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Java控制器案例如何开发

wen java案例 26

本文目录导读：

Java控制器案例如何开发

  1. 基础Spring MVC控制器
  2. Spring Boot控制器进阶
  3. 实用技巧和最佳实践
  4. 控制器测试

我来为你详细介绍Java控制器的开发案例，涵盖Spring MVC和Spring Boot两种主流方式。

基础Spring MVC控制器

1 简单控制器案例

package com.example.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;
@Controller
@RequestMapping("/user")
public class UserController {
    // 返回视图
    @GetMapping("/login")
    public String login() {
        return "login"; // 返回视图名称
    }
    // 返回数据
    @GetMapping("/getInfo")
    @ResponseBody
    public String getUserInfo() {
        return "用户信息";
    }
    // 返回带数据的视图
    @GetMapping("/profile")
    public ModelAndView profile() {
        ModelAndView mv = new ModelAndView("profile");
        mv.addObject("username", "张三");
        mv.addObject("age", 25);
        return mv;
    }
}

2 RESTful风格控制器

package com.example.controller;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import java.util.HashMap;
import java.util.Map;
@RestController
@RequestMapping("/api/users")
public class UserRestController {
    private Map<Integer, User> userMap = new HashMap<>();
    // 查询所有用户
    @GetMapping
    public ResponseEntity<Map<Integer, User>> getAllUsers() {
        return ResponseEntity.ok(userMap);
    }
    // 根据ID查询用户
    @GetMapping("/{id}")
    public ResponseEntity<User> getUserById(@PathVariable Integer id) {
        User user = userMap.get(id);
        if (user == null) {
            return ResponseEntity.notFound().build();
        }
        return ResponseEntity.ok(user);
    }
    // 创建用户
    @PostMapping
    public ResponseEntity<String> createUser(@RequestBody User user) {
        userMap.put(user.getId(), user);
        return ResponseEntity.status(HttpStatus.CREATED)
                .body("用户创建成功");
    }
    // 更新用户
    @PutMapping("/{id}")
    public ResponseEntity<String> updateUser(@PathVariable Integer id, 
                                            @RequestBody User user) {
        if (!userMap.containsKey(id)) {
            return ResponseEntity.notFound().build();
        }
        userMap.put(id, user);
        return ResponseEntity.ok("用户更新成功");
    }
    // 删除用户
    @DeleteMapping("/{id}")
    public ResponseEntity<String> deleteUser(@PathVariable Integer id) {
        if (userMap.remove(id) == null) {
            return ResponseEntity.notFound().build();
        }
        return ResponseEntity.ok("用户删除成功");
    }
    // 查询参数处理
    @GetMapping("/search")
    public ResponseEntity<List<User>> searchUsers(
            @RequestParam(required = false) String name,
            @RequestParam(defaultValue = "0") int page,
            @RequestParam(defaultValue = "10") int size) {
        List<User> result = new ArrayList<>();
        for (User user : userMap.values()) {
            if (name == null || user.getName().contains(name)) {
                result.add(user);
            }
        }
        return ResponseEntity.ok(result);
    }
}
// 用户实体类
class User {
    private Integer id;
    private String name;
    private Integer age;
    private String email;
    // getter和setter方法
    // ...
}

Spring Boot控制器进阶

1 统一响应格式

package com.example.common;
// 统一响应类
public class ApiResponse<T> {
    private int code;
    private String message;
    private T data;
    private long timestamp;
    public ApiResponse(int code, String message, T data) {
        this.code = code;
        this.message = message;
        this.data = data;
        this.timestamp = System.currentTimeMillis();
    }
    // 成功响应
    public static <T> ApiResponse<T> success(T data) {
        return new ApiResponse<>(200, "success", data);
    }
    // 失败响应
    public static <T> ApiResponse<T> error(String message) {
        return new ApiResponse<>(500, message, null);
    }
    // getter和setter
    // ...
}
// 使用统一响应的控制器
@RestController
@RequestMapping("/api/products")
public class ProductController {
    @GetMapping
    public ApiResponse<List<Product>> getAllProducts() {
        List<Product> products = productService.findAll();
        return ApiResponse.success(products);
    }
    @GetMapping("/{id}")
    public ApiResponse<Product> getProduct(@PathVariable Long id) {
        return productService.findById(id)
                .map(ApiResponse::success)
                .orElse(ApiResponse.error("商品不存在"));
    }
}

2 参数校验和异常处理

package com.example.controller;
import javax.validation.Valid;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotBlank;
@RestController
@RequestMapping("/api/orders")
public class OrderController {
    @PostMapping
    public ApiResponse<Order> createOrder(@Valid @RequestBody OrderRequest request) {
        // 参数校验由@Valid触发
        Order order = orderService.create(request);
        return ApiResponse.success(order);
    }
    @GetMapping("/{id}")
    public ApiResponse<Order> getOrder(@PathVariable @Min(1) Long id) {
        return orderService.findById(id)
                .map(ApiResponse::success)
                .orElseThrow(() -> new OrderNotFoundException(id));
    }
}
// 请求体类
class OrderRequest {
    @NotBlank(message = "订单名称不能为空")
    private String name;
    @Min(value = 0, message = "金额不能为负")
    private double amount;
    // getter和setter
}
// 全局异常处理
@RestControllerAdvice
public class GlobalExceptionHandler {
    // 处理参数校验异常
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ApiResponse<?> handleValidationException(MethodArgumentNotValidException e) {
        String message = e.getBindingResult().getAllErrors().stream()
                .map(ObjectError::getDefaultMessage)
                .collect(Collectors.joining(", "));
        return ApiResponse.error(message);
    }
    // 处理自定义异常
    @ExceptionHandler(OrderNotFoundException.class)
    @ResponseStatus(HttpStatus.NOT_FOUND)
    public ApiResponse<?> handleOrderNotFound(OrderNotFoundException e) {
        return ApiResponse.error(e.getMessage());
    }
    // 处理通用异常
    @ExceptionHandler(Exception.class)
    public ApiResponse<?> handleException(Exception e) {
        return ApiResponse.error("系统异常：" + e.getMessage());
    }
}

