SpringMVC基础
Spring MVC是基于Model 2实现的技术框架，Model 2是经典的MVC模型在web应用中的变体。model 1的开发模式是：jsp+javabean的模式，它的核心是jsp页面。model 2的开发模式是：jsp+servlet+javabean的模式。
一、运行原理
用户发起请求后，由前端控制器DispatcherServlet接受用户请求响应，然后前端可控制性请求查找Handler，处理器映射器HandleMapper收到请求后通过xml或者注解，根据url找到对应的Handler（也就是Controller），找到之后前端控制器请求处理器适配器去执行Handler，处理器适配器调用处理器Handler的方法执行，返回ModelAndView，处理器适配器拿到ModelAndView后返回给前端控制器，前端控制器拿到ModelAndView后请求视图解析器去解析，解析完成之后将View返回给前端控制器，前端控制器将View进行渲染之后展示给用户。具体流程如下图所示：
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SpringMVC实现的两种方式
接口方法
1.在web.xml添加标签
<servlet>
<servlet-name>aaa</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mvc.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>aaa</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</pre>
2.添加spring-mvc.xml
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="xml" cid="n7" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/view/" />
<property name="suffix" value=".jsp" />
</bean>
<mvc:default-servlet-handler />
<bean name="/ProductInput" class="com.qfedu.controller.ProductInputController" />
<bean name="/SaveProductController" class="com.qfedu.controller.SaveProductController" />
</beans></pre>
3.会根据输入的地址查找servlet
SaveProductController.java
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n10" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">public class SaveProductController implements Controller {
@Override
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
String spid = request.getParameter("pid");
String pname = request.getParameter("pname");
String sprice = request.getParameter("price");
int pid = spid == null ? 0 : Integer.parseInt(spid);
double price = sprice==null ? 0.0 : Double.parseDouble(sprice);
Product p = new Product();//javaBean
p.setPid(pid);
p.setPname(pname);
p.setPrice(price);
/**
- 创建模型视图对象
- 该代码等同于以前的两行代码
request.setAttribute("p", p);request.getRequestDispatcher("detail.jsp").forward(request, response);
*/
ModelAndView mv = new ModelAndView("detail.jsp", "p", p);
return mv;
}
}</pre>
注解方法
1.在web.xml添加标签
<servlet>
<servlet-name>aaa</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-mvc.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>aaa</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</pre>
2.添加spring-mvc.xml
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="xml" cid="n15" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/view/" />
</bean>
<mvc:default-servlet-handler />
<context:component-scan base-package="com.qfedu.controller" />
<mvc:annotation-driven />
</pre>
在指定包下，扫描，在根据url指定方法
EmpController.java
<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n18" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: var(--monospace); font-size: 0.9em; display: block; break-inside: avoid; text-align: left; white-space: normal; background-image: inherit; background-position: inherit; background-size: inherit; background-repeat: inherit; background-attachment: inherit; background-origin: inherit; background-clip: inherit; background-color: rgb(248, 248, 248); position: relative !important; border: 1px solid rgb(231, 234, 237); border-radius: 3px; padding: 8px 4px 6px; margin-bottom: 15px; margin-top: 15px; width: inherit; color: rgb(51, 51, 51); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">@Controller
public class EmpController {
private IEmpService empService = new EmpServiceImpl();
/**
- 如果有了users请求，那么该方法会被调用，返回值为将来要渲染的页面
- @return
*/
@RequestMapping("/users")
public String getUsersPage(Model model, HttpSession session){
List<Emp> list = empService.getAllEmps();
model.addAttribute("list", list);
session.setAttribute("list", list);
return "user.jsp";
}
@RequestMapping("/getEmpByEid")
public String getEmpByEid(HttpServletRequest request, Model model){
String seid = request.getParameter("eid");
int eid = seid == null ? -1 : Integer.parseInt(seid);
Emp emp = empService.getEmpByEid(eid);
model.addAttribute("emp", emp);
return "updateEmp.jsp";
}
}</pre>
