[转]Delete a range of lines in Vim example

Delete a range of lines in Vim example

In vim, to delete a range of lines, e.g. lines 10 through line 290, do a:

:10,290d

【转】如何正确内置CUE文件

发现很少有人注意这个问题，所以提出来大家参考。大家应该知道在foobar的媒体库设置里提供有限制类型和排除文件类型的选项。比较旧的foobar 版本里这里的设置默认为空，而最新的版本比如v0.9.5.6里默认为排除cue文件。所以有人升级foobar后发现播放列表里只有一个个的ape文 件，没有具体曲目信息。可能大家已经习惯了，右边的分类播放列表里有一个ape文件和对应的cue文件提供的曲目信息。这样多少有点“重复”的意思。有人 问过如何去掉那个ape文件，让播放列表里只有cue曲目信息。这里我提供的建议是，大家保留媒体库里的排除cue文件设置，同时将cue文件内置到 ape文件里。如何内置呢？其实很简单。在最新的foobar播放界面右键点击一个ape文件，选择工具-编辑cue sheet，在弹出的界面中勾选“启用文件里内嵌的cue sheet”，然后点击“载入……”，找到这个ape文件对应的cue文件，确定就可以了。 当内置cue文件成功后，重新扫描媒体库就可以了。播放列表里就没有多余的ape文件了，而cue文件也可以放到回收站了。建议你保留，因为你已经在媒 体库里排除了cue文件，万一以后要用到呢。呵呵！ 下面几点很重要，因为我们有时并不能成功内置cue文件，即使成功了也会发现播放列表显示不正确。需要注意的是以下几点： 1，确保cue文件格式正确。至于这点请查看置顶帖。 2，在进行操作前不能播放当前ape文件里的歌曲，否则会弹出出错提示框。 3，如果cue文件正确，载入成功，重启foobar后发现列表里多余的ape文件也没有了，但是歌曲的标题不正常，并不是cue文件提供的歌曲标题，或 许全部显示为专辑的标题。至于这点请这样做：全选右边播放列表里那个ape文件包含的所有曲目文件,右键选择属性，将元数据栏里的艺术家，标题和专辑的值 全部清空，然后重新内置cue文件，一般就可以解决了。

*原文转自：http://www.foobar2000.com.cn/archiver/showtopic-5705.html

[转] Ubuntu 10.04 LTS 安装 sun-java6-jdk

今天需要用到sun的jdk，但找了半天就是找不到，只有openjdk，后来才知道，是10.04中弄走了sun-java6-jdk，官方的release notes 中看
到如下一段：

Sun Java moved to the Partner repository

For Ubuntu 10.04 LTS, the sun-java6 packages have been dropped from the Multiverse section of the Ubuntu archive. It is recommended that you use openjdk-6 instead.

If you can not switch from the proprietary Sun JDK/JRE to OpenJDK, you can install sun-java6 packages from the Canonical Partner Repository. You can configure your system to use this repository via command-line:

add-apt-repository "deb http://archive.canonical.com/ lucid partner"



于是，添加上面的源后再



sudo apt-get update



sudo apt-get install sun-java6-jdk

*原文转自：http://blog.csdn.net/cangzhubai/archive/2010/06/25/5693021.aspx

alias mysql=/usr/local/mysql/bin/mysql

mysql --user=chen --password=cwang mysql

前提：MySQL 已经打开；

how to check the mac system is 32 or 64 bit

打开终端，输入命令：uname -p
如果是i386就是32位，x86-64就是64位

Resetting the AirPort Express

At the risk of piggybacking on the work of my betters, I'd like to devote today's entry to expanding on some information provided in Jason Snell's Editors' Notes blog. Specifically, I thought I might provide some more details about resetting the AirPort Express.
Jason mentions that you can reset the AirPort Express by holding down the tiny reset button. Absolutely true, but it's only one of three ways to reset the device (and each variety of reset does something a bit different).
The three reset types are soft, hard, and factory default. You issue a soft reset when you need to reset your base station password (if you forget the password you originally entered, for example). A hard reset is for those times when the device stops responding. This kind of reset doesn't erase saved profiles. The final reset -- factory default -- does exactly what it says. It returns the AirPort Express to the condition it was in when you pulled it out of the box. Invoking a factory default reset erases all saved profiles.

To perform each reset, follow these steps:
Soft Reset
With the AirPort Express plugged into a power outlet, launch the Network System preference and choose AirPort from the Show pop-up menu. Click the TCP/IP tab and choose Using DHCP from the Configure pop-up menu. Press and hold the device's reset button for 1 second. The light will flash yellow and you'll have five minutes to make changes before the AirPort Express reverts to its previously saved configuration.
Hard Reset
With the AirPort Express plugged into power, press and hold the device's reset button for 10 seconds. A green light will flash for a bit and then the device will reset itself -- a process that takes about 45 seconds. Once reset, you can configure it with the AirPort Express Assistant or the AirPort Admin Utility.
Factory Default
Unplug the AirPort Express from the power outlet and press and hold the reset button. While still holding down the reset button, plug the device into a power outlet. Hold down the reset button until you see the light flash green four times. Let go of the button and the device will reset itself. Wait the requisite 45 seconds and configure it with the AirPort Express Assistant or AirPort Admin Utility.


