1. 适用场景
有时候我们在表单里提交一系列参数, 到后台封装成一个对象, 要对对象的属性做各种字段值的约束; 这时候, 当然可以if-else一个一个的判断, 有更简洁的做法, 就是使用 JSR303+spring的validation:
2. 使用方法步骤(分3步)
- 实体类加字段约束注解
- Controller类中@Valid标注启用(@Validated也兼容@Valid)
- BindingResult获取报错信息
2.1 实体类加字段约束注解
如我们要收集前端表单的字段数据到Person实体中:
对需要约束的字段进行注解标注;
示例:
2.1.1 Person.java
package com.niewj.demo.model; import lombok.Data; import org.hibernate.validator.constraints.Length; import org.hibernate.validator.constraints.URL; import javax.validation.constraints.*; import java.util.List; @Data public class Person { @Length(min = 4, max = 10) @NotNull(message = "name不能为空") private String name; @Min(0) @Max(40) @NotNull(message = "age不能为空") private Integer age; @NotBlank @NotBlank @URL(message = "logo必须是URL格式") private String logo; @NotEmpty(message = "hobbies不能为空") private List<String> hobbies; @Email @NotNull(message = "email不能为空!") private String mail; }
@NotNull 约束字段不可为空;
@NotEmpty 约束集合/map等不能为空不能为0元素
@Email 约束是 email格式
@URL 约束必须是url的格式
message属性可以修改默认错误说明
2.2 Controller类中@Valid标注启用(@Validated兼容@Valid)
2.2.1 HelloController.java
package com.niewj.demo.controller; import com.google.gson.Gson; import com.niewj.demo.common.Result; import com.niewj.demo.model.Person; import com.niewj.demo.service.TestService1; import org.springframework.stereotype.Controller; import org.springframework.validation.BindingResult; import org.springframework.web.bind.annotation.*; import javax.annotation.Resource; import javax.validation.Valid; import java.util.HashMap; import java.util.Map; /** * test * * @author niewj * @since 2020/11/16 15:22 */ @Controller public class HelloController { /** * @param person * @param bindingResult * @return */ @PostMapping("/test") @ResponseBody public Result doSth(@Valid @RequestBody Person person, BindingResult bindingResult) { Map<String, String> map = new HashMap<>(); if (bindingResult.hasErrors()) { bindingResult.getFieldErrors().stream().forEach(fe-> map.put(fe.getField(), fe.getDefaultMessage())); System.out.println(bindingResult.getFieldError().getDefaultMessage()); return Result.withErrorParamData(map); } return Result.withSuccessData(person); } }
@RequestBody可以将body中的请求流信息(Request.getInputStream)通过HttpMessageConverter自动转换为目标java类型:
- 如果前端 Content-Type为application/json, 就使用 JSON消息转换器 帮你转为JSON对象;
- 如果前端 Content-Type为application/xml, 就使用 XML消息转换器 帮你转为xml;
- 如果前端 Content-Type为text/plain, 就是用 String消息转换器 帮你转成 String; (只有类型为String时才可以转换)
2.2.2 Result.java:
package com.niewj.demo.common; import lombok.Data; import java.io.Serializable; import java.util.Map; /** * 返回结果模板封装 * * @author niewj * @since 2020/12/17 18:05 */ @Data public class Result<T> implements Serializable { private int code; private String msg; private T data; public Result(int code, String msg, T data) { this(code, msg); this.data = data; } public Result(int code, String msg) { this.msg = msg; this.code = code; } public static <T> Result<T> withData(ResponseEnum responseCode, T data) { Result<T> re = new Result(responseCode.getCode(), responseCode.getMsg()); re.data = data; return re; } public static Result<String> withSuccessNoData() { Result re = new Result(ResponseEnum.SUCCESS.getCode(), ResponseEnum.SUCCESS.getMsg()); re.data = ""; return re; } public static <T> Result<T> withSuccessData(T data) { Result re = new Result(ResponseEnum.SUCCESS.getCode(), ResponseEnum.SUCCESS.getMsg()); re.data = data; return re; } public static Result<Map<String, String>> withErrorParamData(Map<String, String> data) { Result re = new Result(ResponseEnum.BAD_REQUEST.getCode(), ResponseEnum.BAD_REQUEST.getMsg()); re.data = data; return re; } }
2.2.3 ResponseEnum.java
package com.niewj.demo.common; /** * 通用响应码 */ public enum ResponseEnum { SUCCESS(200, "成功"), BAD_REQUEST(400, "请求参数不合规"); /** * 错误码 */ private Integer code; /** * 错误信息 */ private String msg; ResponseEnum(Integer code, String msg) { this.code = code; this.msg = msg; } public String getMsg() { return msg; } public Integer getCode() { return code; } }
2.3 BindingResult获取报错信息
- BindingResult用来收集约束字段的错误信息, 可通过 bindingResult.hasErrors()的 true来过滤错误信息;
- bindingResult.getFieldErrors() 会返回 List<FieldError>;
- FieldError 得到字段名: getField(); 得到错误信息: getDefaultMessage()
3. 调用测试:
http://localhost:8888/test
3.1 请求用例1: 字段为空
header: Content-Type: application/json
{ "name": "1" }
响应:
{ "code": 400, "msg": "请求参数不合规", "data": { "mail": "email不能为空!", "hobbies": "hobbies不能为空", "name": "长度需要在4和10之间", "logo": "不能为空", "age": "age不能为空" } }
3.2 请求用例2: list无元素/email/url格式不对
header: Content-Type: application/json
{ "name": "1234", "hobbies": [], "mail": "niewj", "logo": "niewj.com" }
响应:
{ "code": 400, "msg": "请求参数不合规", "data": { "mail": "不是一个合法的电子邮件地址", "hobbies": "hobbies不能为空", "logo": "logo必须是URL格式", "age": "age不能为空" } }
3.3 请求用例3: 完整字段信息
header: Content-Type: application/json
{ "name": "1234", "hobbies": ["running"], "mail": "hi@niewj.com", "logo": "http://niewj.com", "age": 40 }
响应:
{ "code": 200, "msg": "成功", "data": { "name": "1234", "age": 40, "logo": "http://niewj.com", "hobbies": [ "running" ], "mail": "hi@niewj.com" } }
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