?? DispatcherServlet继承自FrameworkServlet,而FrameworkServet继承自HttpServletBean.
HttpServletBean有继承了HttpServlet.
??? 作为Servlet, DispatcherServlet的启动过程和Servlet启动过程是相联系的。在Servlet的初始化过程中，Servlet的init方法被调用，已进行初始化。
HttppServletBean.init()->FrameworkServlet.initWebApplicationContext()->DispatcherServlet.onRefresh().
onRefresh?的源码是：
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/**
* This implementation calls {@link #initStrategies}.
*/
@Override
protected void onRefresh(ApplicationContext context) {
initStrategies(context);
}
?而initStrategies(context)的源码如下：
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protected void initStrategies(ApplicationContext context) {
//初始化多媒体解析器
initMultipartResolver(context);
//初始化位置解析器
initLocaleResolver(context);
//初始化主题解析器
initThemeResolver(context);
//初始化HandlerMappings
initHandlerMappings(context);
// 初始化HandlerAdapters
initHandlerAdapters(context);
//初始化异常解析器
initHandlerExceptionResolvers(context);
//初始化请求到视图名转换器
initRequestToViewNameTranslator(context);
//初始化视图解析器
initViewResolvers(context);
//初始化FlashMapManager
initFlashMapManager(context);
}
?????通过initMultipartResover进行初始化多媒体解析器，如果在配置文件中没有配置id为multipartResolver的bean则没有提供多媒体处理器。
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/**
* Initialize the MultipartResolver used by this class.
* <p>If no bean is defined with the given name in the BeanFactory for this namespace,
* no multipart handling is provided.
*/
private void initMultipartResolver(ApplicationContext context) {
try {
this.multipartResolver = context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class);
if (logger.isDebugEnabled()) {
logger.debug("Using MultipartResolver [" + this.multipartResolver + "]");
}
}
catch (NoSuchBeanDefinitionException ex) {
// Default is no multipart resolver.
this.multipartResolver = null;
if (logger.isDebugEnabled()) {
logger.debug("Unable to locate MultipartResolver with name ‘" + MULTIPART_RESOLVER_BEAN_NAME +
"‘: no multipart request handling provided");
}
}
}
???通过initLocaleResolver方法进行localeResolver的初始化，如果没有配置指定id为localeResolver的bean则使用AcceptHeaderLocaleResolver的位置解析器。
* Initialize the LocaleResolver used by this class.
* <p>If no bean is defined with the given name in the BeanFactory for this namespace,
* we default to AcceptHeaderLocaleResolver.
*/
private void initLocaleResolver(ApplicationContext context) {
try {
this.localeResolver = context.getBean(LOCALE_RESOLVER_BEAN_NAME, LocaleResolver.class);
if (logger.isDebugEnabled()) {
logger.debug("Using LocaleResolver [" + this.localeResolver + "]");
}
}
catch (NoSuchBeanDefinitionException ex) {
// We need to use the default.
this.localeResolver = getDefaultStrategy(context, LocaleResolver.class);
if (logger.isDebugEnabled()) {
logger.debug("Unable to locate LocaleResolver with name ‘" + LOCALE_RESOLVER_BEAN_NAME +
"‘: using default [" + this.localeResolver + "]");
}
}
}
?initThemeResolver初始化主题解析器，如果没有配置指定id的为themeResolver的bean?则使用FixedThemeResolver主题解析器
/**
* Initialize the ThemeResolver used by this class.
* <p>If no bean is defined with the given name in the BeanFactory for this namespace,
* we default to a FixedThemeResolver.
*/
private void initThemeResolver(ApplicationContext context) {
try {
this.themeResolver = context.getBean(THEME_RESOLVER_BEAN_NAME, ThemeResolver.class);
if (logger.isDebugEnabled()) {
logger.debug("Using ThemeResolver [" + this.themeResolver + "]");
}
}
catch (NoSuchBeanDefinitionException ex) {
// We need to use the default.
this.themeResolver = getDefaultStrategy(context, ThemeResolver.class);
if (logger.isDebugEnabled()) {
logger.debug(
"Unable to locate ThemeResolver with name ‘" + THEME_RESOLVER_BEAN_NAME + "‘: using default [" +
this.themeResolver + "]");
}
}
}
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/**
* Initialize the HandlerMappings used by this class.
* <p>If no HandlerMapping beans are defined in the BeanFactory for this namespace,
* we default to BeanNameUrlHandlerMapping.
