Spring AOP的AspectJ註解
在本篇文章中,我將講解如何將AspectJ註解整合到Spring AOP框架。在這個Spring AOP+ AspectJ 例子中,將把你從前一篇文章的繁瑣配置中解脫出來,讓你輕鬆實現攔截方法。
常見AspectJ的註解:
- @Before – 方法執行前執行。
- @After – 執行在方法返回結果後。
- @AfterReturning – 執行在方法返回一個結果後,在攔截器返回結果。
- @AfterThrowing – 執行方法在丟擲異常後。
- @Around – 圍繞方法執行執行,結合以上這三個通知。
依然沿用之前的例子,在之前專案基礎上新增AspectJ的jar依賴
<!-- AspectJ依賴jar --> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjrt</artifactId> <version>1.9.0</version> </dependency> <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjtools --> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjtools</artifactId> <version>1.9.0</version> </dependency> <dependency> <groupId>org.aspectj</groupId> <artifactId>aspectjweaver</artifactId> <version>1.9.0</version> </dependency>
啟用AspectJ
在 Spring 配置檔案,新增“<aop:aspectj-autoproxy />”
<?xml version="1.0" encoding="utf-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"> <aop:aspectj-autoproxy /> ... </beans>
AspectJ @Before
在下面例子中,before()方法將在 ArticleService 介面的 queryArticleById() 方法的執行之前被執行。AspectJ的“切入點”是用來宣告哪種方法將被攔截。
@Aspect public class AspectJDemo { @Before("execution(* com.angelia.spring.service.ArticleServiceImpl.queryArticleById(..))") public void before(JoinPoint point) { System.out.println(point.getSignature().getName()); System.out.println("before is running!"); } }
AspectJ @After
after()方法將在 ArticleService 介面的 queryArticleById() 方法的執行之後執行。
@After("execution(* com.angelia.spring.service.ArticleServiceImpl.queryArticleById(..))")
public void after(JoinPoint point) {
System.out.println(point.getSignature().getName());
System.out.println("after is running!");
}
AspectJ @AfterReturning
afterReturning()方法將在 ArticleService 介面的 queryArticleById() 方法執行之後執行。此外,還可以擷取返回的值使用“returning”屬性。要擷取返回的值,對“returning”屬性(結果)的值必須用相同的方法引數(結果)。
@AfterReturning(
pointcut = "execution(* com.angelia.spring.service.ArticleServiceImpl.queryArticleById(..))",
returning= "result")
public void afterReturning(JoinPoint point, Object result) {
System.out.println("afterReturning() is running!");
System.out.println(point.getSignature().getName());
System.out.println("Method returned value is : " + result);
}
AspectJ @AfterThrowing
如果 ArticleService 介面的 queryArticleById() 方法丟擲異常 afterThrowing() 方法將被執行。
@AfterThrowing(
pointcut = "execution(* com.angelia.spring.service.ArticleServiceImpl.queryArticleById(..))",
throwing= "error")
public void afterThrowing(JoinPoint point, Throwable error) {
System.out.println("logAfterThrowing() is running!");
System.out.println(point.getSignature().getName());
System.out.println("Exception : " + error);
}
AspectJ @Around
在下面例子中,around()方法將在 ArticleService 介面的 queryArticleById() 方法執行之時執行, 必須定義“point.proceed();” 控制何時攔截器返回控制到原來的queryArticleById()方法。
@Around("execution(* com.angelia.spring.service.ArticleServiceImpl.queryArticleById(..))")
public void around(ProceedingJoinPoint point) throws Throwable {
System.out.println("around() is running!");
System.out.println(point.getSignature().getName());
System.out.println("Around before is running!");
point.proceed(); //繼續執行原來的方法
System.out.println("Around after is running!");
}