Spring MVC 高级特性

1. 视图技术

1.1 Thymeleaf 集成

添加依赖

xml

<dependency>
    <groupId>org.thymeleaf</groupId>
    <artifactId>thymeleaf-spring6</artifactId>
    <version>3.1.0.RELEASE</version>
</dependency>

配置视图解析器

java

@Configuration
public class ThymeleafConfig {
    
    @Bean
    public SpringResourceTemplateResolver templateResolver() {
        SpringResourceTemplateResolver resolver = new SpringResourceTemplateResolver();
        resolver.setPrefix("classpath:/templates/");
        resolver.setSuffix(".html");
        resolver.setTemplateMode(TemplateMode.HTML);
        resolver.setCharacterEncoding("UTF-8");
        return resolver;
    }
    
    @Bean
    public SpringTemplateEngine templateEngine() {
        SpringTemplateEngine engine = new SpringTemplateEngine();
        engine.setTemplateResolver(templateResolver());
        engine.setEnableSpringELCompiler(true);
        return engine;
    }
    
    @Bean
    public ThymeleafViewResolver viewResolver() {
        ThymeleafViewResolver resolver = new ThymeleafViewResolver();
        resolver.setTemplateEngine(templateEngine());
        resolver.setCharacterEncoding("UTF-8");
        return resolver;
    }
}

Thymeleaf 模板示例

html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>用户列表</title>
</head>
<body>
    <h1>用户列表</h1>
    
    <table>
        <thead>
            <tr>
                <th>ID</th>
                <th>用户名</th>
                <th>邮箱</th>
            </tr>
        </thead>
        <tbody>
            <tr th:each="user : ${users}">
                <td th:text="${user.id}">1</td>
                <td th:text="${user.username}">张三</td>
                <td th:text="${user.email}">zhangsan@example.com</td>
            </tr>
        </tbody>
    </table>
    
    <a th:href="@{/users/add}">添加用户</a>
    <a th:href="@{/users/{id}(id=${user.id})}">查看详情</a>
</body>
</html>

1.2 常用 Thymeleaf 语法

html

<!-- 文本显示 -->
<span th:text="${user.name}">默认值</span>
<span th:utext="${htmlContent}">HTML内容</span>

<!-- 条件判断 -->
<div th:if="${user != null}">
    欢迎您，<span th:text="${user.name}"></span>
</div>
<div th:unless="${user == null}">
    请先登录
</div>

<!-- 循环 -->
<tr th:each="item, stat : ${items}">
    <td th:text="${stat.index}">0</td>
    <td th:text="${item.name}">名称</td>
</tr>

<!-- 链接 -->
<a th:href="@{/users}">用户列表</a>
<a th:href="@{/users/{id}(id=${user.id})}">用户详情</a>
<a th:href="@{/search(keyword=${keyword})}">搜索</a>

<!-- 表单 -->
<form th:action="@{/users}" th:object="${user}" method="post">
    <input type="text" th:field="*{username}" />
    <input type="email" th:field="*{email}" />
    <button type="submit">提交</button>
</form>

<!-- 日期格式化 -->
<span th:text="${#dates.format(date, 'yyyy-MM-dd HH:mm:ss')}">2024-01-01</span>

<!-- 数字格式化 -->
<span th:text="${#numbers.formatDecimal(price, 1, 2)}">99.99</span>

<!-- 包含片段 -->
<div th:replace="~{fragments/header :: header}"></div>
<div th:insert="~{fragments/footer :: footer}"></div>

1.3 片段定义与复用

html

<!-- fragments/header.html -->
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head th:fragment="head(title)">
    <meta charset="UTF-8">
    <title th:text="${title}">默认标题</title>
</head>
<body>
    <nav th:fragment="header">
        <a href="/">首页</a>
        <a href="/users">用户</a>
    </nav>
</body>
</html>

<!-- 使用片段 -->
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head th:replace="~{fragments/header :: head('用户管理')}"></head>
<body>
    <nav th:replace="~{fragments/header :: header}"></nav>
    
    <!-- 页面内容 -->
    
    <footer th:insert="~{fragments/footer :: footer}"></footer>
</body>
</html>

2. 内容协商

2.1 基于扩展名

java

@GetMapping(value = "/users/{id}", produces = {
    MediaType.APPLICATION_JSON_VALUE,
    MediaType.APPLICATION_XML_VALUE
})
public User getUser(@PathVariable Long id) {
    return userService.findById(id);
}

2.2 基于 Accept 头

java

@GetMapping(value = "/users")
public ResponseEntity<List<User>> getUsers() {
    return ResponseEntity.ok()
            .contentType(MediaType.APPLICATION_JSON)
            .body(userService.findAll());
}

