Btrace示例

在这个示例中，我们将实现Btrace脚本跟踪一个成员变量的变化。
被跟踪类的代码如下：

package com.bo56;
 
class Demo {
    private static int counter;
 
    public void add(){
        try {
            counter++;
            System.out.println(&quot;bo56.com &quot; + counter);
            Thread.sleep(1000);
        } catch (Exception e) {
            System.out.println(e);
        }   
    }   
}
 
public class Test{
 
    public static void main(String[] arg) {
        Demo demo = new Demo();
        for (int i = 0; i &lt; 100; i++) {
            demo.add();
        }   
    }   
}

我们要实现的跟踪目标是，每当demo.add调用完毕Return时，我们输出counter值。Btrace的代码如下：

package com.sun.btrace.samples;
 
import com.sun.btrace.annotations.*;
import static com.sun.btrace.BTraceUtils.*;
 
@BTrace
public class Canglong {
     
    @OnMethod(
        clazz=&quot;com.bo56.Demo&quot;,
        method=&quot;add&quot;,
        location=@Location(value=Kind.RETURN)
    )   
    public static void monitor(@Self Object self, @ProbeMethodName String pmn){
        Class clazz = Reflective.classOf(self);
        int counter = getInt(field(clazz, &quot;counter&quot;), self);
        println(&quot;counter value is &quot; + counter);
    }
}