springboot中@Validated+@ControllerAdvice+@ExceptionHandler注解对全局异常的处理

前言

为了解决什么问题：
1.前端传入大量繁琐数据需要校验，会产生大量 if else语句以及try catch语句导致代码冗杂，不美观。用@Validated注解可以很好的解决。它根据实体类配置的校验规则在进入controller接口的时候就会自动校验参数。
2.controller中每一个接口请求都要对异常进行处理，若接口不断增多，不同的异常也会不断增多，会导致异常太过紊乱，不好维护且不好拓展。因此用@ControllerAdvice+@ExceptionHandler对异常做统一处理。

正文

为了更方便的理解，这里采用demo，提供登录和注册2个接口的方式给大家阐述。

1.编写登录实体类UserLoginReq和注册实体类UserRegisterReq(这里@Getter@Sette注解用的lombok插件可以省去写get，set方法)
@NotEmpty注解校验是否为空
@Size校验字符串的长度
@Pattern正则表达式校验字符串
UserLoginReq：

@Getter
@Setter
public class UserLoginReq {@NotEmpty(message = "用户姓名不能为空")@Size(max = 64, message = "用户姓名长度不能超过64位")private String name;@NotEmpty(message = "密码不能为空")private String password;
}

UserRegisterReq：

@Getter
@Setter
public class UserRegisterReq {@NotEmpty(message = "用户姓名不能为空")@Size(max = 64, message = "用户姓名长度不能超过64位")private String name;@NotEmpty(message = "用户证件类型不能为空")@Pattern(regexp = "^(01|02|03|04|99)$", message = "用户证件类型错误")private String cardType;@NotEmpty(message = "用户证件号码不能为空")@Size(max = 32, message = "用户证件号码长度不能超过32位")private String cardNo;@NotEmpty(message = "用户联系电话不能为空")@Size(max = 32, message = "用户联系电话长度不能超过32位")private String contactNo;@Size(max = 128, message = "联系地址长度不能超过128位")private String contactAddress;
}

2.pom.xml引入依赖
（1）spring-boot-starter-validation：提供上示代码中@NotEmpty，@Size，@Pattern等注解校验参数，message参数用于校验失败响应值

    <!-- 校验入参 --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-validation</artifactId></dependency>

（2）hutool-all：hutool工具类，是一个很强大的工具类，提供如日期，克隆，类型转化等等很多方法简化代码开发，这里只是用于创建json对象和创建随机数（与此文核心内容无关）

    <!-- hutool工具 --><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>4.6.13</version></dependency>

3.编写controller接口，自定义异常枚举类和请求返回result类
UserController：

@RestController
public class UserController {@PostMapping(value = "/register")public void exceptionLoginDemo(@Validated UserRegisterReq userRegisterReq) {System.out.println("user register!");}@PostMapping(value = "/login")public void exceptionRegisterDemo(@Validated UserLoginReq userLoginReq) {System.out.println("user login!");}
}

ExceptionEnum ：枚举类，自定义异常枚举

public enum ExceptionEnum {// 请求异常集LOGIN_PARAM_EXCEPTION("100101", "登录请求参数错误异常"),REGISTER_PARAM_EXCEPTION("100102", "注册请求参数错误异常",true),//系统未知异常UNKNOWN_EXCEPTION("990101", "未知异常", true);// 错误码private String code;// 响应信息private String message;// 异常发现是否警告（此参数这里不考虑，只是用于拓展，比如异常发生会通知异常监听系统发出警告）private boolean isWarn;ExceptionEnum(String code, String message) {this.code = code;this.message = message;this.isWarn = false;}ExceptionEnum(String code, String message, boolean isWarn) {this.code = code;this.message = message;this.isWarn = isWarn;}public String getCode() {return this.code;}public String getMessage() {return this.message;}public boolean isWarn() {return this.isWarn;}
}

Result：自定义返回给用户的结果集：错误码code，信息message，以及响应成功或失败的response数据

@Getter
@Setter
public class Result implements Serializable {private static final long serialVersionUID = -4127817000970452353L;//默认成功正常private static final String SUCCESS_CODE = "200";//默认成功消息private static final String SUCCESS_MESSAGE = "SUCCESS";//状态private String code;//消息private String message;//数据private Object response;private Result(Builder builder) {code = builder.code == null ? SUCCESS_CODE : builder.code + "";message = builder.message == null ? SUCCESS_MESSAGE : builder.message;response = builder.response;}public static Builder newBuilder() {return new Builder();}public static final class Builder {private Integer code;private String message;private Object response;private Builder() {}public Builder code(Integer val) {code = val;return this;}public Builder message(String val) {message = val;return this;}public Builder response(Object val) {response = val;return this;}public Result build() {return new Result(this);}}@Overridepublic String toString() {return JSONUtil.toJsonStr(this);}
}

