spring mvc 学习笔记

柔光的暖阳◎ 2022-01-21 05:01 233阅读 0赞

SpringMVC是一个基于MVC模式的WEB框架，它解决WEB开发中常见的问题(参数接收、文件上传/下载、表单验证、国际化、等等)，使用非常简单，SpringMVC作为**Spring****中的一个模块**,可以与Spring无缝集成。

MVC全名是Model View Controller，是模型(model)－视图(view)－控制器(controller)的缩写，一种软件设计典范，用一种业务逻辑、数据、界面显示分离的方法组织代码，将业务逻辑聚集到一个部件里面，在改进和个性化定制界面及用户交互的同时，不需要重新编写业务逻辑。

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**spring mvc 执行流程：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 1][]

导入jar包：

<dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-webmvc</artifactId>
          <version>5.1.1.RELEASE</version>
        </dependency>
        <dependency>
          <groupId>javax.servlet</groupId>
          <artifactId>javax.servlet-api</artifactId>
          <version>3.1.0</version>
        </dependency>

**新建一个spring mvc 的配置文件： **

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:mvc="http://www.springframework.org/schema/mvc"
           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.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context.xsd
           http://www.springframework.org/schema/mvc
           http://www.springframework.org/schema/mvc/spring-mvc.xsd
    ">
        
        <bean id="/hello" class="cn.mesmile.springmvc.demo.ControllerDemo1">
        </bean>
        
        
        <context:component-scan base-package="cn.mesmile.springmvc.demo">
        </context:component-scan>
    
        
        <mvc:annotation-driven/>
        
        <mvc:default-servlet-handler/>
    
        
        <mvc:annotation-driven>
            <mvc:message-converters register-defaults="true">
                <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                    <property name="supportedMediaTypes">
                        <list>
                            <value>text/html;charset=UTF-8</value>
                            <value>application/json;charset=UTF-8</value>
                        </list>
                    </property>
                </bean>
            </mvc:message-converters>
        </mvc:annotation-driven>
    
    </beans>

配置web.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://java.sun.com/xml/ns/javaee"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                          http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
             version="3.0"
             metadata-complete="false">
    
      <servlet>
        
        <servlet-name>core</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        
        <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>classpath:applicationContext-mvc.xml</param-value>
        </init-param>
      </servlet>
    
      <servlet-mapping>
        
        <servlet-name>core</servlet-name>
        <url-pattern>/</url-pattern>
      </servlet-mapping>
    
    
      
      <filter>
        <filter-name>encodingFilter</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>
        <init-param>
          <param-name>forceEncoding</param-name>
          <param-value>true</param-value>
        </init-param>
      </filter>
      <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
      </filter-mapping>
    
    </web-app>

###  用mvc的方式一，实现controller接口： ###

public class ControllerDemo1 implements Controller{
    
        @Override
        public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
            // ①跳转路径
    //        httpServletResponse.sendRedirect("https://www.baidu.com/");
    
            Employee employee = new Employee();
    
            employee.setUsername("姓名");
    
            ModelAndView modelAndView = new ModelAndView();
            // 设置值
            modelAndView.addObject("data", "数据");
            // 设置对象
            modelAndView.addObject(employee);
    
            // ②转发
            modelAndView.setViewName("/WEB-INF/test.jsp");
    
            return modelAndView;
        }
    }

实体类：

public class Employee {
        private String username;
        private String password;
        public String getUsername() {
            return username;
        }
    
        public void setUsername(String username) {
            this.username = username;
        }
    
        public String getPassword() {
            return password;
        }
    
        public void setPassword(String password) {
            this.password = password;
        }
    
        @Override
        public String toString() {
            return "Employee{" +
                    "username='" + username + '\'' +
                    ", password='" + password + '\'' +
                    '}';
        }
    }

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测试：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 3][]

###  用mvc的方式二，注解方式：  ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 4][]

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**spring mvc 默认是转发：转发时候地址栏不会发生变化。**

### ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 7][] ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 8][]

### 三、在spring mvc 中配置视图解析器  ###

在spring mvc的配置文件中配置 视图解析器：

![20190608112649132.png][]

![20190608112827302.png][] ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 9][]

**在返回值中，用到了 forward的时候会让视图解析器失效。**

![20190608113114814.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 10][]

**在返回值中，用到了 redirect的时候会让视图解析器失效。**

![20190608115936665.png][] ![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3N1cHJlemhlbmc_size_16_color_FFFFFF_t_70 11][]

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[20190608112649132.png]: /images/20220121/9ec21ca94c4b4899835c6220c4e4d5da.png
[20190608112827302.png]: https://img-blog.csdnimg.cn/20190608112827302.png
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[20190608115936665.png]: https://img-blog.csdnimg.cn/20190608115936665.png
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