<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.1.1.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.qikegu</groupId>
	<artifactId>springboot-validation-demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springboot-validation-demo</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

public class RegisterRequest {
	
	@SuppressWarnings("unused")
	private static final org.slf4j.Logger log = LoggerFactory.getLogger(RegisterRequest.class);
	
	@NotNull(message="手機(jī)號必須填")
	@Pattern(regexp = "^[1]([3][0-9]{1}|59|58|88|89)[0-9]{8}$", message="賬號請輸入11位手機(jī)號") // 手機(jī)號
	private String mobile;
	
	@NotNull(message="昵稱必須填")
	@Size(min=1, max=20, message="昵稱1~20個字")
	private String nickname;
	
    @NotNull(message="密碼必須填")
    @Size(min=6, max=16, message="密碼6~16位")
	private String password;

	public String getMobile() {
		return mobile;
	}

	public void setMobile(String mobile) {
		this.mobile = mobile;
	}

	public String getNickname() {
		return nickname;
	}

	public void setNickname(String nickname) {
		this.nickname = nickname;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}
    	
}

package com.qikegu.demo.controller;

import javax.validation.Valid;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.qikegu.demo.common.util.MiscUtil;
import com.qikegu.demo.common.util.Result;
import com.qikegu.demo.model.RegisterRequest;

@RestController
@RequestMapping("/auth")
public class AuthController {
	
    @RequestMapping(value = "/register", method = RequestMethod.POST, produces="application/json")
    public ResponseEntity<Result> register(
    	@Valid @RequestBody RegisterRequest register, 
    	BindingResult bindingResult
    ) {
		if(bindingResult.hasErrors()) {	
			//rfc4918 - 11.2. 422: Unprocessable Entity
//			res.setStatus(422);
//			res.setMessage("輸入錯誤");
//			res.putData("fieldErrors", bindingResult.getFieldErrors());
			
			Result res1 = MiscUtil.getValidateError(bindingResult);
			
			return new ResponseEntity<Result>(res1, HttpStatus.UNPROCESSABLE_ENTITY);
		}
    	
		Result res = new Result(200, "ok");
        return ResponseEntity.ok(res);
    }
}

static public Result getValidateError(BindingResult bindingResult) {
		
		if(bindingResult.hasErrors() == false) 
			return null;
		
		Map<String,String> fieldErrors = new HashMap<String, String>();
		
		for(FieldError error : bindingResult.getFieldErrors()){
			fieldErrors.put(error.getField(), error.getCode() + "|" + error.getDefaultMessage());
		}
		
		Result ret = new Result(422, "輸入錯誤"); //rfc4918 - 11.2. 422: Unprocessable Entity
		ret.putData("fieldErrors", fieldErrors);
		
		return ret;
	}