Spring MVC

spring 的 hello world

新建並配置 web.xml，web.xml提供路徑與servlet的映射關係

    <servlet>
        <servlet-name>springmvc</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
    </servlet>
    <servlet-mapping>    <!--這裏將 / 即任意路徑映射到 DispatcherServlet -->
        <servlet-name>springmvc</servlet-name>    <!--這裏的name要和上面的springmvc保持一致-->
        <url-pattern>/</url-pattern>    <!-- 這裏表示映射的路徑，/表示任意路徑-->
    </servlet-mapping>

建立springmvc-servlet.xml並配置，這是Spring MVC的 映射配置文件，表示訪問路徑/index會交給id=indexController的bean處理；id=indexController的bean配置爲類：dexController

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id="simpleUrlHandlerMapping"
        class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
        <property name="mappings">
            <props>
                <prop key="/index">indexController</prop>
            </props>
        </property>
    </bean>
    <bean id="indexController" class="controller.IndexController"></bean>
</beans>

控制類要實現接口controller，並提供方法handleRequest處理請求

package controller;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;
 
public class IndexController implements Controller {
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView mav = new ModelAndView("index.jsp");    //ModelAndView 將視圖層和模型層聯繫在一塊兒，new ModelAndView("index.jsp")表示視圖是index.jsp
        mav.addObject("message", "Hello Spring MVC");    //向視圖層傳遞數據，數據的名字是message，內容是 Hello Spring MVC
   　　　return mav; 
    } 
}

準備index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" isELIgnored="false"%>
 
<h1>${message}</h1>  //這裏的message與controller中的message相對應，是變量名

原理圖：

跳轉

package controller;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
 
@Controller    //註解，表示該類是一個控制器，這樣不用再實現controller接口
public class IndexController {
    @RequestMapping("/index")    //再handleRequest方法前加註解，表示 /index 路徑慧映射到該函數上
    public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
        ModelAndView mav = new ModelAndView("index");
        mav.addObject("message", "Hello Spring MVC");
        return mav;
    }
     
    @RequestMapping("/jump")    //同理將 /jump路徑映射到該函數
    public ModelAndView jump() {
        ModelAndView mav = new ModelAndView("redirect:/index");    // redirect:/index 表示服務端跳轉，跳轉到index
        return mav;
    }    
}

使用session

    @RequestMapping("/check")
    public ModelAndView check(HttpSession session) {
        Integer i = (Integer) session.getAttribute("count");
        if (i == null)
            i = 0;
        i++;
        session.setAttribute("count", i);
        ModelAndView mav = new ModelAndView("check");
        return mav;
    }