2.3 配置内容协商

java

@Configuration
public class WebConfig implements WebMvcConfigurer {
    
    @Override
    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
        configurer
            .favorParameter(true)
            .parameterName("format")
            .ignoreAcceptHeader(false)
            .defaultContentType(MediaType.APPLICATION_JSON)
            .mediaType("json", MediaType.APPLICATION_JSON)
            .mediaType("xml", MediaType.APPLICATION_XML);
    }
}

3. 跨域处理

3.1 @CrossOrigin 注解

java

@RestController
@RequestMapping("/api")
@CrossOrigin(origins = "http://localhost:3000", maxAge = 3600)
public class ApiController {
    
    @GetMapping("/users")
    @CrossOrigin(origins = "*")
    public List<User> getUsers() {
        return userService.findAll();
    }
}

3.2 全局配置

java

@Configuration
public class WebConfig implements WebMvcConfigurer {
    
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/api/**")
                .allowedOrigins("http://localhost:3000", "http://example.com")
                .allowedMethods("GET", "POST", "PUT", "DELETE", "OPTIONS")
                .allowedHeaders("*")
                .allowCredentials(true)
                .maxAge(3600);
    }
}

3.3 CorsFilter

java

@Configuration
public class CorsConfig {
    
    @Bean
    public CorsFilter corsFilter() {
        CorsConfiguration config = new CorsConfiguration();
        config.setAllowedOrigins(List.of("http://localhost:3000"));
        config.setAllowedMethods(List.of("GET", "POST", "PUT", "DELETE"));
        config.setAllowedHeaders(List.of("*"));
        config.setAllowCredentials(true);
        
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/api/**", config);
        
        return new CorsFilter(source);
    }
}

4. 国际化

4.1 配置国际化

java

@Configuration
public class I18nConfig {
    
    @Bean
    public MessageSource messageSource() {
        ResourceBundleMessageSource source = new ResourceBundleMessageSource();
        source.setBasenames("i18n/messages");
        source.setDefaultEncoding("UTF-8");
        return source;
    }
    
    @Bean
    public LocaleResolver localeResolver() {
        SessionLocaleResolver resolver = new SessionLocaleResolver();
        resolver.setDefaultLocale(Locale.SIMPLIFIED_CHINESE);
        return resolver;
    }
    
    @Bean
    public LocaleChangeInterceptor localeChangeInterceptor() {
        LocaleChangeInterceptor interceptor = new LocaleChangeInterceptor();
        interceptor.setParamName("lang");
        return interceptor;
    }
}

4.2 消息资源文件

properties

# messages_zh_CN.properties
user.welcome=欢迎，{0}！
user.login=登录
user.logout=退出
user.profile=个人中心

# messages_en_US.properties
user.welcome=Welcome, {0}!
user.login=Login
user.logout=Logout
user.profile=Profile

4.3 使用国际化消息

java

@Controller
public class UserController {
    
    @Autowired
    private MessageSource messageSource;
    
    @GetMapping("/welcome")
    public String welcome(Locale locale, Model model) {
        String message = messageSource.getMessage(
            "user.welcome", 
            new Object[]{"张三"}, 
            locale
        );
        model.addAttribute("message", message);
        return "welcome";
    }
}

html

<!-- Thymeleaf 中使用 -->
<h1 th:text="#{user.welcome(${user.name})}">欢迎！</h1>
<button th:text="#{user.login}">登录</button>

5. 类型转换

5.1 自定义类型转换器

java

public class StringToDateConverter implements Converter<String, Date> {
    
    private static final DateTimeFormatter FORMATTER = 
        DateTimeFormatter.ofPattern("yyyy-MM-dd");
    
    @Override
    public Date convert(String source) {
        LocalDate localDate = LocalDate.parse(source, FORMATTER);
        return Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());
    }
}

public class StringToEnumConverter implements Converter<String, UserStatus> {
    
    @Override
    public UserStatus convert(String source) {
        return UserStatus.valueOf(source.toUpperCase());
    }
}

5.2 注册转换器

java

@Configuration
public class WebConfig implements WebMvcConfigurer {
    
    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(new StringToDateConverter());
        registry.addConverter(new StringToEnumConverter());
    }
}

5.3 自定义格式化器

java

public class DateFormatter implements Formatter<Date> {
    
    private static final DateTimeFormatter FORMATTER = 
        DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    
    @Override
    public String print(Date date, Locale locale) {
        return date.toInstant()
                   .atZone(ZoneId.systemDefault())
                   .format(FORMATTER);
    }
    
    @Override
    public Date parse(String text, Locale locale) throws ParseException {
        LocalDate localDate = LocalDate.parse(text, FORMATTER);
        return Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());
    }
}

