Btrace 拦截时机

Kind.ENTRY 入口，默认值

Kind.RETURN:  返回

Kind.THROW: 异常

Kind.Line: 行

一、返回时拦截

package com.example.monitor_tuning.chapter4;

import com.sun.btrace.AnyType;
import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;


@BTrace
public class PrintReturn {


    @OnMethod(
            clazz = "com.example.monitor_tuning.chapter4.Ch4Controller",
            method="arg1",
            location = @Location(Kind.RETURN)
    )
    public static  void anyRead(@ProbeClassName String pcn, @ProbeMethodName String  pmn, @Return AnyType result)
    {
        BTraceUtils.println(pcn + "," + pmn + "," + result);
        BTraceUtils.println();
    }
}

　　

2、运行和返回结果

1）、运行

2）、调用接口：

http://127.0.0.1:8080/monitor_tuning/ch4/arg1?name=nick

3）返回结果见上图

二、异常时拦截

1、创建异常代码

 2、创建异常脚本

package com.example.monitor_tuning.chapter4;

import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;

/**
 * 拦截异常
 */
@BTrace
public class PrintOnThrow {

    @TLS
    static Throwable currentException;


    @OnMethod(
            clazz = "java.lang.Throwable",
            method="<init>"
    )
    //拦截 new Throwable
    public static  void onthrow(@Self Throwable self)
    {
       currentException = self;
    }


    @OnMethod(
            clazz = "java.lang.Throwable",
            method="<init>"
    )
    //拦截 new Throwable(String msg)
    public static  void onthrow1(@Self Throwable self, String s)
    {
        currentException = self;
    }

    @OnMethod(
            clazz = "java.lang.Throwable",
            method="<init>"
    )
    //拦截 new Throwable(Throwable self, String s, Throwable cause)
    public static  void onthrow1(@Self Throwable self, String s, Throwable cause)
    {
        currentException = self;
    }

    @OnMethod(
            clazz = "java.lang.Throwable",
            method="<init>"
    )
    //拦截 new Throwable( Throwable self,  Throwable cause)
    public static  void onthrow2(@Self Throwable self,  Throwable cause)
    {
        currentException = self;
    }


    @OnMethod(
            clazz = "java.lang.Throwable",
            method="<init>",
            location = @Location(Kind.RETURN)
    )
    public static  void onthrowreturn()
    {
        if(currentException != null){
            BTraceUtils.Threads.jstack(currentException); //打印异常堆栈
            BTraceUtils.println("==============");
            currentException = null;
        }
    }

}

　　

3、运行btrace脚本

调用接口

http://127.0.0.1:8080/monitor_tuning/ch4/exception

显示结果

三、打印行号

1、打印36行是否执行

2、创建btrace脚本

package com.example.monitor_tuning.chapter4;

import com.sun.btrace.BTraceUtils;
import com.sun.btrace.annotations.*;

/**
 * 打印行号，查看指定行号是否执行到
 */
@BTrace
public class PrintLine {


    @OnMethod(
            clazz = "com.example.monitor_tuning.chapter4.Ch4Controller",
            location = @Location(value = Kind.LINE, line = 36)
    )

    public static  void anyRead(@ProbeClassName String pcn, @ProbeMethodName String  pmn, int line)
    {
        BTraceUtils.println(pcn + "," + pmn + ", " + line);
        BTraceUtils.println();
    }
}

　　

　　

3、执行

调用接口

 http://localhost:8080/monitor_tuning/ch4/exception

显示结果

4、打印所有执行的行号

1）接口对应的行号

2、修改btrace脚本 line为-1

显示结果

说明 36， 37， 39， 42行被执行了。38行没有被执行到。