4.编写3个异常类以及异常handle：1个父异常FatherException，2个子异常ChildLoginException，ChildRegisterException，ExceptionHandle
这里示例2个自定义子异常，实际工作中可动态拓展新增多个异常处理
FatherException：

public abstract class FatherException extends Exception{private static final long serialVersionUID = 2287623661547050627L;protected boolean isWarn;protected String code;protected String message;public FatherException(ExceptionEnum exceptionEnum, String type, JSONObject params) {this.code = exceptionEnum.getCode();this.message = exceptionEnum.getMessage();this.isWarn = exceptionEnum.isWarn();}
}

ChildLoginException：

public class ChildLoginException extends FatherException {private static final long serialVersionUID = -7065580338200227702L;private static final String EXCEPTION_TYPE = "LOGIN";public ChildLoginException(ExceptionEnum exceptionEnum, JSONObject params) {super(exceptionEnum, EXCEPTION_TYPE, params);}
}

ChildRegisterException:

public class ChildRegisterException extends FatherException {private static final long serialVersionUID = 816726270176940141L;private static final String EXCEPTION_TYPE = "REGISTER";public ChildRegisterException(ExceptionEnum exceptionEnum, JSONObject params) {super(exceptionEnum, EXCEPTION_TYPE, params);}
}

核心类：
ExceptionHandle
当请求来的时候，校验失败会进入ExceptionHandle类，通过instanceof 关键字根据异常类型去跑各自具体的异常处理逻辑，如登录就处理登录的异常，注册就处理注册的异常，若是BindException则是参数校验失败，根据请求url，封装各自的result返回值返回给用户
（提示：代码中Result.newBuilder()等于new Result（），这是lombok插件创建对象的写法）

@ControllerAdvice
public class ExceptionHandle {private Logger logger = LoggerFactory.getLogger(ExceptionHandle.class);private Snowflake snowflake = IdUtil.createSnowflake(1, 1);@ExceptionHandler(Exception.class)@ResponseBodypublic Result handle(Exception exception, HttpServletRequest request) {/*创建一个json Response对象（这里写法是因为用的huto工具类） ，请求返回值形如data = {"code": "100101","message": "用户证件类型错误","response": {"reqId": "1277545207021309952"}}*/JSONObject data = JSONUtil.createObj();// 生成随机数（huto工具类的方法）data.put("reqId", snowflake.nextIdStr());if (exception instanceof FatherException) {/*处理自定义的FatherException异常*/} else if (exception instanceof ChildLoginException) {/*处理ChildLoginException 登录的异常*/} else if (exception instanceof ChildRegisterException) {/*处理ChildRegisterException 注册的异常*/} else if (exception instanceof BindException) {// 取得请求的urlString reqUrl = this.getRequestUrl(request);// 取得BindException异常提示信息String message = this.getBindExceptionMessage((BindException) exception);switch (reqUrl) {// 请求一：登录case "/login":request.setAttribute("resCode", ExceptionEnum.LOGIN_PARAM_EXCEPTION.getCode());return Result.newBuilder().code(Integer.valueOf(ExceptionEnum.LOGIN_PARAM_EXCEPTION.getCode())).message(message).response(data).build();// 请求二：注册case "/register":request.setAttribute("resCode", ExceptionEnum.REGISTER_PARAM_EXCEPTION.getCode());return Result.newBuilder().code(Integer.valueOf(ExceptionEnum.REGISTER_PARAM_EXCEPTION.getCode())).message(message).response(data).build();}} else {// 处理未知异常logger.error(exception.getMessage(), exception);request.setAttribute("resCode", ExceptionEnum.UNKNOWN_EXCEPTION.getCode());return Result.newBuilder().code(Integer.valueOf(ExceptionEnum.UNKNOWN_EXCEPTION.getCode())).message(ExceptionEnum.UNKNOWN_EXCEPTION.getMessage()).response(data).build();}return null;}

postman调用返回

返回响应码code，响应信息message，返回值response
1.注册证件类型支持01，02，03，04，99.不支持22报证件类型错误

2.登录密码不能为空

本文以及demo已收录至GitHub地址：https://github.com/taochengbin/spring/tree/master/springMvc-global-exception