springMVC源码分析--AbstractHandlerMapping（二）

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

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

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//获得一个HandlerExecutionChain

@Override

public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {

//从实现类中获得HanlderMethod

Object handler = getHandlerInternal(request);

if (handler == null) {

handler = getDefaultHandler();

}

if (handler == null) {

return null;

}

// Bean name or resolved handler?

if (handler instanceof String) {

String handlerName = (String) handler;

handler = getApplicationContext().getBean(handlerName);

}

//获得HandlerExecutionChain

HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);

if (CorsUtils.isCorsRequest(request)) {

CorsConfiguration globalConfig = this.corsConfigSource.getCorsConfiguration(request);

CorsConfiguration handlerConfig = getCorsConfiguration(handler, request);

CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig);

executionChain = getCorsHandlerExecutionChain(request, executionChain, config);

}

return executionChain;

}

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

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//模板方法，用于子类中实现，通过request去查找对应的执行方法HandlerMethod

protected abstract Object getHandlerInternal(HttpServletRequest request) throws Exception;

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

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//

protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {

//如果没有获得则创建一个

HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?

(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));

//获得IP地址及端口后的URL地址

String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);

//在HandlerExecutionChain中添加拦截器

for (HandlerInterceptor interceptor : this.adaptedInterceptors) {

if (interceptor instanceof MappedInterceptor) {

MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor;

//根据lookupPath来获取Interceptor

if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {

chain.addInterceptor(mappedInterceptor.getInterceptor());

}

}

else {

chain.addInterceptor(interceptor);

}

}

return chain;

}

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

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//设置不同HandlerMapping实现类的执行顺序

public final void setOrder(int order) {

this.order = order;

}

@Override

public final int getOrder() {

return this.order;

}

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

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//初始化时调用，初始化一些基本信息，这里主要是初始化一些拦截器

@Override

protected void initApplicationContext() throws BeansException {

extendInterceptors(this.interceptors);//添加或修车intercept，现在并没有具体实现

detectMappedInterceptors(this.adaptedInterceptors);//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中

initInterceptors();

}

protected void extendInterceptors(List<Object> interceptors) {

}

//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中

protected void detectMappedInterceptors(List<HandlerInterceptor> mappedInterceptors) {

mappedInterceptors.addAll(

BeanFactoryUtils.beansOfTypeIncludingAncestors(

getApplicationContext(), MappedInterceptor.class, true, false).values());

}

//初始化Interceptor,将interceptors属性里所包含的对象按类型添加到mappedInterceptors或者adaptedInterceptors中。

protected void initInterceptors() {

if (!this.interceptors.isEmpty()) {

for (int i = 0; i < this.interceptors.size(); i++) {

Object interceptor = this.interceptors.get(i);

if (interceptor == null) {

throw new IllegalArgumentException("Entry number " + i + " in interceptors array is null");

}

this.adaptedInterceptors.add(adaptInterceptor(interceptor));

}

}

}

protected HandlerInterceptor adaptInterceptor(Object interceptor) {

if (interceptor instanceof HandlerInterceptor) {

return (HandlerInterceptor) interceptor;

}

else if (interceptor instanceof WebRequestInterceptor) {

return new WebRequestHandlerInterceptorAdapter((WebRequestInterceptor) interceptor);

}

else {

throw new IllegalArgumentException("Interceptor type not supported: " + interceptor.getClass().getName());

}

}

protected final HandlerInterceptor[] getAdaptedInterceptors() {

int count = this.adaptedInterceptors.size();

return (count > 0 ? this.adaptedInterceptors.toArray(new HandlerInterceptor[count]) : null);

}

protected final MappedInterceptor[] getMappedInterceptors() {

List<MappedInterceptor> mappedInterceptors = new ArrayList<MappedInterceptor>();

for (HandlerInterceptor interceptor : this.adaptedInterceptors) {

if (interceptor instanceof MappedInterceptor) {

mappedInterceptors.add((MappedInterceptor) interceptor);

}

}

int count = mappedInterceptors.size();

return (count > 0 ? mappedInterceptors.toArray(new MappedInterceptor[count]) : null);

