However, Java provides a more elegant solution: the volatile keyword. If a variable is marked as volatile, every time the variable is used it must be read from main memory. Similarly, every time the variable is written, the value must be stored in main memory. Since these operations are atomic, we can avoid the race condition in our example by marking our done flag as volatile.

在tij中也有讲述

 Thinking   in   java   的   13.7   范例   CanStop   里面有代码  
  //Must   be   volatile:  
  private   volatile   boolean   stop   =   false;  
  这里boolean类型应该就已经是原子操作了，不需要再保证了。  
   
  书里说   stop标志必须是volatile的，以便run()方法肯定看到他（否则的话，这个值可能本地缓存)  
   
  我猜想   volatile表示这个值可能被别的线程改变，所以被标志为volatile的变量，每次都是从存储区中读取变量对应的值，而不是在该线程中本地缓存的值。因为本地缓存的值不能及时反映其他线程对这个变量的影响。   
 


在线程中 该关键字还是会用到的..

地址：http://tap.javalobby.org/javaee5.mp3

歌词：
Ladies and gentlemen, this is Java EE 5!

One, two, three, four, five
There's a technology I use day and night
For my application with a web frontend
They told me to use .Net
But I really don´t wanna

So many bugs I fixed last week.
My code is neat and talk is a cheap
I like Glassfish, JSF, persistence API
And as I continue you know they´re gettin´ sweeter

So what can I do I really beg you my Lord
To me codin' it´s just like a sport
All the bad code from the past, let me dump it
Please set in the trumpet

A little bit of injection in my life
A little bit of persistence by my side
A little bit of NetBeans is all I need
A little bit of EJB's what I see
A little bit of standards in the sun
A little bit of XML all night long
A little bit web services here I am
A little bit of code makes me real man

This is Java EE 5!

Jump up and down and move your code around
Shake your head to the sound bury bad code under ground
Move one step left and one step right
One to the front and one to the side
Refactor it once and refactor it twice
If it looks like this you're doin´ it right

A little bit of injection in my life
A little bit of persistence by my side
A little bit of NetBeans is all I need
A little bit of EJB's is what I see
A little bit of standards in the sun
A little bit of XML all night long
A little bit web services here I am
A little bit of code makes me real man

This is Java EE 5!

还不错哦.

from csdn

Francois Orsini has announced that Apache Derby has become bundled with the latest 1.6 JDK. "...yes it has become a reality! - It is a very exciting event indeed to have an Open Source Java Database System bundled into Sun's *latest* 1.6 JDK (Mustang build 88 to be more precised), and at no cost."



相关连接:

学习使用Java DataBase (Derby) -- 嵌入式数据库

在derby(Java DB) 中操作 clob 和 blob

关于关闭Java DB(Derby)时抛出异常的问题

用户讨论区: http://www.hexiao.cn/bbs/thread.php?fid=9

大家都知道开发Swing程序有三大难点:
布局设置,事件处理,和数据绑定. 使用netbean中的新的布局管理器已经解决了第一个问题, 那么后面两个呢?

Breezy 就是用来简化后面两个问题而推出的.
下面我们先来看看一个简单的例子:

package test;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;

import javax.swing.JButton;
import javax.swing.JFrame;

import net.sf.breezy.event.EventInstaller;
import net.sf.breezy.event.annotations.ActionPerformed;
import net.sf.breezy.event.annotations.DefAction;

@SuppressWarnings("serial")
public class TestBreezy extends JFrame {
     
     private JButton button = new JButton("Test Breezy!");
     
     public TestBreezy() {
           this.setLayout(new BorderLayout());
           this.add(button,BorderLayout.CENTER);
           
           // 用来处理所有的Breezy的Annotations
                    EventInstaller.processEventAnnotation(this);
           
           this.setSize(400, 300);
           this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
           
           EventInstaller.setAction(button, "action");
     }
     
  // button的事件响应方法
     @ActionPerformed("button")
     public void myButtonAction() {
          System.out.println("God, this is terrific!");//设置另外一个事件
     }
     
// 使用id注册另外一个事件响应方法
     @DefAction(id="action", name="Button")
     void action(ActionEvent e) {
           System.out.println(e + ":" + e);
     }

     /**
      * @param args
      */
     public static void main(String[] args) {
           // TODO Auto-generated method stub
           JFrame frame = new TestBreezy();
           frame.setVisible(true);
     }

}

怎么样, 看起来不错吧.

现在Breezy几乎支持所有的Swing EventListeners. 详细情况请查看类net.sf.breezy.event.annotations.*

当然了, 作为一个优秀的框架,还要有可扩展性,在Breezy中开发者还可以自定义自己的事件响应Annotation 来实现自己的功能. 详细情况请查看API.

