springboot-统一异常

深藏阁楼爱情的钟 2022-02-21 01:44 233阅读 0赞

1.  模拟异常

不做全局统一异常时，当项目中出现异常，会报500.

如：

@PostMapping(value=**"/testerror"**)  
@ApiOperation(value = **"获取用户信息"**)  
**public** Result.Base testerror(HttpServletRequest request)\{   
    Integer inte = 1/0;  
    **return new** Result.Success<>(inte);  
\}

访问接口时报500错误：

![20190410104730948.png][]

2.处理异常

利用@ControllerAdvice和@ExceptionHandler定义一个统一异常处理类

*  @ControllerAdvice：控制器增强，使@ExceptionHandler、@InitBinder、@ModelAttribute注解的方法应用到所有的 @RequestMapping注解的方法。
 *  @ExceptionHandler：异常处理器，此注解的作用是当出现其定义的异常时进行处理的方法

因此只需要添加如下类即可：

如果是自定义异常，可单独再配。

**package** com.wps.education.exception;  
  
**import** com.wps.education.LoginInterceptor.LoginInterceptor;  
**import** com.wps.education.common.response.Result;  
**import** org.slf4j.Logger;  
**import** org.slf4j.LoggerFactory;  
**import** org.springframework.web.bind.annotation.ControllerAdvice;  
**import** org.springframework.web.bind.annotation.ExceptionHandler;  
**import** org.springframework.web.bind.annotation.ResponseBody;  
  
**import** javax.servlet.http.HttpServletRequest;  
  
@ControllerAdvice  
**public class** GlobalExceptionHandler \{   
    **private static final** Logger ***logger*** = LoggerFactory.*getLogger*(GlobalExceptionHandler.**class**);  
  
    @ExceptionHandler(value = Exception.**class**)  
    @ResponseBody  
    **public** Result.Base jsonErrorHandler(HttpServletRequest req, Exception e) **throws** Exception \{   
        ***logger***.error(**"\{\} | \{\}"**, req.getRequestURL().toString(), e.getMessage());  
        e.printStackTrace();  
        **return new** Result.ErrorData<>(e.getMessage());  
    \}  
\}

接口返回：

![20190410104815222.png][]

后台输出：

![20190410104825528.png][]

3.项目级处理方式

上面的例子可以全局处理异常，并返回错误内容。

但在项目中使用时，不能给用户显示500，也不能显示这些错误内容。而是定义一套错误码，后台统一返回格式，前端处理接口中的错误码，给出相应的业务处理，或更合理的提示信息。

1.  定义errorcode类：

**import** org.apache.http.HttpStatus;  
*/\*\**  
* \* 定义错误类*  
* \*/*  
**public abstract class** ErrorCode \{   
  
    */\*\**  
*     3.1 code:0表示成功, -1表示未知错误*  
*     3.1 系统集合（1-99）：*  
*     3.4 业务相关code集合 (100-399):*  
*     \*/*  
  
*/\*\* 成功 \*/*  
**public static final** Integer ***SUCCESS*** = 0;  
*/\*\* 未知 \*/*  
**public static final** Integer ***UNKNOWN*** = -1;  
  
*/\*\* 未知错误 \*/*  
**public static final** Result.Error ***ERROR\_UNKNOWN*** = **new** Result.Error(***UNKNOWN***, **"unknown error"**, HttpStatus.***SC\_INTERNAL\_SERVER\_ERROR***);  
  
*/\*\* system error code, 1-99 \*/*  
*/\*\* 参数错误,不正确的参数 \*/*  
**public static final** Result.Error ***ARGUMENT\_INVALID*** = **new** Result.Error(1, **"parameter is invalid"**, HttpStatus.***SC\_BAD\_REQUEST***);  
*/\*\* 没有Token \*/*  
**public static final** Result.Error ***NO\_TOKEN\_ERROR*** = **new** Result.Error(2, **"no token error"**, HttpStatus.***SC\_OK***);  
*/\*\* 没找到对应的对象 \*/*  
**public static final** Result.Error ***NO\_SUCH\_ELEMENT\_ERROR*** = **new** Result.Error(3, **"no such element error"**, HttpStatus.***SC\_OK***);  
*/\*\* 没有足够的权限 \*/*  
**public static final** Result.Error ***NO\_RIGHT\_ERROR*** = **new** Result.Error(4, **"current user have no right do this"**, HttpStatus.***SC\_OK***);  
*/\*\* Token过期 \*/*  
**public static final** Result.Error ***TOKEN\_EXPIRED\_ERROR*** = **new** Result.Error(5, **"token expired"**, HttpStatus.***SC\_OK***);  
  
*/\*\* 用户相关code集合（100-399）\*/*  
*/\*\* 登陆参数不正确 \*/*  
**public static final** Result.Error ***LOGIN\_PARAM\_ERROR*** = **new** Result.Error(100, **"login param error, or login expire"**, HttpStatus.***SC\_BAD\_REQUEST***);  
*/\*\* 创建用户失败\*/*  
**public static final** Result.Error ***INSERT\_USER\_ERROR*** = **new** Result.Error(161,**"****insert user error****"**, HttpStatus.***SC\_OK***);  
\}