Original Link: http://www.macworld.com/article/36834/2004/08/000282.html

[zz] Tomcat install woes – Cannot find …bin/catalina.sh

November 14th, 2007

This week I was assisting a customer with installing Tomcat on the System i5 and ran into an issue I thought I would post here to assist others.
After placing a non-IBM version of Tomcat in the IFS, I started up a QShell session, changed directory to the Tomcat bin directory, and executed startup.sh. The result of running startup.sh was the following:

startup.sh
Cannot find /tomcat/v4.1/bin/catalina.sh
This file is needed to run this program

After reviewing the bin directory I confirmed that catalina.sh DOES exist. I modified the files permissions through WRKLNK thinking that may be the issue – no go. After digging around the internet I found somebody with the same issue except they were on a Linux machine and were directed to chmod the execution authority on that file. So I ran the same from QShell and walla! It worked! I am not sure why it worked because I had already set that file to *PUBLIC *RWX on the i5OS side [scratching head]. Anyways, to remedy the situation, and keep further such things from happening, I ran chmod on all files in the bin directory that I thought might need it:

chmod +x startup.sh
chmod +x shutdown.sh
chmod +x catalina.sh
chmod +x setclasspath.sh
chmod +x bootstrap.jar
chmod +x tomcat-jni.jar

Hope that helps someone else in need!

[Mac] How to set Environment Variable

1: open a terminal;

2: type "vi ~/.profile";

3: Find a line like:
"export PATH=/opt/local/bin:/opt/local/sbin:$PATH"...

4: Add the path of your java home:
"export PATH=/opt/local/bin:/opt/local/sbin:/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home/bin:$PATH"

5: Save and quit.

【转】操作系统版本

Alpha版：内部测试版，一般不向外部发布,会有很多Bug。一般只有测试人员使用。

Beta版：也是测试版，这个阶段的版本会一直加入新的功能。在Alpha版之后推出。

RC版：(ReleaseCandidate)候选版本。系统平台上就是发行候选版本。RC版不会再加入新功能，主要着重于除错。

RTM版：(Release to Manufacture)给工厂大量压片的版本，内容跟正式版是一样的，不过RTM版也有出限制、评估版的。但是和正式版本的主要程序代码都是一样的。

OEM版：是给计算机厂商随着计算机贩卖的，也就是随机版。只能随机器出货，不能零售。只能全新安装，不能从旧有操作系统升级。包装不像零售版精美，通常只有一面CD和说明书(授权书)。

RVL版：其实RVL根本不是版本的名称。它是中文版/英文版文档破解出来的。

EVAL版：流通在网络上的EVAL版，与“评估版”类似，功能上和零售版没有区别。

RTL版：Retail(零售版)，是真正的正式版，正式上架零售版。

【转】Mac OS X 下Apache2.2、MySQL 5.1和PHP 5.3的安装与配置

• 十一月 27th, 2009
• 归类于 Mac服务器技术
• 作者赵 汐桃

法律申明：原创文章，禁止转载！
Mac OS X基于强大的UNIX底层技术创建，具有极高的安全性和网络服务能力，很多朋友都希望在自己的Mac上搭建一个Web Server，虽然目前已经有MAMP、XAMPP等简单易用的傻瓜式打包程序，但是如果我们要修改详细的配置文件来搭建最适合我们自己的Web服务器， 恐怕还是得自己动手，手动安装了，这也符合咋DIY得精神要领嘛。废话不多，教程开始！
1.安装环境
操作系统：Mac OS X Leoaprd 10.5.6 (Snow Leoapd相同)
数据库：MySQL 5.1.41
Web服务器：Apache 2.2.14
脚本语言：PHP 5.3.0
2.安装MySQL 5.1.41
下载MySQL，在www.mysql.com上有提供下载，直接下载对应你系统环境的DMG包就好了，方便，省的编译。
挂载DMG镜像，安装两个pkg程序包进行安装，最后安装MySQL.prefPane偏好设置面板。
然后开启终端，首先确定你计算机启用了root帐户，进行如下操作：
$ sudo /usr/local/mysql/bin/mysqld_safe –user=root & //启动MySQL(也可以通过偏好设置面板来启动)
$ sudo /usr/local/mysql/bin/mysqladmin -uroot password yourpassword //设置MySQL密码（注意，这是第一次MySQL密码为空的时候的设置命令，如果是修改密码，还需在-uroot 后面加上-pyourpassword 来进行权限确认.yourpassword是你的密码）
$ sudo /usr/local/mysql/bin/mysqladmin -uroot -pyourpassword shutdown //停止MySQL（也可以通过偏好设置面板来停止）
3.安装Apache 2.2.14 (Mac OS X 已经自带了Apache了，这里写出来是为了方便大家安装到最新版或者日后升级Apache参考，嫌麻烦的直接跳过此步)
系统自带Apache路径为/etc/apache2/
要启动系统自带Apache，只要在System Preferences -> Sharing 选择Web Sharing即可开启内置的Apache.
配置文件位置是:
/etc/apache2/httpd.conf
httpd的文档更目录是: /Library/WebServer/Documents/
user_dir模块默认自动开启,访问地址是: http://localhost/~username
user_dir的目录路径是: ~/Sites
restart Apache命令是: sudo apachectl graceful
如果要自己安装Apache，可以参考此文
首先，到www.apache.org下载最新的没编译过的UNIX源码，然后就是解压，输入命令编译，命令如下
$ sudo ./configure –prefix=/etc/apache2 \
> –enable-module-most \
> –enable-shared=max
可能这时候很多人就要出问题了，编译不成功，因为编译是需要编译器的，因为这些代码都是用C或C++写成的，所以最常用的就是GCC，但是单独下载GCC 是不行的，后面编译的时候机子会找不到编译器的，所以必须安装Apple自己提供的强大，多功能的（Apple自己说的）IDE—-XCode。可以到 Apple的官方网站下载（首先需要注册ADC的账号，免费）然后就可以下载，安装，再编译，成功！
然后安装：
$ make
$ make install
安装成功后配置Apache，配置文件为/etc/apache2/httpd.conf，关于Apache，我会另外花时间专门写一篇Apache的配置教程。
4.安装PHP 5.3.0
安装PHP，可以自己编译，也可以下载现成的打包程序，自己编译的话，去php.net下载源码，解压编译安装即可，命令如下
$ sudo ./configure –prefix=/usr/local/php5
$ make
$ make install
如果嫌麻烦，就直接下载编译好的打包程序，点此进入官方下载页面
下载后，运行程序包安装！
测试PHP安装
首先，重启Apache服务器
然后建立一个纯文本文件，内容为
然后保存文件名为test.php到/User/youruersname/Sites下（yourusername为你的登陆用户名）
然后打开浏览器，键入地址:http://localhost/~yourusername/test.php，然后看显示结果，如果已经显示出PHO信息，则说明你的Apache+PHP已经正确安装，但是，还需要调试，否这PHP无法正常运行，
先下载此文件，（PHP探针，可以测试很多PHP和数据库相关的东西）然后解压到/User/youruersname/Sites下
然后在浏览器键入http://localhost/~yourusername/iprober,看显示结果，此时应该是空白的，什么都显示不出来，此时，需要修改php.ini配置文件
在Finder中按快捷键Shift+苹果+G，输入路径/usr/local/php5/bin，然后找到php.ini，复制到桌面上，然后用文本编辑打开，找到
display-errors ＝ Off
把Off改成On，打开错误提示，保存，然后复制回/usr/local/php5/bin，需要键入密码，重启Apache服务，然后继续访问 http://localhost/~yourusername/iprober，此刻，PHP错误显示错来了，根据错误，我们再来配置php.ini， 找到
short_open_tag = Off
把Off改成on，打开，因为只有把short_open_tag设置为On，
安装配置篇，目前就暂时写到这里了，后面我会写一个系列的文章，教大家在自己的Mac上安装PHP网站，设计制作自己的网站，动态域名链接以及用Mac OS X搭建虚拟主机存放多个网站等等！谢谢大家的关注，有什么问题，留言给我，我非常希望和大家探讨，共同学习！


