1、Spring mvc介绍
SpringMVC框架是以请求为驱动,围绕Servlet设计,将请求发给控制器,然后通过模型对象,分派器来展示请求结果视图。其中核心类是DispatcherServlet,它是一个Servlet,顶层是实现的Servlet接口。
2、SpringMVC使用
需要在web.xml中配置DispatcherServlet。并且需要配置spring监听器ContextLoaderListener
-
<listener>
-
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
-
</listener>
-
<servlet>
-
<servlet-name>springmvc</servlet-name>
-
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
-
<!-- 如果不设置init-param标签,则必须在/WEB-INF/下创建xxx-servlet.xml文件,其中xxx是servlet-name中配置的名称。 -->
-
<init-param>
-
<param-name>contextConfigLocation</param-name>
-
<param-value>classpath:spring/springmvc-servlet.xml</param-value>
-
</init-param>
-
<load-on-startup>1</load-on-startup>
-
</servlet>
-
<servlet-mapping>
-
<servlet-name>springmvc</servlet-name>
-
<url-pattern>/</url-pattern>
-
</servlet-mapping>
3、SpringMVC运行原理
如图所示:
流程说明:
(1)客户端(浏览器)发送请求,直接请求到DispatcherServlet。
(2)DispatcherServlet根据请求信息调用HandlerMapping,解析请求对应的Handler。
(3)解析到对应的Handler后,开始由HandlerAdapter适配器处理。
(4)HandlerAdapter会根据Handler来调用真正的处理器开处理请求,并处理相应的业务逻辑。
(5)处理器处理完业务后,会返回一个ModelAndView对象,Model是返回的数据对象,View是个逻辑上的View。
(6)ViewResolver会根据逻辑View查找实际的View。
(7)DispaterServlet把返回的Model传给View。
(8)通过View返回给请求者(浏览器)
4、DispatcherServlet详细解析
首先看下源码:
-
package org.springframework.web.servlet;
-
@SuppressWarnings("serial")
-
public class DispatcherServlet extends FrameworkServlet {
-
public static final String MULTIPART_RESOLVER_BEAN_NAME = "multipartResolver";
-
public static final String LOCALE_RESOLVER_BEAN_NAME = "localeResolver";
-
public static final String THEME_RESOLVER_BEAN_NAME = "themeResolver";
-
public static final String HANDLER_MAPPING_BEAN_NAME = "handlerMapping";
-
public static final String HANDLER_ADAPTER_BEAN_NAME = "handlerAdapter";
-
public static final String HANDLER_EXCEPTION_RESOLVER_BEAN_NAME = "handlerExceptionResolver";
-
public static final String REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME = "viewNameTranslator";
-
public static final String VIEW_RESOLVER_BEAN_NAME = "viewResolver";
-
public static final String FLASH_MAP_MANAGER_BEAN_NAME = "flashMapManager";
-
public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE = DispatcherServlet.class.getName() + ".CONTEXT";
-
public static final String LOCALE_RESOLVER_ATTRIBUTE = DispatcherServlet.class.getName() + ".LOCALE_RESOLVER";
-
public static final String THEME_RESOLVER_ATTRIBUTE = DispatcherServlet.class.getName() + ".THEME_RESOLVER";
-
public static final String THEME_SOURCE_ATTRIBUTE = DispatcherServlet.class.getName() + ".THEME_SOURCE";
-
public static final String INPUT_FLASH_MAP_ATTRIBUTE = DispatcherServlet.class.getName() + ".INPUT_FLASH_MAP";
-
public static final String OUTPUT_FLASH_MAP_ATTRIBUTE = DispatcherServlet.class.getName() + ".OUTPUT_FLASH_MAP";
-
public static final String FLASH_MAP_MANAGER_ATTRIBUTE = DispatcherServlet.class.getName() + ".FLASH_MAP_MANAGER";
-
public static final String EXCEPTION_ATTRIBUTE = DispatcherServlet.class.getName() + ".EXCEPTION";
-
public static final String PAGE_NOT_FOUND_LOG_CATEGORY = "org.springframework.web.servlet.PageNotFound";
-
private static final String DEFAULT_STRATEGIES_PATH = "DispatcherServlet.properties";
-
protected static final Log pageNotFoundLogger = LogFactory.getLog(PAGE_NOT_FOUND_LOG_CATEGORY);
-
private static final Properties defaultStrategies;
-
static {
-
try {
-
ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, DispatcherServlet.class);
-
defaultStrategies = PropertiesLoaderUtils.loadProperties(resource);
-
}
-
catch (IOException ex) {
-
