“无法加载Premain-Class清单属性”同时尝试使用java代理获取对象的大小 [英] "Failed to load Premain-Class manifest attribute" while trying to get the size of an object using java agent

问题描述

当我尝试运行java程序（ java -javaagent：size.jar ObjectSizeTest ）时，我收到以下错误：

When i try to run a java program (java -javaagent:size.jar ObjectSizeTest) i get the following error:

Failed to load Premain-Class manifest attribute from D:\workspace\ObjectSizeTest\size.jar
Error occurred during initialization of VM
agent library failed to init: instrument

这是ObjectSizeTest的代码：

Here is ObjectSizeTest's code:

public class ObjectSizeTest {
    public static void main(String[] args) {
        String s = new String("sai");
        System.out.println(ObjectSizeFetcher.getObjectSize(s));
    }
}

MANIFEST.MF（适用于size.jar）：

MANIFEST.MF (for size.jar):

Manifest-Version: 1.0
Created-By: 1.5.0_18 (Sun Microsystems Inc.)

Premain-Class: ObjectSizeFetcher

这里是ObjectSizeFetcher的代码：

and here is ObjectSizeFetcher's code:

import java.lang.instrument.Instrumentation;

public class ObjectSizeFetcher {
    private static Instrumentation instrumentation;

    public static void premain(String args, Instrumentation inst) {
        instrumentation = inst;
    }

    public static long getObjectSize(Object o) {
        return instrumentation.getObjectSize(o);
    }
}

推荐答案

制作确定你已经给出了包含pre-main方法的类的完整java路径。
例如像org.eclipse.anotherpckg.ObjectSizeFetcher。其次，名称和运输结束前必须有一个空格。例如

Make sure you have give full java path of the class containing the pre-main method. for example like this org.eclipse.anotherpckg.ObjectSizeFetcher. Secondly there must be a space before the name and carriage return at the end. for example

Manifest-Version: 1.0
Created-By: 1.5.0_18 (Sun Microsystems Inc.)
Premain-Class: org.eclipse.package.ObjectSizeFetcher

最后一行是由于回车。

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