原文地址：http://blog.hellomac.com.cn/?p=44

【转】诺基亚输入解锁码的方法

解锁的步骤如下：
Model : All Nokia

1 - Switch ON your phone without SIM Card,
2 - Compose #PW+CODE+1#

The letter P appear after press 3 times quickly the button star ( * )
The letter W appear after press 4 times quickly the button star ( * )
The letter + appear after press 2 times quickly the button star ( * )

3 - The phone show "SIM Restriction Off" and was unlocked !


简单翻译一下：
1. 不要插sim卡，开机
2. 输入： #PW+CODE+1#
3.SIM Restriction Off
说明：
1.code就是我给你的解锁码，如果解锁码是： 123456789123456 那么只需要输入
#PW+123456789123456+1#
即可解锁。
2. p w + 这三个字符的输入方法
连续快速的按 * 键 3次----出现 p
连续快速的按 * 键 4次----出现 w
连续快速的按 * 键 2次----出现 +



注意：
如果输入错误的解锁码5次，以后显示的是Can Not Undo Restriction或Not Allowed，这种情况下就不能通过解锁码解了（即使你输入正确的解锁码）！

原文地址： http://hi.baidu.com/51jiesuo/blog/item/f4da682fd3df81574fc2269f.html

How to install style files in TexShop in Mac OSX Machine

Michael B. Williams wrote:

I am using the mactex distribution with texshop as my front end.

I have started using a package that does not come with the mactex
distribution, namely cleveref. I have the cleveref.sty file, and
currently if I want to use it I have to keep it in the same directory
as the tex file I am working on.

so, I would like to find out how I can install this package so that I
can use \usepackage{cleveref} from any tex document on my computer.

when I compile I see that texshop looks in the directory /usr/local/
texlive/2007/texmf-dist/tex/latex/ for the standard packages, such as
amsmath. so in this directory I created a new directory cleveref, and
dropped the sty file in it. unfortunately when I try to compile it
says it is missing the cleveref.sty file.

anyone know how I can install this package with my current set up?

Don't put packages not coming with the main distribution there. Rather
use /usr/local/texlive/texmf-local; otherwise the added file will
vanish when an update to the main distribution will be done.

From the Terminal, assuming you are in the directory where the

package files are:

% sudo mkdir -p /usr/local/texlive/texmf-local/tex/latex/cleveref
% sudo mv cleveref.sty /usr/local/texlive/texmf-local/tex/latex/cleveref
% ...(do the same for the other files)...
% sudo mktexlsr

Here "%" stands for the shell prompt, which will be different.
You can also navigate to /usr/local/texlive/texmf-local in the Finder
and copy the files this way. However you'll need to give the

sudo mktexlsr

anyway from the Terminal. If you don't know about "sudo", just do
as stated, giving your password when requested. Of course, this
assumes you are an administrator of the machine. The "mktexlsr"
command makes TeX know about the added files.

Another way is to put the package files in

~/Library/texmf/tex/latex

(~ stands for your home directory). Other users of your machine will
not be able to use the added package, though. With this technique the
"mktexlsr" command is not needed.

Ciao
Enrico

Cite from: http://newsgroups.derkeiler.com/Archive/Comp/comp.text.tex/2008-05/msg00295.html

[转] LaTex 注释

在LaTex中的注释有3种:
1. 用%注释一行文字, 在%后的文字都不予编译;
2. 用\iffalse .... \fi 包含一段文字, 被包含的文字被注释掉了;
3. 用\begin{comment} ... \end{comment} 包含被注释的文字, 但是需要在引言区包括相应的宏包, 即 \usepackage{verbatim}.

[转] LNCS LaTeX style works

I’m writing a paper for a conference. It should be written with conformance to the Lecture Notes in Computer Science style. After visiting the page with information for LNCS authors) I though that it might be a sort of magic for many people.
Springer encourages authors to use LaTeX2e, provides a style file for LaTeX, documentation and samples. The samples and instructions are quite good to start writing a paper immediately if

• you know LaTeX, and
• the llncs style is installed.

