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SpringMVC源码分析（4）剖析DispatcherServlet重要组件
<SpringMVC源码分析（3）DispatcherServlet的请求处理流程 >简单介绍了一个请求的处理过程， 简略描述了调用过程，并没有涉及过多细节，如url匹配,报文解析转换等。
<SpringMVC源码分析（2）DispatcherServlet的初始化>:介绍了servlet的初始化过程，尤其initStrategies方法。
本文主要总结DispatcherServlet几个重要组件的关系。
1.类图
该类图并没有全面的描述SpringMVC相关类，重点说明组件的关系。
该类图基于springmvc3.0.5版本。
很多类属性并没有完全罗列，进行了取舍。
基于DispatcherServlet,而且深度尽量适可而止，否则造成图复杂混乱。
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2.HanlerMapping组件介绍
2.1 HanlerMapping类图
HanlerMapping是springmvc中完成url到controller映射的组件。
2.2 HanlerMappingAPI
public interface HandlerMapping {
//根据选择策略，返回Handler
HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception;
}3.HandlerAdapter
3.1类图
是MVC framework SPI ；负责具体干活。如调用方法，参数解析等。
3.2 API
public interface HandlerAdapter {
/**
判断是否可以处理handler
*/
boolean supports(Object handler);
/**
* 处理请求
*/
ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception;
/**
* getLastModified
*/
long getLastModified(HttpServletRequest request, Object handler);
}4.HandlerExceptionResolver
4.1 HandlerExceptionResolver类图
专门处理异常情况，根据异常情况，构造ModelAndView
4.2 HandlerExceptionResolver API
public interface HandlerExceptionResolver {
/**
* 处理异常
*/
ModelAndView resolveException(
HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex);
}5. ViewResolver
5.1 ViewResolver类图
作用：将string的视图名称解析为View类型的视图
5.2 ViewResolver API
public interface ViewResolver {
/**
* Resolve the given view by name.
解析视图
*/
View resolveViewName(String viewName, Locale locale) throws Exception;
}6.RequestToViewNameTranslator
默认实现是DefaultRequestToViewNameTranslator.主要作用是根据请求信息获取视图名称。
public interface RequestToViewNameTranslator {
String getViewName(HttpServletRequest request) throws Exception;
}7.LocaleResolver
7.1 LocaleResolver类图
从request解析Locale,实现本地化;一般使用在解析视图时使用；和使用国际化资源和主题时使用
7.2 LocaleResolver API
public interface LocaleResolver {
/**
* Resolve the current locale via the given request.
* Should return a default locale as fallback in any case.
* @param request the request to resolve the locale for
* @return the current locale (never <code>null</code>)
*/
Locale resolveLocale(HttpServletRequest request);
/**
* Set the current locale to the given one.
* @param request the request to be used for locale modification
* @param response the response to be used for locale modification
* @param locale the new locale, or <code>null</code> to clear the locale
* @throws UnsupportedOperationException if the LocaleResolver implementation
* does not support dynamic changing of the theme
*/
void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale);
}8.ThemeResolver
8.1 ThemeResolver类图
主要用来设置主题。
8.2 API
public interface ThemeResolver {
/**
* Resolve the current theme name via the given request.
* Should return a default theme as fallback in any case.
* @param request request to be used for resolution
* @return the current theme name
*/
String resolveThemeName(HttpServletRequest request);
/**
* Set the current theme name to the given one.
* @param request request to be used for theme name modification
* @param response response to be used for theme name modification
* @param themeName the new theme name
* @throws UnsupportedOperationException if the ThemeResolver implementation
* does not support dynamic changing of the theme
*/
void setThemeName(HttpServletRequest request, HttpServletResponse response, String themeName);
}9.MultipartResolver
默认实现为CommonsMultipartResolver，处理文件上传请求。
public interface MultipartResolver {
/**
* Determine if the given request contains multipart content.
*/
boolean isMultipart(HttpServletRequest request);
/**
* Parse the given HTTP request into multipart files and parameters,
* and wrap the request inside a
*/
MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException;
/**
* Cleanup any resources used for the multipart handling,
*/
void cleanupMultipart(MultipartHttpServletRequest request);
}10 总结。
简单极少了下各个组件，每个组件都各司其职，互相配合。才有了强大的SpringMVC功能。在以后的文章里，针对每个组件，会结合具体例子，由浅入深式的进行剖析。
另外一个重要的核心部分是HandlerMethodInvoker，涉及的东西比较多，非常有看头。
本文出自 “简单” 博客，请务必保留此出处http://dba10g.blog.51cto.com/764602/1878735
SpringMVC源码分析（4）剖析DispatcherServlet重要组件