在网上找了很久才找到developerWorks上的一个解决方案：

在命令提示符里切换到目录“C:\Program Files\IBM\SDP70\jdk\jre\bin”，运行“java.exe -Xshareclasses:destroyAll”

这样就能正常启动RAD了！ 

原因描述如下：

（摘录自http://www-1.ibm.com/support/docview.wss?uid=swg21281393，并通过Google Translate转译，译文已作修改）

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问题（摘要）
此说明解释如何解决错误“JVM的终止。退出代码= 1”。

起因
RAD自带的IBM JVM使用了一个高速缓存参数来提高性能。而因为JVM的崩溃，比如蓝屏，或断电，都可能造成Java高速缓存被损坏。 而JVM会拒绝连接到一个损坏的高速缓存。

解决问题
要解决这个问题，使用“-Xshareclasses:destroyAll”的Java选项将销毁所有的共享级缓存。这是一种实用工具选项，所以不会启动JVM 。如果您想要这么做，只要从命令提示符使用参数“-Xshareclasses:destroyAll”来运行RAD使用的java。

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2、jsp:usebean 的class属性应该是类的全名（包括包名）。在前面<%@ import>中import的包，在tag里不起作用，只对jsp里面的java代码有用，所以tag里要使用类的全名

3、post时如果表单里有中文，会出现中文乱码，在servlet里调用request.getParameter之前执行request.setCharacterEncoding("gb2312");就可以正确识别和显示中文了；

如果是url中用中文参数，如someaction.jsp?q=中文问题，则要加一个filter来setEncoding，因为post和get传送参数的处理方式不一样。url中包含中文参数的设置参考：http://www.itet.cn/0512456328001529/JSP/0691214511318687.html

String sql  =   " select s.name from student s where s.id=' "   +  sId  +   " ' "；

后来我开始使用PreparedStatement，在SQL里使用“？”标记参数，然后用setXXX方法给参数赋值。当时只知道这样用是因为有setDate，setTimeStamp这些用“+”连接不能直接嵌入的值。

感觉PreparedStatement在性能方面应该也能快点，可能DBMS会重用，但不明底层原理。

这次《数据库实现》课程终于让我弄懂了：每个SQL语句都要通过 语法分析 -> 生成逻辑查询计划 -> 逻辑优化 -> 物理优化 等步骤生成具体的执行计划，用PreparedStatement就可以生成一个执行计划，以后只是参数改变（相当于执行计划的执行环境改变），前面的四个步骤也会省略，从而提高了效率。

如果一个SQL语句要被反复多次执行，或多用户同时操作，则应选用PreparedStatement！

最后作者以Struts为例，介绍了几种选择Ajax的场景：

1 现有的Struts应用程序要使用Ajax，请使用AjaxAnywhere

2 建立新的应用程序准备使用Ajax，参考Appfuse，它集成了DWR的Ajax

3 中期目标： 使用一种支持Ajax的JSF的实现，MyFaces或者Struts Shale

原文地址：http://blog.csdn.net/danny_xcz/archive/2006/03/03/614302.aspx

用户可设定“深度搜索”：每搜到一个url就放在list的最前面
也可广度

有些网页链接要特殊处理：

读取资源代码：

Allow access only from a friend code

Java by default restricts the friends of a class to those classes that are in the same package. If there is a functionality that you want share just among classes in the same package, use package-private modifier in definition of a constructor, a field or a method and then it will remain accessible only to friends.

Sometimes however it is more useful to extend the set of friends to a wider range of classes - for example one wants to define a pure API package and put the implementation into separate one. In such cases following trick can be found useful. Imagine there is a class item:

public final class api.Item {
    /** Friend only constructor */
    Item(int value) {
        this.value = value;
    }

    /** API method(s) */
    public int getValue() {
        return value;
    }
        
    /** Friend only method */
    final void addListener(Listener l) {
        // some impl
    }
}

public abstract class impl.Accessor {
    public static Accessor DEFAULT;

    static {
        // invokes static initializer of Item.class
        // that will assign value to the DEFAULT field above
        Class c = api.Item.class;
        try {
            Class.forName(c.getName(), true, c.getClassLoader());
        } catch (ClassNotFoundException ex) {
            assert false : ex;
        }
        assert DEFAULT != null : "The DEFAULT field must be initialized";
    }

    /** Accessor to constructor */
    public abstract Item newItem(int value);
    /** Accessor to listener */
    public abstract void addListener(Item item, Listener l);
}

final class api.AccessorImpl extends impl.Accessor {
    public Item newItem(int value) {
        return new Item(value);
    }
    public void addListener(Item item, Listener l) {
        return item.addListener(l);
    }
}

public final class Item {
    static {
        impl.Accessor.DEFAULT = new api.AccessorImpl();
    }

    // the rest of the Item class as shown above
}

api.Item item = impl.Accessor.DEFAULT.newItem(10);
impl.Accessor.DEFAULT.addListener(item, this);

• Content with Style: Fixing the Back Button and Enabling Bookmarking for AJAX Apps - Mike Stenhouse explains how to fix two of the more distracting problems with Ajax. These can be particularly problematic for users new to Ajax applications.  Since Ajax apps typically load into a single web page, it makes pressing the Back button meaningless or actually harmful.  And this breaks the browser usage model annoyingly.  Also, individual views of data in an Ajax application cannot have a URL or permalinks unless precautions are taken.  Mike does a great job covering how to reduce these problems.
  