6. 异步处理

6.1 Callable 返回

java

@GetMapping("/async")
public Callable<String> asyncRequest() {
    return () -> {
        Thread.sleep(2000);
        return "async-result";
    };
}

6.2 DeferredResult

java

@GetMapping("/deferred")
public DeferredResult<String> deferredRequest() {
    DeferredResult<String> result = new DeferredResult<>(5000L, "timeout");
    
    CompletableFuture.runAsync(() -> {
        try {
            Thread.sleep(2000);
            result.setResult("deferred-result");
        } catch (InterruptedException e) {
            result.setErrorResult(e);
        }
    });
    
    return result;
}

6.3 ResponseBodyEmitter

java

@GetMapping("/events")
public ResponseBodyEmitter handleEvents() {
    ResponseBodyEmitter emitter = new ResponseBodyEmitter(60000L);
    
    CompletableFuture.runAsync(() -> {
        try {
            for (int i = 0; i < 10; i++) {
                emitter.send("Event " + i + "\n");
                Thread.sleep(1000);
            }
            emitter.complete();
        } catch (Exception e) {
            emitter.completeWithError(e);
        }
    });
    
    return emitter;
}

6.4 Server-Sent Events

java

@GetMapping(value = "/sse", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
public SseEmitter handleSse() {
    SseEmitter emitter = new SseEmitter(60000L);
    
    CompletableFuture.runAsync(() -> {
        try {
            for (int i = 0; i < 10; i++) {
                SseEmitter.SseEventBuilder event = SseEmitter.event()
                    .data("Event data " + i)
                    .id(String.valueOf(i))
                    .name("message");
                emitter.send(event);
                Thread.sleep(1000);
            }
            emitter.complete();
        } catch (Exception e) {
            emitter.completeWithError(e);
        }
    });
    
    return emitter;
}

7. WebSocket

7.1 添加依赖

xml

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-websocket</artifactId>
    <version>7.0.0</version>
</dependency>

7.2 WebSocket 配置

java

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
    
    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(chatHandler(), "/chat")
                .setAllowedOrigins("*");
    }
    
    @Bean
    public ChatHandler chatHandler() {
        return new ChatHandler();
    }
}

7.3 WebSocket 处理器

java

public class ChatHandler extends TextWebSocketHandler {
    
    private final List<WebSocketSession> sessions = new CopyOnWriteArrayList<>();
    
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        sessions.add(session);
        broadcast("用户加入: " + session.getId());
    }
    
    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        broadcast("用户 " + session.getId() + ": " + message.getPayload());
    }
    
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        sessions.remove(session);
        broadcast("用户离开: " + session.getId());
    }
    
    private void broadcast(String message) throws IOException {
        for (WebSocketSession session : sessions) {
            session.sendMessage(new TextMessage(message));
        }
    }
}

7.4 STOMP 协议

java

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketStompConfig implements WebSocketMessageBrokerConfigurer {
    
    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");
        config.setApplicationDestinationPrefixes("/app");
    }
    
    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/ws")
                .setAllowedOriginPatterns("*")
                .withSockJS();
    }
}

java

@Controller
public class ChatController {
    
    @MessageMapping("/chat")
    @SendTo("/topic/messages")
    public ChatMessage send(ChatMessage message) {
        return new ChatMessage(
            message.sender(),
            message.content(),
            LocalDateTime.now()
        );
    }
    
    @MessageMapping("/private")
    @SendToUser("/queue/messages")
    public ChatMessage sendPrivate(ChatMessage message, Principal principal) {
        return new ChatMessage(
            principal.getName(),
            message.content(),
            LocalDateTime.now()
        );
    }
}

public record ChatMessage(
    String sender,
    String content,
    LocalDateTime timestamp
) {}

8. 过滤器

8.1 定义过滤器

java

@Component
public class RequestLoggingFilter implements Filter {
    
    private static final Logger logger = LoggerFactory.getLogger(RequestLoggingFilter.class);
    
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, 
                        FilterChain chain) throws IOException, ServletException {
        
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        
        logger.info("Request: {} {}", httpRequest.getMethod(), httpRequest.getRequestURI());
        
        long startTime = System.currentTimeMillis();
        chain.doFilter(request, response);
        long duration = System.currentTimeMillis() - startTime;
        
        logger.info("Response: {} ms", duration);
    }
}

8.2 过滤器注册

java

@Configuration
public class FilterConfig {
    
    @Bean
    public FilterRegistrationBean<RequestLoggingFilter> loggingFilter() {
        FilterRegistrationBean<RequestLoggingFilter> registration = new FilterRegistrationBean<>();
        registration.setFilter(new RequestLoggingFilter());
        registration.addUrlPatterns("/api/*");
        registration.setOrder(1);
        return registration;
    }
}

