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怀�늽��U�_��?�?

.Sun — Mon, 21 Jun 2010 17:38:00 GMT

摘要: 一个男人，要走多远的�\�Q�才能成为真正的男�h�Q?nbsp; 阅读全文

.Sun 2010-06-22 01:38 发表评论

.Sun — Mon, 21 Jun 2010 17:34:00 GMT

摘要: 来吧�Q�罗�U�_��多！
无论时光��逝多��?
阅读全文

.Sun 2010-06-22 01:34 发表评论

无题

.Sun — Sun, 20 Jun 2010 09:43:00 GMT

城市灯火何止万家
那星星点点的光亮
映衬风雨健硕�ȝ��的舞�?br /> �q�逐自由�Ş骸的放浪
而偏�q�乡村沉寂在自然�?br /> 只有一息微��q��影在清风中摇�?br /> �{�待希冀的再�?br /> 渴望冒出拔地楼房
伤逝隐�q�梦的土�?br />

.Sun 2010-06-20 17:43 发表评论

webService�Q�Provider org.apache.xalan.processor.TransformerFactoryImpl not found

.Sun — Thu, 13 May 2010 13:28:00 GMT

webService��目
Tomcat5.0.28 + JDK1.5 + xfire1.2.6

��目从Tomcat6.0��目拯��回来�Q�tomcat6.0�q�行正常�?br /> 问题出在Tomcat�?br /> \common\endorsed\�?br /> 删除或apache�|�站下蝲更新�q�两个jar卛_��?br />

.Sun 2010-05-13 21:28 发表评论

关于字节码增�?摘要

.Sun — Sat, 08 May 2010 15:57:00 GMT

JPOX requires that all classes that are persisted implement PersistenceCapable, an interface defined by JDO. Why should we do this, Hibernate/TopLink dont need it ?. Well thats a simple question really

JPOX uses this PersistenceCapable interface, and adds it using bytecode enhancement techniques so that you never need to actually change your classes. This means that you get transparent persistence, and your classes always remain your classes. ORM tools that use a mix of reflection and/or proxies are not totally transparent.
JPOX' use of PersistenceCapable provides transparent change tracking. When any change is made to an object the change creates a notification to JPOX allowing it to be optimally persisted. ORM tools that dont have access to such change tracking have to use reflection to detect changes. The performance of this process will break down as soon as you read a large number of objects, but modify just a handful, with these tools having to compare all object states for modification at transaction commit time.

In a JDO-enabled application there are 3 categories of classes. These are PersistenceCapable, PersistenceAware and normal classes. The Meta-Data defines which classes fit into these categories. To give an example for JDO, we have 3 classes. The class A is to be persisted in the datastore. The class B directly updates the fields of class A but doesn't need persisting. The class C is not involved in the persistence process. We would define JDO MetaData for these classes like this

1 <class name="A" persistence-modifier="persistence-capable">
2     <field name="myField">
3
4     field>
5
6 class>
7 <class name="B" persistence-modifier="persistence-aware">
8 class>

So our MetaData is mainly for those classes that are PersistenceCapable and are to be persisted to the datastore (we don't really need the persistence-modifier for thse classes since this is the default). For PersistenceAware classes we simply notate that the class knows about persistence. We don't define MetaData for any class that has no knowledge of persistence.

JDO requires that all classes to be persisted must implement the PersistenceCapable interface . Users could manually do this themselves but this would impose work on them. JDO permits the use of a byte-code enhancer that converts the users normal classes to implement this interface. JPOX provides its own byte-code enhancer (this can be found in the jpox-enhancer.jar). This section describes how to use this enhancer with JPOX. The JPOX enhancer fully implements JDO2 and so is the recommended choice when persisting using the JDO2 API. The enhancement process adds the necessary methods to the users class in order to implement PersistenceCapable.

The example above doesn't show all PersistenceCapable methods, but demonstrates that all added methods and fields are prefixed with "jdo" to distinguish them from the users own methods and fields. Also each persistent field of the class will be given a jdoGetXXX, jdoSetXXX method so that accesses of these fields are intercepted so that JDO can manage their "dirty" state.

The MetaData defines which classes are required to be persisted, and also defines which aspects of persistence each class requires. For example if a class has the detachable attribute set to true, then that class will be enhanced to also implement Detachable

Again, the example above doesn't show all methods added for the Detachable interface but the main thing to know is that the detached state (object id of the datastore object, the version of the datastore object when it was detached, and which fields were detached is stored in "jdoDetachedState"). Please see the JDO spec for more details.

If the MetaData is changed in any way during development, the classes should always be recompiled and re-enhanced afterwards.

