SpringMVC架构实现原理
一、SpringMVC介绍
Spring mvc是一个基于mvc的web框架 。其中核心类是DispatcherServlet，它是一个Servlet，顶层是实现的Servlet接口 。
Spring mvc是spring框架的一个模块，springmvc和spring无需通过中间整合层进行整合 。
二、SpringMVC使用
需要在web.xml中配置DispatcherServlet 。并且需要配置spring监听器ContextLoaderListener
<?xml version="1.0" encoding="UTF-8"?> <!-- 当前的XML文档版本与字符编码 --><web-App xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://JAVA.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>SpringMVC</display-name><!-- SpringMVC前段控制器 --> <servlet> <servlet-name>springmvc</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><!-- contextConfigLocation配置SpringMVC加载的配置文件(配置处理器映射器、适配器等等)如果不配置ContextConfigLocation,默认加载的是/WEB-INF/servlet名称-servlet.xml(springmvc-servlet.xml) --> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:springmvc-config.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet><servlet-mapping> <servlet-name>springmvc</servlet-name> <!-- 第一种：*.action，访问以.action结尾由DispatcherServlet进行解析 第二种：/，所以访问的地址都由DispatcherServlet进行解析，对于静态文件的配置不让DispatcherServlet解析 第三种：/*，这样配置不对 --> <url-pattern>*.action</url-pattern> </servlet-mapping> </web-app>三、SpringMVC运行原理
1、 运行流程图：
【SpringMVC架构实现原理】
文章插图
2、流程说明：
（1）客户端（浏览器）发送请求，直接请求到DispatcherServlet 。（请求DispatcherServlet）
（2）DispatcherServlet根据请求信息调用HandlerMapping，解析请求对应的Handler 。（查找@Controller）
（3）解析到对应的Handler后，开始由HandlerAdapter适配器处理 。（查找@RequestMapping）
（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 。（处理方法）
（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 。（返回处理结果）
（6）ViewResolver会根据逻辑View查找实际的View 。（逻辑视图解析为真正的视图）
（7）DispatcherServlet把返回的Model传给View 。（DispatcherServlet试图渲染）
（8）通过View返回给请求者（浏览器）
四、DispatcherServlet详细解析
源码分析：
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); }}
推荐阅读
- 小程序开发：调用百度文字识别接口实现图文识别，Node.js开发
- 教你怎么实现缩短网址功能
- 使用PHP实现文件下载功能
- 六种常用的微服务架构设计模式
- 微信支付软件架构重构之旅
- 架构设计：文件服务的设计与实现
- 大白话告诉你Hadoop架构原理
- Web前端开发基础：HTML、CSS、JavaScript分别实现什么功能？
- 从微信小程序开发者工具源码看小程序架构设计实现原理
- 如何一步步构建大型网站架构