我正在为方法参数创建自定义注释NullCheck以检查值是否为空或不是hello(@NullCheck String text),但我无法在Annotation周围调用Aspect。
主类
package com.example.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
@SpringBootApplication
@EnableAutoConfiguration
@EnableAspectJAutoProxy
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
控制器类,只调用POC的一个方面,而不是返回任何东西
package com.example.demo;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/")
class HelloController {
@GetMapping
public void hello() {
hello("hi");
}
private void hello(@NullCheck String text) {
System.out.println(text);
}
}
注解
package com.example.demo;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
@Documented
@Retention(RUNTIME)
@Target(ElementType.PARAMETER)
public @interface NullCheck { }
方面
package com.example.demo;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;
@Aspect
@Component
public class NullCheckAspect {
这是有效的
@Before("@annotation(org.springframework.web.bind.annotation.GetMapping)")
但事实并非如此
@Before("@annotation(com.example.demo.NullCheck)")
public void beforeAdvice(JoinPoint joinPoint) {
System.out.println("Before method:" + joinPoint.getSignature());
}
}
的build.gradle
buildscript {
ext {
springBootVersion = '2.1.2.RELEASE'
}
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
}
}
apply plugin: 'java'
apply plugin: 'idea'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'
group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'
idea {
module {
// if you hate browsing Javadoc
downloadJavadoc = true
// and love reading sources :)
downloadSources = true
}
}
bootJar {
launchScript()
}
repositories {
mavenCentral()
jcenter()
}
bootJar {
launchScript()
}
dependencies {
implementation 'org.springframework.boot:spring-boot-starter-actuator'
implementation 'org.springframework.boot:spring-boot-starter-aop'
implementation 'org.springframework.boot:spring-boot-starter-web'
runtimeOnly 'org.springframework.boot:spring-boot-devtools'
}
我错过了什么?
根据我的理解,在google上进行一些搜索之后,您可以使用以下代码获取方法参数及其特定注释的值:
package com.example.demo;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;
@Component
@Aspect
public class NullCheckAspect {
@Around("execution(* com.example.demo.HelloController.nullChecker(String))")
public Object around(ProceedingJoinPoint pJoinPoint) throws Throwable {
Object[] args = pJoinPoint.getArgs();
Method method = MethodSignature.class.cast(pJoinPoint.getSignature()).getMethod();
Annotation[][] parametersAnnotations = method.getParameterAnnotations();
Map<String, Object> annotatedParameters = new HashMap<>();
int i = 0;
for(Annotation[] parameters : parametersAnnotations) {
Object arg = args[i];
String name = method.getParameters()[i++].getDeclaringExecutable().getName();
for(Annotation parameter: parameters) {
if ((parameter instanceof NullCheck)) {
System.out.println("Found the null checker annotation with name: " + name);
System.out.println("Found the null checker annotation with arg: " + arg);
annotatedParameters.put(name, arg);
}
}
}
System.out.println(annotatedParameters);
return pJoinPoint.proceed(args);
}
}
并使用界面注释:
package com.example.demo;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import org.springframework.stereotype.Component;
@Component
@Retention(RUNTIME)
@Target(ElementType.PARAMETER)
public @interface NullCheck {
}
关于我的代码的更多细节你可以在我的github存储库中查看,我已经创建了spring boot demo版本并在https://github.com/krishnaiitd/learningJava/blob/master/springBoot/gs-spring-boot/src/main/java/com/example/demo/HelloController.java为你推送它
这还包括其他类型的方面,例如跟踪特定方法的时间。
希望这能帮助您在Spring启动中获得对@Aspect
的基本了解。