3 文件上传控制器

package com.example.controller;
import org.springframework.web.multipart.MultipartFile;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.UUID;
@RestController
@RequestMapping("/api/file")
public class FileUploadController {
    private final String uploadDir = "uploads/";
    @PostMapping("/upload")
    public ApiResponse<String> uploadFile(@RequestParam("file") MultipartFile file) {
        if (file.isEmpty()) {
            return ApiResponse.error("文件不能为空");
        }
        try {
            // 生成唯一文件名
            String originalFilename = file.getOriginalFilename();
            String extension = originalFilename.substring(originalFilename.lastIndexOf("."));
            String newFilename = UUID.randomUUID().toString() + extension;
            // 保存文件
            Path uploadPath = Paths.get(uploadDir + newFilename);
            Files.createDirectories(uploadPath.getParent());
            Files.write(uploadPath, file.getBytes());
            return ApiResponse.success("文件上传成功：" + newFilename);
        } catch (IOException e) {
            return ApiResponse.error("文件上传失败：" + e.getMessage());
        }
    }
    @PostMapping("/upload/multiple")
    public ApiResponse<List<String>> uploadMultipleFiles(
            @RequestParam("files") List<MultipartFile> files) {
        List<String> filenames = new ArrayList<>();
        for (MultipartFile file : files) {
            if (!file.isEmpty()) {
                try {
                    String filename = saveFile(file);
                    filenames.add(filename);
                } catch (IOException e) {
                    return ApiResponse.error("部分文件上传失败");
                }
            }
        }
        return ApiResponse.success(filenames);
    }
    private String saveFile(MultipartFile file) throws IOException {
        String originalFilename = file.getOriginalFilename();
        String extension = originalFilename.substring(originalFilename.lastIndexOf("."));
        String newFilename = UUID.randomUUID().toString() + extension;
        Path uploadPath = Paths.get(uploadDir + newFilename);
        Files.createDirectories(uploadPath.getParent());
        Files.write(uploadPath, file.getBytes());
        return newFilename;
    }
}

实用技巧和最佳实践

1 路径映射配置

@RestController
@RequestMapping("/api/v1")  // API版本控制
public class AdvancedController {
    // 路径变量
    @GetMapping("/users/{userId}/orders/{orderId}")
    public Order getUserOrder(
            @PathVariable("userId") Long userId,
            @PathVariable("orderId") Long orderId) {
        return orderService.getUserOrder(userId, orderId);
    }
    // 通配符和正则
    @GetMapping("/files/{filename:.+}")
    public ResponseEntity<Resource> downloadFile(@PathVariable String filename) {
        // 处理文件下载
    }
}

2 请求拦截器

package com.example.config;
@Component
public class LoggingInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, 
                            HttpServletResponse response, 
                            Object handler) throws Exception {
        System.out.println("请求URL: " + request.getRequestURL());
        System.out.println("请求方法: " + request.getMethod());
        System.out.println("开始时间: " + System.currentTimeMillis());
        return true; // 返回true继续执行，false中断请求
    }
    @Override
    public void postHandle(HttpServletRequest request, 
                          HttpServletResponse response, 
                          Object handler, 
                          ModelAndView modelAndView) throws Exception {
        System.out.println("请求处理完成");
    }
    @Override
    public void afterCompletion(HttpServletRequest request, 
                               HttpServletResponse response, 
                               Object handler, 
                               Exception ex) throws Exception {
        System.out.println("请求结束");
    }
}
// 注册拦截器
@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Autowired
    private LoggingInterceptor loggingInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loggingInterceptor)
                .addPathPatterns("/api/**")
                .excludePathPatterns("/api/public/**");
    }
}

3 跨域配置

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

控制器测试

@SpringBootTest
@AutoConfigureMockMvc
public class UserControllerTest {
    @Autowired
    private MockMvc mockMvc;
    @Test
    public void testGetUser() throws Exception {
        mockMvc.perform(get("/api/users/1")
                .accept(MediaType.APPLICATION_JSON))
                .andExpect(status().isOk())
                .andExpect(jsonPath("$.name").value("张三"));
    }
    @Test
    public void testCreateUser() throws Exception {
        String userJson = "{\"name\":\"李四\",\"age\":25}";
        mockMvc.perform(post("/api/users")
                .contentType(MediaType.APPLICATION_JSON)
                .content(userJson))
                .andExpect(status().isCreated())
                .andExpect(jsonPath("$.code").value(200));
    }
}

这些案例涵盖了Java控制器开发的主要场景和最佳实践，建议根据实际项目需求选择合适的实现方式,注意代码的规范性和可维护性。

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