blocks|key|1228136|text|我没有专门尝试过获取VM设置，但是JMX实用程序中有大量的信息，特别是MXBean实用程序。这将是我要开始的地方。希望你能找到一些对你有帮助的东西。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1228137|sun网站上有一堆关于这项技术的内容：|1228138|http://java.sun.com/javase/6/docs/technotes/guides/management/mxbeans.html|offset|length|1228139|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|22|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@$F|R|G|S|1|T]]|A|$]]|$1|H|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|E]]]]

I haven't tried specifically getting the VM settings, but there is a wealth of information in the JMX utilities specifically the MXBean utilities. This would be where I would start. Hopefully you find something there to help you.

The sun website has a bunch on the technology:

<a href="http://java.sun.com/javase/6/docs/technotes/guides/management/mxbeans.html" rel="nofollow noreferrer">http://java.sun.com/javase/6/docs/technotes/guides/management/mxbeans.html</a>

blocks|key|1443148|text|使用以下代码，您可以获得JVM参数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1443149|import+java.lang.management.ManagementFactory;
import+java.lang.management.RuntimeMXBean;
...
RuntimeMXBean+runtimeMxBean+=+ManagementFactory.getRuntimeMXBean();
List<String>+arguments+=+runtimeMxBean.getInputArguments();|code-block|syntax|javascript|1443150|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

With this code you can get the JVM arguments:

<pre><code>import java.lang.management.ManagementFactory;
import java.lang.management.RuntimeMXBean;
...
RuntimeMXBean runtimeMxBean = ManagementFactory.getRuntimeMXBean();
List&lt;String&gt; arguments = runtimeMxBean.getInputArguments();
</code></pre>

blocks|key|1228356|text|在启动时传递此-Dname=value|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1228357|然后在你的代码中你应该使用|1228358|value=System.getProperty("name");|code-block|syntax|javascript|1228359|来获得这个值|1228360|entityMap^0|7|C|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|V|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

At startup pass this <code>-Dname=value</code>

and then in your code you should use

<pre><code>value=System.getProperty("name");
</code></pre>

to get that value

blocks|key|1443378|text|如果您想要java进程的整个命令行，可以使用：JvmArguments.java+(使用JNA+%2B+/proc的组合来覆盖大多数unix实现)|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1443379|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/zolyfarkas/spf4j/blob/master/spf4j-core/src/main/java/org/spf4j/unix/JVMArguments.java^0|N|H|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

If you want the entire command line of your java process, you can use: <a href="https://github.com/zolyfarkas/spf4j/blob/master/spf4j-core/src/main/java/org/spf4j/unix/JVMArguments.java" rel="nofollow noreferrer">JvmArguments.java</a>
(uses a combination of JNA + /proc to cover most unix implementations)

blocks|key|1443490|text|我发现HotSpot列出了管理bean中除-client和-server之外的所有VM参数。因此，如果您从VM名称推断出-client/-server参数，并将其添加到运行时管理bean的列表中，就会得到完整的参数列表。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1443491|下面是SSCCE：|1443492|import+java.util.*;
import+java.lang.management.ManagementFactory;

class+main+{
++public+static+void+main(final+String[]+args)+{
++++System.out.println(fullVMArguments());
++}

++static+String+fullVMArguments()+{
++++String+name+=+javaVmName();
++++return+(contains(name,+"Server")+?+"-server+"
++++++:+contains(name,+"Client")+?+"-client+"+:+"")
++++++%2B+joinWithSpace(vmArguments());
++}

++static+List<String>+vmArguments()+{
++++return+ManagementFactory.getRuntimeMXBean().getInputArguments();
++}

++static+boolean+contains(String+s,+String+b)+{
++++return+s+!=+null+&&+s.indexOf(b)+>=+0;
++}

++static+String+javaVmName()+{
++++return+System.getProperty("java.vm.name");
++}

++static+String+joinWithSpace(Collection<String>+c)+{
++++return+join("+",+c);
++}

++public+static+String+join(String+glue,+Iterable<String>+strings)+{
++++if+(strings+==+null)+return+"";
++++StringBuilder+buf+=+new+StringBuilder();
++++Iterator<String>+i+=+strings.iterator();
++++if+(i.hasNext())+{
++++++buf.append(i.next());
++++++while+(i.hasNext())
++++++++buf.append(glue).append(i.next());
++++}
++++return+buf.toString();
++}
}|code-block|syntax|javascript|1443493|如果您想在List<String>中使用参数，可以将其缩短。|offset|length|style|CODE|1443494|最后注意:我们可能还想扩展它，以处理命令行参数中有空格的罕见情况。|1443495|entityMap^0|0|0|0|5|C|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@$K|W|L|X|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I found that HotSpot lists all the VM arguments in the management bean except for -client and -server. Thus, if you infer the -client/-server argument from the VM name and add this to the runtime management bean's list, you get the full list of arguments.

Here's the SSCCE:

<pre><code>import java.util.*;
import java.lang.management.ManagementFactory;

class main {
 public static void main(final String[] args) {
 System.out.println(fullVMArguments());
 }

 static String fullVMArguments() {
 String name = javaVmName();
 return (contains(name, "Server") ? "-server "
 : contains(name, "Client") ? "-client " : "")
 + joinWithSpace(vmArguments());
 }

 static List&lt;String&gt; vmArguments() {
 return ManagementFactory.getRuntimeMXBean().getInputArguments();
 }

 static boolean contains(String s, String b) {
 return s != null &amp;&amp; s.indexOf(b) &gt;= 0;
 }

 static String javaVmName() {
 return System.getProperty("java.vm.name");
 }

 static String joinWithSpace(Collection&lt;String&gt; c) {
 return join(" ", c);
 }

 public static String join(String glue, Iterable&lt;String&gt; strings) {
 if (strings == null) return "";
 StringBuilder buf = new StringBuilder();
 Iterator&lt;String&gt; i = strings.iterator();
 if (i.hasNext()) {
 buf.append(i.next());
 while (i.hasNext())
 buf.append(glue).append(i.next());
 }
 return buf.toString();
 }
}
</code></pre>

Could be made shorter if you want the arguments in a <code>List&lt;String&gt;</code>.

Final note: We might also want to extend this to handle the rare case of having spaces within command line arguments.

I need to check if some option that can be passed to JVM is explicitly set or has its default value.

To be more specific:
I need to create one specific thread with higher native stack size than the default one, but in case the user wants to take care of such things by himself by specifying the <code>-Xss</code> option I want to create all threads with default stack size (which will be specified by user in -Xss option).

I've checked classes like <code>java.lang.System</code> and <code>java.lang.Runtime</code>, but these aren't giving me any useful information about VM arguments.

Is there any way to get the information I need?

How to get VM arguments from inside of Java application?

我需要检查可以传递给JVM的某些选项是否已显式设置或具有其默认值。更具体地说:我需要创建一个具有比默认堆栈大小更大的本机堆栈大小的特定线程，但如果用户想要通过指定-Xss选项自己处理这些事情，我希望创建所有具有默认堆栈大小的线程(这将由用户在-Xss选项中指定)。我检查了像java.lang.System和java.l...

问如何从Java应用程序内部获取VM参数？
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