Spring Boot中@PathVariable参数验证的正确实践与异常处理

import org.springframework.http.ResponseEntity;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.validation.constraints.Min;
import java.util.List;
import java.util.ArrayList; // 示例用

@RestController
@Validated // 关键：激活方法参数验证
@RequestMapping("/api/v1")
public class EmployeeController {

    // 假设 ApiResponse 和 Employee 存在，这里仅为示例提供简化定义
    public static class ApiResponse<T> {
        private String message;
        private T data;

        public ApiResponse(String message, T data) {
            this.message = message;
            this.data = data;
        }

        // Getters and setters (省略)
    }

    public static class Employee {
        private Long id;
        private String name;

        public Employee() {
            this.id = 1L; // 示例数据
            this.name = "Test Employee";
        }
        // Getters and setters (省略)
    }

    @GetMapping("/employees/{limit}")
    public ResponseEntity<ApiResponse<List<Employee>>> findTopNEmployeeBySalary(
            @PathVariable("limit") @Min(value = 1, message = "查询限制参数limit必须大于等于1") int limit) {

        // 业务逻辑：根据limit查询员工
        List<Employee> employees = new ArrayList<>();
        for (int i = 0; i < limit; i++) {
            employees.add(new Employee());
        }
        return ResponseEntity.ok(new ApiResponse<>("查询成功", employees));
    }
}

// 请求：GET http://localhost:8080/api/v1/employees/0
{
    "timestamp": "2023-10-27T10:30:00.000+00:00",
    "status": 500,
    "error": "Internal Server Error",
    "path": "/api/v1/employees/0"
}

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Collectors;

@ControllerAdvice
public class GlobalExceptionHandler {

    /**
     * 处理 @PathVariable 或 @RequestParam 参数验证失败的异常
     * 返回 400 Bad Request
     */
    @ExceptionHandler(ConstraintViolationException.class)
    public ResponseEntity<Map<String, String>> handleConstraintViolationException(ConstraintViolationException ex) {
        Map<String, String> errors = new HashMap<>();
        String errorMessage = ex.getConstraintViolations().stream()
                .map(violation -> {
                    // 提取参数名。例如，对于 "findTopNEmployeeBySalary.limit: must be greater than or equal to 1"
                    // 我们希望只显示 "limit: must be greater than or equal to 1"
                    String propertyPath = violation.getPropertyPath().toString();
                    int lastDotIndex = propertyPath.lastIndexOf('.');
                    String paramName = (lastDotIndex != -1 && lastDotIndex < propertyPath.length() - 1) ?
                            propertyPath.substring(lastDotIndex + 1) : propertyPath;

                    return paramName + ": " + violation.getMessage();
                })
                .collect(Collectors.joining("; ")); // 多个验证错误用分号连接

        errors.put("error", "Validation Failed");
        errors.put("details", errorMessage);
        return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);
    }

    // 可以根据需要添加其他异常处理方法
}

// 请求：GET http://localhost:8080/api/v1/employees/0
{
    "error": "Validation Failed",
    "details": "limit: 查询限制参数limit必须大于等于1"
}