Spring—Ioc注解配置（纯java配置）

spring Ioc注解配置

不使用xml，纯java配置Ioc，首先创建一个mave工程，导入jar依赖

<dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.7.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>

        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <version>5.5.2</version>
        </dependency>

        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.7.4</version>
        </dependency>

        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.7.4</version>
        </dependency>

    </dependencies>

我们首先创建一个配置类Config.java

@EnableAspectJAutoProxy     //开启自动代理
@Configuration
@ComponentScan(basePackages = "org.youyuan")
public class Config {
}

@EnableAspectJAutoProxy表示开启自动代理，相当于application.xml当中的

<aop:aspectj-autoproxy></aop:aspectj-autoproxy>

@Configuration表示当前是一个配置类
@ComponentScan(basePackages = “org.youyuan”)表示扫码当前包位置下的所有的类

在创建一个类，拦截其中的方法

Calculate.java

@Component
public class Calculate {
    public int add(int a,int b){
        return a+b;
    }
}

定义一个切面类
aspect.java

@Component
@Aspect
public class aspect {

    /*统一定义切点*/
    @Pointcut("execution(* org.youyuan.aop.Calculate.add(..))")
    public void pointcut(){
    }

    /*前置通知*/
    @Before(value ="pointcut()")
    public void before(JoinPoint point){
        System.out.println("before");
        String name = point.getSignature().getName();
        System.out.println(name);
    }
    /*后置通知*/
    @After(value = "pointcut()")
    public void after(JoinPoint joinPoint){
        System.out.println("after");
        String name = joinPoint.getSignature().getName();
        System.out.println(name);
    }

    /*返回通知*/
    @AfterReturning(value = "pointcut()" ,returning = "res")
    public void afterReturning(JoinPoint point,int res){
        System.out.println("afterReturning----->结果为="+res);
        String name = point.getSignature().getName();
        System.out.println(name);
    }

    /*异常通知*/
    @AfterThrowing(value = "pointcut()",throwing = "e")
    public void afterThrowing (JoinPoint point,Exception e) {
        System.out.println("afterThrowing");
        System.out.println("异常为-->"+e);
        String name = point.getSignature().getName();
        System.out.println(name);
    }

    /*环绕通知*/
    @Around(value = "pointcut()")
    public int around (ProceedingJoinPoint joinPoint){
        System.out.println("around1");
        try {
            Object proceed = joinPoint.proceed();
        } catch (Throwable throwable) {
            throwable.printStackTrace();
        }
        System.out.println("around2");
        return 4;
    }

}

@Aspect表示当前类是一个切面类

运行程序

 @Test
    public void test6(){
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
        Calculate bean = context.getBean(Calculate.class);
        bean.add(1,2);
    }

结果

从结果当中我们可以看出，环绕通知的 Object proceed = joinPoint.proceed();方法的前面相当于是前置通知，后面相当于是后置通知，且因为环绕通知的执行return的时候比add方法执行return的时间晚，所有把原结果3给覆盖掉了，所以返回通知的结果是4。