SpringBoot如何统一处理返回结果和异常情况
作者:sw-code
原因
在springboot项目里我们希望接口返回的数据包含至少三个属性:
- code:请求接口的返回码,成功或者异常等返回编码,例如定义请求成功。
- message:请求接口的描述,也就是对返回编码的描述。
- data:请求接口成功,返回的结果。
{ "code":20000, "message":"成功", "data":{ "info":"测试成功" } }
开发环境
- 工具:IDEA
- SpringBoot版本:2.2.2.RELEASE
依赖
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <!-- fastjson --> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.62</version> </dependency> <!-- Spring web --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!-- lombok --> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </dependency> <!-- swagger3 --> <dependency> <groupId>io.springfox</groupId> <artifactId>springfox-boot-starter</artifactId> <version>3.0.0</version> </dependency>
创建 SpringBoot 工程#
新建 SpringBoot 项目common_utils,包名com.spring.utils
返回结果统一
创建code枚举
在com.spring.utils中创建 pojo 包,并添加枚举ResultCode
public enum ResultCode { /* 成功状态码 */ SUCCESS(20000, "成功"), /* 参数错误 */ PARAM_IS_INVALID(1001, "参数无效"), PARAM_IS_BLANK(1002, "参数为空"), PARAM_TYPE_BIND_ERROR(1003, "参数类型错误"), PARAM_NOT_COMPLETE(1004, "参数缺失"), /* 用户错误 2001-2999*/ USER_NOTLOGGED_IN(2001, "用户未登录"), USER_LOGIN_ERROR(2002, "账号不存在或密码错误"), SYSTEM_ERROR(10000, "系统异常,请稍后重试"); private Integer code; private String message; private ResultCode(Integer code, String message) { this.code = code; this.message = message; } public Integer code() { return this.code; } public String message() { return this.message; } }
**可根据项目自定义,结果返回码
创建返回结果实体
在 pojo 包中添加返回结果类R**
@Data @ApiModel(value = "返回结果实体类", description = "结果实体类") public class R implements Serializable { private static final long serialVersionUID = 1L; @ApiModelProperty(value = "返回码") private Integer code; @ApiModelProperty(value = "返回消息") private String message; @ApiModelProperty(value = "返回数据") private Object data; private R() { } public R(ResultCode resultCode, Object data) { this.code = resultCode.code(); this.message = resultCode.message(); this.data = data; } private void setResultCode(ResultCode resultCode) { this.code = resultCode.code(); this.message = resultCode.message(); } // 返回成功 public static R success() { R result = new R(); result.setResultCode(ResultCode.SUCCESS); return result; } // 返回成功 public static R success(Object data) { R result = new R(); result.setResultCode(ResultCode.SUCCESS); result.setData(data); return result; } // 返回失败 public static R fail(Integer code, String message) { R result = new R(); result.setCode(code); result.setMessage(message); return result; } // 返回失败 public static R fail(ResultCode resultCode) { R result = new R(); result.setResultCode(resultCode); return result; } }
自定义一个注解
新建包annotation,并添加ResponseResult注解类
@Retention(RetentionPolicy.RUNTIME) @Target({ ElementType.TYPE, ElementType.METHOD}) @Documented public @interface ResponseResult { }
定义拦截器
新建包interceptor,并添加ResponseResultInterceptorJava类
@Component public class ResponseResultInterceptor implements HandlerInterceptor { //标记名称 public static final String RESPONSE_RESULT_ANN = "RESPONSE-RESULT-ANN"; @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { // TODO Auto-generated method stub if (handler instanceof HandlerMethod) { final HandlerMethod handlerMethod = (HandlerMethod) handler; final Class<?> clazz = handlerMethod.getBeanType(); final Method method = handlerMethod.getMethod(); // 判断是否在类对象上添加了注解 if (clazz.isAnnotationPresent(ResponseResult.class)) { // 设置此请求返回体,需要包装,往下传递,在ResponseBodyAdvice接口进行判断 request.setAttribute(RESPONSE_RESULT_ANN, clazz.getAnnotation(ResponseResult.class)); } else if (method.isAnnotationPresent(ResponseResult.class)) { request.setAttribute(RESPONSE_RESULT_ANN, method.getAnnotation(ResponseResult.class)); } } return true; } }
用于拦截请求,判断 Controller 是否添加了@ResponseResult注解
注册拦截器
