btrace exercise

最新推荐文章于 2024-06-03 18:25:06 发布

mooninday

最新推荐文章于 2024-06-03 18:25:06 发布

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本文链接：https://blog.youkuaiyun.com/mooninday/article/details/9047383

本文介绍了使用BTrace工具对Java应用程序进行实时跟踪的方法。包括打印调用堆栈、记录方法执行时间、显示方法参数及返回值等实用技巧。

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1. 方法被调用时打印调用堆栈

    @OnMethod(clazz = "com.test.test.btrace.AppObj", method = "execute")
    public static void traceExecute() {
        println("call AppObj called");
        jstack();
    }

2. 打印这个类哪些行被调用

    @OnMethod(clazz = "com.test.test.btrace.AppObj", location = @Location(value = Kind.LINE, line = -1))
    public static void line(@ProbeClassName String pcn, @ProbeMethodName String pmn, int line) {
        print(Strings.strcat(pcn, "."));
        println(Strings.strcat(pmn, ":"));
        println(line);
    }

3. 打印方法花费时间

    @TLS
    static long beginTime1;

    @OnMethod(clazz = "com.test.test.btrace.AppObj", method = "execute")
    public static void traceBegin1() {
        beginTime1 = timeMillis();
    }

    @OnMethod(clazz = "com.test.test.btrace.AppObj", method = "execute", location = @Location(Kind.RETURN))
    public static void traceExecute1() {
        println(strcat("time:", str(timeMillis() - beginTime1)));
    }

4. 打印方法参数

    @OnMethod(clazz = "com.test.test.btrace.AppObj", method = "execute")
    public static void traceExecute2(@Self Object instance, AnyType[] args) {
        printArray(args);
    }

5. 打印返回值

    @OnMethod(clazz = "com.test.test.btrace.AppObj", method = "execute", location = @Location(Kind.RETURN))
    public static void traceExecute(@Self Object instance, @Return boolean result) {
        println("call AppObj called");
        println(strcat("result=", str(result)));
    }

6. 打印对象属性值

    @OnMethod(clazz = "com.test.test.btrace.AppObj", method = "execute")
    public static void traceExecute(@Self AppObj self) {
        println(get(field("com.test.test.btrace.AppObj", "sum"), self));
    }