AOP切面编程后置通知实现返回值的判空值处理（项目中使用）

超、凢脫俗 2022-05-25 07:40 87阅读 0赞

目的：因为根据平常的代码在service层根据返回值要做判断空值处理，抛对应的错误信息，得每个方法判断一次，比较麻烦。现在的处理方法是根据放回值类型判断是否list.class，是的话list.size（）=0抛对应的错误信息，然后在判断是否int.class等，希望能给大家代理帮助。

平常的代码写法

if(i==0){
        throw new AppcationException(ExceptionEnum.DELETEDATADEFEAIED);
    }

错误类的种类

INSERTDATADEFEATED(1001,"数据插入失败,"),
    NOTFOUNTVALUE(1002,"找不到对应的值"),
    UPDATEDATADEFEAIED(1003,"更新数据失败"),
    DElETEDATADEFEAIED(1004,"更新数据失败");

现在的写法

注意：1.

Class returnType = ((MethodSignature) signature).getReturnType();

Api地址：

http://www.eclipse.org/aspectj/doc/released/runtime-api/org/aspectj/lang/reflect/MethodSignature.html\#getReturnType()

![70][]

获取返回值类型

2.先判断list.class，int.class然后看是否是get或select开头的。

因为正规的话select开头返回object，get开头返回list，由于大家把两个闹乱了 所以做了一下改造，测试通过。

@Aspect
    @Component
    public class ExceptionInterceptor {
    
        protected Logger log = (Logger) Logger.getLogger(this.getClass());
    
        /**
         * select开头  返回值为object
         * get开头  返回值为list
         * updat  返回值为int
         * delete开头  返回值为int
         * insert  返回值为int
         */
    
        @AfterReturning(value = "execution(* com.lenovo.pcsd.bp.businesspartner.mapper.*.*(..))", returning = "result")
        @SuppressWarnings("unchecked")
        public void afterReturning(JoinPoint joinPoint, Object result) {
            Signature signature = joinPoint.getSignature();
            String methodName = signature.getName();
    
            String selectregex = "^select.*$";
            String getregex = "^get.*$";
            String updateregex = "^updat.*$";
            String deleteregex = "^delete.*$";
            String insertregex = "^insert.*$";
            Class returnType = ((MethodSignature) signature).getReturnType();
            Pattern selectp = Pattern.compile(selectregex);
            Pattern getp = Pattern.compile(getregex);
            Pattern updatp = Pattern.compile(updateregex);
            Pattern deletep = Pattern.compile(deleteregex);
            Pattern insertp = Pattern.compile(insertregex);
            if (returnType.equals(List.class)) {
                List<? extends Object> list = (ArrayList<T>) result;
                if (list.size() == 0) {
                    throw new AppcationException(ExceptionEnum.NOTFOUNTVALUE);
                }
            } else if (returnType.equals(Integer.class)) {
                Integer taskList = (Integer) result;
                if (taskList == 0) {
    
                    if (updatp.matcher(methodName).matches()) {
                        throw new AppcationException(ExceptionEnum.UPDATEDATADEFEAIED);
                    } else if (deletep.matcher(methodName).matches()) {
                        throw new AppcationException(ExceptionEnum.DElETEDATADEFEAIED);
                    } else if (insertp.matcher(methodName).matches()) {
                        throw new AppcationException(ExceptionEnum.INSERTDATADEFEATED);
                    }
                }
            } else {
                if (StringUtils.isEmpty(result)) {
                    if (getp.matcher(methodName).matches() || selectp.matcher(methodName).matches()) {
                        throw new AppcationException(ExceptionEnum.NOTFOUNTVALUE);
                    }
    
                }
            }
    
        }
    }

[70]: /images/20220525/e6ea9d7524234c418c88a24e314863d7.png