新建包config,并添加WebAppConfig配置类
@Configuration public class WebAppConfig implements WebMvcConfigurer { // SpringMVC 需要手动添加拦截器 @Override public void addInterceptors(InterceptorRegistry registry) { ResponseResultInterceptor interceptor = new ResponseResultInterceptor(); registry.addInterceptor(interceptor); WebMvcConfigurer.super.addInterceptors(registry); } }
方法返回值拦截处理器
新建包handler,并添加ResponseResultHandler配置类,实现ResponseBodyAdvice重写两个方法
import org.springframework.web.method.HandlerMethod; /** * 使用 @ControllerAdvice & ResponseBodyAdvice * 拦截Controller方法默认返回参数,统一处理返回值/响应体 */ @ControllerAdvice public class ResponseResultHandler implements ResponseBodyAdvice<Object> { // 标记名称 public static final String RESPONSE_RESULT_ANN = "RESPONSE-RESULT-ANN"; // 判断是否要执行 beforeBodyWrite 方法,true为执行,false不执行,有注解标记的时候处理返回值 @Override public boolean supports(MethodParameter arg0, Class<? extends HttpMessageConverter<?>> arg1) { ServletRequestAttributes sra = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); HttpServletRequest request = sra.getRequest(); // 判断请求是否有包装标记 ResponseResult responseResultAnn = (ResponseResult) request.getAttribute(RESPONSE_RESULT_ANN); return responseResultAnn == null ? false : true; } // 对返回值做包装处理,如果属于异常结果,则需要再包装 @Override public Object beforeBodyWrite(Object body, MethodParameter arg1, MediaType arg2, Class<? extends HttpMessageConverter<?>> arg3, ServerHttpRequest arg4, ServerHttpResponse arg5) { if (body instanceof R) { return (R) body; } return R.success(body); } }
实现ResponseBodyAdvice重写两个方法
添加@ControllerAdvice注解
测试#
新建包controller,并添加TestController测试类
@RestController @ResponseResult public class TestController { @GetMapping("/test") public Map<String, Object> test() { HashMap<String, Object> data = new HashMap<>(); data.put("info", "测试成功"); return data; } }
添加@ResponseResult注解
启动项目,在默认端口: 8080
浏览器访问地址:localhost:8080/test
{"code":20000,"message":"成功","data":{"info":"测试成功"}}
总结
1、创建code枚举和返回结果实体类
2、自定义一个注解@ResponseResult
3、定义拦截器,拦截请求,判断Controller上是否添加了@ResponseResult注解。如果添加了注解在request中添加注解标记,往下传递
4、添加@ControllerAdvice注解 ,实现ResponseBodyAdvice接口,并重写两个方法,通过判断request中是否有注解标记,如果有就往下执行,进一步包装。没有就直接返回,不需包装。
问题
1、如果要返回错误结果,这种方法显然不方便
@GetMapping("/fail") public R error() { int res = 0; // 查询结果数 if( res == 0 ) { return R.fail(10001, "没有数据"); } return R.success(res); }
2、我们需要对错误和异常进行进一步的封装
封装错误和异常结果#
创建错误结果实体#
在包pojo中添加ErrorResult实体类
/** * 异常结果包装类 * @author sw-code * */ public class ErrorResult { private Integer code; private String message; private String exception; public Integer getCode() { return code; } public void setCode(Integer code) { this.code = code; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } public String getException() { return exception; } public void setException(String exception) { this.exception = exception; } public static ErrorResult fail(ResultCode resultCode, Throwable e, String message) { ErrorResult errorResult = ErrorResult.fail(resultCode, e); errorResult.setMessage(message); return errorResult; } public static ErrorResult fail(ResultCode resultCode, Throwable e) { ErrorResult errorResult = new ErrorResult(); errorResult.setCode(resultCode.code()); errorResult.setMessage(resultCode.message()); errorResult.setException(e.getClass().getName()); return errorResult; } public static ErrorResult fail(Integer code, String message) { ErrorResult errorResult = new ErrorResult(); errorResult.setCode(code); errorResult.setMessage(message); return errorResult; } }
自定义异常类
在包pojo中添加BizException实体类,继承RuntimeException
