SpringMVC基础

最新推荐文章于 2025-06-13 15:06:56 发布

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最新推荐文章于 2025-06-13 15:06:56 发布

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分类专栏： SpringMVC 文章标签： java spring 后端开发语言 maven jvm

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本文详细介绍了SpringMVC框架的三层架构、工作原理，包括Model-View-Controller的职责划分，以及入门案例中的配置、请求处理流程。还涵盖了静态资源加载、中文乱码处理和注解驱动的配置方法。

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1.SpringMVC概述

三层架构

表现层：负责数据展示

业务层：负责业务处理

数据层：负责数据操作

MVC（Model View Controller），一种用于设计创建Web应用程序表现层的模式

Model（模型）：数据模型，用于封装数据

View（视图）：页面视图，用于展示数据

jsp

html

Controller（控制器）：处理用户交互的调度器，用于根据用户需求处理程序逻辑

Servlet

SpringMVC

SpringMVC简介

SpringMVC是一种基于Java实现MVC模型的轻量级Web框架

SpringMVC的优点

使用简单

性能突出（相比现有的框架技术）

灵活性强

2.入门案例

入门案例工作流程分析

服务器启动

加载web.xml中DispatcherServlet

读取spring-mvc.xml中的配置，加载所有com包中所有标记为bean的类

读取bean中方法上方标注@RequestMapping的内容

处理请求

DispatcherServlet配置拦截所有请求 /

使用请求路径与所有加载的@RequestMapping的内容进行比对

执行对应的方法

根据方法的返回值在webapp目录中查找对应的页面并展示

实现

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com</groupId>
    <artifactId>SpringMVCrumen</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.1.19.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.3.22</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.16</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.13</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.33</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.7</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.4</version>
        </dependency>
        <!--servlet3.1规范的坐标-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <!--jsp坐标-->
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
            <scope>provided</scope>
        </dependency>
        <!--spring web坐标-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
        <!--springmvc坐标-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.9.RELEASE</version>
        </dependency>
    </dependencies>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <!--构建-->
    <build>
        <!--设置插件-->
        <plugins>
            <!--具体的插件配置-->
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.1</version>
                <configuration>
                    <port>80</port>
                    <path>/</path>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

package com.web;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class UserServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("user servlet running...");
        req.getRequestDispatcher("success.jsp").forward(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

package com.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class UserController {
    @RequestMapping("/save")
    public String save(){
        System.out.println("user mvc controller is running...");
        return "success.jsp";
    }
}

web.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">

    <servlet>
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath*:spring-mvc.xml</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>DispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" pageEncoding="utf-8" %>
<html>
<body>
<h1>第一个spring-mvc页面</h1>
</body>
</html>

3.SpringMVC技术架构

六大核心组件

DispatcherServlet：前端控制器，是整体流程控制的中心，由其调用其它组件处理用户的请求，有

效的降低了组件间的耦合性

HandlerMapping：处理器映射器，负责根据用户请求找到对应具体的Handler处理器

Handler：处理器，业务处理的核心类，通常由开发者编写，描述具体的业务

HandlAdapter：处理器适配器，通过它对处理器进行执行

View Resolver：视图解析器，将处理结果生成View视图

View：视图，最终产出结果，常用视图如jsp、html

4.基本配置

1.Controller加载控制

SpringMVC的处理器对应的bean必须按照规范格式开发，未避免加入无效的bean可通过bean加载过滤器进行包含设定或排除设定，表现层bean标注通常设定为@Controller

<context:component-scan base-package="com">
    <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
</context:component-scan>

2.静态资源加载

图片并未加载成功

回到代码中发现

当发起一个请求以后

DispatcherServlet配置拦截所有请求/

这使静态资源无法成功加载

解决方法

核心控制器拦截的是所有请求，需要对静态资源请求进行方行，通过配置放行资源实现

<!--放行指定类型静态资源配置方式-->
<mvc:resources mapping="/img/**" location="/img/"/>
<mvc:resources mapping="/js/**" location="/js/"/>
<mvc:resources mapping="/css/**" location="/css/"/>

使用简化格式可以放行所有普通资源调用，无需一一枚举

<!--SpringMVC提供的通用资源放行方式-->
<mvc:default-servlet-handler/>

样例

<?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:util="http://www.springframework.org/schema/util"
       xmlns:set="http://www.springframework.org/schema/util"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
		https://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">

    <context:component-scan base-package="com">
        <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>
   <!-- <mvc:resources mapping="/img/**" location="/img/"/>
    <mvc:resources mapping="/js/**" location="/img/"/>
    <mvc:resources mapping="/css/**" location="/img/"/>-->
    <mvc:default-servlet-handler/>
</beans>

3.中文乱码处理

SpringMVC提供专用的中文字符过滤器，用于处理乱码问题

配置在web.xml中

<!--乱码处理过滤器，与Servlet中使用的完全相同，差异之处在于处理器的类由Spring提供-->
<filter>
    <filter-name>CharacterEncodingFilter</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>CharacterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

4.注解驱动

目的：去掉spring-mvc.xml与web.xml

使用注解形式转化SpringMVC核心配置文件为配置类

创建com.config.SpringMVCConfiguration

package com.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
@ComponentScan(value = "com",includeFilters =
    @ComponentScan.Filter(type = FilterType.ANNOTATION,classes = {Controller.class})
)
public class SpringMVCConfiguration implements WebMvcConfigurer {
   /* <mvc:resources mapping="/img/**" location="/img/"/>
    <mvc:resources mapping="/js/**" location="/img/"/>
    <mvc:resources mapping="/css/**" location="/img/"/>*/
    //代替
//    @Override
//    public void addResourceHandlers(ResourceHandlerRegistry registry) {
//        registry.addResourceHandler("/img/**").addResourceLocations("/img/");
//        registry.addResourceHandler("/js/**").addResourceLocations("/js/");
//        registry.addResourceHandler("/css/**").addResourceLocations("/css/");
//    }

//    <mvc:default-servlet-handler/>
    //代替
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }
}

基于servlet3.0规范，自定义Servlet容器初始化配置类，加载SpringMVC核心配置类

创建com.config.ServletContainersInitConfig

package com.config;

import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.servlet.support.AbstractDispatcherServletInitializer;

import javax.servlet.DispatcherType;
import javax.servlet.FilterRegistration;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import java.lang.annotation.Annotation;
import java.util.EnumSet;

public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {
   /* <servlet>
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath*:spring-mvc.xml.bak</param-value>
        </init-param>
    </servlet>*/
    //代替
    @Override
    protected WebApplicationContext createServletApplicationContext() {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(SpringMVCConfiguration.class);
        return ctx;
    }

   /* <servlet-mapping>
        <servlet-name>DispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>*/
    //代替
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    @Override
    protected WebApplicationContext createRootApplicationContext() {
        return null;
    }

   /* <filter>
        <filter-name>CharacterEncodingFilter</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>CharacterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>*/
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        super.onStartup(servletContext);
        CharacterEncodingFilter cef = new CharacterEncodingFilter();
        cef.setEncoding("UTF-8");

        FilterRegistration.Dynamic registration = servletContext.addFilter("characterEncodingFilter",cef);
        registration.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST,DispatcherType.FORWARD,DispatcherType.INCLUDE),false,"/*");
    }
}

此时就可以删除spring-mvc.xml与web.xml