小编use*_*006的帖子

如何防止并发访问.我有这样的代码

public class MC implements Runnable {

    public void run() {
        sync();
    }

    public static void main(String p[]){
        MC mc = new MC();
        MC mc2 = new MC();
        MC mc3 = new MC();
        MC mc4 = new MC();
        Thread t = new Thread(mc);
            t.start();
            Thread t2 = new Thread(mc2);
            t2.start();
            Thread t3 = new Thread(mc3);
            t3.start();
            Thread t4 = new Thread(mc4);
            t4.start();
    }

    private synchronized void sync(){
        try {
            System.out.println(System.currentTimeMillis());
            Thread.sleep(10000);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }
    }
} …

我有一个JFrame和以下组件.

JButton = jButton1 Progress Bar = progressBar及其公共静态JLabel = status及其公共静态

按钮单击时,执行不同的语句.我希望在每个语句后更新我的进度条.这是我的代码

   private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        Task pbu = new Task(25, "Step 1....");
        pbu.execute();

        try {
            Thread.sleep(1000);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }

        pbu = new Task(50, "Step 2....");
        pbu.execute();

        try {
            Thread.sleep(1000);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }

        pbu = new Task(75, "Step 3....");
        pbu.execute();

        try {
            Thread.sleep(1000);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        }

        pbu = new Task(100, "Done");
        pbu.execute();
    }

这是我使用SwingWorker扩展的Task类

public class Task extends …

我在httpd.conf中启用了mod_cache,mod_expires,mod_headers模块,并添加了以下文本

 ExpiresActive On


<ifModule mod_deflate.c>
  <filesMatch "\.(css|js|x?html?|php)$">
    SetOutputFilter DEFLATE
  </filesMatch>
</ifModule>



<ifModule mod_expires.c>
  ExpiresActive On
  ExpiresDefault "access plus 1 seconds"
  ExpiresByType image/x-icon "access plus 2592000 seconds"
  ExpiresByType image/jpeg "access plus 2592000 seconds"
  ExpiresByType image/png "access plus 2592000 seconds"
  ExpiresByType image/gif "access plus 2592000 seconds"
  ExpiresByType application/x-shockwave-flash "access plus 2592000 seconds"
  ExpiresByType text/css "access plus 604800 seconds"
  ExpiresByType text/javascript "access plus 216000 seconds"
  ExpiresByType application/javascript "access plus 216000 seconds"
  ExpiresByType application/x-javascript "access plus 216000 seconds"
  ExpiresByType text/html "access plus 600 seconds" …

例如，如果我在这样的列中有数据

data
I love book
I love apple
I love book
I hate apple
I hate apple

我怎样才能得到这样的结果

I = 5
love = 3
hate = 2
book = 2
apple = 3

我们可以用 MySQL 来实现吗？

我在mysql表中有1M行,当我执行下面的代码时,我是java持久性api然后我得到java堆错误:

int counter = 0;
while (counter < 1000000) {
   java.util.Collection<MyEntityClass> data = myQuery.setFirstResult(counter)
       .setMaxResults(1000).getResultList();
   for(MyEntityClass obj : data){
       System.out.println(obj);
   }
   counter += 1000;
}