SpringMVC 本质也是解耦
先提前插一嘴
这里用到的是简单的maven项目:
在添加web应用时报错
Artifacts Web facet resources 爆红
参考:https://blog.csdn.net/weixin_43739266/article/details/122133398 添加web依赖
要为项目添加web项目依赖否则无法tomcat访问
为了介绍MVC我打算直接用一个例子来看:、
首先位于WEB-INF下文件夹jsp建一个hello.jsp 用于显示
没用springboot之前我们需要手动编写xml文件:
来看几步死的:
1.web.xml的配置 需要更改的就是 classpath:你的.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<!--1.注册DispatcherServlet-->
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!--关联一个springmvc的配置文件:【servlet-name】-servlet.xml-->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc_servlet.xml</param-value>
</init-param>
<!--启动级别-1-->
<load-on-startup>1</load-on-startup>
</servlet>
<!--/ 匹配所有的请求;(不包括.jsp)-->
<!--/* 匹配所有的请求;(包括.jsp)-->
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!--spring提供解决乱码问题-->
<filter>
<filter-name>encoding</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
2.你对应路径下的 Springmvc.xml
classpath 下即resource下创建的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"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
<!--视图解析器:DispatcherServlet给他的ModelAndView-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="InternalResourceViewResolver">
<!--前缀-->
<property name="prefix" value="/WEB-INF/jsp/"/>
<!--后缀-->
<property name="suffix" value=".jsp"/>
</bean>
<!-- bean注册controller跳转-->
<bean id="/hello" class="controller.hello"/>
</beans>
3.controller层编写
package controller;
import org.springframework.web.servlet.mvc.Controller;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//一个继承的controller
//不使用注解
public class hello implements Controller {
public ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception {
//ModelAndView 模型和视图
ModelAndView mv = new ModelAndView();
//封装对象,放在ModelAndView中。Model
mv.addObject("msg","HelloSpringMVC!");
//封装要跳转的视图,放在ModelAndView中
mv.setViewName("hello"); //: /WEB-INF/jsp/hello.jsp
return mv;
}
}
是的你咋看咋不顺眼 改为注解形式:
package controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
@RequestMapping("/gao")
public class hello {
@RequestMapping("/hello")
public String hello(Model model) {
model.addAttribute("msg", "高低远近");
return "hello";
}
}
最终体的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"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!-- 自动扫描包,让指定包下的注解生效,由IOC容器统一管理 -->
<context:component-scan base-package="controller"/>
<!-- 让Spring MVC不处理静态资源 -->
<mvc:default-servlet-handler />
<!--
支持mvc注解驱动
在spring中一般采用@RequestMapping注解来完成映射关系
要想使@RequestMapping注解生效
必须向上下文中注册DefaultAnnotationHandlerMapping
和一个AnnotationMethodHandlerAdapter实例
这两个实例分别在类级别和方法级别处理。
而annotation-driven配置帮助我们自动完成上述两个实例的注入。
-->
<mvc:annotation-driven />
<!-- 视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
id="internalResourceViewResolver">
<!-- 前缀 -->
<property name="prefix" value="/WEB-INF/jsp/" />
<!-- 后缀 -->
<property name="suffix" value=".jsp" />
</bean>
</beans>
等会总结 这里还有个蛋疼的问题就是关于jdk编译改码的问题还有lib包问题
参考:https://blog.csdn.net/qq_46906413/article/details/131815212
正常web下项目要有lib文件所有资源识别在此:
是的感觉不是框架阶段 还是javaweb阶段 还得手动导包!
然后tomcat启动测试就行
那来看下过程:
来看看之前的:那两个省略的:
<bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/>
<bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter"/>
两个的作用呢:
- HandlerMapping
把请求映射为 HandlerExecutionChain 对象(包含一 个Handler 处理器(页面控制器)对象、多个HandlerInterceptor 拦截器)对象,通过这种策略模式,很容易添加新 的映射策略 - HandlerAdapter
处理器功能处理方法的调用,HandlerAdapter 将会根据适配的结果调用真正的处理器的功能处 理方法,完成功能处理;并返回一个ModelAndView 对象(包含模型数据、逻辑视图名)
当然还有其他组件 这就是Springmvc的强大之处例如:
filter过滤器拦截器
locale resolve国际化
multipartresolver文件上传
......
