIntrospector.selectMethods(userType,
(MethodIntrospector.MetadataLookup<T>) method -> {
try {
return getMappingForMethod(method, userType);
}
catch (Throwable ex) {
throw new IllegalStateException("Invalid mapping on handler class [" +
userType.getName() + "]: " + method, ex);
}
});
if (logger.isTraceEnabled()) {
logger.trace(formatMappings(userType, methods));
}
else if (mappingsLogger.isDebugEnabled()) {
mappingsLogger.debug(formatMappings(userType, methods));
}
methods.forEach((method, mapping) -> {
Method invocableMethod = AopUtils.selectInvocableMethod(method, userType);
//注册处理器方法
registerHandlerMethod(handler, invocableMethod, mapping);
});
}
}
5、selectMethods( )
public static <T> Map<Method, T> selectMethods(Class<?> targetType, final MetadataLookup<T> metadataLookup) {
final Map<Method, T> methodMap = new LinkedHashMap<>();
Set<Class<?>> handlerTypes = new LinkedHashSet<>();
Class<?> specificHandlerType = null;
if (!Proxy.isProxyClass(targetType)) {
specificHandlerType = ClassUtils.getUserClass(targetType);
handlerTypes.add(specificHandlerType);
}
handlerTypes.addAll(ClassUtils.getAllInterfacesForClassAsSet(targetType));
for (Class<?> currentHandlerType : handlerTypes) {
final Class<?> targetClass = (specificHandlerType != null ? specificHandlerType : currentHandlerType);
//处理所有方法以及父类的方法
ReflectionUtils.doWithMethods(currentHandlerType, method -> {
Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);
T result = metadataLookup.inspect(specificMethod);
if (result != null) {
Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);
if (bridgedMethod == specificMethod || metadataLookup.inspect(bridgedMethod) == null) {
//保存方法和RequestMappingInfo
methodMap.put(specificMethod, result);
}
}
}, ReflectionUtils.USER_DECLARED_METHODS);
}
return methodMap;
}
6、getMappingForMethod( )
protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
//处理方法上的@RequestMapping
RequestMappingInfo info = createRequestMappingInfo(method);
if (info != null) {
//处理类上的@RequestMapping
RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType);
if (typeInfo != null) {
//合并操作
info = typeInfo.combine(info);
}
String prefix = getPathPrefix(handlerType);
if (prefix != null) {
info = RequestMappingInfo.paths(prefix).options(this.config).build().combine(info);
}
}
return info;
}
createRequestMappingInfo( )
private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {
//找@RequestMapping
RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class);
RequestCondition<?> condition = (element instanceof Class ?
getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element));
//创建RequestMappingInfo
return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null);
}
createRequestMappingInfo( )
protected RequestMappingInfo createRequestMappingInfo(
RequestMapping requestMapping, @Nullable RequestCondition<?> customCondition) {
//解析注解RequestMapping中的各种信息
RequestMappingInfo.Builder builder = RequestMappingInfo
.paths(resolveEmbeddedValuesInPatterns(requestMapping.path()))
.methods(requestMapping.method())
.params(requestMapping.params())
.headers(requestMapping.headers())
.consumes(requestMapping.consumes())
.produces(requestMapping.produces())
.mappingName(requestMapping.name());
if (customCondition != null) {
builder.customCondition(customCondition);
}
return builder.options(this.config).build();
}
7、registerHandlerMethod( )
注册Controller、method、RequestMappingInfo
protected void registerHandlerMethod(Object handler, Method method, RequestMappingInfo mapping) {
super.registerHandlerMethod(handler, method, mapping);
updateConsumesCondition(mapping, method);
}
super.registerHandlerMethod( )
protected void registerHandlerMethod(Object handler, Method method, T mapping) {
