引言
编写接口时，常用的参数校验使用hibernate-validator注解+@Validated注解进行参数校验。当遇到一些特殊场景或需求，需要自己对参数进行手动校验时，会出现以下问题：
不可避免的需要对接受的参数进行判断，此时便会出现大量if…else…影响代码可读性，且校验不够优雅。
本文给出一个参数校验方案，给大家一个思路。如果只是想使用，基本校验的已足够。
使用举例
具体项目中是如何使用的，可以参考博客中我正在开发的U-Learning后端开发日志，其中有GitHub项目地址
Before1
@PostMapping("/save")
public ResponseEntity<JsonResult> save(TeacherDto teacher) {
if(StringUtil.isEmpty(teacher.getTeaName())){
return ...;
}
if(StringUtil.isEmpty(teacher.getTeaNumber())){
return ...;
}
if(StringUtil.isEmpty(teacher.getTeaEmail())){
return ...;
}
//接口处理业务代码
...
}
After1
@PostMapping("/save")
public ResponseEntity<JsonResult> save(TeacherDto teacher) {
ValidatorBuilder.build()
.on(StringUtil.isEmpty(teacher.getTeaName()), SystemErrorCodeEnum.NAME_CANNOT_BE_NULL)
.on(StringUtil.isEmpty(teacher.getTeaNumber()), SystemErrorCodeEnum.TEA_NUMBER_CANNOT_BE_NULL)
.on(StringUtil.isEmpty(teacher.getTeaEmail()), SystemErrorCodeEnum.EMAIL_CANNOT_BE_NULL)
.doValidate().checkResult();
//接口处理业务代码
...
}
Beafore2
当你只有一个需要校验的参数时，可能会觉得这有些啰嗦
@GetMapping("/delete")
public ResponseEntity<JsonResult> delete(Long id) {
if(StringUtil.isEmpty(id)){
return ...;
}
//接口处理业务代码
...
}
After2
@GetMapping("/delete")
public ResponseEntity<JsonResult> delete(Long id) {
ValidateHandler.checkParameter(StringUtil.isEmpty(id), SystemErrorCodeEnum.ID_CANNOT_BE_NULL);
//接口处理业务代码
...
}
知识点
涉及到的知识点
- 建造者模式
- 链式调用
- 枚举
- 异常
- 继承与多态
拓展所需知识点
- 委托模式
使用前准备
自定义异常
public class BaseException extends RuntimeException {
private Integer status = HttpStatus.BAD_REQUEST.value();
public BaseException(Integer status) {
this.status = status;
}
public BaseException(BaseEnum baseEnum) {
super(baseEnum.getMessage());
this.status = baseEnum.getCode();
}
public BaseException(String message) {
super(message);
}
public BaseException(String message, Throwable cause) {
super(message, cause);
}
public BaseException(Throwable cause) {
super(cause);
}
public BaseException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
super(message, cause, enableSuppression, writableStackTrace);
}
public Integer getStatus() {
return status;
}
}
举个栗子
@Getter
public class BadRequestException extends BaseException {
public BadRequestException(String msg) {
super(msg);
}
public BadRequestException(BaseEnum baseEnum) {
super(baseEnum);
}
}
统一异常管理
@Slf4j
@RestControllerAdvice
public class GlobalExceptionHandler {
/**
* 处理系统自定义异常
*/
@ExceptionHandler(BaseException.class)
public ResponseEntity handleBaseException(BaseException e) {
String message = StringUtil.isContainChinese(e.getMessage()) ? e.getMessage() : null;
return ResponseEntityUtil.badRequest(JsonResult.buildErrorMsg(e.getStatus(),
Optional.ofNullable(message).orElse(MicroErrorCodeEnum.OPERATE_ERROR.getMessage())));
}
/**
* Throwable
* 接收非系统预测内的异常
*/
@ExceptionHandler(Throwable.class)
public ResponseEntity handleThrowable(Throwable e) {
log.error("系统捕捉Throwable异常并处理 ==> " + e.getMessage(), e);
String message = StringUtil.isContainChinese(e.getMessage()) ? e.getMessage() : null;
return ResponseEntityUtil.internalServerError(JsonResult.buildErrorMsg(HttpStatus.INTERNAL_SERVER_ERROR.value(),
Optional.ofNullable(message).orElse(MicroErrorCodeEnum.SYSTEM_ERROR.getMessage())));
}
}
自定义枚举
基础枚举接口
public interface BaseEnum {
Integer getCode();
String getMessage();
}
举个栗子(根据自己需求创建)
public enum SystemErrorCodeEnum implements BaseEnum {
/**
* 后台管理系统错误状态码
*/
PARAMETER_EMPTY(HttpStatus.BAD_REQUEST, "参数不可为空!"),
TEACHER_NOT_EXISTS(HttpStatus.BAD_REQUEST, "教师不存在!"),
ID_CANNOT_BE_NULL(HttpStatus.BAD_REQUEST, "ID不可为空!"),
EMAIL_CANNOT_BE_NULL(HttpStatus.BAD_REQUEST, "邮箱不可为空!"),
;
private Integer code;
private String message;
SystemErrorCodeEnum(HttpStatus httpStatus, String message) {
this.code = httpStatus.value();
this.message = message;
}
@Override
public Integer getCode() {
return code;
}
@Override
public String getMessage() {
return message;
}
}
Validate核心代码
校验类context
@Data
@AllArgsConstructor
public class ValidatorContext {
/** 校验结果 */
private Boolean checkResult;
/** 错误信息枚举 */
private BaseEnum baseEnum;
}
校验类上下文
public class ValidatorHolder {
/** context集合 */
private List<ValidatorContext> validatorContexts;
/** 校验结果 */
private Boolean result;
/** 若result = true，保存错误信息 */
private BaseEnum baseEnum;
/** 初始化 */
public ValidatorHolder() {
this.validatorContexts = new ArrayList<>();
this.result = true;
this.baseEnum = null;
}
/** 校验链 */
public ValidatorHolder on(Boolean checkResult, BaseEnum baseEnum){
if(checkResult != null && baseEnum != null){
addContext(checkResult, baseEnum);
}
return this;
}
/** 添加待校验属性和错误信息 */
private void addContext(Boolean checkResult, BaseEnum baseEnum){
validatorContexts.add(new ValidatorContext(checkResult, baseEnum));
}
/** 校验 */
public ValidatorHolder doValidate(){
for (ValidatorContext validatorContext : validatorContexts) {
if(validatorContext.getCheckResult()){
result = false;
baseEnum = validatorContext.getBaseEnum();
break;
}
}
return this;
}
public void checkResult(){
ValidateHandler.checkValidator(this);
}
public Boolean getResult() {
return result;
}
public BaseEnum getBaseEnum() {
return baseEnum;
}
}
校验builder类
public class ValidatorBuilder {
public static ValidatorHolder build(){
return new ValidatorHolder();
}
}
校验处理器
参考Guava类库中提供的一个作参数检查的工具类--Preconditions类
public class ValidateHandler {
/**
* 判断校验是否成功，若存在错误，抛出异常
* 针对ValidatorHolder
*/
public static void checkValidator(ValidatorHolder validator){
if(! validator.getResult()){
throw new BadRequestException(validator.getBaseEnum());
}
}
/**
* 针对单参数校验
*
* @param checkResult true:参数错误; false:参数正确
* @param baseEnum 错误码
*/
public static void checkParameter(Boolean checkResult, BaseEnum baseEnum){
if(checkResult){
throw new BadRequestException(baseEnum);
}
}
}