@Controller 被spring接管 返回值若为string 则进行跳转
@RequestMapping("") 是一个总的
参考:https://blog.csdn.net/weixin_61034310/article/details/135324203
ResultFul
package controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;
@Controller
public class ResultFulController {
// @RequestMapping(value = "/haha/{a}/{b}",method = RequestMethod.DELETE)
// 等同下面
// @DeleteMapping("/haha/{a}/{b}")
// @PostMapping(path = "/haha/{a}/{b}")
// @PostMapping(value = "/haha/{a}/{b}")
//传参的方式为get 请求post会报405错误
@PostMapping("/haha/{a}/{b}")
//@PathVariable 对应ResultFul传参
public String hello(@PathVariable int a,@PathVariable int b, Model model){
int res=a+b;
model.addAttribute("msg",res);
return "hello";
}
@GetMapping("/hahaha/{a}/{b}")
public String hello2(@PathVariable int a,@PathVariable int b, Model model){
int res=a+b;
model.addAttribute("msg",res);
return "hello";
}
}
package controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import pojo.User;
@Controller
@RequestMapping("/user")
public class Usercontroller {
@RequestMapping("/one")
//传参数必须为 user=
public String haha(@RequestParam("user") String name, Model model) {
model.addAttribute("msg", name);
return "hello";
}
@RequestMapping("/two")
//传参数必须对应实体类User的字段 name=
public String haha(User user, Model model) {
model.addAttribute("msg", user.getName());
return "hello";
}
}
再来看一个拦截功能 即登录实现
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2024/5/21
Time: 10:24
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<h1>登录页面</h1>
<hr>
<body>
<form action="${pageContext.request.contextPath}/user/login">
用户名:<input type="text" name="username"> <br>
密码:<input type="password" name="pwd"> <br>
<input type="submit" value="提交">
</form>
</body>
</html>
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2024/5/21
Time: 10:24
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>登录成功页面</h1>
<hr>
${user}
<a href="${pageContext.request.contextPath}/user/logout">注销</a>
</body>
</html>
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2024/5/24
Time: 15:43
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<h1>首页</h1>
<hr>
<%--登录--%>
<a href="${pageContext.request.contextPath}/user/jumplogin">登录</a>
<a href="${pageContext.request.contextPath}/user/jumpSuccess">成功页面</a>
</body>
</html>
package controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpSession;
@Controller
@RequestMapping("/user")
public class Usercontroller {
//跳转到登陆页面
@RequestMapping("/jumplogin")
public String jumpLogin() throws Exception {
return "login";
}
//跳转到成功页面
@RequestMapping("/jumpSuccess")
public String jumpSuccess() throws Exception {
return "success";
}
//登陆提交
@RequestMapping("/login")
public String login(HttpSession session, String username, String pwd) throws Exception {
// 向session记录用户身份信息
System.out.println("接收前端==="+username);
session.setAttribute("user", username);
return "success";
}
//退出登陆
@RequestMapping("logout")
public String logout(HttpSession session) throws Exception {
// session 过期
session.invalidate();
return "login";
}
}
package config;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
public class loginconfig implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws ServletException, IOException {
// 如果是登陆页面则放行
System.out.println("uri: " + request.getRequestURI());
if (request.getRequestURI().contains("login")) {
return true;
}
HttpSession session = request.getSession();
// 如果用户已登陆也放行
if(session.getAttribute("user") != null) {
return true;
}
// 用户没有登陆跳转到登陆页面
request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
return false;
}
public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
}
public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
}
}
<!--关于拦截器的配置-->
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<bean id="loginInterceptor" class="config.loginconfig"/>
</mvc:interceptor>
</mvc:interceptors>
还有就是文件上传下载 也是死东西可以直接运用:
参考:https://cloud.tencent.com/developer/article/1594124
文章更详细参考:https://pdai.tech/md/spring/spring-x-framework-springmvc.html