概述
Spring MVC 是 Spring Framework 的一部分，是基于 Java 实现 MVC 设计模式的轻量级 Web 框架。核心组件
| 组件 | 说明 |
|---|---|
| DispatcherServlet | 前端控制器，统一处理请求和响应 |
| HandlerMapping | 处理器映射器，根据 URL 找到处理器 |
| HandlerAdapter | 处理器适配器，执行处理器 |
| ViewResolver | 视图解析器，解析视图 |
| Handler/Controller | 处理器/控制器，处理业务逻辑 |
执行流程
1. 用户发送请求
│
▼
2. DispatcherServlet（前端控制器）
│
├──▶ 3. HandlerMapping（处理器映射器）
│ 找到对应的 Handler
│
├──▶ 4. HandlerAdapter（处理器适配器）
│ 执行 Handler
│
├──▶ 5. Handler（控制器）
│ 处理业务，返回 ModelAndView
│
├──▶ 6. ViewResolver（视图解析器）
│ 解析视图名称
│
└──▶ 7. View（视图）
渲染数据，返回响应
环境搭建
Maven 依赖
<dependencies>
<!-- Spring MVC -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>6.1.0</version>
</dependency>
<!-- Servlet API -->
<dependency>
<groupId>jakarta.servlet</groupId>
<artifactId>jakarta.servlet-api</artifactId>
<version>6.0.0</version>
<scope>provided</scope>
</dependency>
<!-- JSON 处理 -->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.15.0</version>
</dependency>
<!-- Thymeleaf（可选） -->
<dependency>
<groupId>org.thymeleaf</groupId>
<artifactId>thymeleaf-spring6</artifactId>
<version>3.1.0.RELEASE</version>
</dependency>
</dependencies>
配置 web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee
https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd"
version="6.0">
<!-- 配置 DispatcherServlet -->
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!-- 指定配置文件位置 -->
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc.xml</param-value>
</init-param>
<!-- 启动时加载 -->
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<!-- 拦截所有请求 -->
<url-pattern>/</url-pattern>
</servlet-mapping>
<!-- 字符编码过滤器 -->
<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>
<init-param>
<param-name>forceEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
Spring MVC 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"
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
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!-- 组件扫描 -->
<context:component-scan base-package="com.example.controller"/>
<!-- 开启注解驱动 -->
<mvc:annotation-driven/>
<!-- 视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/"/>
<property name="suffix" value=".jsp"/>
</bean>
<!-- 静态资源处理 -->
<mvc:resources mapping="/static/**" location="/static/"/>
<!-- 默认 Servlet 处理 -->
<mvc:default-servlet-handler/>
</beans>
Java 配置方式
// 配置类
@Configuration
@EnableWebMvc
@ComponentScan("com.example")
public class WebConfig implements WebMvcConfigurer {
// 视图解析器
@Bean
public ViewResolver viewResolver() {
InternalResourceViewResolver resolver = new InternalResourceViewResolver();
resolver.setPrefix("/WEB-INF/views/");
resolver.setSuffix(".jsp");
return resolver;
}
// 静态资源处理
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
registry.addResourceHandler("/static/**")
.addResourceLocations("/static/");
}
// 默认 Servlet 处理
@Override
public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
configurer.enable();
}
}
// Web 应用初始化器
public class WebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
@Override
protected Class<?>[] getRootConfigClasses() {
return new Class[]{RootConfig.class};
}
@Override
protected Class<?>[] getServletConfigClasses() {
return new Class[]{WebConfig.class};
}
@Override
protected String[] getServletMappings() {
return new String[]{"/"};
}
@Override
protected Filter[] getServletFilters() {
CharacterEncodingFilter filter = new CharacterEncodingFilter();
filter.setEncoding("UTF-8");
filter.setForceEncoding(true);
return new Filter[]{filter};
}
}
第一个 Controller
@Controller
public class HelloController {
// 返回视图
@RequestMapping("/hello")
public String hello(Model model) {
model.addAttribute("message", "Hello, Spring MVC!");
return "hello"; // 返回视图名，由视图解析器解析
}
// 返回 JSON
@RequestMapping("/api/hello")
@ResponseBody
public Map<String, String> helloJson() {
Map<String, String> result = new HashMap<>();
result.put("message", "Hello, Spring MVC!");
return result;
}
}
@Controller vs @RestController
| 注解 | 说明 |
|---|---|
| @Controller | 标识控制器，方法返回视图名 |
| @RestController | @Controller + @ResponseBody，返回数据 |
// @Controller - 返回视图
@Controller
public class ViewController {
@RequestMapping("/page")
public String page() {
return "page"; // 返回视图名
}
@RequestMapping("/data")
@ResponseBody
public User data() {
return new User(); // 返回 JSON
}
}
// @RestController - 返回 JSON
@RestController
public class ApiController {
@RequestMapping("/api/user")
public User getUser() {
return new User(); // 自动转为 JSON
}
}