【SpringMVC源码】执行源码分析 刺骨的言语ヽ痛彻心扉 2023-02-18 11:55 25阅读 0赞 # 前言 # Github:[https://github.com/yihonglei/thinking-in-springmvc][https_github.com_yihonglei_thinking-in-springmvc](文章基于springmvc-xml工程说明) Spring MVC启动流程:[https://jpeony.blog.csdn.net/article/details/106793070][https_jpeony.blog.csdn.net_article_details_106793070] # 一 SpringMVC概述 # Spring MVC封装servlet的MVC Web开发框架,减轻直接操作Servlet的繁琐,提高开发效率。 # 二 Spring MVC执行流程源码 # ## 1、时序图 ## 先上一个简易版本的。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70][] DispatcherServlet负责请求的转发 ------> HandlerMapping基于url查找Handler \------> HandlerAdapter基于Handler查找处理器 ------> 对应url的Handler执行业务 \------> 处理结果交给ViewResolver视图解析器尽心处理 ------> 数据返回给端上进行渲染展示,请求响应完成! ## 2、执行流程详细 ## web.xml配置如下: <?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <servlet> <servlet-name>springMVCDispatcherServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <!-- 初始化参数 --> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:spring-mvc.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <!-- 拦截所有以do结尾的请求 --> <servlet-mapping> <servlet-name>springMVCDispatcherServlet</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping> <display-name></display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app> spring-mvc.xml配置如下: <?xml version="1.0" encoding="UTF-8"?> <!-- - Application context definition for JPetStore's business layer. - Contains bean references to the transaction manager and to the DAOs in - dataAccessContext-local/jta.xml (see web.xml's "contextConfigLocation"). --> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd"> <!-- 定义映射 --> <bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping"> <property name="mappings"> <props> <prop key="helloWorld.do">helloWorldController</prop> </props> </property> </bean> <!-- 定义视图解析器,bean的id,property的name都是spring约定的 --> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="viewClass"> <value>org.springframework.web.servlet.view.InternalResourceView</value> </property> </bean> <!-- 定义控制器 --> <bean id="helloWorldController" class="com.jpeony.springmvc.controller.HelloWorldController"> <property name="helloWorld"> <value>HelloWorld</value> </property> <property name="viewPage"> <value>/WEB-INF/jsp/index.jsp</value> </property> </bean> </beans> 上面通过简易时序图了解了大概流程,下面详细搞下请求从哪个代码进来的,在哪个代码处理,从哪个代码出去的。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 1][] 假设用Tomcat容器,SpringMVC包装Servlet,应用靠web容器Tomcat启动。 应用请求过来先到Tomcat,Tomcat 默认使用NIO模型,请求最后访问到Servlet的service()方法。 Spring MVC请求故事从Servlet的service()方法开始。 先看下DispatcherServlet的结构关系图。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 2][] 每一次的请求,根据Servlet标准,都会访问Servlet的service()方法,根据Servlet继承实现关系,SpringMVC的FrameworkServlet 重写了service()方法。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 3][] 调用父类HttpServlet的service()方法。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 4][] 假设使用的是Post请求,doPost()在FrameworkServlet中实现。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 5][] ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 6][] 调用FrameworkServlet\#doService()方法,DispatcherServlet重写doService()。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 7][] 请求具体处理在DispatcherServlet\#doDispatch()方法中,代码有点长,分开截图。 获取执行责任链。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 8][] 获取执行适配器SimpleControllerHandlerAdapter,通过handle()调用实际处理器。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 9][] 继续往下走。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 10][] 这里调用我们自己的Controller的handleRequest()方法。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 11][] 久违已久的Controller,终于进来了。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 12][] 在doDispatch()的下面部分代码,对返回结果进行处理,对ModelAndView进行处理。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 13][] ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 14][] render对结果进行处理,解析视图名称,以及将结果塞在response返回。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 15][] ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 16][] 终于,进到了spring-mvc.xml里面配置的InternalResourceViewResolver视图解析器中。 ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 17][] 返回视图地址、内容、然后端上解析、展现。 [https_github.com_yihonglei_thinking-in-springmvc]: https://github.com/yihonglei/thinking-in-springmvc [https_jpeony.blog.csdn.net_article_details_106793070]: https://jpeony.blog.csdn.net/article/details/106793070 [watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200617105028427.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk=,size_16,color_FFFFFF,t_70 [watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3lobF9qeHk_size_16_color_FFFFFF_t_70 1]: 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