從MySql5中運行本地腳本創建數據庫，當插入中文字段時發生“data too long for column”錯誤。上網一查，發現多字節用戶大都碰到了這種情況。google搜索網上的解決方法大都是要將數據庫的編碼方式為GBK或UTF8，可我在安裝MySql時就選擇了UTF8格式。原來錯誤原因是本地的腳本文件不是UTF8編碼的，用記事本或UltraEdit將編碼轉為UTF8后問題解決。再次強調，JSP頁面，數據庫聯接接方式，數據庫創建，…，都須一致使用UTF8編碼！
BTW，MySql最近借著Web2.0的浪潮風頭很勁啊，techn orati（好像這幾天被GFW filter了），flickr，del.icio.us等一批網站都是用了MySql。MySql還專門在首頁開了一大塊來炫耀。
Installed
JDK6
(Mustang) beta and
Eclipse3.2
. As
Sun promised
, Swing library, especially the?WindowsLookAndFeel feels much better. It’s hard to tell the difference between a Swing drawn window and a WINXP native window. Developing Java desktop applications is worth considering. Mattise, a free easy-to-use WYSIWYG Swing UI designer, is the only reason for many to use the tedious NetBeans. Recently,
Genuitec
provided Matisse4Eclipse, which is?an implementation of Matisse that integrates its functionality into MyEclipse Workbench to enable the easy creation of Swing applications with Eclipse. So the only reason to use NetBeans has gone.
去年7月決定考研后暫停了對Java技術的學習。錄研上后專心開發導師負責的項目，到4月份從深圳出差回來后又忙著做畢設。快一年的時間沒跟新這，幾乎都要abandon了。百度剛開放了百度空間的注冊，不過看起來不咋的。選國外的BSP會面臨隨時偉大的GFW過濾掉的后果。總的來說，BlogJava還是很適合post技術方面的東西，優點是流量大，被google收錄快；缺點就是沒有trackback。前幾天下午跑到圖書館看了看上半年的程序員，新鮮玩意并不多。SOA，這個被預測為06年最熱點的技術，并沒有什么有趣的文章，或許這個名詞還是沒有個明確的含義和應用。在學校里，IBM的SOA大賽倒是舉辦的風風火火。JavaEE5，JDK 6的發布還是給Java界帶來不少有趣又實用的新東東，比如annotation，persistence API和script supporting。得跟上技術前進的步伐了，以后技術的筆記還是發這里，平日的雜想就寫在
我的MSN space上。
@title [筆記]事務處理
#1 Transaction Propagation Behavior
Required:Excute within a current tx, create a new one if none exists.
Supports: Excute within a current tx, execute without a tx if none exsits.
Mandatory: Excute within a current tx, throw an exception if none exists.
Requires New: Create a new tx and excute within the tx, suspend the current tx if one exists.
Not Supported: Excute without a tx, suspend the current tx if none exsits.
Never: Excute without a tx, throw an exception if a tx exsits.
#2 Transaction Isolation Level[1]
#2.1 Concurrent Problem
Dirty Reads: 臟讀（臟數據指已更新，還沒提交的數據）。事務T1讀取到事務T2中的臟數據。
Unrepeatable Reads: 不可重復讀。事務T1檢索到某行后，事務T2更新并提交了該行，若事務T2再次檢索該行，則會看到不一樣的結果。
Phantom Reads: 虛讀。事務T1檢索到符合某條件的行集后，事務T2插入并提交了滿足該條件的新行，若事務T2再次按該條件檢索，則會看到以前不存在的行“Phantom”。
#2.2 Isolation Level
+---------------+-------+------------------+-----------+
|Isolation Level|Phantom|Unrepeatable Reads|Dirty Reads|
+---------------+-------+------------------+-----------+
|Read Uncommited| Y | Y | Y |
+---------------+-------+------------------+-----------+
|Read Commited | Y | Y | N |
+---------------+-------+------------------+-----------+
|Repeatable Read| Y | N | N |
+---------------+-------+------------------+-----------+
|Serializable | N | N | N |
+---------------+-------+------------------+-----------+
#3 Timeout
#4 ReadOnly Transaction
只讀事務保證了多條查詢SQL的在事務級別的讀一致性。JDBC和數據庫會對只讀事務做一些優化。
[1] C.J.Date, An Introduction to Database Systems 7th.
