Spring全家桶笔记九：Web层与RESTful
Spring MVC概述
Spring MVC是Spring框架的Web层模块，基于Servlet API构建，实现了MVC设计模式。
请求处理流程
- 请求 → DispatcherServlet
- HandlerMapping查找处理器
- HandlerAdapter执行处理器
- Controller处理业务逻辑
- ViewResolver解析视图
- 渲染视图 → 响应
核心组件
DispatcherServlet
前端控制器，统一处理请求和响应。
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<servlet>
<servlet-name>dispatcher</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>
<load-on-startup>1</load-on-startup>
</servlet>
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@Controller vs @RestController
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@Controller
public class UserController {
@GetMapping("/user/{id}")
public String getUser(Model model) {
model.addAttribute("user", userService.findById(id));
return "userDetail";
}
}
@RestController
public class UserController {
@GetMapping("/user/{id}")
public User getUser(@PathVariable Long id) {
return userService.findById(id);
}
}
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请求参数绑定
路径参数
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| @GetMapping("/user/{id}")
public User getUser(@PathVariable Long id) {
return userService.findById(id);
}
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请求参数
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| @GetMapping("/user/list")
public List<User> list(
@RequestParam(defaultValue = "1") int page,
@RequestParam(defaultValue = "10") int size,
@RequestParam(required = false) String name
) {
return userService.list(page, size, name);
}
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请求体
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| @PostMapping("/user")
public User create(@RequestBody User user) {
return userService.save(user);
}
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表单提交
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| @PostMapping("/user/save")
public String save(@ModelAttribute User user, BindingResult result) {
if (result.hasErrors()) {
return "userForm";
}
userService.save(user);
return "redirect:/user/list";
}
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RESTful API设计
规范
| 方法 |
用途 |
示例 |
| GET |
查询 |
GET /users |
| POST |
创建 |
POST /users |
| PUT |
更新 |
PUT /users/1 |
| DELETE |
删除 |
DELETE /users/1 |
响应结构
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| public class ApiResponse<T> {
private int code;
private String message;
private T data;
public static <T> ApiResponse<T> success(T data) {
return new ApiResponse<>(200, "success", data);
}
public static <T> ApiResponse<T> error(String message) {
return new ApiResponse<>(500, message, null);
}
}
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统一异常处理
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| @RestControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(BusinessException.class)
public ApiResponse<Void> handleBusinessException(BusinessException e) {
return ApiResponse.error(e.getMessage());
}
@ExceptionHandler(Exception.class)
public ApiResponse<Void> handleException(Exception e) {
return ApiResponse.error("系统错误");
}
}
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文件上传
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| @PostMapping("/upload")
public ApiResponse<String> upload(@RequestParam("file") MultipartFile file) {
if (file.isEmpty()) {
return ApiResponse.error("文件为空");
}
String filename = file.getOriginalFilename();
return ApiResponse.success(filename);
}
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跨域处理
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| @CrossOrigin(origins = "*")
@RestController
public class UserController {}
@Configuration
public class WebConfig implements WebMvcConfigurer {
@Override
public void addCorsMappings(CorsRegistry registry) {
registry.addMapping("/api/**")
.allowedOrigins("*")
.allowedMethods("GET", "POST", "PUT", "DELETE");
}
}
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拦截器
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| @Component
public class AuthInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
String token = request.getHeader("Authorization");
if (token == null) {
response.setStatus(401);
return false;
}
return true;
}
}
@Configuration
public class WebConfig implements WebMvcConfigurer {
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new AuthInterceptor())
.addPathPatterns("/api/**");
}
}
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总结
Spring MVC提供了强大的Web开发能力，RESTful风格的API设计已成为现代Web服务的主流选择。掌握请求参数绑定、异常处理、拦截器等核心功能是开发高效Web应用的基础。