this.mappingRegistry.register(mapping, handler, method);
}
register( )
public void register(T mapping, Object handler, Method method) {
this.readWriteLock.writeLock().lock();
try {
//创建HandlerMethod
HandlerMethod handlerMethod = createHandlerMethod(handler, method);
validateMethodMapping(handlerMethod, mapping);
Set<String> directPaths = AbstractHandlerMethodMapping.this.getDirectPaths(mapping);
for (String path : directPaths) {
//缓存path和mapping
this.pathLookup.add(path, mapping);
}
String name = null;
if (getNamingStrategy() != null) {
name = getNamingStrategy().getName(handlerMethod, mapping);
//缓存name和handlerMethod
addMappingName(name, handlerMethod);
}
CorsConfiguration corsConfig = initCorsConfiguration(handler, method, mapping);
if (corsConfig != null) {
corsConfig.validateAllowCredentials();
//缓存handlerMethod和corsConfig
this.corsLookup.put(handlerMethod, corsConfig);
}
//缓存mapping和MappingRegistration
this.registry.put(mapping,
new MappingRegistration<>(mapping, handlerMethod, directPaths, name, corsConfig != null));
}
finally {
this.readWriteLock.writeLock().unlock();
}
}
HandlerMethod的构造方法
public HandlerMethod(String beanName, BeanFactory beanFactory, Method method) {
Assert.hasText(beanName, "Bean name is required");
Assert.notNull(beanFactory, "BeanFactory is required");
Assert.notNull(method, "Method is required");
//bean名称
this.bean = beanName;
//beanFactory
this.beanFactory = beanFactory;
Class<?> beanType = beanFactory.getType(beanName);
if (beanType == null) {
throw new IllegalStateException("Cannot resolve bean type for bean with name '" + beanName + "'");
}
//bean类型
this.beanType = ClassUtils.getUserClass(beanType);
//方法
this.method = method;
this.bridgedMethod = BridgeMethodResolver.findBridgedMethod(method);
this.parameters = initMethodParameters();
//解析@ResponseStatus
evaluateResponseStatus();
this.description = initDescription(this.beanType, this.method);
}
MappingRegistry 中的一些主要属性
class MappingRegistry {
//RequestMappingInfo与MappingRegistration
private final Map<T, MappingRegistration<T>> registry = new HashMap<>();
//path和RequestMappingInfo
private final MultiValueMap<String, T> pathLookup = new LinkedMultiValueMap<>();
//name和List<HandlerMethod>
private final Map<String, List<HandlerMethod>> nameLookup = new ConcurrentHashMap<>();
//HandlerMethod和CorsConfiguration
private final Map<HandlerMethod, CorsConfiguration> corsLookup = new ConcurrentHashMap<>();
//读写锁
private final ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock();
}
8、updateConsumesCondition(mapping, method)
回到第七步中
private void updateConsumesCondition(RequestMappingInfo info, Method method) {
ConsumesRequestCondition condition = info.getConsumesCondition();
if (!condition.isEmpty()) {
for (Parameter parameter : method.getParameters()) {
//@RequestBody
MergedAnnotation<RequestBody> annot = MergedAnnotations.from(parameter).get(RequestBody.class);
if (annot.isPresent()) {
condition.setBodyRequired(annot.getBoolean("required"));
break;
}
}
}
}
三、getHandler( )
1、DispatcherServlet.getHandler( )
@Nullable
protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
if (this.handlerMappings != null) {
for (HandlerMapping mapping : this.handlerMappings) {
//遍历所有handlerMappings，这里分析RequestMappingHandlerMapping
HandlerExecutionChain handler = mapping.getHandler(request);
if (handler != null) {
return handler;
}
}
}
return null;
}
2、AbstractHandlerMapping.getHandler( )
public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
//调用子类的getHandlerInternal
Object handler = getHandlerInternal(request);
if (handler == null) {
//没有找到，使用默认的
handler = getDefaultHandler();
}
if (handler == null) {
return null;
}
// Bean name or resolved handler?