Springer can’t help with the first issue. But it isn’t important.
The problem is that they don’t provide (or I haven’t found) help on installing the style. The number of people that can do it is much smaller of those who know LaTeX.
Fortunately, I’m one from that small group. Here is my way to use the style locally without putting it into the core LaTeX directories.
The style files are stored in the file llncs2e.zip. I unpacked them into the folder “~/univer/gpce05/springer/texmf/tex/latex/llncs2e“. In fact, the path before “texmf” is not important.
First of all, I decided to check the sample file llncs.dem. As dvi-file already exists, I generated pdf:

$ pdflatex llncs.dem
$ pdflatex llncs.dem

The command was given twice to get correct links. On the first run, the database of links is created, and on the next runs the database is used.
Now goes local installation of the style. I’m not going to comment it. Consider it as magic:

$ export TEXMFLOCAL=~/univer/gpce05/springer/texmf
$ texconfig rehash
$ file ~/univer/gpce05/springer/texmf/ls-R

The first command specifies location of the local TeX repository. The second commands indexes the repository, and the last one just makes sure that the index is created.
To check, use the sample from the file typeinst.zip. Let me demonstrate a failure first. Open a new window and try to compile the TeX-file:

$ latex typeinst.tex

You get an error like:

LaTeX Error: File `llncs.cls' not found.

The right way is to specify the location of the repository first:

$ export TEXMFLOCAL=~/univer/gpce05/springer/texmf
$ latex typeinst.tex
$ latex typeinst.tex

Again, I’m running LaTeX twice to get correct links.
Original link: http://uucode.com/blog/2005/04/08/lncs-latex-style-works/

[转]15 个第三方 Web 表单资源

http://www.cnbeta.com/articles/102464.htm

新闻来源:vandelaydesign.com
几乎每个 Web 站点都需要表单，不管是留言表单，还是会员注册表单，还是调查表或订单，尽管表单很有用，但对 Web 开发与设计者来说，表单的设计非常繁琐，本文搜集了15个免费或收费的第三方 Web 表单资源，可以轻松实现 Web 表单的设计与集成，它们中的一些还可以帮你实现非常专业的表单设计。 表单创建资源
FormSpring

FormSpring 可以创建标准的联系，调查，捐赠接收，注册等表单，无需编码，它会帮你管理和接收数据，甚至集成付款功能。分免费和收费两种服务，免费服务允许创建3个表单，每个表单10个栏，每月接收50次数据。



Wufoo

Wufoo 可以实现联系，调查，注册，在线支付等表单的设计，可以使用模板，包含多种报告，同样，也包含免费和收费服务。免费服务允许一个用户，3个表单，3个报告，10个栏，每月100次数据。



Icebrrg

Icebrrg 可用于创建联系，注册，调查，应用程序等表单，可以查看发送的数据或将数据导出到 Excel 文件。为收费服务，不包含免费或试用服务。



FormSite

FormSite 用于超过100个预定义表单，并可以进行定制以符合自己的要求，可以创建联系，调查，这册，订单等表单，免费服务可以创建5个表单，每月100次数据。



FormExperts

FormExperts 包含上百个模板，可用来创建各种 Web 表单，支持自动回复，自定义感谢页面以及自定义邮件格式，可以免费试用10天。



MachForm

MatchForm 可以帮你设计 PHP 表单，这是一个独立程序（有别于前面的托管服务），用 MySQL 数据库存储数据，单站点许可39美金。



Email Me Form

Email Me Form 是一个在线服务，用来创建 HTML 或 PHP 表单，收费服务可以去掉 Email Me Form 的反向链接。



FormLogix

FormLogix 可以用来创建反馈，调查，投票，注册，邀请，在线支付等表单，免费服务只用于测试。



FormAssembly

FormAssembly 可用于创建联系，注册，订单等 Web 表单，免费服务包含广告链接。



Visitor Contact

这一个免费资源，包含 WordPress 插件，顾名思义，主要用于创建联系表单，功能包括自动回复，显示用户地理位置，还可以导出数据。



Contactable

这是一个来自 theodin.co.uk 的 jQuery 插件，可以轻松实现联系与反馈表单。


WordPress 插件
Gravity Forms

这是一个收费 WordPress 插件（39美金），可用于创建各种 Web 表单，可以集成到 WordPress 控制面板。



CForms II

这是一个功能强大的联系表单创建插件。



Contact Form 7

这是一个非常受欢迎的联系表单设计插件，非常容易上手，可以轻松创建各种表单并插入到页面。



Fast and Secure Contact Form

该插件可以创建安全联系表单，使用 CAPTCHAs 与 Akismet 防止垃圾信息。



本文来源：http://vandelaydesign.com/blog/tools/web-forms/
中文翻译来源：COMSHARP CMS 网站内容管理系统官方站

【转】菜谱：洋葱牛肉丝

洋葱牛肉丝的做法:

主料：牛肉300克，洋葱250克�

辅料：鸡蛋清1个，淀粉10克，酱油、盐、料酒、白糖各适量，味精、胡椒粉各少许，食油50克。

做法： 1.牛肉洗净，切成筷子般粗的条形，放入酱油适量，盐少许腌约10分钟；洋葱纵切两半，再横切成条备用。

2.腌好的牛肉用鸡蛋清1个、淀粉、料酒、白糖、味精、胡椒粉和少量的食油拌匀，然后放入小火低温的热油中泡至嫩熟。

3.炒锅上火，倒油烧热，放入洋葱炒至变色，即下牛肉煸炒片刻，将酱抽、盐、料酒、白糖倒入，用淀粉勾芡，加入味精、胡椒粉，炒匀即可出锅上碟。

特点：此菜肉质滑软，口味清爽鲜香。

【转】Java操作SQL数据库[查询，更新，存储过程，类型对照]

一，SQL复习

1，SQL语句分为两类：DDL(Data Definition Language)和DML(Dat Manipulation Languge,数据操作语言)。前者主要是定义数据逻辑结构，包括定义表、视图和索引;DML主要是对数据库进行查询和更新操作。

2，Create Table(DDL):

Create Table tabName(
colName1 colType1 [else],
colName2 colType2 [else],
...,
colNamen colTypen [else]
);

例如：Cteate Table pJoiner(
pno char(6) not null,
eno char(6) nut null
);

char int varchar等等都是用来定义列数据类型的保留字，其中varchar表示可变字符类型。

3，Select ,,...,
From ,,...,
[Where<条件>]

条件中的子查询：

Where Not Exists(
Select * From tab2 Where col1=col2
)//当查询结果为空时，条件为真。

4，INSERT INTO VALUES(, ...)