2.定义接口返回格式类Result

**package** com.gary.exception;  
  
**import** com.fasterxml.jackson.annotation.JsonInclude;  
**import** lombok.Getter;  
**import** lombok.Setter;  
**import** org.apache.http.HttpStatus;  
  
*/\*\**  
* \* 返回客户端结果类*  
* \*/*  
**public class** Result **extends** ErrorCode \{   
  
    @Getter  
    @Setter  
    **public static class** Base \{   
        **private** Integer **code**;  
  
        **public** Base(Integer code) \{   
            **this**.**code** = code;  
        \}  
  
        **void** check() \{   
            **if** (**code** == **null**)  
                **throw new** IllegalArgumentException(**"code can not be null"**);  
        \}  
    \}  
  
    @Getter  
    @Setter  
    @JsonInclude(value = JsonInclude.Include.***NON\_NULL***)  
    **public static class** Success<T> **extends** Base \{   
        **private** T **data**;  
        **private** Integer **status**;  
  
        **public** Success(T data) \{   
            **super**(***SUCCESS***);  
            **this**.**data** = data;  
            check();  
        \}  
  
        **public** Success() \{   
            **super**(***SUCCESS***);  
            **this**.**data** = (T) **"success"**;  
  
            check();  
        \}  
  
        **void** check() \{   
            **super**.check();  
        \}  
    \}  
  
    @JsonInclude(value = JsonInclude.Include.***NON\_EMPTY***)  
    @Getter  
    @Setter  
    **public static class** Error **extends** Base \{   
        **private** String **result**;  
        **private** Integer **httpStatus**;  
  
        **public** Error(Integer code, String result, Integer status) \{   
            **super**(code);  
            **this**.**result** = result;  
            **this**.**httpStatus** = status;  
            check();  
        \}  
  
        **void** check() \{   
            **super**.check();  
            **if** (**result** == **null** || **httpStatus** == 0)  
                **throw new** IllegalArgumentException(**"result can not be null and http status cannot be zero"**);  
        \}  
  
    \}  
  
    @Getter  
    @Setter  
    @JsonInclude(value = JsonInclude.Include.***NON\_EMPTY***)  
    **public static class** ErrorData<T> **extends** Base \{   
        **private** T **data**;  
  
        **public** ErrorData(T data) \{   
            **super**(HttpStatus.***SC\_INTERNAL\_SERVER\_ERROR***);  
            **this**.**data** = data;  
        \}  
  
        **void** check() \{   
            **super**.check();  
        \}  
    \}  
  
\}

3.添加自定义异常类

派生自运行时异常，将Result的Error类作为成员：

**package** com.gary.exception;  
  
**import** lombok.Getter;  
**import** lombok.Setter;  
  
@Getter  
@Setter  
**public class** CustomException **extends** RuntimeException\{   
    **private static final long** ***serialVersionID*** = 1L;  
  
    **private** Result.Error **error**;  
  
    **public** CustomException() \{   
        **super**();  
    \}  
  
    **public** CustomException(String message) \{   
        **super**(message);  
    \}  
  
    **public** CustomException(String message, Throwable cause) \{   
        **super**(message, cause);  
    \}  
  
    **public** CustomException(Throwable cause) \{   
        **super**(cause);  
    \}  
  
    **public** CustomException(Result.Error error) \{   
        **super**(error.getResult());  
        checkErrorMessage(error);  
        **this**.**error** = error;  
    \}  
  
    **public** CustomException(Result.Error error, String message) \{   
        **super**(message);  
        checkErrorMessage(error);  
        **this**.**error** = error;  
    \}  
  
    **public** CustomException(Result.Error error, String message, Throwable cause) \{   
        **super**(message, cause);  
        checkErrorMessage(error);  
        **this**.**error** = error;  
    \}  
  
    **public** CustomException(Result.Error error, Throwable cause) \{   
        **super**(cause);  
        checkErrorMessage(error);  
        **this**.**error** = error;  
    \}  
  
    **public void** checkErrorMessage(Result.Error error)\{   
        **if**(error.getCode()!=**null** && error.getCode()==0)\{   
            **throw new** RuntimeException(**"errorMessage code must not be 0"**);  
        \}  
    \}  
\}

4.完善统一异常处理

**package** com.gary.exception;  
  
**import** org.slf4j.Logger;  
**import** org.slf4j.LoggerFactory;  
**import** org.springframework.http.HttpHeaders;  
**import** org.springframework.http.HttpStatus;  
**import** org.springframework.http.ResponseEntity;  
**import** org.springframework.web.bind.annotation.ControllerAdvice;  
**import** org.springframework.web.bind.annotation.ExceptionHandler;  
**import** org.springframework.web.bind.annotation.ResponseBody;  
**import** javax.servlet.http.HttpServletRequest;  
  
@ControllerAdvice  
**public class** GlobalExceptionHandler \{   
    **private static final** Logger ***logger*** = LoggerFactory.*getLogger*(GlobalExceptionHandler.**class**);  
  
