MVC 框架整合思想

为什么要整合 MVC 框架

MVC 框架提供了控制器（Controller）调用 Servlet
DAO —> Service
请求响应的处理
接收请求参数 request.getParameter("")
控制程序的运行流程
视图解析（JSP、JSON、Freemarker、Thymeleaf）

Spring 可以整合哪些 MVC 框架？

struts1
webwork
jsf
struts2
springMVC

搭建 Web 运行环境

<dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>5.1.14.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-core</artifactId><version>5.1.14.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-beans</artifactId><version>5.1.14.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>5.2.6.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.1.4.RELEASE</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-aop</artifactId><version>5.1.14.RELEASE</version></dependency><dependency><groupId>org.aspectj</groupId><artifactId>aspectjrt</artifactId><version>1.8.8</version></dependency><dependency><groupId>org.aspectj</groupId><artifactId>aspectjweaver</artifactId><version>1.8.3</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>2.0.4</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.1.12</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.43</version></dependency><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.4</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.11</version><scope>test</scope></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>1.7.25</version></dependency><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.17</version></dependency><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency><dependency><groupId>javax.servlet</groupId><artifactId>jstl</artifactId><version>1.2</version></dependency><dependency><groupId>javax.servlet.jsp</groupId><artifactId>javax.servlet.jsp-api</artifactId><version>2.3.1</version><scope>provided</scope></dependency></dependencies>

Spring 整合 MVC 框架的核心思路

1. 准备工厂

Web 开发过程中如何创建工厂?

ApplicationContext ctx = new WebXmlApplicationContext("/applicationContext.xml");

如何保证工厂唯一，同时被共用？

共用：工厂存储在 ServletContext 这个作用域中，ServletContext.setAttribute("xxx", ctx);
唯一：在 ServletContext 对象创建的同时创建工厂。
ServletContextListener 在 ServletContext 对象创建的同时，被调用（只会被调用一次），
把创建工厂的代码写在 ServletContextListener 中，也会保证只调用一次，保证了工厂的唯一性。

Spring 封装了一个 ContextLoaderListener，主要做了两件事：

创建工厂
把工厂存在 ServletContext 中

ContextLoaderListener 使用方式：web.xml 中

<listener><listener-class> org.springframework.web.context.ContextLoaderListener </listen-class>
</listener><context-param><param-name> contextConfigLocation </param-name><param-value> classpath:applicationContext.xml </param-value>
</context-param>