java代码列出jvm中所有的线程组和线程，javajvm,java代码列出jvm中

java代码列出jvm中所有的线程组和线程，javajvm,java代码列出jvm中

java代码列出jvm中所有的线程组和线程:

/* * Copyright (c) 2004 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 3nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose, * including teaching and use in open-source projects. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book,  * please visit http://www.davidflanagan.com/javaexamples3. */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);  }}