Byte-Code Enhancement Myths

Some groups (e.g Hibernate) perpetuated arguments against "byte-code enhancement" saying that it was somehow 'evil'. The most common were :-

Slows down the code-test cycle. This is erroneous since you only need to enhance just before test and the provided plugins for Ant, Eclipse and Maven all do the enhancement job automatically and rapidly.
Is less "lazy" than the proxy approach since you have to load the object as soon as you get a pointer to it. In a 1-1 relation you have to load the object then since you would cause issues with null pointers otherwise. With 1-N relations you load the elements of the collection/map only when you access them and not the collection/map. Hardly an issue then is it!
Fail to detect changes to public fields unless you enhance your client code. Firstly very few people will be writing code with public fields since it is bad practice in an OO design, and secondly, this is why we have "PersistenceAware" classes.

So as you can see, there are no valid reasons against byte-code enhancement, and the pluses are that runtime detection of dirty events on objects is much quicker, hence your persistence layer operates faster without any need for iterative reflection-based checks. The fact is that Hibernate itself also now has a mode whereby you can do bytecode enhancement although not the default mode of Hibernate. So maybe it wasn't so evil after all ?

.Sun 2010-05-08 23:57 发表评论

MySQL #1005 - Can't create table(...) (errno: 121)

.Sun — Wed, 05 May 2010 14:30:00 GMT

摘要: MySQL #1005 - Can't create table(...) (errno: 121) 阅读全文

.Sun 2010-05-05 22:30 发表评论

腾讯怎么能这��P��

.Sun — Thu, 22 Apr 2010 02:01:00 GMT

腾讯�q�么大的企业�Q�QQ�I�间的日志竟然不控制多次提交的问题�?br /> 中国的公叔R��q�么��躁�?br /> ��公��ؓ了生存还能理解�?br /> 腾讯�q�么大的�U�x��辑օ�上市企业也这�?..

.Sun 2010-04-22 10:01 发表评论

关于struts动态form_DynaActionForm

.Sun — Tue, 20 Apr 2010 07:56:00 GMT

今天有�h问前台表单form动态生成，后台使用DynaActionForm怎么用，说了他没懂，��写了个例子�?br />
Action配置

ActionForm配置

<form-bean name="testMappingForm" type="org.apache.struts.action.DynaActionForm">
<form-property name="fnames" type="java.util.HashMap">form-property>
form-bean>

��h��意name属性，�q�个属性后面要用到�?br />

然后是页面index.jsp,�q�里只模拟动�?/p>

<html:form action="/testMapping.do" method="post">
   <%
   for(int i=0;i<5;i++){
   %>
           <html:text property="<%="fnames(name_"+i+")"%>" value="<%="gangye_"+i%>">html:text><br>
   <%}%>
   <br>
   <html:submit value="Submit Form" />
   html:form>

��h��意html:text的property标签�?br />

index.jsp效果如下

后台Action

public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request,
            HttpServletResponse response) {
        HashMap   hm=(HashMap)((DynaActionForm)form).get("fnames");
        Iterator it = hm.entrySet().iterator();
        Map.Entry entry = null;
        while(it.hasNext()){
            entry  = (Map.Entry)it.next();
            System.out.println(entry.getKey() + " = " + entry.getValue());
        }
        return null;
    }

输出表单��?/p>

name_4 = gangye_4
name_0 = gangye_0
name_2 = gangye_2
name_1 = gangye_1
name_3 = gangye_3

.Sun 2010-04-20 15:56 发表评论

org.springframework.web.struts.ContextLoaderPlugIn �?org.springframework.web.context.ContextLoaderListener

.Sun — Sat, 10 Apr 2010 18:24:00 GMT

org.springframework.web.struts.ContextLoaderPlugIn �?nbsp;org.springframework.web.context.ContextLoaderListener

是视囑ֱ�加蝲sping的两�U�方式�?br style="font-family: " /> 那么�q�两�U�方式谁的优先��高，从容器加载程度上看，是org.springframework.web.context.ContextLoaderListener

那么中方式都被配�|�在��目中，会��用哪个一个呢�Q?br style="font-family: " /> �{�案是org.springframework.web.struts.ContextLoaderPlugIn

