Java实现优雅的参数校验方法详解

    public static void utilA(String a,BigDecimal b){
        if (StringUtils.isEmpty(a)){
            System.out.println("a不可为空");
            return;
        }
        if (b == null){
            System.out.println("b不可为空");
            return;
        }
        if (b.compareTo(BigDecimal.ZERO) != 1){
            System.out.println("b的取值范围不正确");
            return;
        }
        System.out.println("do something");
    }

@Service
@Validated
public class MyBean {
 
    public Archive findByCodeAndAuthor(@Size(min = 8, max = 10) String code,
            Author author) {
        ...
    }
 
}

 <!-- https://mvnrepository.com/artifact/org.hibernate.validator/hibernate-validator -->
        <dependency>
            <groupId>org.hibernate.validator</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>6.1.5.Final</version>
        </dependency>

import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import javax.validation.constraints.NotEmpty;
 
/**
 * @Author: wangxia
 * @Date: 2021/10/20 16:30
 */
public class TestPerson {
 
    @NotEmpty(message = "用户名不能为空")
    private String username;
 
    @Min(value = 0,message = "年龄不能小于0岁")
    @Max(value =150,message = "年龄不能大于150岁")
    private int age;
 
    public String getUsername() {
        return username;
    }
 
    public void setUsername(String username) {
        this.username = username;
    }
 
    public int getAge() {
        return age;
    }
 
    public void setAge(int age) {
        this.age = age;
    }
}

@RequestMapping("/")
@RestController
public class TestValidatController {
 
    @PostMapping("/testValid")
    public String testValid(@Validated @RequestBody TestPerson testPerson){
        return "测试成功";
    }
 
}

@ControllerAdvice
@ResponseBody 
public class MethodArgumentNotValidHandel {
 
 
    @ExceptionHandler(value=MethodArgumentNotValidException.class)
    public JSONObject MethodArgumentNotValidHandler(HttpServletRequest request,
                                                    MethodArgumentNotValidException exception) throws Exception
    {
        JSONObject result=new JSONObject();
        result.put("code","fail");
        JSONObject errorMsg=new JSONObject();
        for (FieldError error : exception.getBindingResult().getFieldErrors()) {
            errorMsg.put(error.getField(),error.getDefaultMessage());
        }
        result.put("msg",errorMsg);
        return result;
    }
 
}