5，DELETE FROM [WHERE<条件>]

6，UPDATE
SET =
...
=
[WHERE<条件>]

例如：
Update exployee
Set age=27
Where name=''赵一''

二，JDBC 主要接口：

java.sql.DriverManager类用于处理驱动程序的调入并且对新的数据库连接提供支持。
java.sql.Connection，指应用程序与特定数据库的连接。
java.sql.Statement，用于一般sql语句的执行（可以是查询、更新甚至可以创建数据库的执行过程）
java.sql.ResultSet,查询所返回的结果保存在此对象中，用它可以浏览和存取数据库内的记录。

1，通过jdbc-odbc桥使用odbc数据库（并不需要jdbc Drivers）
先在odbc DSN(Data Source Name)设置处设置pubs sysDSN,sa为username,密码为空

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");//加载驱动程序
con=DriverManager.getConnection("jdbc:odbc:pubs","sa","");//jdbc:odbc:pubs
con.close();
//应当catch ClassNotFoundException和SQLException
Connection的getWarning方法返回一个SQLWarning对象，在连接之前应当先检查。
使用jdbc-odbc的最大好处是：免费的。但是性能受odbc的限制，而且一般odbc驱动比较昂贵。

2，使用专门的jdbc驱动程序。//此处是mm jdbc Driver
先将jar文件放在ClassPath里面。
Class.forName("org.gjt.mm.mysql.Driver");
con=DriverManager.getConnection("jdbc:mysql://localhost:3306/dbname","root","");
con.close();

可见使用何种方式连接何种数据库与数据库的操作和连接数据库是无关的。

三，查询数据库

Statement stmt=con.createStatement();
stmt.setMaxRows()可以控制输出记录最大数量;
ResultSet rs=stmt.executeQuery("select .....");
ResultSet指向当前记录:
int userId=rs.getInt("userid");
String userName=rs.getString("username");

...或者用序号（从1开始的）

int userId=rs.getInt(1);
Stirng userName=rs.getString(2);
ClassNotFoundException是由于Class.forName()无法载入jdbc驱动程序触发的

SQLException是jdbc在执行过程中发生问题时产生。有一个额外的方法getNextException()
catch(SQLException e){
out.println(e.getMessage());
while(e=e.getNextException()){
out.println(e.getMessage());
}

}

一般来说并不建议在jsp中编写数据库的访问程序，可以将数据库的访问封装在一个javabean中。

四，ResultSet深入

1，ResultSetMetaData
ResultSet rs=stmt.executeQuery("select....");
ResultSetMetaData rsmd=rs.getMetaData(); //获取ResultSetMateData对象
int numberOfColumns=rsmd.getColumnCount();//返回列数
boolean b=rsmd.isSearchable(int i);//返回第i列是否可以用于where子句
String c=rsmd.getColumnLabel(int i);//获取第i列的列标
Objcet obj=rs.getObject();
if(obj!=null)out.println(obj.toString());
else println("");

2，SQL类型与ResultSet的getObject返回类型及对应的XXX getXXX()方法
SQL类型 JSP类型 对应的getXXX()方法
————————————————————————————————————————————
CHAR － String － String getString()
VARCHAR － String － String getString()
LONGVARCHAR － String － InputStream getAsciiStream()/getUnicodeStream()
NUMERIC － java.math.BigDecimal － java.math.BigDecimal getBigDecimal()
DECIMAL － 同上
BIT － Boolean － boolean getBoolean()
TINYINT － Integer － byte getByte()
SMALLINT － Integer － short getShort()
INTEGER － Integer － int getInt()
BIGINT － Long － long getLong()
REAL － Float － float getFloat()
FLOAT － Double － double getDouble()
DOUBLE － Double － double getDouble()
BINARY － byte[] － byte[] getBytes()
VARBINARY － byte[] － byte[] getBytes()
LONGVARBINARY － byte[] － InputStream getBinaryStream()
DATE － java.sql.Date － java.sql.Date getDate()
TIME － java.sql.Time － java.sql.Time getTime()
TIMESTAMP － java.sql.Timestamp － java.sql.Timestamp getTimestamp()

3，null
int i=rs.getInt("age");
if(!rs.wasNull())....//RecordSet::wasNull()用来检查null

4,存取大字符串和二进制文本
对于数据库中longvarchar和langvarbinary进行流操作
ResultSet rs=stmt.executeQueryString("select ...");
BufferedReader br=new BufferedReader(new InputStream(rs.getAsciiStream("vol1")));//长文本串
BufferedReader br=new BufferedReader(new InputStream(rs.getUnicodeStream("vol1")));
BufferedReader br=new BufferedReader(new InputStream(rs.getBinaryStream("vol2")));//长二进制文本
//取数据必须在rs.getAsciiStream(), rs.getUnicodeStream(), rs.getBinaryStream()等之后马上进行
五，浏览ResultSet
1，JDBC2.0提供了更多浏览ResultSet的方法
首先，确定你的jdbc驱动程序支持jdbc2.0
其次，由Connection生成Statement时要指定参数
Statement stmt=con.getStatement("游标类型", "记录更新权限");
游标类型：
ResultSet.TYPE_FORWORD_ONLY:只可以向前移动
ResultSet.TYPE_SCROLL_INSENSITIVE:可卷动。但是不受其他用户对数据库更改的影响。
ResultSet.TYPE_SCROLL_SENSITIVE:可卷动。当其他用户更改数据库时这个记录也会改变。

