threadlister.java

java应用举例4

import java.io.*;
import java.awt.*;     
import javax.swing.*; 

public class ThreadLister {
    public 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"));
    }
    
    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 + "    ");
    }
    
    public static void listAllThreads(PrintWriter out) {
        ThreadGroup current_thread_group;
        ThreadGroup root_thread_group;
        ThreadGroup parent;
        
        current_thread_group = Thread.currentThread().getThreadGroup();
        
        root_thread_group = current_thread_group;
        parent = root_thread_group.getParent();
        while(parent != null) {
            root_thread_group = parent;
            parent = parent.getParent();
        }
        
        printGroupInfo(out, root_thread_group, "");
    }
    
    public static void main(String[] args) {
	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);

	StringWriter sout = new StringWriter();   
	PrintWriter out = new PrintWriter(sout);
	ThreadLister.listAllThreads(out);        
	out.close();                             
	String threadListing = sout.toString();  

	textarea.setText(threadListing);
    }
}