if (handler instanceof String) {
String handlerName = (String) handler;
//根据beanName获取Bean
handler = obtainApplicationContext().getBean(handlerName);
}
// Ensure presence of cached lookupPath for interceptors and others
if (!ServletRequestPathUtils.hasCachedPath(request)) {
initLookupPath(request);
}
//获取执行器链，包含handler和interceptors
HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);
if (logger.isTraceEnabled()) {
logger.trace("Mapped to " + handler);
}
else if (logger.isDebugEnabled() && !DispatcherType.ASYNC.equals(request.getDispatcherType())) {
logger.debug("Mapped to " + executionChain.getHandler());
}
//处理跨域
if (hasCorsConfigurationSource(handler) || CorsUtils.isPreFlightRequest(request)) {
CorsConfiguration config = getCorsConfiguration(handler, request);
if (getCorsConfigurationSource() != null) {
CorsConfiguration globalConfig = getCorsConfigurationSource().getCorsConfiguration(request);
config = (globalConfig != null ? globalConfig.combine(config) : config);
}
if (config != null) {
config.validateAllowCredentials();
}
executionChain = getCorsHandlerExecutionChain(request, executionChain, config);
}
return executionChain;
}
3、RequestMappingHandlerMapping.getHandlerInternal( )
protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception {
request.removeAttribute(PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE);
try {
//又进入父类的getHandlerInternal
return super.getHandlerInternal(request);
}
finally {
ProducesRequestCondition.clearMediaTypesAttribute(request);
}
}
4、AbstractHandlerMethodMapping.getHandlerInternal( )
protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception {
//查找访问的路径，具有全路径匹配、进行URL的decode操作、移除URL中分号的内容等功能
String lookupPath = initLookupPath(request);
this.mappingRegistry.acquireReadLock();
try {
//根据路径找到访问的方法，从缓存中获取
HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request);
//根据Bean name创建Controller Bean对象
return (handlerMethod != null ? handlerMethod.createWithResolvedBean() : null);
}
finally {
this.mappingRegistry.releaseReadLock();
}
}
5、lookupHandlerMethod( )
从springmvc容器中找出对应的controller和method的信息，当结果大于一个时，通过比较器比较RequestMappingInfo中的各属性，获取最优匹配的方法。
protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
List<Match> matches = new ArrayList<>();
//从缓存中获取
List<T> directPathMatches = this.mappingRegistry.getMappingsByDirectPath(lookupPath);
if (directPathMatches != null) {
addMatchingMappings(directPathMatches, matches, request);
}
if (matches.isEmpty()) {
addMatchingMappings(this.mappingRegistry.getRegistrations().keySet(), matches, request);
}
if (!matches.isEmpty()) {
Match bestMatch = matches.get(0);
//找出最优的匹配方法
if (matches.size() > 1) {
Comparator<Match> comparator = new MatchComparator(getMappingComparator(request));
matches.sort(comparator);
bestMatch = matches.get(0);
if (logger.isTraceEnabled()) {
logger.trace(matches.size() + " matching mappings: " + matches);
}
if (CorsUtils.isPreFlightRequest(request)) {
for (Match match : matches) {
if (match.hasCorsConfig()) {
return PREFLIGHT_AMBIGUOUS_MATCH;
}
}
}
else {
Match secondBestMatch = matches.get(1);
if (comparator.compare(bestMatch, secondBestMatch) == 0) {
Method m1 = bestMatch.getHandlerMethod().getMethod();
Method m2 = secondBestMatch.getHandlerMethod().getMethod();
String uri = request.getRequestURI();
throw new IllegalStateException(
"Ambiguous handler methods mapped for '" + uri + "': {" + m1 + ", " + m2 + "}");
}
}
}
request.setAttribute(BEST_MATCHING_HANDLER_ATTRIBUTE, bestMatch.getHandlerMethod());
handleMatch(bestMatch.mapping, lookupPath, request);
return bestMatch.getHandlerMethod();
}
else {
return handleNoMatch(this.mappingRegistry.getRegistrations().keySet(), lookupPath, request);
}
}
总结
本文简单介绍了RequestMappingHandlerMapping的初始化流程以及解析@Controller或@RequestMapping的流程以及getHandler的过程。