*/
private void initHandlerMappings(ApplicationContext context) {
this.handlerMappings = null;
if (this.detectAllHandlerMappings) {
// 在应用上下文包括其祖先上下文中查找所有HandlerMappings
Map<String, HandlerMapping> matchingBeans =
BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false);
//如果matchingBeans这个map是不为空，则创建一个新的ArrayList
if (!matchingBeans.isEmpty()) {
this.handlerMappings = new ArrayList<HandlerMapping>(matchingBeans.values());
//并对其进行排序
OrderComparator.sort(this.handlerMappings);
}
}
else {
try {
//从应用上下文中查找所有的HandlerMapping
HandlerMapping hm = context.getBean(HANDLER_MAPPING_BEAN_NAME, HandlerMapping.class);
this.handlerMappings = Collections.singletonList(hm);
}
catch (NoSuchBeanDefinitionException ex) {
// Ignore, we‘ll add a default HandlerMapping later.
}
}
// Ensure we have at least one HandlerMapping, by registering
// a default HandlerMapping if no other mappings are found.
if (this.handlerMappings == null) {
// 如果没有配置HandlerMapping 则使用默认的HandlerMapping 策略
this.handlerMappings = getDefaultStrategies(context, HandlerMapping.class);
if (logger.isDebugEnabled()) {
logger.debug("No HandlerMappings found in servlet ‘" + getServletName() + "‘: using default");
}
}
}
?通过initHandlerAdapters进行初始化HandlerAdapter,如果没有配置HandlerAdapter则使用SimpleControllerHandlerAdapter
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/**
* Initialize the HandlerAdapters used by this class.
* <p>If no HandlerAdapter beans are defined in the BeanFactory for this namespace,
* we default to SimpleControllerHandlerAdapter.
*/
private void initHandlerAdapters(ApplicationContext context) {
this.handlerAdapters = null;
if (this.detectAllHandlerAdapters) {
// Find all HandlerAdapters in the ApplicationContext, including ancestor contexts.
Map<String, HandlerAdapter> matchingBeans =
BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerAdapter.class, true, false);
if (!matchingBeans.isEmpty()) {
this.handlerAdapters = new ArrayList<HandlerAdapter>(matchingBeans.values());
// We keep HandlerAdapters in sorted order.
OrderComparator.sort(this.handlerAdapters);
}
}
else {
try {
HandlerAdapter ha = context.getBean(HANDLER_ADAPTER_BEAN_NAME, HandlerAdapter.class);
this.handlerAdapters = Collections.singletonList(ha);
}
catch (NoSuchBeanDefinitionException ex) {
// Ignore, we‘ll add a default HandlerAdapter later.
}
}
// Ensure we have at least some HandlerAdapters, by registering
// default HandlerAdapters if no other adapters are found.
if (this.handlerAdapters == null) {
this.handlerAdapters = getDefaultStrategies(context, HandlerAdapter.class);
if (logger.isDebugEnabled()) {
logger.debug("No HandlerAdapters found in servlet ‘" + getServletName() + "‘: using default");
}
}
}
??初始化异常处理器，如果没有配置指定Id为handlerExceptionResolver的Bean，默认是没有异常处理器
/**
* Initialize the HandlerExceptionResolver used by this class.
* <p>If no bean is defined with the given name in the BeanFactory for this namespace,
* we default to no exception resolver.
*/
private void initHandlerExceptionResolvers(ApplicationContext context) {
this.handlerExceptionResolvers = null;
if (this.detectAllHandlerExceptionResolvers) {
// Find all HandlerExceptionResolvers in the ApplicationContext, including ancestor contexts.
Map<String, HandlerExceptionResolver> matchingBeans = BeanFactoryUtils
.beansOfTypeIncludingAncestors(context, HandlerExceptionResolver.class, true, false);
if (!matchingBeans.isEmpty()) {
this.handlerExceptionResolvers = new ArrayList<HandlerExceptionResolver>(matchingBeans.values());
// We keep HandlerExceptionResolvers in sorted order.
OrderComparator.sort(this.handlerExceptionResolvers);
}
}
else {
try {
HandlerExceptionResolver her =
context.getBean(HANDLER_EXCEPTION_RESOLVER_BEAN_NAME, HandlerExceptionResolver.class);
this.handlerExceptionResolvers = Collections.singletonList(her);
}
catch (NoSuchBeanDefinitionException ex) {
// Ignore, no HandlerExceptionResolver is fine too.
}
}
// Ensure we have at least some HandlerExceptionResolvers, by registering
// default HandlerExceptionResolvers if no other resolvers are found.
if (this.handlerExceptionResolvers == null) {
this.handlerExceptionResolvers = getDefaultStrategies(context, HandlerExceptionResolver.class);
if (logger.isDebugEnabled()) {
logger.debug("No HandlerExceptionResolvers found in servlet ‘" + getServletName() + "‘: using default");
}
}
}
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初始化请求到视图名称的转换器，如果不配置则使用默认的转换器。
/**
* Initialize the RequestToViewNameTranslator used by this servlet instance.
* <p>If no implementation is configured then we default to DefaultRequestToViewNameTranslator.
