今天移动电话面试那头问的一个问题，不过面试官的技能才一般，估计他还不懂怎么做，我现在把这个过程的代码贴一下
思路：
1、设置一个最大允许线程数量，首先是要通过你自身的机器承压能力和程序运行复杂情况来设定的
2、利用线程组来获取目前运行的线程数量
import java.util.LinkedList; import java.util.Queue; public class ThreadGroudTest { private static final ThreadGroup tg = new ThreadGroup("tg"); private static final int maxthread=3;//最大允许线程数量 private static final int num = 100000;//模拟跑程序 public static void main(String[] args) { //添加队列 Queue<Thread> queue = new LinkedList<Thread>(); queue.add(Thread1(tg)); queue.add(Thread2(tg)); queue.add(Thread3(tg)); queue.add(Thread4(tg)); queue.add(Thread5(tg)); queue.add(Thread6(tg)); queue.add(Thread7(tg)); queue.add(Thread8(tg)); queue.add(Thread9(tg)); queue.add(Thread10(tg)); Thread thread; int i=0; while((thread=queue.poll())!=null){ thread.start();//运行线程 while(true){ if(tg.activeCount()<=maxthread){//判断是否超过最大值 break; }else{ System.out.println("等待前..."+System.currentTimeMillis()); waits(); System.out.println("等待后..."+System.currentTimeMillis()); i++; System.out.println("超过了，需要等待！"+i+"次"); } } } } private static void waits(){ try { Thread.sleep(100); } catch (Exception e) { e.printStackTrace(); } } public static Thread Thread1(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread1:"+i); } } }); } public static Thread Thread2(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread2:"+i); } } }); } public static Thread Thread3(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread3:"+i); } } }); }public static Thread Thread4(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread4:"+i); } } }); }public static Thread Thread5(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread5:"+i); } } }); }public static Thread Thread6(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread6:"+i); } } }); }public static Thread Thread7(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread7:"+i); } } }); }public static Thread Thread8(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread8:"+i); } } }); }public static Thread Thread9(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread9:"+i); } } }); }public static Thread Thread10(ThreadGroup tg){ return new Thread(tg,new Runnable(){ public void run() { for(int i=0;i<num;i++){ //System.out.println("thread10:"+i); } } }); } }
运行结果是
等待前...1493968016581 等待后...1493968016681 超过了，需要等待！1次 等待前...1493968016681 等待后...1493968016782 超过了，需要等待！2次
适当调整模拟跑程序数量，有时候可能不输出，有时候还可能输出
等待前...1493968300130 等待后...1493968300231 超过了，需要等待！1次
说明程序是OK的l
