由于在项目中controller层频繁用到log打印入参和回参以及入参的DTO校验，存在很多的重复操作。
最近了解到了aop相关的知识，决定写一个切面来替代这些重复操作。
因为我这里是spring boot 项目，所以加入依赖：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
创建自定义注解@BeanValidated：
/**
* BeanValidated
* V1.0
* 用于方法的参数校验(第一个参数)以及入参和回参的打印
*
* @Author watermelon
* @CreateDate 2019/5/17
* @Description BeanValidated
*/
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface BeanValidated {
Class<?>[] value() default {};
}
创建切面处理类：
/**
* AOPValidation
*
* @Author watermelon
* @CreateDate 2019/5/17
* @Description AOPValidation
*/
@Aspect
@Configuration
@Slf4j
public class AOPValidation {
//切点
@Pointcut("@annotation(com.watermelon.basic.bean.annotation.BeanValidated)")
public void execute() {
}
//环绕
@Around("execute() && @annotation(validated)")
public Object around(ProceedingJoinPoint pjp, BeanValidated validated) throws Throwable {
Signature signature = pjp.getSignature();
MethodSignature methodSignature = (MethodSignature) signature;
//方法名
String methodName = signature.getName();
//类名
String className = signature.getDeclaringTypeName();
//获取所有参数名
String[] parameterNames = methodSignature.getParameterNames();
log.info("{}.{}:入参{}={}", className, methodName, Arrays.toString(parameterNames), Arrays.toString(pjp.getArgs()));
try {
//注解中填入的class
Class<?>[] value = validated.value();
if (value.length > 0) {
Object o = pjp.getArgs()[0];
if (o != null) {
//校验Util
BeanValidation.validate(o, value);
}
}
} catch (ArrayIndexOutOfBoundsException e) {
log.info("{}.{}:该方法入参为空!", className, methodName);
} catch (ClassCastException e) {
log.info("{}.{}:参数对象未继承于校验指定的BaseDTO!", className, methodName);
} catch (IllegalArgumentException e) {
log.info("{}.{}:参数校验出错={}", className, methodName, e.getMessage());
//这里可以不做判断直接返回你已知或者确定的返回类型
//下面的ResultBase、successMvView、failView是自己封装的返回Util
Class returnType = methodSignature.getReturnType();
//根据返回值类型返回错误信息
if (ResultBase.class.isAssignableFrom(returnType)) {//判断returnType是否是ResultBase的子类
return ResultBase.fail(e.getMessage());
} else if (returnType == ModelAndView.class) {
return BaseController.successMvView("404", "error", e.getMessage());
} else {
return BaseController.failView(e.getMessage());
}
} catch (ConstraintViolationException e) {
log.info("{}.{}:参数校验失败={}", className, methodName, e.getMessage());
}
//执行方法
Object proceed = pjp.proceed();
log.info("{}.{}:返回{}", className, methodName, proceed);
return proceed;
}
}
ps:
使用@Slf4j注解需要导入lombok注解，以及在idea中开启lombok,或者也可以自己获取logger
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.2</version>
</dependency>
clipboard.png
BeanValidation：
/**
* bean验证
*
* @Author watermelon
* @CreateDate 2019/1/17
* @Description bean验证
*/
public class BeanValidation {
/**
* 默认propertyPath与message分隔符.
*/
public static final String DEFAULT_SEPARATOR = "";
/**
* 默认错误消息间分隔符.
*/
public static final String ERRORMESSAGES_SEPARATOR = ", ";
private static ValidatorFactory validatorFactory;
static {
validatorFactory = Validation.buildDefaultValidatorFactory();
}
/**
* 调用JSR303的validate方法, 验证失败时抛出ConstraintViolationException, 而不是返回constraintViolations.
*/
@SuppressWarnings({"rawtypes", "unchecked"})
public static void validate(Object object, Class<?>... groups) throws ConstraintViolationException {
String errorMessages = null;
Set constraintViolations = getValidator().validate(object, groups);
if (!constraintViolations.isEmpty()) {
errorMessages = extractPropertyAndMessageAsString(constraintViolations);
// 有错误信息则抛出IllegalArgumentException异常.
if (isNotBlank(errorMessages)) {
System.out.println("校验返回信息errorMessages=" + errorMessages);
throw new IllegalArgumentException(errorMessages);
}
}
}
/**
* 辅助方法, 转换Set<ConstraintViolations>为String.
*/
@SuppressWarnings("rawtypes")
public static String extractPropertyAndMessageAsString(Set<? extends ConstraintViolation> constraintViolations) {
return extractPropertyAndMessageAsString(constraintViolations, DEFAULT_SEPARATOR);
}
/**
* 辅助方法, 转换Set<ConstraintViolation>为String.
*/
@SuppressWarnings("rawtypes")
public static String extractPropertyAndMessageAsString(Set<? extends ConstraintViolation> constraintViolations, String separator) {
StringBuilder errorMessages = new StringBuilder();
int index = 0;
for (ConstraintViolation violation : constraintViolations) {
if (0 != index) {
errorMessages.append(ERRORMESSAGES_SEPARATOR);
}
errorMessages.append(violation.getPropertyPath()).append(separator).append(violation.getMessage());
index++;
}
return errorMessages.toString();
}
public static Validator getValidator() {
return validatorFactory.getValidator();
}
private static boolean isNotBlank(String str) {
int len;
if (str != null && (len = str.length()) != 0) {
for (int i = 0; i < len; ++i) {
if (!Character.isWhitespace(str.charAt(i))) {
return true;
}
}
return false;
} else {
return false;
}
}
}
运用切面还可以完成权限验证等功能，大家可以自己试着写一下。
