4、pointcut(call、execution、within、withincode)

call捕获的joinpoint是调用方法的地方，execution捕获的joinpoint是执行的地方

验证execution

HelloAspect.aj

package aspectj;

public aspect HelloAspect {

    pointcut HelloWorldPointCut() : execution(* aspectj.HelloWorld.main(int));
    
    before() : HelloWorldPointCut() {
        System.out.println("拦截位置"+thisJoinPoint.getSourceLocation());
    }
}

image.png

输出：

main
拦截位置HelloWorld.java:11
i=5

验证call

直接修改HelloAspect.aj这个aspect的pointcut为call
输出：

main
拦截位置HelloWorld.java:8
i=5

within

新建Student类和Teacher类

image.png

HelloWorld.java

package aspectj;

public class HelloWorld {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("main");
        Teacher teacher=new Teacher();
        teacher.print();
        Student student=new Student();
        student.print();

    }

}

HelloAspet.aj

package aspectj;

public aspect HelloAspect {

    pointcut PrintPointCut() : execution(* print(..));
    
    before() : PrintPointCut() {
        System.out.println("拦截位置"+thisJoinPoint.getSourceLocation());
    }
}

Student.java

package aspectj;

public class Student {

    
    
    public void print()
    {
        System.out.println("student");
    }
}

Teacher.java

package aspectj;

public class Teacher {

    public void print()
    {
        System.out.println("Teacher");
    }
}

运行结果：

main
拦截位置Teacher.java:5
Teacher
拦截位置Student.java:7
student

image.png

image.png

image.png

image.png

如果现在有个需求，只想拦截Teacher类中的print方法，其余的类不拦截（这里只演示了一个Student类，假设有很多类都有print方法该怎么实现呢？）
修改程序的pointcut

package aspectj;

public aspect HelloAspect {

    pointcut PrintPointCut() : execution(* print(..))&&within(Teacher);
    
    before() : PrintPointCut() {
        System.out.println("拦截位置"+thisJoinPoint.getSourceLocation());
    }
}

输出结果：

main
拦截位置Teacher.java:5
Teacher
student

withincode

相对于within来说，这个pointcut是针对类内部进行拦截的，看个示例就清楚了
修改
Teacher.java

package aspectj;

public class Teacher {

    public void print()
    {
        System.out.println("Teacher");
    }
    public void  callPrintfirst()
    {
        print();
    }
    public void callPrintSecond()
    {
        print();
    }
    public void callPrintThree()
    {
        print();
    }
}

Teacher中有三个方法都调用了print()方法，但是现在只想要拦截callPrintfirst()方法调用的print方法，其余的不拦截
HelloWorld.java

package aspectj;

public class HelloWorld {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("main");
        Teacher teacher=new Teacher();
        teacher.callPrintfirst();
        teacher.callPrintSecond();
        teacher.callPrintThree();

    }

}

HelloAspect.aj

package aspectj;

public aspect HelloAspect {

    pointcut PrintPointCut() : call(* print(..))&&withincode(* aspectj.Teacher.callPrintfirst(..));
    
    before() : PrintPointCut() {
        System.out.println("拦截位置"+thisJoinPoint.getSourceLocation());
    }
}

运行代码，输出结果：

main
拦截位置Teacher.java:11
Teacher
Teacher
Teacher

image.png