iteration::two Cairngorm 0.99 開發指南
@author sakis
@version 0.1
#0
MXML優點：使用方便，XML代碼簡潔易懂
缺點：事件、函數、界面描混在一起。程序規模大了難于開發維護。
#1
Cairngorm框架是iterationtwo推出的號稱基于JEE Best Practice的Flex程序開發的light-weight framework。(恩,light-weight這個詞還真是流行呢)。目前最新版本為0.99。
Cairngorm的結構如下：
org
└─nevis
└─cairngorm
├─application
│ CairngormApplication.as
│
├─business
│ Responder.as
│ ServiceLocator.as
│
├─commands
│ Command.as
│ SequenceCommand.as
│
├─control
│ Event.as
│ EventBroadcaster.as
│ FrontController.as
│
├─model
│ ModelLocator.as
│
├─view
│ ViewHelper.as
│ ViewLocator.as
│
└─vo
ValueObject.as
#2
下面給大家簡單介紹Cairngorm的實現思路。
#2.1
Command/FrontController將Event與Viwe分離。
FrontController實現Singleton模式(以下簡寫為SP)。所有自定義的Command在要在FrontController構造函數中實例化并以關聯數組的方式注冊FrontController#addCommand(eventType:String, commandInstance:Command)。EventBroadcaster實現SP。Event類的結構為{type:eventType, data:eventData}。我們通過EventBroadcaster#broadcastEvent(eventType:String, eventData:Object)發布Event。Event發布后,與eventType對應的command instance執行Command#execute(event:Event)。
BTW：在Cairngorm的源碼中，eventType、commandName、eventName混用，我統一用eventType。
#2.2
ServiceLocator將Remote Service聲明與View分離。
ServiceLocator實現SP。在Cairngorm的demo中，又通過Delegate對象解除Command/Responder和ServiceLocator之間的依賴。這個Delegate做的事情其實意義不大，就是調用ServiceLocator中的Method，設置莫個Responder為相應遠程方法的handler。個人覺得無謂地增加了代碼量，而且Delegate對象也沒實現SP，也就是說我們每次調用一次Remote Service中的Method，都要new一個Delegate對象，實在浪費。
#2.3
ViewLocator/ViewHelper將View（MXML）中夾雜的function與View分離。
ViewHelper有點意思，當一個ViewHelper在某個MXML頁面中聲明時，如<view:LoginViewHelper id="loginViewHelper" />。ViewHelper能自動取得所在MXML對象的引用，并通過ViewLocator#register(id, this:ViewHelper)將自身注冊到ViewLocator中。ViewLocator實現SP。借助ViewLocator/ViewHelper,我們就可以方便的調用不同MXML頁面中的方法。
#2.4
ModelLocator是一個marker interface，程序中Model可以放在某個ModelLocator方便調用。
#2.5
ValueObject也是一個marker interface, 基本不需要。
#3
Cairngorm.99給我們開發Flex程序提供了很不錯的架構模式,M/V/C/Remote之間可以做到完全解構。但在實際開發時沒有必要死扣,代碼結構清晰有活力就好。
Hibernate一對一關聯實用介紹
#0
書和文檔上寫的都不是特清楚的。自己記下來。
#1 Using a PK association
#1.1 POJO with XDolclet annotation
public class Customer {
/**
* @return Returns the shoppingCart.
* @hibernate.many-to-one cascade="delete" column="shopping_cart_id"
* unique="true" foreign-key="FK_SHOPPING_CART__CUSTOMER"
*/
public ShoppingCart getShoppingCart() {
return shoppingCart;
}
}
public class ShoppingCart {
/**
* @return Returns the customer.
* @hibernate.one-to-one property-ref="shoppingCart"
*/
public Customer getCustomer() {
return customer;
}
}
property-ref="shoppingCart" 告訴Hibernate ShoppingCart#customer和Customer#shoppingCart是反向的關系。所以Hibernate知道如何從ShoppingCart#getCustomer中檢索到相應的customer對象。取出某個Customer對象時，Hibernate會生成DEBUG SQL:324 - 3中的SQL語句。
#1.2 HBM
Customer.hbm.xml
<many-to-one
name="shoppingCart"
class="ShoppingCart"
cascade="delete"
outer-join="auto"
foreign-key="FK_SHOPPING_CART__CUSTOMER"
column="shopping_cart_id"
/>
ShoppingCart.hbm.xml
<one-to-one
name="customer"
class="Customer"
cascade="none"
outer-join="auto"
constrained="false"
property-ref="shoppingCart"
/>
#1.3 SCHEMA SQL
create table CUSTOMER (
ID bigint generated by default as identity (start with 1),
SHOPPING_CART_ID bigint,
primary key (ID)
)
create table SHOPPING_CART (
ID bigint generated by default as identity (start with 1)
primary key (ID)
)
alter table CUSTOMER
add constraint FK_SHOPPING_CART__CUSTOMER
foreign key (SHOPPING_CART_ID)
references SHOPPING_CART
#1.4 Query SQL
DEBUG SQL:324 - 1
select customer0_.ID as ID, customer0_.SHOPPING_CART_ID as SHOPPING2_3_, customer0_.USERNAME as USERNAME3_, customer0_.PWD as PWD3_
from CUSTOMER customer0_
where customer0_.USERNAME=? and customer0_.PWD=?