throw new IllegalStateException("Could not load 'DispatcherServlet.properties': " + ex.getMessage());
-
}
-
}
-
/** Detect all HandlerMappings or just expect "handlerMapping" bean? */
-
private boolean detectAllHandlerMappings = true;
-
/** Detect all HandlerAdapters or just expect "handlerAdapter" bean? */
-
private boolean detectAllHandlerAdapters = true;
-
/** Detect all HandlerExceptionResolvers or just expect "handlerExceptionResolver" bean? */
-
private boolean detectAllHandlerExceptionResolvers = true;
-
/** Detect all ViewResolvers or just expect "viewResolver" bean? */
-
private boolean detectAllViewResolvers = true;
-
/** Throw a NoHandlerFoundException if no Handler was found to process this request? **/
-
private boolean throwExceptionIfNoHandlerFound = false;
-
/** Perform cleanup of request attributes after include request? */
-
private boolean cleanupAfterInclude = true;
-
/** MultipartResolver used by this servlet */
-
private MultipartResolver multipartResolver;
-
/** LocaleResolver used by this servlet */
-
private LocaleResolver localeResolver;
-
/** ThemeResolver used by this servlet */
-
private ThemeResolver themeResolver;
-
/** List of HandlerMappings used by this servlet */
-
private List<HandlerMapping> handlerMappings;
-
/** List of HandlerAdapters used by this servlet */
-
private List<HandlerAdapter> handlerAdapters;
-
/** List of HandlerExceptionResolvers used by this servlet */
-
private List<HandlerExceptionResolver> handlerExceptionResolvers;
-
/** RequestToViewNameTranslator used by this servlet */
-
private RequestToViewNameTranslator viewNameTranslator;
-
private FlashMapManager flashMapManager;
-
/** List of ViewResolvers used by this servlet */
-
private List<ViewResolver> viewResolvers;
-
public DispatcherServlet() {
-
super();
-
}
-
public DispatcherServlet(WebApplicationContext webApplicationContext) {
-
super(webApplicationContext);
-
}
-
@Override
-
protected void onRefresh(ApplicationContext context) {
-
initStrategies(context);
-
}
-
protected void initStrategies(ApplicationContext context) {
-
initMultipartResolver(context);
-
initLocaleResolver(context);
-
initThemeResolver(context);
-
initHandlerMappings(context);
-
initHandlerAdapters(context);
-
initHandlerExceptionResolvers(context);
-
initRequestToViewNameTranslator(context);
-
initViewResolvers(context);
-
initFlashMapManager(context);
-
}
-
}
DispatcherServlet类中的属性beans:
HandlerMapping:用于handlers映射请求和一系列的对于拦截器的前处理和后处理,大部分用@Controller注解。
HandlerAdapter:帮助DispatcherServlet处理映射请求处理程序的适配器,而不用考虑实际调用的是 哪个处理程序。
HandlerExceptionResolver:处理映射异常。
ViewResolver:根据实际配置解析实际的View类型。
LocaleResolver:解决客户正在使用的区域设置以及可能的时区,以便能够提供国际化视野。
ThemeResolver:解决Web应用程序可以使用的主题,例如提供个性化布局。
MultipartResolver:解析多部分请求,以支持从HTML表单上传文件。
FlashMapManager:存储并检索可用于将一个请求属性传递到另一个请求的input和output的FlashMap,通常用于重定向。
在Web MVC框架中,每个DispatcherServlet都拥自己的WebApplicationContext,它继承了ApplicationContext。WebApplicationContext包含了其上下文和Servlet实例之间共享的所有的基础框架beans。
- HandlerMapping:
HandlerMapping接口处理请求的映射
HandlerMapping接口的实现类:
SimpleUrlHandlerMapping类通过配置文件把URL映射到Controller类。
DefaultAnnotationHandlerMapping类通过注解把URL映射到Controller类。
- HandlerAdapter:
HandlerAdapter接口-处理请求映射
AnnotationMethodHandlerAdapter:通过注解,把请求URL映射到Controller类的方法上。
- HandlerExceptionResolver:
HandlerExceptionResolver接口-异常处理接口
SimpleMappingExceptionResolver通过配置文件进行异常处理。
AnnotationMethodHandlerExceptionResolver:通过注解进行异常处理。
- ViewResolver:
ViewResolver接口解析View视图。
UrlBasedViewResolver类 通过配置文件,把一个视图名交给到一个View来处理。
参考资料:http://elf8848.iteye.com/blog/875830
装载于:https://blog.csdn.net/yanweihpu/article/details/80366218