SpringMVC异常处理

一、引言

  一般项目开发中有两类异常：

• 预期异常
• 运行时异常

其中预期异常一般是由程序员主动抛出的异常，而运行时异常很难控制，只能通过规范代码编写、增加测试等手段来减少该类异常。

  通常项目是分层开发的，由外到内可分为前端项目、前端控制器、控制层、业务层、持久层。如果在控制层、业务层或持久层出现异常，SpringMVC框架如何处理呢？我们可以在前端控制器中定义全局异常处理器，之后如果控制层、业务层或持久层出现异常，直接往外抛异常即可。关于全局异常处理器，有如下定义方法：

  1. 基于注解的异常处理
  2. 基于配置的异常处理

二、示例

2.1 基于注解的异常处理

  首先，定义一个业务异常，该异常作为预期异常在项目中手动抛出。

public class CustomException extends RuntimeException {private AppHttpCodeEnum appHttpCodeEnum;public CustomException(AppHttpCodeEnum appHttpCodeEnum){this.appHttpCodeEnum = appHttpCodeEnum;}public AppHttpCodeEnum getAppHttpCodeEnum() {return appHttpCodeEnum;}
}

其中AppHttpCodeEnum类是一个枚举类，用于指定http响应状态码和响应信息，定义如下。

public enum AppHttpCodeEnum {// 成功段0SUCCESS(200,"操作成功"),// 登录段1~50NEED_LOGIN(1,"需要登录后操作"),LOGIN_PASSWORD_ERROR(2,"密码错误"),// TOKEN50~100TOKEN_INVALID(50,"无效的TOKEN"),TOKEN_EXPIRE(51,"TOKEN已过期"),TOKEN_REQUIRE(52,"TOKEN是必须的"),// SIGN验签 100~120SIGN_INVALID(100,"无效的SIGN"),SIG_TIMEOUT(101,"SIGN已过期"),// 参数错误 500~1000PARAM_REQUIRE(500,"缺少参数"),PARAM_INVALID(501,"无效参数"),PARAM_IMAGE_FORMAT_ERROR(502,"图片格式有误"),SERVER_ERROR(503,"服务器内部错误"),// 数据错误 1000~2000DATA_EXIST(1000,"数据已经存在"),AP_USER_DATA_NOT_EXIST(1001,"用户数据不存在"),DATA_NOT_EXIST(1002,"数据不存在"),// 数据错误 3000~3500NO_OPERATOR_AUTH(3000,"无权限操作"),NEED_ADMIND(3001,"需要管理员权限");int code;String errorMessage;AppHttpCodeEnum(int code, String errorMessage){this.code = code;this.errorMessage = errorMessage;}public int getCode() {return code;}public String getErrorMessage() {return errorMessage;}
}

之后，通过@ControllerAdvice和@ExceptionHandler注解定义全局异常处理器，分别捕获自定义的业务异常和不可控异常。

@ControllerAdvice  //控制器增强类
public class ExceptionCatch {/*** 处理不可控异常* @param e* @return*/@ExceptionHandler(Exception.class)@ResponseBodypublic ResponseResult exception(Exception e){e.printStackTrace();return ResponseResult.errorResult(AppHttpCodeEnum.SERVER_ERROR);}/*** 处理可控异常  自定义异常* @param e* @return*/@ExceptionHandler(CustomException.class)@ResponseBodypublic ResponseResult exception(CustomException e){return ResponseResult.errorResult(e.getAppHttpCodeEnum());}
} 

其中ResponseResult类是一个向前端返回的统一结果类。

public class ResponseResult<T> implements Serializable {private String host;private Integer code;private String errorMessage;private T data;public ResponseResult() {this.code = 200;}public ResponseResult(Integer code, T data) {this.code = code;this.data = data;}public ResponseResult(Integer code, String msg, T data) {this.code = code;this.errorMessage = msg;this.data = data;}public ResponseResult(Integer code, String msg) {this.code = code;this.errorMessage = msg;}public static ResponseResult errorResult(int code, String msg) {ResponseResult result = new ResponseResult(code, msg);return result;}public static ResponseResult errorResult(AppHttpCodeEnum enums) {return setAppHttpCodeEnum(enums, enums.getErrorMessage());}public static ResponseResult errorResult(AppHttpCodeEnum enums, String errorMessage) {return setAppHttpCodeEnum(enums, errorMessage);}public static ResponseResult okResult(int code, String msg) {ResponseResult result = new ResponseResult(code, msg);return result;}public static ResponseResult okResult(Object data) {ResponseResult result = setAppHttpCodeEnum(AppHttpCodeEnum.SUCCESS, AppHttpCodeEnum.SUCCESS.getErrorMessage());if (data != null) {result.setData(data);}return result;}public static ResponseResult okResult(AppHttpCodeEnum enums) {ResponseResult result = setAppHttpCodeEnum(enums);return result;}public static ResponseResult setAppHttpCodeEnum(AppHttpCodeEnum enums) {return okResult(enums.getCode(), enums.getErrorMessage());}private static ResponseResult setAppHttpCodeEnum(AppHttpCodeEnum enums, String errorMessage) {return okResult(enums.getCode(), errorMessage);}public Integer getCode() {return code;}public void setCode(Integer code) {this.code = code;}public String getErrorMessage() {return errorMessage;}public void setErrorMessage(String errorMessage) {this.errorMessage = errorMessage;}public T getData() {return data;}public void setData(T data) {this.data = data;}public String getHost() {return host;}public void setHost(String host) {this.host = host;}
}

2.2 基于配置的异常处理

  SpringMVC提供了一个自定义异常处理器的接口，我们通过实现@HandlerExceptionResolver接口来捕获异常。

public class GlobalExceptionResolver implements HandlerExceptionResolver {
​@Overridepublic ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler,Exception exception) {//根据实际业务编写代码return null;}
}

然后在spring配置文件中配置刚才新建的全局异常处理器，或者加上@Component注解。

<!--全局异常捕捉 -->
<bean class="包名.GlobalExceptionResolver" />