数据绑定问题主要 就是 JTable 和JTree的问题:
使用Breezy来处理该问题,有点类似于Hibernate中的xml映射数据库属性字段差不多. 可以很方便的映射.
请看下面的例子: 和Breezy文档:

package test;

import java.util.Date;

public class Name {
     private String name = "Starwhisperer";

     private Date time = new Date();

     public String getName() {
           return name;
     }

     public void setName(String name) {
           this.name = name;
     }

     public Date getTime() {
           return time;
     }

     public void setTime(Date time) {
           this.time = time;
     }

}


User.java
package test;

import java.util.Date;

import net.sf.breezy.datatable.TableField;

public class User {
     @TableField(head = "名称", editable = false)
     private String name;

     @TableField(head = "年龄", editable = false, type = "number")
     private int age;

     @TableField(head = "阵营", type = "boolean", editable = false)
     private boolean light;

     @TableField(head = "时间", type = "time", pattern = "yyyy/MM/dd")
     private Date date = new Date();

     @TableField(head = "名称", property = "name", type="string")
     private Name nameBean = new Name();

     public Name getNameBean() {
           return nameBean;
     }

     public void setNameBean(Name nameBean) {
           this.nameBean = nameBean;
     }

     public boolean isLight() {
           return light;
     }

     public void setLight(boolean light) {
           this.light = light;
     }

     public int getAge() {
           return age;
     }

     public void setAge(int age) {
           this.age = age;
     }

     public String getName() {
           return name;
     }

     public void setName(String name) {
           this.name = name;
     }

     public Date getDate() {
           return date;
     }

     public void setDate(Date date) {
           this.date = date;
     }

}

DataTableTest .java

package test;

import java.awt.BorderLayout;
import java.util.LinkedList;
import java.util.List;

import javax.swing.JFrame;
import javax.swing.JScrollPane;

import net.sf.breezy.datatable.DataTable;
import net.sf.breezy.datatable.DataTableScrollPane;


public class DataTableTest {
     private JFrame mainFrm = new JFrame();
     
     protected void setUp() {            
           mainFrm.setSize(100, 600);
           mainFrm.setLocationRelativeTo(null);
           mainFrm.setLayout(new BorderLayout());

           mainFrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     }
     
     public static void main(String[] args) {
           DataTableTest test = new DataTableTest();

           test.setUp();
           test.testTable();
     }
     
     public void testTable() {            
           java.util.List list = new LinkedList();
           for(int i = 0; i < 120; i ++) {
                 User u = new User();
                 
                 u.setAge(33);
                 u.setName("Cain " + i);
                 list.add(u);
           }
           DataTableScrollPane<User> pane = DataTable.getEntityTablePane(list, User.class);
           
           mainFrm.add(pane, BorderLayout.CENTER);            
           mainFrm.setVisible(true);
     }
}


映射文件:datatable-mappings.xml
<?xml version="1.0"?>

<class-mapping>
     <class name="test.User">
           <property name="age" head="年龄" />
           <property name="light" head="光芒" type="boolean" editable="true"/>
           <property name="nameBean" property="time" head="姓名" pattern="yyyy/mm/dd" type="time"/>
           <property name="date" head="Date"/>
           <property name="name" head="Name"/>
     </class>
</class-mapping>

也是很简单的吧. 关于JTree的应用也是很简单的哦. 详细情况请查看用户文档:


更多信息请关注 用户交流论坛: http://www.hexiao.cn/bbs/thread.php?fid=9 

  - Build AJAX apps in the Java language

Google Web Toolkit (GWT) is a Java software development framework that makes writing AJAX applications like Google Maps and Gmail easy for developers who don't speak browser quirks as a second language. Writing dynamic web applications today is a tedious and error-prone process; you spend 90% of your time working around subtle incompatabilities between web browsers and platforms, and JavaScript's lack of modularity makes sharing, testing, and reusing AJAX components difficult and fragile.

GWT lets you avoid many of these headaches while offering your users the same dynamic, standards-compliant experience. You write your front end in the Java programming language, and the GWT compiler converts your Java classes to browser-compliant JavaScript and HTML.

Learn more »

GWT的特性:

• Dynamic, reusable UI components
  Create a Widget by compositing other Widgets. Lay out Widgets automatically in Panels. Send your Widget to other developers in a JAR file.
• Really simple RPC
  To communicate from your web application to your web server, you just need to define serializable Java classes for your request and response. In production, GWT automatically serializes the request and deserializes the response from the server. GWT's RPC mechanism can even handle polymorphic class hierarchies, and you can throw exceptions across the wire.
• Browser history management
  No, AJAX applications don't need to break the browser's back button. GWT lets you make your site more usable by easily adding state to the browser's back button history.
• Real debugging
  In production, your code is compiled to JavaScript, but at development time it runs in the Java virtual machine. That means when your code performs an action like handling a mouse event, you get full-featured Java debugging, with exceptions and the advanced debugging features of IDEs like Eclipse.
• Browser compatible
  Your GWT applications automatically support IE, Firefox, Mozilla, Safari, and Opera with no browser detection or special-casing within your code in most cases.
• Interoperability and fine-grained control
  If GWT's class library doesn't meet your needs, you can mix handwritten JavaScript in your Java source code using our JavaScript Native Interface (JSNI).

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