异常校验处理

本文旨在提供业务访问的高效性，针对异常校验进行新的思路规划设计：

     先校验正常的业务流程，不匹配再走异常，而不是一开始就校验异常（提高80%效率）

适用于：业务异常校验场景

8-2定律：业务中80%以上的场景都是正常的，剩余20%可能需要考虑异常

例如：国际业务中，校验到方  洲/省  城市   邮编

传统校验,从上到下：

提示1：到方洲/省份不对，提示洲/省份错误

提示1：如果城市不正确，提示城市错误

提示2：如果邮编不正确，提示邮编错误

改进异常校验：先校验正确业务场景，不匹配再逐层走异常校验逻辑  即

1.洲/省  +城市 +  邮编  有，走正常逻辑，异常走

2.城市 +  邮编  有，走正常逻辑，异常走；提示异常信息

3.邮编  有，走正常逻辑，异常走；提示异常信息

对于异常可以使用优雅的AOP思想返回异常信息处理；需要的异常自定义定义

import com.system.entity.BusinessException;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.view.json.MappingJackson2JsonView;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
 
/**
 * description:
 */
@Component
@ControllerAdvice
public class GlobalExceptionAdvice {
 
    @ExceptionHandler
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Exception e) {
        ModelAndView modelAndView = new ModelAndView();
        MappingJackson2JsonView mappingJackson2JsonView = new MappingJackson2JsonView();
        Map hashMap = new HashMap<>();
        if (Objects.nonNull(e)) {
            if (e instanceof BusinessException) {
                BusinessException e1 = (BusinessException) e;
                hashMap.put("code", e1.getCode());
                hashMap.put("success", false);
                hashMap.put("msg", e1.getMsg());
            }
            if (e instanceof IllegalArgumentException) {
                IllegalArgumentException e1 = (IllegalArgumentException) e;
                hashMap.put("code", 400);
                hashMap.put("success", false);
                hashMap.put("msg", e1.getMessage());
            } else {
                hashMap.put("code", 500);
                hashMap.put("success", false);
                hashMap.put("msg", e.getMessage());
            }
        }
        modelAndView.addAllObjects(hashMap);
        modelAndView.setView(mappingJackson2JsonView);
        return modelAndView;
    }
}

import lombok.Data;

/**
 * description:
 */
@Data
public class BusinessException extends RuntimeException{
    private int code;
    private int msg;
}

如果需要自定义注解场景可以使用拦截器处理方案

步骤1：自定义注解

import java.lang.annotation.*;

@Target(ElementType.METHOD)
@Documented
@Retention(RetentionPolicy.RUNTIME)
public @interface ResponseNotNull {

}

步骤2 自定义拦截器

import com.system.annotations.ResponseNotNull;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.stereotype.Service;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Objects;

/**
 * description:
 */
@Service
public class ResponseNotNullInterceptor implements HandlerInterceptor {
    private static final String RESPONSE_NOT_NULL_RESULT = "response_not_null_result";

    /**
     * 在请求前置中设置
     *
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        if (Objects.nonNull(handler) && handler instanceof HandlerMethod) {
            ResponseNotNull annotation = AnnotationUtils.findAnnotation(((HandlerMethod) handler).getMethod(), ResponseNotNull.class);
            if (Objects.nonNull(annotation)) {
                request.setAttribute(RESPONSE_NOT_NULL_RESULT, RESPONSE_NOT_NULL_RESULT);
                return true;
            }
        }
        return HandlerInterceptor.super.preHandle(request, response, handler);
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

步骤3 注册拦截器

import com.system.interceptors.ResponseNotNullInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

/**
 * description: 拦截器添加地方
 */
@Configuration
public class AllWebMvcConfig implements WebMvcConfigurer {


    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new ResponseNotNullInterceptor());
    }


}

步骤4 返回处理

import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONWriter;
import com.system.common.ResponseResult;
import org.springframework.core.MethodParameter;
import org.springframework.http.MediaType;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;

import java.util.Objects;

/**
 * description:
 */
@Component
public class ResponseNotNullAdvice implements ResponseBodyAdvice {

    private static final String YYYY_MM_DD_HH_MM_SS = "yyyy-MM-dd HH:mm:ss";


    private static final String RESPONSE_NOT_NULL_RESULT = "response_not_null_result";

    @Override
    public boolean supports(MethodParameter returnType, Class converterType) {
        Object attribute = RequestContextHolder.getRequestAttributes().getAttribute(RESPONSE_NOT_NULL_RESULT, RequestAttributes.SCOPE_SESSION);
        if (Objects.nonNull(attribute)) {
            return true;
        }
        return false;
    }

    @Override
    public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
        if (body instanceof ResponseResult) {
            return JSON.parseObject(JSON.toJSONString(body, YYYY_MM_DD_HH_MM_SS, JSONWriter.Feature.PrettyFormat));
        }
        return body;
    }
}

上面采用了一些其他工具jar包如下：

    com.alibaba.fastjson2
    fastjson2
    2.0.18