}

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

完整的AbstractHandlerMapping源码如下：

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public abstract class AbstractHandlerMapping extends WebApplicationObjectSupport

implements HandlerMapping, Ordered {

private int order = Integer.MAX_VALUE; // default: same as non-Ordered

private Object defaultHandler;

private UrlPathHelper urlPathHelper = new UrlPathHelper();

private PathMatcher pathMatcher = new AntPathMatcher();

private final List<Object> interceptors = new ArrayList<Object>();

private final List<HandlerInterceptor> adaptedInterceptors = new ArrayList<HandlerInterceptor>();

private CorsProcessor corsProcessor = new DefaultCorsProcessor();

private final UrlBasedCorsConfigurationSource corsConfigSource = new UrlBasedCorsConfigurationSource();

//设置不同HandlerMapping实现类的执行顺序

public final void setOrder(int order) {

this.order = order;

}

@Override

public final int getOrder() {

return this.order;

}

public void setDefaultHandler(Object defaultHandler) {

this.defaultHandler = defaultHandler;

}

public Object getDefaultHandler() {

return this.defaultHandler;

}

public void setAlwaysUseFullPath(boolean alwaysUseFullPath) {

this.urlPathHelper.setAlwaysUseFullPath(alwaysUseFullPath);

this.corsConfigSource.setAlwaysUseFullPath(alwaysUseFullPath);

}

public void setUrlDecode(boolean urlDecode) {

this.urlPathHelper.setUrlDecode(urlDecode);

this.corsConfigSource.setUrlDecode(urlDecode);

}

public void setRemoveSemicolonContent(boolean removeSemicolonContent) {

this.urlPathHelper.setRemoveSemicolonContent(removeSemicolonContent);

this.corsConfigSource.setRemoveSemicolonContent(removeSemicolonContent);

}

public void setUrlPathHelper(UrlPathHelper urlPathHelper) {

Assert.notNull(urlPathHelper, "UrlPathHelper must not be null");

this.urlPathHelper = urlPathHelper;

this.corsConfigSource.setUrlPathHelper(urlPathHelper);

}

public UrlPathHelper getUrlPathHelper() {

return urlPathHelper;

}

public void setPathMatcher(PathMatcher pathMatcher) {

Assert.notNull(pathMatcher, "PathMatcher must not be null");

this.pathMatcher = pathMatcher;

this.corsConfigSource.setPathMatcher(pathMatcher);

}

public PathMatcher getPathMatcher() {

return this.pathMatcher;

}

public void setInterceptors(Object[] interceptors) {

this.interceptors.addAll(Arrays.asList(interceptors));

}

public void setCorsProcessor(CorsProcessor corsProcessor) {

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sp;Assert.notNull(corsProcessor, "CorsProcessor must not be null");

this.corsProcessor = corsProcessor;

}

/**

* Return the configured {@link CorsProcessor}.

*/

public CorsProcessor getCorsProcessor() {

return this.corsProcessor;

}

public void setCorsConfigurations(Map<String, CorsConfiguration> corsConfigurations) {

this.corsConfigSource.setCorsConfigurations(corsConfigurations);

}

/**

* Get the CORS configuration.

*/

public Map<String, CorsConfiguration> getCorsConfigurations() {

return this.corsConfigSource.getCorsConfigurations();

}

//初始化时调用，初始化一些基本信息，这里主要是初始化一些拦截器

@Override

protected void initApplicationContext() throws BeansException {

extendInterceptors(this.interceptors);//添加或修车intercept，现在并没有具体实现

detectMappedInterceptors(this.adaptedInterceptors);//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中

initInterceptors();

}

protected void extendInterceptors(List<Object> interceptors) {

}

//将springMVC容器或者父容器中的所有MappedInterceptor类型的Bean添加到mappedInterceptors属性中

protected void detectMappedInterceptors(List<HandlerInterceptor> mappedInterceptors) {

mappedInterceptors.addAll(

BeanFactoryUtils.beansOfTypeIncludingAncestors(

getApplicationContext(), MappedInterceptor.class, true, false).values());

}

//初始化Interceptor,将interceptors属性里所包含的对象按类型添加到mappedInterceptors或者adaptedInterceptors中。

protected void initInterceptors() {

if (!this.interceptors.isEmpty()) {

for (int i = 0; i < this.interceptors.size(); i++) {

Object interceptor = this.interceptors.get(i);

if (interceptor == null) {

throw new IllegalArgumentException("Entry number " + i + " in interceptors array is null");

