如何隐藏警告“非法反射访问"在没有JVM参数的Java 9中? [英] How to hide warning "Illegal reflective access" in java 9 without JVM argument?

问题描述

我刚刚尝试使用Java 9运行服务器，并收到下一条警告:

I just tried to run my server with Java 9 and got next warning:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by io.netty.util.internal.ReflectionUtil (file:/home/azureuser/server-0.28.0-SNAPSHOT.jar) to constructor java.nio.DirectByteBuffer(long,int)
WARNING: Please consider reporting this to the maintainers of io.netty.util.internal.ReflectionUtil
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

我想隐藏此警告，而不必在启动过程中将--illegal-access=deny添加到JVM选项.像这样:

I would like to hide this warning without adding --illegal-access=deny to JVM options during start. Something like:

System.setProperty("illegal-access", "deny");

有什么办法吗?

所有建议使用JVM选项的相关答案，我想从代码中关闭它.有可能吗?

All related answers suggesting to use JVM options, I would like to turn off this from code. Is that possible?

为了澄清-我的问题是关于通过代码而不是通过类似问题中所述的JVM参数/标志来打开此警告.

To clarify - my question is about turning this warning from the code and not via JVM arguments/flags as stated in similar questions.

推荐答案

有一些方法可以禁用非法访问警告，尽管我不建议这样做.

There are ways to disable illegal access warning, though I do not recommend doing this.

由于将警告打印到默认错误流，因此您只需关闭该流并将stderr重定向到stdout.

Since the warning is printed to the default error stream, you can simply close this stream and redirect stderr to stdout.

public static void disableWarning() {
    System.err.close();
    System.setErr(System.out);
}

注意:

• 此方法合并错误和输出流.在某些情况下，这可能是不可取的.
• 您不能仅通过调用System.setErr重定向警告消息，因为错误流的引用在JVM引导程序的早期就保存在IllegalAccessLogger.warningStream字段中.

• This approach merges error and output streams. That may not be desirable in some cases.
• You cannot redirect warning message just by calling System.setErr, since the reference to error stream is saved in IllegalAccessLogger.warningStream field early at JVM bootstrap.

一个好消息是sun.misc.Unsafe仍可以在JDK 9中访问而不会发出警告.解决方案是在Unsafe API的帮助下重置内部IllegalAccessLogger.

A good news is that sun.misc.Unsafe can be still accessed in JDK 9 without warnings. The solution is to reset internal IllegalAccessLogger with the help of Unsafe API.

public static void disableWarning() {
    try {
        Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
        theUnsafe.setAccessible(true);
        Unsafe u = (Unsafe) theUnsafe.get(null);

        Class cls = Class.forName("jdk.internal.module.IllegalAccessLogger");
        Field logger = cls.getDeclaredField("logger");
        u.putObjectVolatile(cls, u.staticFieldOffset(logger), null);
    } catch (Exception e) {
        // ignore
    }
}

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