• Saving Session Across Page Loads Without Cookies, On The Client Side - Ajax virtuoso Brad Neuberg strikes again with a detailed explanation of how to deal with saving session information across page loads without relying on cookies.  This is important in larger applications which typically want to store more information than a cookie can hold.  Brad also has some terrific tools to deal with this as well (see AMASS below)
  
• Call SOAP Web services with AJAX - By design, Ajax is a voracious consumer of web services like XML/HTTP, REST, and SOAP.  A great article at IBM's DeveloperWorks describes how to easily call SOAP web services from Ajax.  This is important because SOAP is a complex protocol that requires some familiarity to use.  While Ajax development tools like Atlas, General Interface, and Bindows will solve this by providing a SOAP stack, for many, hand development of back-end SOAP request is the only option right now to achieve interoperability with WS-I Basic Profile web services.
  
• Ajax using only an image - Browsers and networks continue to get more secure and many configurations will not allow an Ajax application to use web services, and almost none of them will allow you to access a server other than the one the Ajax app loaded from.  Enter an elegant technique to solve this by using image URLs.  Not for the faint of heart, and certainly a possible security hole but a compelling solution nonetheless.
  

• TIBCO's General Interface - I've not used this Ajax development environment extensively yet but it apparently eats its own dog food and runs entirely inside a browser (which apparently must be Internet Explorer).  Supposedly containing an entire SOAP stack, a full-blown IDE, and numerous libraries, General Interface is one of the leading solutions in this space and can be downloaded and used today.  TIBCO cautions you not to use it for production apps yet, but my initial use was encouraging.
  
• Microsoft Atlas - A serious contender in the Ajax IDE space (details here), Microsoft is planning for Atlas to be a heavy-duty, enterprise scale Ajax solution.  Integrated into Visual Studio 2005, Atlas is just a code name but expect that it will be a leading Ajax player from the get go and will live up to its name.
  
• Dojo - Still in early release, the open source Ajax library, Dojo, is getting lots of attention from folks in the know.  Dojo is billed as a "powerful, portable, lightweight, and tested tools for constructing dynamic interfaces. Dojo lets you prototype interactive widgets quickly, animate transitions, and build Ajax requests with the most powerful and easiest to use abstractions available."  I haven't used it yet, but you can bet I will be soon.
  
• Script.aculo.us - One of the very best Ajax visual effects libraries that I've used is the eponymous script.aculo.us.  Advertised as "Web 2.0 JavaScript", script.aculo.us has numerous effects and convenience tools, all built on nice, tight object-oriented abstractions.  I've used it and I can recommend it for its simplicity and reliability.
  
• Bindows - Mind-blowing Ajax library for recreating the full richness of native applications, and includes a SOAP stack.
  
• AMASS - Ajax gets good client-side storage.  A brilliant piece of work by Brad Neuberg, check out a description of how AMASS works here.
  
• TrimQuery - A robust JavaScript database for Ajax.  When combined with AMASS above, neat things can really happen.
  
  
  
  
  
  
• Ruby on Rails - Should probably be listed first, not down here.  The best lightweight, server-side Ajax framework out there today.  Note that Ajax pioneers and Web 2.0 leaders 37Signals sponsor this site and RoR is used by a great many successful Web 2.0 sites.
  
  
• Log4Ajax - Many serious developers wouldn't switch to a new programming model without a Log4J equivalent and here it is.  Both traditional console as well as advanced logging support for Ajax is here today.  SourceForge site here.
  
• Backbase - This IDE is getting good reviews but it apparently uses an abstraction layer like Morfik.  I haven't used it yet but I keep hearing about it.
  
• Sajax - A good competent server-side framework featuring support for most common back-end languages like Perl, Python, Ruby and much more.
  

• The Ajax Developer's Journal - Good sources of news for Ajax are still pretty scarce but that's starting to change in a big way.  SYS-CON has recently launched their Ajax Developer's Journal and has been working closely with Jesse James Garrett, who coined the term.  Expect lots of interesting and topical new articles and coverage on a regular basis.
  
• Ajaxian - Dion Almaer and Ben Galbraith have been working on Ajaxian for a while now and it remains one of the very best sources for the latest Ajax news, tools, events, and general inspiration.
  

• Ajax Mistakes - This is Alex Bosworth's terrific analysis of the early problems with Ajax.  He a big believer in the technology and his Ajax-powered LiveMarks site is one of my absolute favorites.  A good place to start to understand some of the challenges with Ajax.
  
• Fixing Ajax: XmlHttpRequest Considered Harmful - Some good coverage of why Ajax doesn't really enable the use of the services of other web sites without a lot of work.  This is a big barrier to leveraging Web 2.0's global services landscape.  This can be solved a number of ways however and the options are explored here.  The image URL solution a few paragraphs above is missing but otherwise this is an excellent summary.
  
  
  
  
  
  
• 10 Places You Must Use Ajax - Alex is back and carefully enumerates the good places to use Ajax.  He also covers when to avoid it.  Excellent material for those learning how to design with Ajax.
  
• Top 10 Reasons Ajax Is Here To Stay - Andre Charland nails it.  Though some folks dislike Ajax for a variety of reasons, here are some terrific positive motivations for using it today.
  

posted Friday, 30 December 2005