}

this.adaptedInterceptors.add(adaptInterceptor(interceptor));

}

}

}

protected HandlerInterceptor adaptInterceptor(Object interceptor) {

if (interceptor instanceof HandlerInterceptor) {

return (HandlerInterceptor) interceptor;

}

else if (interceptor instanceof WebRequestInterceptor) {

return new WebRequestHandlerInterceptorAdapter((WebRequestInterceptor) interceptor);

}

else {

throw new IllegalArgumentException("Interceptor type not supported: " + interceptor.getClass().getName());

}

}

protected final HandlerInterceptor[] getAdaptedInterceptors() {

int count = this.adaptedInterceptors.size();

return (count > 0 ? this.adaptedInterceptors.toArray(new HandlerInterceptor[count]) : null);

}

protected final MappedInterceptor[] getMappedInterceptors() {

List<MappedInterceptor> mappedInterceptors = new ArrayList<MappedInterceptor>();

for (HandlerInterceptor interceptor : this.adaptedInterceptors) {

if (interceptor instanceof MappedInterceptor) {

mappedInterceptors.add((MappedInterceptor) interceptor);

}

}

int count = mappedInterceptors.size();

return (count > 0 ? mappedInterceptors.toArray(new MappedInterceptor[count]) : null);

}

//获得一个HandlerExecutionChain

@Override

public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {

//从实现类中获得HanlderMethod

Object handler = getHandlerInternal(request);

if (handler == null) {

handler = getDefaultHandler();

}

if (handler == null) {

return null;

}

// Bean name or resolved handler?

if (handler instanceof String) {

String handlerName = (String) handler;

handler = getApplicationContext().getBean(handlerName);

}

//获得HandlerExecutionChain

HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request);

if (CorsUtils.isCorsRequest(request)) {

CorsConfiguration globalConfig = this.corsConfigSource.getCorsConfiguration(request);

CorsConfiguration handlerConfig = getCorsConfiguration(handler, request);

CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig);

executionChain = getCorsHandlerExecutionChain(request, executionChain, config);

}

return executionChain;

}

//模板方法，用于子类中实现，通过request去查找对应的执行方法HandlerMethod

protected abstract Object getHandlerInternal(HttpServletRequest request) throws Exception;

//

protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {

//如果没有获得则创建一个

HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?

(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));

//获得IP地址及端口后的URL地址

String lookupPath = this.urlPathHelper.getLookupPathForRequest(request);

//在HandlerExecutionChain中添加拦截器

for (HandlerInterceptor interceptor : this.adaptedInterceptors) {

if (interceptor instanceof MappedInterceptor) {

MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor;

//根据lookupPath来获取Interceptor

if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) {

chain.addInterceptor(mappedInterceptor.getInterceptor());

}

}

else {

chain.addInterceptor(interceptor);

}

}

return chain;

}

protected CorsConfiguration getCorsConfiguration(Object handler, HttpServletRequest request) {

if (handler instanceof HandlerExecutionChain) {

handler = ((HandlerExecutionChain) handler).getHandler();

}

if (handler instanceof CorsConfigurationSource) {

return ((CorsConfigurationSource) handler).getCorsConfiguration(request);

}

return null;

}

protected HandlerExecutionChain getCorsHandlerExecutionChain(HttpServletRequest request,

HandlerExecutionChain chain, CorsConfiguration config) {

if (CorsUtils.isPreFlightRequest(request)) {

HandlerInterceptor[] interceptors = chain.getInterceptors();

chain = new HandlerExecutionChain(new PreFlightHandler(config), interceptors);

}

else {

chain.addInterceptor(new CorsInterceptor(config));

}

return chain;

}

private class PreFlightHandler implements HttpRequestHandler {

private final CorsConfiguration config;

public PreFlightHandler(CorsConfiguration config) {

this.config = config;

}

@Override

public void handleRequest(HttpServletRequest request, HttpServletResponse response)

throws IOException {

corsProcessor.processRequest(this.config, request, response);

}

}

private class CorsInterceptor extends HandlerInterceptorAdapter {

private final CorsConfiguration config;

public CorsInterceptor(CorsConfiguration config) {

this.config = config;

}

@Override

public boolean preHandle(HttpServletRequest request, HttpServletResponse response,

Object handler) throws Exception {

return corsProcessor.processRequest(this.config, request, response);

}

}

}