springmvc框架helloword

spring框架提供了构建web的应用程序的全功能MVC模块-spring mvc。我们首先来写一个springmvc的hellword的配置文件的形式

工程结构如下

index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>欢迎页面</title>
</head>
<body>
<!-- 页面可以访问Controller传递传递出来的message,requestScope:表示变量能在本次请求中使用 -->
${requestScope.message}
</body>
</html>

requestScope:表示变量的作用域，一共4种。pageScope: 表示变量只能在本页面使用。requestScope:表示变量能在本次请求中使用。sessionScope:表示变量能在本次会话中使用。applicationScope:表示变量能在整个应用程序中使用

web.xml配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
    http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         id="WebApp_ID" version="3.1">

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

<!--    <context-param>
        <param-name>contextClass</param-name>
      <param-value>org.springframework.web.context.support.XmlWebApplicationContext</param-value>
    </context-param>-->

    <!-- 定义Spring MVC的前端控制器 -->
    <servlet>
        <servlet-name>HelloWord</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
           <init-param>
              <param-name>contextConfigLocation</param-name>
              <param-value>config.xml</param-value>
            </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!-- 让Spring MVC的前端控制器拦截所有请求 -->
    <servlet-mapping>
        <servlet-name>HelloWord</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

config.xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-4.2.xsd">

    <!-- 配置Handle，映射"/hello"请求 -->
    <bean name="/hello" class="com.rookie.bigdata.HelloController"/>

	<!-- 处理映射器将bean的name作为url进行查找，需要在配置Handle时指定name（即url） -->
	<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>

	<!-- SimpleControllerHandlerAdapter是一个处理器适配器，所有处理适配器都要实现 HandlerAdapter接口-->
	<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>

	<!-- 视图解析器 -->
	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"/>

</beans>

HelloController.java

package com.rookie.bigdata;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.Controller;

public class HelloController implements Controller {
    private static final Log logger = LogFactory
            .getLog(HelloController.class);

    /**
     * handleRequest是Controller接口必须实现的方法。
     * 该方法的参数是对应请求的HttpServletRequest和HttpServletResponse。
     * 该方法必须返回一个包含视图路径或视图路径和模型的ModelAndView对象。
     */
    @Override
    public ModelAndView handleRequest(HttpServletRequest request,
                                      HttpServletResponse response) throws Exception {
        logger.info("handleRequest 被调用");
        // 创建准备返回的ModelAndView对象，该对象通常包含了返回视图的路径、模型的名称以及模型对象
        ModelAndView mv = new ModelAndView();
        // 添加模型数据 可以是任意的POJO对象
        mv.addObject("message", "Hello World!");
        // 设置逻辑视图名，视图解析器会根据该名字解析到具体的视图页面
        mv.setViewName("/index.jsp");
        // 返回ModelAndView对象。
        return mv;
    }

}

在idea中启动该程序，在浏览器访问即可

HelloWord的注解形式

spring2.5版本开始新增了可基于注解的控制器，控制器不需要实现Controller接口，通过注解即可达到上面的要求

web.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
    http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         id="WebApp_ID" version="3.1">

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

<!--    <context-param>
        <param-name>contextClass</param-name>
      <param-value>org.springframework.web.context.support.XmlWebApplicationContext</param-value>
    </context-param>-->

    <!-- 定义Spring MVC的前端控制器 -->
    <servlet>
        <servlet-name>HelloWord</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
           <init-param>
              <param-name>contextConfigLocation</param-name>
              <param-value>config.xml</param-value>
            </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <!-- 让Spring MVC的前端控制器拦截所有请求 -->
    <servlet-mapping>
        <servlet-name>HelloWord</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

HelloController

package com.rookie.bigdata;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

/**
 * Created by dell on 2019/6/14.
 */
@Controller
public class HelloController {

    private static final Log logger = LogFactory.getLog(HelloController.class);

    @RequestMapping(value = "/hello")
    public ModelAndView hello() {
        logger.info("该方法调用");
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject("message", "helloWord");
        modelAndView.setViewName("WEB-INF/welcome.jsp");

        return modelAndView;
    }

}

config.xml文件

<?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:context="http://www.springframework.org/schema/context"
	   xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

	<!-- spring可以自动去扫描base-pack下面的包或者子包下面的java文件，
        如果扫描到有Spring的相关注解的类，则把这些类注册为Spring的bean -->
	<context:component-scan base-package="com.rookie.bigdata"/>

	<!-- 配置处理映射器 -->
	<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/>

	<!-- 配置处理器适配器-->
	<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"/>

	<!-- 视图解析器 -->
	<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"/>

</beans>

welcome.jsp文件

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>welcome</title>
</head>
<body>
<!-- 页面可以访问Controller传递传递出来的message -->
${requestScope.message}
</body>
</html>

启动应用程序，在浏览器访问可以出现相同的效果