DEBUG SQL:324 - 2
select shoppingca0_.ID as ID0_, shoppingca0_.TOTAL as TOTAL8_0_
from SHOPPING_CART shoppingca0_
where shoppingca0_.ID=?
DEBUG SQL:324 - 3
select customer0_.ID as ID1_, customer0_.SHOPPING_CART_ID as SHOPPING2_3_1_, customer0_.USERNAME as USERNAME3_1_, customer0_.PWD as PWD3_1_, shoppingca1_.ID as ID0_, shoppingca1_.TOTAL as TOTAL8_0_
from
CUSTOMER customer0_
left outer join
SHOPPING_CART shoppingca1_
on customer0_.SHOPPING_CART_ID=shoppingca1_.ID
where customer0_.SHOPPING_CART_ID=?
#2 Using a FK association
#2.1 POJO with XDolclet annotation
public class Customer {
/**
* @return Returns the shoppingCart.
* @hibernate.one-to-one cascade="delete"
*/
public ShoppingCart getShoppingCart() {
return shoppingCart;
}
}
public class ShoppingCart {
/**
* @return Returns the id.
* @hibernate.id generator-class="foreign"
* @hibernate.generator-param name="property" value="customer"
*/
public Long getId() {
return id();
}
/**
* @return Returns the customer.
* @hibernate.one-to-one constrained="true" foreign-key="FK_CUSTOMER__SHOPPING_CART"
*/
public Customer getCustomer() {
return customer;
}
}
constrained="true" 告訴Hibernate ShoppingCart的PK還應該是一個FK，這個FK引用Customer的PK。還需要多做一點工作，聲明ShoppingCart的PK生成策略是foreign，對應ShoppingCart#customer。這和上面一句話不是一個意思嘛，FT~~
#2.2 HBM
Customer.hbm.xml
<one-to-one
name="shoppingCart"
class="ShoppingCart"
cascade="delete"
outer-join="auto"
constrained="false"
/>
ShoppingCart.hbm.xml
<id
name="id"
column="id"
type="java.lang.Long"
>
<generator class="foreign">
<param name="property">customer</param>
</generator>
</id>
<one-to-one
name="customer"
class="Customer"
cascade="none"
outer-join="auto"
constrained="true"
/>
#2.3 SCHEMA SQL
create table CUSTOMER (
ID bigint generated by default as identity (start with 1),
primary key (ID)
)
create table SHOPPING_CART (
ID bigint not null,
TOTAL integer,
primary key (ID)
)
alter table SHOPPING_CART
add constraint FK_CUSTOMER__SHOPPING_CART
foreign key (ID)
references CUSTOMER
#2.4 Query SQL
DEBUG SQL:324 -
select customer0_.ID as ID, customer0_.USERNAME as USERNAME3_, customer0_.PWD as PWD3_
from CUSTOMER customer0_
where customer0_.USERNAME=? and customer0_.PWD=?
DEBUG SQL:324 -
select shoppingca0_.ID as ID0_, shoppingca0_.TOTAL as TOTAL8_0_
from SHOPPING_CART shoppingca0_
where shoppingca0_.ID=?
這個“真正”的one-to-one的好處是少條關聯SQL語句，看到了嗎？
1 Open the Apache Tomcat configuration app in sys tray, and on the "Java" tab, bump up the initial memory pool size and the maximum memory pool size to 512 Initial and 768 Max, click Ok.
2 In \Program Files\Apache software Foundation\Tomcat 5.0\bin\catalina.bat, in the last section immediately after "rem Execute Java with the applicable properties", insert this line, set CATALINA_OPTS=-mx1024m. Save the file.