Java实现多线程并发

 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Semaphore;

 public class ThreadTest {
     private static int thread_num = 500;
     private static int client_num = 5000;

     public static void main(String[] args,String no) {
         ExecutorService exec = Executors.newCachedThreadPool();

         final Semaphore semp = new Semaphore(thread_num);

         for (int index = 0; index < client_num; index++) {

             final int NO = index;

             Runnable run = new Runnable() {
                 public void run() {
                     try {
                         semp.acquire();
                         //HttpClientTest.postLogin();
                         System.out.println("Thread:" + NO);
                         semp.release();
                     } catch (Exception e) {
                         e.printStackTrace();
                     }
                 }
             };
             exec.execute(run);
         }
         exec.shutdown();
     }
 }