    @ExceptionHandler(value = Exception.**class**)  
    @ResponseBody  
    **public** Result.Base jsonErrorHandler(HttpServletRequest req, Exception e) **throws** Exception \{   
        ***logger***.error(**"\{\} | \{\}"**, req.getRequestURL().toString(), e.getMessage());  
  
        e.printStackTrace();  
        **return new** Result.ErrorData<>(e.getMessage());  
    \}  
  
    @ExceptionHandler(CustomException.**class**)  
    @ResponseBody  
    **public** ResponseEntity<Object> handleCustomException(CustomException e) \{   
        Result.Error error = e.getError();  
        HttpStatus httpStatus = HttpStatus.***INTERNAL\_SERVER\_ERROR***;  
        **if** (error != **null** && error.getHttpStatus() != **null**) \{   
            httpStatus = getHttpStatus(e.getError().getHttpStatus());  
        \} **else** \{   
            ***logger***.error(**"unknown error "**, e);  
            error = ErrorCode.***ERROR\_UNKNOWN***;  
        \}  
        **return** handleResponse(error, httpStatus);  
    \}  
  
    **private** ResponseEntity<Object> handleResponse(Result.Error error, HttpStatus status) \{   
        **return** handleResponse(error, **null**, status);  
    \}  
  
    **private** ResponseEntity<Object> handleResponse(Result.Error error, HttpHeaders headers, HttpStatus status) \{   
        **return new** ResponseEntity<>(error, headers, status);  
    \}  
  
    **private** HttpStatus getHttpStatus(Integer statusCode)\{   
        HttpStatus httpStatus=HttpStatus.***INTERNAL\_SERVER\_ERROR***;  
        **try** \{   
            httpStatus=HttpStatus.*valueOf*(statusCode);  
        \} **catch** (IllegalArgumentException e) \{   
            ***logger***.error(**"get HttpStatus error"**,e);  
  
        \}  
        **return** httpStatus;  
    \}  
\}

5.使用

这样的好处是正常业务和有异常的情况，接口返回前端的结构一样，前端可统一处理返回格式，获取code进行判断处理，是0则正常，其他值根据业务作不同处理。

**正常业务返回：**

@GetMapping(**"/hello"**)  
**public** Result.Base hello()\{   
    System.***out***.println(**"/hello"**);  
    **return new** Result.Success<>(**"hello world"**);  
\}

![20190410105239443.png][]

**未处理的异常：**

@GetMapping(**"/testerror"**)  
**public** Result.Base error()\{   
    System.***out***.println(**"/error"**);  
    Integer inte = 1/0;  
    **return new** Result.Success<>(**"hello world"**);  
\}

默认code为500，内容为错误内容：

![20190410105306524.png][]

**自定义异常：**

定义错误值：

**public static final** Result.Error ***NUMBER\_ERROR*** = **new** Result.Error(300,**"数字不正确"**, HttpStatus.***SC\_OK***);

Controller中直接返回错误

@GetMapping(**"/testerror"**)  
**public** Result.Base error()\{   
    System.***out***.println(**"/error"**);  
    **try**\{   
        Integer inte = 1/0;  
    \}**catch** (Exception e)\{   
        **return** Result.***NUMBER\_ERROR***;  
    \}  
  
    **return new** Result.Success<>(**"hello world"**);  
\}

或者主动抛自定义异常：

@GetMapping(**"/testerror"**)  
    **public** Result.Base error()\{   
        System.***out***.println(**"/error"**);  
        **try**\{   
            Integer inte = 1/0;  
        \}**catch** (Exception e)\{   
*//            return Result.NUMBER\_ERROR;*  
*            ***throw new** CustomException(Result.***NUMBER\_ERROR***);  
        \}  
  
        **return new** Result.Success<>(**"hello world"**);  
    \}

效果一样：

![20190410105338387.png][]

两者的差别是：前者只能在conroller中使用，因为是直接返回错误。后者可以在任意地方，如service层dao层。

6.说明

其中用到了httpstatus，和lombok，因此需要添加这两个依赖包：

<**dependency**>  
    <**groupId**>org.projectlombok</**groupId**>  
    <**artifactId**>lombok</**artifactId**>  
    <**version**>1.16.20</**version**>  
</**dependency**>  
<**dependency**>  
    <**groupId**>org.apache.httpcomponents</**groupId**>  
    <**artifactId**>httpclient</**artifactId**>  
</**dependency**>

[20190410104730948.png]: /images/20220221/a9d31bd918dd40888ed9740719917501.png
[20190410104815222.png]: /images/20220221/34ad53d3ed354c019189af36818c292d.png
[20190410104825528.png]: /images/20220221/32900d15aa4a48e097a788d7c182ac4d.png
[20190410105239443.png]: /images/20220221/4ba1b7bf88ba4c0b887706c35d50bbed.png
[20190410105306524.png]: /images/20220221/caa1d74d440746fb9e631dd2cc98bf75.png
[20190410105338387.png]: /images/20220221/d9d530bc4feb416598810790bfef423e.png