记录更新权限：
ResultSet.CONCUR_READ_ONLY,只读
ResultSet.CONCUR_UPDATABLE,可更新
getStatement()缺省参数：getStatement(ResultSet.TYPE_FORWORD_ONLY, ResultSet.CONCUR_READ_ONLY)

2,如果ResultSet是可卷动的，以下函数可以使用：
rs.absolute()//绝对位置，负数表示从后面数
rs.first()第一条
rs.last()最后一条
rs.previoust()前一条
rs.next()后一条
rs.beforeFirst()第一条之前
rs.afterLast()最后之后
rs.isFirst(),rs.isLast(),rs.isBeforeFirst(),rs.isAfterLast

注意，刚打开的时候是处于第一条记录之前的

六，更新数据库

1，stmt.executeUpdate("strSql"),strSql是一条sql更新语句。update,insert,delete返回影响到的条数
2，stmt.execute()方法在不知道sql语句是查询还是更新的时候用。如果产生一条以上的对象时，返回true,此时可用stmt.getResultSet()和stmt.getUpdateCount()来获取execute结果，如果不返回ResultSet对象则返回false.
3,除了Statement的executeUpdate之外还可以用ResultSet:
rs.updateInt(1,10);
rs.updateString(2,"sfafd");
rs.updateRow();

七，使用预编译PreparedStatement

PreparedStatement对象和Statement对象类似，都可以用来执行SQL语句。不同在于，数据库会对PreparedStatement的SQL语句进行预编译，而且仍旧能输入参数并重复执行编译好的查询速度比未编译的要快。
PreparedStatement stmt=con.preparedStatement("Insert Into users(userid, username) values(?,?)");
stmt.clearParameters();
stmt.setInt(1,2);
stmt.setString(2,"Big");
stmt.executeUpdate();

八，执行存储过程

1，JDBC调用存储过程，并使用存储过程的返回值。这样可以将处理工作分为服务端和客户端两部分，并大大加快系统的设计和开发的时间。比如可以重复使用服务器上的组件。使用存储过程之后大量诸计算工作可以交给数据库服务器来处理，这将降低Web服务器的负载，从而提高整个系统的性能。

2，有两个表UserMain{UserID,UserName,UserType},UserRef{BrefID, UserID, UserBrief}
下面的存储过程可以接受jdbc传来的参数，新增内容到UserMain和UserRef，并输出一个OutUserID.
CREATE PROCEDURE ap_adduser
(
@OutUserID int output, //此为输出参数,output标记
@UserName varchar(25), //参数表示方法："@XXX"为变量名，"变量名 类型 [output]"
@UserType tinyint,
@UserBrief varchar(255),
)

AS
Declare @UserID int //定义局部变量
insert into UserMain(UserName, UserType)
values(@UserName,@UserType)
select @UserID=@@IDENTITY //赋值用select,此处自动获得ID
insert into UserRef(UserID, UserBrief)
select @OutUserID=@UserID
GO/*结束，基本结构：
CREATE PROCEDURE procedureName(
parameters
)

AS
actions
GO
*/


JSP页面中这样使用：
CallableStatement stmt=con.prepareCall("{call ap_adduser(?,?,?,?)}");
stmt.registerOutParameter(1,Types.INTEGER,1);//注册输出变量
stmt.setString(2,"edmund");
stmt.setInt(3,1);
stmt.setString(4,"description");
stmt.execute();
int userid=stmt.getInt(1);
stmt.close()

八，使用事务

1，事务中的操作是一个整体，要么都执行成功要么都不成功：事务开始后，如果所有的改变都正确，则使用commit方法将这些动作全部存入数据库，否则就使用rollback取消所有的改变动作，而这时数据库中的数据和执行事务前的是相同的。

2，使用事务时应当先用 con.setAutoCommit(false)，最后使用commit或者rollback

3，rollback一般在catch段执行

九，数据库连接池

1，如果有一个数据库连接请求并且连接中没有连接，则生成一个新的连接。这个连接使用完之后并不关闭它，而是将它放入连接池。在这个过程中，还要判断连接池中的连接是否超期。如果超期则将它关闭。

2，有很多已有的Connection Pool包可以使用。

3，一般将Connection Pool作为一个application作用域的变量使用

<%@page import="java.sql.*"%>
<%@page import="javastart.tools.*"%>

DBConnection con=null;
try{
con=pool.getConnection("sun.jdbc.odbc.JdbcOdbcDriver","jdbc:odbc:access","","");
Statement stmt=con.createStatement();
stmt.setMaxRows(10);
String query=request.getParameter("quey");
ResultSet rs=stml.executeQuery(query);
ResultSetMetaData rsmd=rs.getMetaData();
}
.....
finally{
pool.releaseConnection(con);
}

也可以使用一个Servlet初始化连接池

RMI ClassNotFoundException

RMI

多主机运行RMI 代码，遇到类似如下的错误：

java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: examples.callback.MessageReceiverImpl_Stub

需要把Stub 类放在Internet 能访问到的目录下！

× 需要一个安全侧略文件：
grant codeBase "file:/Users/cwang/Documents/workspace/hocl/bin/" {
permission java.security.AllPermission;
};

×显示指出哪里能找到Stub 类：
-Djava.rmi.server.codebase=file:/Users/cwang/Documents/workspace/hocl/bin/

×指明本RMI 主机HOSTNAME，如没有可用IP 代替：
-Djava.rmi.server.hostname=131.254.14.42

【转】Dynamic code downloading using RMI

Dynamic code downloading using RMI
(Using the java.rmi.server.codebase Property)

---

This tutorial is organized as follows:

