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列出JVM中所有的线程组和线程

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这个类包含一个有用的静态方法列出所有在JVM中的线程和线程组。它也有一个简单的main()方法,以便它可以作为一个独立的程序运行。```python import java.awt.BorderLayout; import java.io.PrintWriter; import java.io.StringWriter;

import javax.swing.JFrame; import javax.swing.JScrollPane; import javax.swing.JTextArea;

/ * This class contains a useful static method for listing all threads and * threadgroups in the VM. It also has a simple main() method so it can be run * as a standalone program. */ public class ThreadLister { / Display information about a thread. */ private static void printThreadInfo(PrintWriter out, Thread t, String indent) { if (t == null) return; out.println(indent + "Thread: " + t.getName() + " Priority: " + t.getPriority() + (t.isDaemon() ? " Daemon" : "") + (t.isAlive() ? "" : " Not Alive")); }

/* Display info about a thread group and its threads and groups / private static void printGroupInfo(PrintWriter out, ThreadGroup g, String indent) { if (g == null) return; int num_threads = g.activeCount(); int num_groups = g.activeGroupCount(); Thread[] threads = new Thread[num_threads]; ThreadGroup[] groups = new ThreadGroup[num_groups];

g.enumerate(threads, false);
g.enumerate(groups, false);

out.println(indent + "Thread Group: " + g.getName() + "  Max Priority: " + g.getMaxPriority()
    + (g.isDaemon() ? " Daemon" : ""));

for (int i = 0; i < num_threads; i++)
  printThreadInfo(out, threads[i], indent + "    ");
for (int i = 0; i < num_groups; i++)
  printGroupInfo(out, groups[i], indent + "    ");

}

/* Find the root thread group and list it recursively / public static void listAllThreads(PrintWriter out) { ThreadGroup current_thread_group; ThreadGroup root_thread_group; ThreadGroup parent;

// Get the current thread group
current_thread_group = Thread.currentThread().getThreadGroup();

// Now go find the root thread group
root_thread_group = current_thread_group;
parent = root_thread_group.getParent();
while (parent != null) {
  root_thread_group = parent;
  parent = parent.getParent();
}

// And list it, recursively
printGroupInfo(out, root_thread_group, "");

}

/* * The main() method create a simple graphical user interface to display the * threads in. This allows us to see the "event dispatch thread" used by AWT * and Swing. / public static void main(String[] args) { // Create a simple Swing GUI JFrame frame = new JFrame("ThreadLister Demo"); JTextArea textarea = new JTextArea(); frame.getContentPane().add(new JScrollPane(textarea), BorderLayout.CENTER); frame.setSize(500, 400); frame.setVisible(true);

// Get the threadlisting as a string using a StringWriter stream
StringWriter sout = new StringWriter(); // To capture the listing
PrintWriter out = new PrintWriter(sout);
ThreadLister.listAllThreads(out); // List threads to stream
out.close();
String threadListing = sout.toString(); // Get listing as a string

// Finally, display the thread listing in the GUI
textarea.setText(threadListing);

} } ```

标签:java

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