SpringMVC

自己配置的第一个基于spring框架的简单登录程序（不含验证，有简单的拦截功能，也没有事务）

简单说下自己的理解，可能有错误欢迎大家指正补充，也希望自己能借此更进一步，谢谢了。

发送请求request----》到达服务器端由servlet容器分派------》相应的servlet处理完返回结果由servlet容器根据结果处理响应-----》response

springMVC中dispacherServlet继承HttpServlet，我们现在web.xml里面配置servlet

  <servlet>
      <servlet-name>springmvc</servlet-name>
      <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
      <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>classpath:springmvc-servlet.xml</param-value>
      </init-param>
      <load-on-startup>1</load-on-startup>
  </servlet>
  
  <servlet-mapping>
      <servlet-name>springmvc</servlet-name>
      <url-pattern>/</url-pattern>
  </servlet-mapping>

作用域是所有的jsp网页

servlet根据注解通过反射开始执行响应流程

先配置

springmvc-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:tx="http://www.springframework.org/schema/tx"
    xmlns:context="http://www.springframework.org/schema/context"  
    xmlns:mvc="http://www.springframework.org/schema/mvc"  
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">


    <!-- 自动扫描的包名 -->
    <context:component-scan base-package="com.zhanghaobo" ></context:component-scan>
     <!-- 默认的注解映射的支持 -->
    <mvc:annotation-driven />
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
</bean>
    
     <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />
    
     <!-- 对静态资源文件的访问  -->
     <mvc:default-servlet-handler/>
    <!--作用全局的拦截器-->
     <mvc:interceptors>
         <bean class="com.zhanghaobo.interceptor.MyAllInterceptor"></bean>
 
     </mvc:interceptors>

</beans> 

dispatherservlet通过handlermapping执行响应的操作（interceptor,handler）

拦截器就在此执行操作

识别都是通过注解的方式反射得到的所以我们要将执行的类@Controller

@RequestMapping相当于要struts2中的action配置myFirst对应的class不过这个可以直接作用于方法更灵活，不知道理解的对不对

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class MyController {
    @RequestMapping(value="/myFirst",method=RequestMethod.POST)
    public String hello(String username,String password,Model model){
        model.addAttribute("username", username);
        model.addAttribute("password", password);
        System.out.println(username+password);
        return "hello";
    }
}

拦截器在调用方法前会执行

import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class MyAllInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
        if("admin".equals(request.getParameter("username"))&&"admin".equals(request.getParameter("password"))){
            System.out.println("pre invoke");
            System.out.println(handler);
            return true;
        }
        response.sendRedirect("index.jsp");
        System.out.println("print agin");
        return false;
    }

    @Override
    public void postHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler,
            ModelAndView modelAndView) throws Exception {
        Map<String, Object> mm=modelAndView.getModel();
        for(String key:mm.keySet()){
            System.out.println(key+"-=======================-");
            mm.put("username", "张三");
            mm.put("password", "sdadsa");
        }
        System.out.println(modelAndView);
        

    }

    @Override
    public void afterCompletion(HttpServletRequest request,
            HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        
        System.out.println("over");
    }

}

拦截器要实现HandlerInterceptor，也可以根据需要选择继承（接口适配器）先执行prehandler执行成功才会下步执行响应的controller方法，接着调用posthandler这就是为什么参数里会有一个ModelAndView类型的参数，此类型有个model属性存放参数信息，我们可以打印出来，也可以修改model里面的信息，最后通过视图解析传回客户端。

 <form action="myFirst" method="post">
        username:<input type="text" name="username"><br>
        password:<input type="password" name="password"><br>
        <input type="submit" value="submit">
    </form>

返回的客户端页面hello.jsp

<body>
    
    user:${username}
        pass:${password}
  </body>

页面结果： user:张三 pass:sdadsa

控制台输出结果：

print agin
pre invoke
public java.lang.String com.zhanghaobo.MyController.hello(java.lang.String,java.lang.String,org.springframework.ui.Model)
adminadmin
username-=======================-
password-=======================-
ModelAndView: reference to view with name 'hello'; model is {username=张三, password=sdadsa}
over