1. Starting out
2. What is a codebase?
3. How does it work?
4. Using codebase in RMI for more than just stub downloading
5. Command-line examples
6. Troubleshooting tips

---

1.0 Starting out

One of the most significant capabilities of the Java^TM platform is the ability to dynamically download Java software from any Uniform Resource Locator (URL) to a Java virtual machine* (JVM) running in a separate process, usually on a different physical system. The result is that a remote system can run a program, for example an applet, which has never been installed on its disk. For the first few sections of this document, codebase with regard to applets will be discussed in order to help describe codebase with regard to Java Remote Method Invocation (RMI).
For example, a JVM running from within a web browser can download the bytecodes for subclasses of java.applet.Applet and any other classes needed by that applet. The system on which the browser is running has most likely never run this applet before, nor installed it on its disk. Once all the necessary classes have been downloaded from the server, the browser can start the execution of the applet program using the local resources of the system on which the client browser is running.
Java RMI takes advantage of this capability to download and execute classes and on systems where those classes have never been installed on disk. Using the RMI API any JVM, not only those in browsers, can download any Java class file including specialized RMI stub classes, which enable the execution of method calls on a remote server using the server system's resources.
The notion of a codebase originates from the use of ClassLoaders in the Java programming language. When a Java program uses a ClassLoader, that class loader needs to know the location(s) from which it should be allowed to load classes. Usually, a class loader is used in conjunction with an HTTP server that is serving up compiled classes for the Java platform. Most likely, the first ClassLoader/codebase pairing that you came into contact with was the AppletClassLoader, and the "codebase" part of the HTML tag, so this tutorial will assume that you have some experience with Java RMI programming, as well as writing HTML files that contain applet tags. For example, the HTML source will contain something like:

2.0 What is a codebase?

A codebase can be defined as a source, or a place, from which to load classes into a Java virtual machine. For example, if you invited a new friend over for dinner, you would need to give that friend directions to the place where you lived, so that he or she could locate your house. Similarly, you can think of a codebase as the directions that you give to a JVM, so it can find your [potentially remote] classes.
You can think of your CLASSPATH as a "local codebase", because it is the list of places on disk from which you load local classes. When loading classes from a local disk-based source, your CLASSPATH variable is consulted. Your CLASSPATH can be set to take either relative or absolute path names to directories and/or archives of class files. So just as CLASSPATH is a kind of "local codebase", the codebase used by applets and remote objects can be thought of as a "remote codebase".

3.0 How does it work?

3.1 How codebase is used in applets

To interact with an applet, that applet and any classes that it needs to run must be accessible by remote clients. While applets can be accessed from "ftp://" or local "file:///" URLs, they are usually accessed from a remote HTTP server.

1. The client browser requests an applet class that is not found in the client's CLASSPATH
2. The class definition of the applet (and any other class(es) that it needs) is downloaded from the server to the client using HTTP
3. The applet executes on the client

Figure 1: Downloading applets
The applet's codebase is always relative to the URL of the HTML page in which the tag is contained.

3.2 How codebase is used in RMI

Using RMI, applications can create remote objects that accept method calls from clients in other JVMs. In order for a client to call methods on a remote object, the client must have a way to communicate with the remote object. Rather than having to program the client to speak the remote object's protocol, RMI uses special classes called stubs that can be downloaded to the client that are used to communicate with (make method calls on) the remote object. The java.rmi.server.codebase property value represents one or more URL locations from which these stubs (and any classes needed by the stubs) can be downloaded.
Like applets, the classes needed to execute remote method calls can be downloaded from "file:///" URLs, but like applets, a "file:///" URL generally requires that the client and the server reside on the same physical host, unless the file system referred to by the URL is made available using some other protocol, such as NFS.
Generally, the classes needed to execute remote method calls should be made accessible from a network resource, such as an HTTP or FTP server.

Figure 2: Downloading RMI stubs

1. The remote object's codebase is specified by the remote object's server by setting the java.rmi.server.codebase property. The RMI server registers a remote object, bound to a name, with the RMI registry. The codebase set on the server JVM is annotated to the remote object reference in the RMI registry.
2. The RMI client requests a reference to a named remote object. The reference (the remote object's stub instance) is what the client will use to make remote method calls to the remote object.
3. The RMI registry returns a reference (the stub instance) to the requested class. If the class definition for the stub instance can be found locally in the client's CLASSPATH , which is always searched before the codebase, the client will load the class locally. However, if the definition for the stub is not found in the client's CLASSPATH, the client will attempt to retrieve the class definition from the remote object's codebase.
4. The client requests the class definition from the codebase. The codebase the client uses is the URL that was annotated to the stub instance when the stub class was loaded by the registry. Back in step 1, the annotated stub for the exported object was then registered with the RMI registry bound to a name.
5. The class definition for the stub (and any other class(es) that it needs) is downloaded to the client.

Note: Steps 4 and 5 are the sames steps that the registry took to load the remote object class, when the remote object was bound to a name in (registered with) the RMI registry. When the registry attempted to load the remote object's stub class, it requested the class definition from the codebase associated with that remote object.