*/
private void initRequestToViewNameTranslator(ApplicationContext context) {
try {
this.viewNameTranslator =
context.getBean(REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME, RequestToViewNameTranslator.class);
if (logger.isDebugEnabled()) {
logger.debug("Using RequestToViewNameTranslator [" + this.viewNameTranslator + "]");
}
}
catch (NoSuchBeanDefinitionException ex) {
// We need to use the default.
this.viewNameTranslator = getDefaultStrategy(context, RequestToViewNameTranslator.class);
if (logger.isDebugEnabled()) {
logger.debug("Unable to locate RequestToViewNameTranslator with name ‘" +
REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME + "‘: using default [" + this.viewNameTranslator +
"]");
}
}
}
??初始化视图解析器，如果没有配置视图解析器则使用默认的InternalResourceViewResolver视图解析器
/**
* Initialize the ViewResolvers used by this class.
* <p>If no ViewResolver beans are defined in the BeanFactory for this
* namespace, we default to InternalResourceViewResolver.
*/
private void initViewResolvers(ApplicationContext context) {
this.viewResolvers = null;
if (this.detectAllViewResolvers) {
// Find all ViewResolvers in the ApplicationContext, including ancestor contexts.
Map<String, ViewResolver> matchingBeans =
BeanFactoryUtils.beansOfTypeIncludingAncestors(context, ViewResolver.class, true, false);
if (!matchingBeans.isEmpty()) {
this.viewResolvers = new ArrayList<ViewResolver>(matchingBeans.values());
// We keep ViewResolvers in sorted order.
OrderComparator.sort(this.viewResolvers);
}
}
else {
try {
ViewResolver vr = context.getBean(VIEW_RESOLVER_BEAN_NAME, ViewResolver.class);
this.viewResolvers = Collections.singletonList(vr);
}
catch (NoSuchBeanDefinitionException ex) {
// Ignore, we‘ll add a default ViewResolver later.
}
}
// Ensure we have at least one ViewResolver, by registering
// a default ViewResolver if no other resolvers are found.
if (this.viewResolvers == null) {
this.viewResolvers = getDefaultStrategies(context, ViewResolver.class);
if (logger.isDebugEnabled()) {
logger.debug("No ViewResolvers found in servlet ‘" + getServletName() + "‘: using default");
}
}
}
?获取默认设置，首先获取接口的名称，然后从DispatcherServlert.properties的配置文件中读取value,然后将其分割为字符串数组。
/**
* Create a List of default strategy objects for the given strategy interface.
* <p>The default implementation uses the "DispatcherServlet.properties" file (in the same
* package as the DispatcherServlet class) to determine the class names. It instantiates
* the strategy objects through the context‘s BeanFactory.
* @param context the current WebApplicationContext
* @param strategyInterface the strategy interface
* @return the List of corresponding strategy objects
*/
@SuppressWarnings("unchecked")
protected <T> List<T> getDefaultStrategies(ApplicationContext context, Class<T> strategyInterface) {
String key = strategyInterface.getName();
String value = defaultStrategies.getProperty(key);
if (value != null) {
String[] classNames = StringUtils.commaDelimitedListToStringArray(value);
List<T> strategies = new ArrayList<T>(classNames.length);
for (String className : classNames) {
try {
Class<?> clazz = ClassUtils.forName(className, DispatcherServlet.class.getClassLoader());
Object strategy = createDefaultStrategy(context, clazz);
strategies.add((T) strategy);
}
catch (ClassNotFoundException ex) {
throw new BeanInitializationException(
"Could not find DispatcherServlet‘s default strategy class [" + className +
"] for interface [" + key + "]", ex);
}
catch (LinkageError err) {
throw new BeanInitializationException(
"Error loading DispatcherServlet‘s default strategy class [" + className +
"] for interface [" + key + "]: problem with class file or dependent class", err);
}
}
return strategies;
}
else {
return new LinkedList<T>();
}
}
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DispatcherSerlvet.properties
# Default implementation classes for DispatcherServlet‘s strategy interfaces. # Used as fallback when no matching beans are found in the DispatcherServlet context. # Not meant to be customized by application developers. org.springframework.web.servlet.LocaleResolver=org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver org.springframework.web.servlet.ThemeResolver=org.springframework.web.servlet.theme.FixedThemeResolver org.springframework.web.servlet.HandlerMapping=org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping, org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping org.springframework.web.servlet.HandlerAdapter=org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter, org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter, org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter org.springframework.web.servlet.HandlerExceptionResolver=org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver, org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver, org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver org.springframework.web.servlet.RequestToViewNameTranslator=org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator org.springframework.web.servlet.ViewResolver=org.springframework.web.servlet.view.InternalResourceViewResolver org.springframework.web.servlet.FlashMapManager=org.springframework.web.servlet.support.SessionFlashMapManager
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Spring MVC之DispatcherServlet初始化
原文：http://zhangwei-david.iteye.com/blog/2170778