springmvc

image.png

整体过程

1. 发起请求到前端控制器(DispatcherServlet)
2. 前端控制器请求HandlerMapping查找Handler
   可以根据xml配置， 注解进行查找
3. 处理器映射器HandlerMapping 向前端控制器返回Handler
4. 前端控制器调用处理器适配handleAdapter器去执行Handler
5. 处理器适配器去执行handler
6. handler执行完成给适配器返回modelandview
7. 处理器适配器向前端控制器返回modelAndview
   modelandview是springmvc框架的 一个底层对象，包括modelandview
8. 前端控制器请求视图解析器去进行视图解析
9. 视图解析器向前端控制器返回view
10. 前端控制器进行视图渲染
    视图渲染将Modelandview中的数据填充到response域
    11.前端控制器向用户响应结果

基于非注解的配置

• 使用

<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"></bean>
    <bean class="org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter"></bean>

要注意对应的handler需要分别实现对应的接口才会被适配器所执行

public class HttpRequestHandlerAdapter implements HandlerAdapter {
    @Override
    public boolean supports(Object handler) {
        return (handler instanceof HttpRequestHandler);
    }
}
public class SimpleControllerHandlerAdapter implements HandlerAdapter {
    @Override
    public boolean supports(Object handler) {
        return (handler instanceof Controller);
    }
}

这两种也是dispatcher的默认配置，所以不需要在dispatcher-servlet.xml中显式配置也可以。默认配置文件可以在对应jar包(org.springframework.web.servlet)中获取

# Default implementation classes for DispatcherServlet's strategy interfaces.
# Used as fallback when no matching beans are found in the DispatcherServlet context.
# Not meant to be customized by application developers.

org.springframework.web.servlet.LocaleResolver=org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver

org.springframework.web.servlet.ThemeResolver=org.springframework.web.servlet.theme.FixedThemeResolver

org.springframework.web.servlet.HandlerMapping=org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,\
    org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping

org.springframework.web.servlet.HandlerAdapter=org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,\
    org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,\
    org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter

org.springframework.web.servlet.HandlerExceptionResolver=org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver,\
    org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver,\
    org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver

org.springframework.web.servlet.RequestToViewNameTranslator=org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator

org.springframework.web.servlet.ViewResolver=org.springframework.web.servlet.view.InternalResourceViewResolver

org.springframework.web.servlet.FlashMapManager=org.springframework.web.servlet.support.SessionFlashMapManager

基于注解的方式配置

配置annotationdispatcher-servlet.xml

<?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.mvc.method.annotation.RequestMappingHandlerMapping"></bean>-->
    <!--<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"></bean>-->
    <!--mvc:annotation-driven可以用来代替以上RequestMappingHandlerMapping和RequestMappingHandlerAdapter 的关系-->
    <mvc:annotation-driven></mvc:annotation-driven>

    <context:component-scan base-package="com.vee.controller"></context:component-scan>
    <!--视图解析器，解析jsp，默认使用jstl标签-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--配置前缀和后缀就可以在写modleAndView的viewName的时候不用写出完整的绝对路径名-->
        <property name="prefix" value="/WEB-INF/jsp/"></property>
        <property name="suffix" value=".jsp"></property>
    </bean>
</beans>

同时web.xml中servlet也要修改成annotationdispatcher

      <servlet>
        <servlet-name>annotationdispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>annotationdispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

使用注解的Controller类

//使用注解标识的控制器
@Controller
public class AnnotationHandler {
    @RequestMapping("/wocaolei")
    public ModelAndView handle(){
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject("mesg", "annotationHandler..");
        //这个是没有使用前后缀的完整路径
        modelAndView.setViewName("/WEB-INF/jsp/welcome.jsp");
        return modelAndView;
    }
    //如果返回结果是字符串adapter会把他当成modelAndView中的viewName 来处理
    @RequestMapping("/wocaolei2")
    public String handle2(){
        System.out.println("annotation handle2");
        return  "welcome";
    }
}