@Data public class BizException extends RuntimeException { /** * 错误码 */ private Integer code; /** * 错误信息 */ private String message; public BizException() { super(); } public BizException(ResultCode resultCode) { super(resultCode.message()); this.code = resultCode.code(); this.message = resultCode.message(); } public BizException(ResultCode resultCode, Throwable cause) { super(resultCode.message(), cause); this.code = resultCode.code(); this.message = resultCode.message(); } public BizException(String message) { super(message); this.setCode(-1); this.message = message; } public BizException(Integer code, String message) { super(message); this.code = code; this.message = message; } public BizException(Integer code, String message, Throwable cause) { super(message, cause); this.code = code; this.message = message; } @Override public synchronized Throwable fillInStackTrace() { return this; } }
全局异常处理类
在包handler中添加GlobalExceptionHandler,添加@RestControllerAdvice注解
/** * 全局异常处理类 * @RestControllerAdvice(@ControllerAdvice),拦截异常并统一处理 * @author sw-code * */ @Slf4j @RestControllerAdvice public class GlobalExceptionHandler { /** * 处理自定义的业务异常 * @param e 异常对象 * @param request request * @return 错误结果 */ @ExceptionHandler(BizException.class) public ErrorResult bizExceptionHandler(BizException e, HttpServletRequest request) { log.error("发生业务异常!原因是: {}", e.getMessage()); return ErrorResult.fail(e.getCode(), e.getMessage()); } // 拦截抛出的异常,@ResponseStatus:用来改变响应状态码 @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR) @ExceptionHandler(Throwable.class) public ErrorResult handlerThrowable(Throwable e, HttpServletRequest request) { log.error("发生未知异常!原因是: ", e); ErrorResult error = ErrorResult.fail(ResultCode.SYSTEM_ERROR, e); return error; } // 参数校验异常 @ExceptionHandler(BindException.class) public ErrorResult handleBindExcpetion(BindException e, HttpServletRequest request) { log.error("发生参数校验异常!原因是:",e); ErrorResult error = ErrorResult.fail(ResultCode.PARAM_IS_INVALID, e, e.getAllErrors().get(0).getDefaultMessage()); return error; } @ExceptionHandler(MethodArgumentNotValidException.class) public ErrorResult handleMethodArgumentNotValidException(MethodArgumentNotValidException e, HttpServletRequest request) { log.error("发生参数校验异常!原因是:",e); ErrorResult error = ErrorResult.fail(ResultCode.PARAM_IS_INVALID,e,e.getBindingResult().getAllErrors().get(0).getDefaultMessage()); return error; } }
添加注解@RestControllerAdvice(@ControllerAdvice),拦截异常并统一处理
修改方法返回值拦截处理器#
将错误和异常结果也进行统一封装
/** * 使用 @ControllerAdvice & ResponseBodyAdvice * 拦截Controller方法默认返回参数,统一处理返回值/响应体 */ @ControllerAdvice public class ResponseResultHandler implements ResponseBodyAdvice<Object> { // 标记名称 public static final String RESPONSE_RESULT_ANN = "RESPONSE-RESULT-ANN"; // 判断是否要执行 beforeBodyWrite 方法,true为执行,false不执行,有注解标记的时候处理返回值 @Override public boolean supports(MethodParameter arg0, Class<? extends HttpMessageConverter<?>> arg1) { ServletRequestAttributes sra = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); HttpServletRequest request = sra.getRequest(); // 判断请求是否有包装标记 ResponseResult responseResultAnn = (ResponseResult) request.getAttribute(RESPONSE_RESULT_ANN); return responseResultAnn == null ? false : true; } // 对返回值做包装处理,如果属于异常结果,则需要再包装 @Override public Object beforeBodyWrite(Object body, MethodParameter arg1, MediaType arg2, Class<? extends HttpMessageConverter<?>> arg3, ServerHttpRequest arg4, ServerHttpResponse arg5) { if (body instanceof ErrorResult) { ErrorResult error = (ErrorResult) body; return R.fail(error.getCode(), error.getMessage()); } else if (body instanceof R) { return (R) body; } return R.success(body); } } 测试# Copy @GetMapping("/fail") public Integer error() { int res = 0; // 查询结果数 if( res == 0 ) { throw new BizException("没有数据"); } return res; }
返回结果
{"code":-1,"message":"没有数据","data":null}
我们无需担心返回类型,如果需要返回错误提示信息,可以直接抛出自定义异常(BizException),并添加自定义错误信息。
总结
以上为个人经验,希望能给大家一个参考,也希望大家多多支持脚本之家。