9. 请求限流

9.1 基于 Guava RateLimiter

xml

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>33.0.0-jre</version>
</dependency>

java

@Component
public class RateLimitInterceptor implements HandlerInterceptor {
    
    private final RateLimiter rateLimiter = RateLimiter.create(10.0);
    
    @Override
    public boolean preHandle(HttpServletRequest request, 
                            HttpServletResponse response,
                            Object handler) throws Exception {
        if (!rateLimiter.tryAcquire()) {
            response.setStatus(429);
            response.getWriter().write("请求过于频繁，请稍后再试");
            return false;
        }
        return true;
    }
}

9.2 基于 IP 限流

java

@Component
public class IpRateLimitInterceptor implements HandlerInterceptor {
    
    private final ConcurrentHashMap<String, RateLimiter> limiters = new ConcurrentHashMap<>();
    
    @Override
    public boolean preHandle(HttpServletRequest request, 
                            HttpServletResponse response,
                            Object handler) throws Exception {
        String ip = getClientIp(request);
        RateLimiter limiter = limiters.computeIfAbsent(ip, k -> RateLimiter.create(5.0));
        
        if (!limiter.tryAcquire()) {
            response.setStatus(429);
            response.getWriter().write("请求过于频繁");
            return false;
        }
        return true;
    }
    
    private String getClientIp(HttpServletRequest request) {
        String ip = request.getHeader("X-Forwarded-For");
        if (ip == null || ip.isEmpty() || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("X-Real-IP");
        }
        if (ip == null || ip.isEmpty() || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }
        return ip.split(",")[0].trim();
    }
}

10. 小结

本章学习了 Spring MVC 的高级特性：

特性	应用场景
Thymeleaf	服务端渲染，模板引擎
内容协商	多格式响应，JSON/XML
跨域处理	前后端分离，API 调用
国际化	多语言支持
类型转换	参数解析，格式化
异步处理	长时间请求，实时推送
WebSocket	实时通信，聊天室
过滤器	请求日志，编码处理
请求限流	防止滥用，保护服务

下一章将学习 Spring Boot 4 的快速入门。

Spring MVC 高级特性 ​

1. 视图技术 ​

1.1 Thymeleaf 集成 ​

添加依赖 ​

配置视图解析器 ​

Thymeleaf 模板示例 ​

1.2 常用 Thymeleaf 语法 ​

1.3 片段定义与复用 ​

2. 内容协商 ​

2.1 基于扩展名 ​

2.2 基于 Accept 头 ​

2.3 配置内容协商 ​

3. 跨域处理 ​

3.1 @CrossOrigin 注解 ​

3.2 全局配置 ​

3.3 CorsFilter ​

4. 国际化 ​

4.1 配置国际化 ​

4.2 消息资源文件 ​

4.3 使用国际化消息 ​

5. 类型转换 ​

5.1 自定义类型转换器 ​

5.2 注册转换器 ​

5.3 自定义格式化器 ​

6. 异步处理 ​

6.1 Callable 返回 ​

6.2 DeferredResult ​

6.3 ResponseBodyEmitter ​

6.4 Server-Sent Events ​

7. WebSocket ​

7.1 添加依赖 ​

7.2 WebSocket 配置 ​

7.3 WebSocket 处理器 ​

7.4 STOMP 协议 ​

8. 过滤器 ​

8.1 定义过滤器 ​

8.2 过滤器注册 ​

9. 请求限流 ​

9.1 基于 Guava RateLimiter ​

9.2 基于 IP 限流 ​

10. 小结 ​

Spring MVC 高级特性

1. 视图技术

1.1 Thymeleaf 集成

添加依赖

配置视图解析器

Thymeleaf 模板示例

1.2 常用 Thymeleaf 语法

1.3 片段定义与复用

2. 内容协商

2.1 基于扩展名

2.2 基于 Accept 头

2.3 配置内容协商

3. 跨域处理

3.1 @CrossOrigin 注解

3.2 全局配置

3.3 CorsFilter

4. 国际化

4.1 配置国际化

4.2 消息资源文件

4.3 使用国际化消息

5. 类型转换

5.1 自定义类型转换器

5.2 注册转换器

5.3 自定义格式化器

6. 异步处理

6.1 Callable 返回

6.2 DeferredResult

6.3 ResponseBodyEmitter

6.4 Server-Sent Events

7. WebSocket

7.1 添加依赖

7.2 WebSocket 配置

7.3 WebSocket 处理器

7.4 STOMP 协议

8. 过滤器

8.1 定义过滤器

8.2 过滤器注册

9. 请求限流

9.1 基于 Guava RateLimiter

9.2 基于 IP 限流

10. 小结