当然如果你不需要在视图层采用lazy而配�|�org.springframework.orm.hibernate3.support.OpenSessionInViewFilter
那么你可以两个都配置�?br style="font-family: " /> 但如果你需要��用，那就会�?br style="font-family: " />
我们知道�Q�容器初始化Spring配置文�g�Ӟ��使用getServletContext().setAttribute�Ҏ��key,value全局保存�?br style="font-family: " /> 那么当你使用OpenSessionInViewFilter�Ӟ��他取得的是哪个呢�Q?br style="font-family: " />
其实OpenSessionInViewFilter是sping的Filter,�?/span>采用WebApplicationContextUtils的方式获得WebApplicationContext
�Q�但它�ƈ不能加蝲由struts-config.xml文�gContextLoaderPlugIn提供初始化的上下文�?br />
如果你需要在视图层加载一对对....�{�关联对象。那么就会有
could not initialize proxy - the owning Session was closed
错误�?br /> 到此处我们看刎ͼ�sping在应用程序和OpenSessionInViewFilter之间�Q�加载了不同的上下文�?br /> 我们知道OpenSessionInViewFilter下无法获得ContextLoaderPlugIn加蝲的上下文�Q�那我们可以推算�Q?br /> 应用�E�序应该加蝲了ContextLoaderPlugIn上下文，而OpenSessionInViewFilter却加载了ContextLoaderListener的上下文�?br /> 才导致视囑ֱ�session有关闭的问题�?br />
��试解决此问题，若你配置了两个，则删除ContextLoaderPlugIn的加载方式�?br /> 若你只配�|�了ContextLoaderPlugIn的加载方式，则改成ContextLoaderListener加蝲方式�?br />
原创文章�Q��{载请注明出处�?br /> http://www.tkk7.com/beijing2008/articles/317973.html

.Sun 2010-04-11 02:24 发表评论

getHibernateTemplate().save和super.getHibernateTemplate().merge

.Sun — Sat, 10 Apr 2010 04:10:00 GMT

代码1_save�Q?/p>

super.getHibernateTemplate().save(user);
System.out.println("�Q?/span>"+user.getId());

输出1�Q?br />

Hibernate: insert into user (userid, userpwd, userques, userans, usermail, integral, grade, sex, realname) values (?, ?, ?, ?, ?, ?, ?, ?, ?)
�Q?/span>9

代码2_merge�Q?br />

super.getHibernateTemplate().merge(user);
System.out.println("�Q?/span>"+user.getId());

输出2�Q?br />

Hibernate: insert into user (userid, userpwd, userques, userans, usermail, integral, grade, sex, realname) values (?, ?, ?, ?, ?, ?, ?, ?, ?)
�Q?/span>0

代码3_merge�Q?br />

user = (User)super.getHibernateTemplate().merge(user);
System.out.println("�Q?/span>"+user.getId());

输出3�Q?br />

Hibernate: insert into user (userid, userpwd, userques, userans, usermail, integral, grade, sex, realname) values (?, ?, ?, ?, ?, ?, ?, ?, ?)
�Q?/span>11

当我们��用merge的时候，执行完成�Q�我们提供的对象A�q�是��q��状态，hibernate或者new了一个B�Q�或者检索到
一个持久对象B�Q��ƈ把我们提供的对象A的所有的值拷贝到�q�个B�Q�执行完成后B是持久状态，而我们提供的A�q�是托管状�?br />

�l�箋看代码：

super.getHibernateTemplate().save(user);
user.setUserans("杭州BST");
System.out.println("�Q?/span>"+user.getId());

输出�Q?br />

Hibernate: insert into user (userid, userpwd, userques, userans, usermail, integral, grade, sex, realname) values (?, ?, ?, ?, ?, ?, ?, ?, ?)
�Q?/span>13
Hibernate: update user set userid=?, userpwd=?, userques=?, userans=?, usermail=?, integral=?, grade=?, sex=?, realname=? where id=?

super.getHibernateTemplate().merge(user);
user.setUserans("杭州BST");
System.out.println("�Q?/span>"+user.getId());

-------------------------
Hibernate: insert into user (userid, userpwd, userques, userans, usermail, integral, grade, sex, realname) values (?, ?, ?, ?, ?, ?, ?, ?, ?)
�Q?

其实�Q�我们也可以�q�样昄��修改状态�?br />

user = (User)super.getHibernateTemplate().merge(user);
user.setUserans("杭州BST");
System.out.println("�Q?/span>"+user.getId());

--------------------

Hibernate: insert into user (userid, userpwd, userques, userans, usermail, integral, grade, sex, realname) values (?, ?, ?, ?, ?, ?, ?, ?, ?)
�Q?/span>16
Hibernate: update user set userid=?, userpwd=?, userques=?, userans=?, usermail=?, integral=?, grade=?, sex=?, realname=? where id=?

原创文章�Q��{载请注明出处�?/strong>
http://www.tkk7.com/beijing2008/articles/317924.html

.Sun 2010-04-10 12:10 发表评论