6. Now the client has all the information that it needs to invoke remote methods on the remote object. The stub instance acts as a proxy to the remote object that exists on the server; so unlike the applet which uses a codebase to execute code in its local JVM, the RMI client uses the remote object's codebase to execute code in another, potentially remote JVM, as illustrated in Figure 3:

Figure 3: RMI client making a remote method call

4.0 Using codebase in RMI for more than just stub downloading

In addition to downloading stubs and their associated classes to clients, the java.rmi.server.codebase property can be used to specify a location from which any class, not only stubs, can be downloaded.
When a client makes a method call to a remote object, the method that it calls could be written to accept no arguments or a number of arguments. There are three distinct cases that may occur, based on the data type(s) of the method argument(s).
In the first case, all of the method parameters (and return value) are primitive data types, so the remote object knows how to interpret them as method parameters, and there is no need to check its CLASSPATH or any codebase.
In the second case, at least one remote method parameter or the return value is an object, for which the remote object can find the class definition locally in its CLASSPATH.
In the third case (shown as Step 6, in Figure 4), the remote method receives an object instance, for which the remote object cannot find the class definition locally in its CLASSPATH. This type of remote method call is illustrated in Figure 4. The class of the object sent by the client will be a subtype of the declared parameter type. A subtype is either:

• An implementation of the interface that is declared as the method parameter (or return) type
• A subclass of the class that is declared as the method parameter (or return) type

Figure 4: RMI client making a remote method call, passing an unknown subtype as a method parameter
7. Like the applet's codebase, the client-specified codebase is used to download Remote classes, non-remote classes, and interfaces to other JVMs. If the codebase property is set on the client application, then that codebase is annotated to the subtype instance when the subtype class is loaded by the client. If the codebase is not set on the client, the remote object will mistakenly use its own codebase.

5.0 Command-line examples

In the case of an applet, the applet codebase value is embedded in an HTML page, as we saw in the HTML example in the first section of this tutorial.
In the case of Java RMI codebase, rather than having a reference to the class embedded in an HTML page, the client first contacts the RMI registry for a reference to the remote object. Because the remote object's codebase can refer to any URL, not just one that is relative to a known URL, the value of the RMI codebase must be an absolute URL to the location of the stub class and any other classes needed by the stub class. This value of the codebase property can refer to:

• The URL of a directory in which the classes are organized in package-named sub-directories
• The URL of a JAR file in which the classes are organized in package-named directories
• A space-delimited string containing multiple instances of JAR files and/or directories that meet the criteria above

Note: When the codebase property value is set to the URL of a directory, the value must be terminated by a "/".

Examples

If the location of your downloadable classes is on an HTTP server named "webvector", in the directory "export" (under the web root), your codebase property setting might look like this:

-Djava.rmi.server.codebase=http://webvector/export/

If the location of your downloadable classes is on an HTTP server named "webline", in a JAR file named "mystuff.jar", in the directory "public" (under the web root), your codebase property setting might look like this:

-Djava.rmi.server.codebase=http://webline/public/mystuff.jar

Now let's suppose that the location of your downloadable classes has been split between two JAR files, "myStuff.jar" and "myOtherStuff.jar". If these JAR files are located on different servers (named "webfront" and "webwave"), your codebase property setting might look like this:

-Djava.rmi.server.codebase="http://webfront/myStuff.jar http://webwave/myOtherStuff.jar"

6.0 Troubleshooting tips

Any serializable class, including RMI stubs, can be downloaded if your RMI programs are configured properly. Here are the conditions under which dynamic stub downloading will work:

1. The stub class and any of the classes that the stub relies on are served up from a URL reachable from the client.
2. The java.rmi.server.codebase property has been set on the server program (or in the case of activation, the "setup" program) that makes the call to bind or rebind, such that:
   • The value of the codebase property is the URL in step A and
   • If the URL specified as the value of the codebase property is a directory, it must end in a trailing "/"
3. The rmiregistry cannot find the stub class or any of the classes that the stub relies on in its CLASSPATH. This is so the codebase gets annotated to the stub when the registry does its class load of the stub, as a result of calls to bind or rebind in the server or setup code.
4. The client has installed a SecurityManager that allows the stub to be downloaded. In the Java 2 SDK, Standard Edition, v1.2 and later this means that the client must also have a properly configured security policy file.

There are two common problems associated with the java.rmi.server.codebase property, which are discussed next.

6.1 If you encounter a problem running your RMI server

The first problem you might encounter is the receipt of a ClassNotFoundException when attempting to bind or rebind a remote object to a name in the registry. This exception is usually due to a malformed codebase property, resulting in the registry not being able to locate the remote object's stubs or other classes needed by the stub.
It is important to note that the remote object's stub implements all the same interfaces as the remote object itself, so those interfaces, as well as any other custom classes declared as method parameters or return values, must also be available for download from the specified codebase.
Most frequently, this exception is thrown as a result of omitting the trailing slash from the URL value of the property. Other reasons would include: the value of the property is not a URL; the path to the classes specified in the URL is incorrect or misspelled; the stub class or any other necessary classes are not all available from the specified URL.
The exception that you may encounter in such a case would look like this:

java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: examples.callback.MessageReceiverImpl_Stub
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: examples.callback.MessageReceiverImpl_Stub
java.lang.ClassNotFoundException: examples.callback.MessageReceiverImpl_Stub
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Compiled Code)
at sun.rmi.transport.StreamRemoteCall.executeCall(Compiled Code)
at sun.rmi.server.UnicastRef.invoke(Compiled Code)
at sun.rmi.registry.RegistryImpl_Stub.rebind(Compiled Code)
at java.rmi.Naming.rebind(Compiled Code)
at examples.callback.MessageReceiverImpl.main(Compiled Code)
RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: examples.callback.MessageReceiverImpl_Stub

6.2 If you encounter a problem running your RMI client

The second problem you could encounter is the receipt of a ClassNotFoundException when attempting to lookup a remote object in the registry. If you receive this exception in a stacktrace resulting from an attempt to run your RMI client code, then your problem is the CLASSPATH with which your RMI registry was started. See requirement C in section 6.0. Here is what the exception will look like:

java.rmi.UnmarshalException: Return value class not found; nested exception is:
java.lang.ClassNotFoundException: MyImpl_Stub
at sun.rmi.registry.RegistryImpl_Stub.lookup(RegistryImpl_Stub.java:109
at java.rmi.Naming.lookup(Naming.java:60)
at RmiClient.main(MyClient.java:28)

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Other resources

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http://java.sun.com/j2se/1.4.2/docs/guide/rmi/codebase.html#sixStepC