$yum install java-1.6.0-openjdk-devel

You can also install all the OpenJDK 6 packages, including the API documentation, by using the wildcard java-1.6.0-openjdk*.

1.Agile model driven development(AMDD): focus on model

2.Extreme programmning: focus on full development life cycle.

3.Jconsole: c:\program files\java\jdk1.6.0_14\bin\jconsole, which could dectect the memory issue, class loading,

garbage collection...
 

Java profilers: analyze the heap for memory usage and leaks, CPU utilization, trace object and methods,determine performance bottlenecks...

4.Ant new feature:

      <exec command="date"/>

   Get:  fetch a file using HTTP GET.

      <get src="http://visualpatterns.com/comics/funny.gif" dest="funny.gif"  verbose="true"/>

   Sleep: pause processing.
 
 <sleep seconds="2"/>
 
   FTP: use FTP directly. The example transfe the files to ftp server automatically using windows scheduled tasks
 <ftp server="mirror.kernel.org"
      action="get"
      remotedir=...> </ftp>

   MAIL: ...

5. JMX: my thought: I can use it to track how many user signed into, and so on.

6.unchecked exception: do not need to be caught by the code. Checked exception require the code to either cathch the exception or throw it up the call chain using throws. "If  a client can reasonble to recover from an exception, make it a checked exception. If client cannot do anything to recover from the excepetion, make it unchecked"

    DOM适合于当今流行的各种语言，包括Java,JavaScripte,VB,VBScript，Perl,C,C++等。它了为HTML和XML文档提供了一个可应用于不同平台的编程接口。W3C DOM的最新信息可从http://www.w3.org/TR2001/WD-DOM-Lever-3-Core-20010913查阅。微软在http://msdn.microsoft.com/library/default.asp?url=/library/en-us/xmlsdk30/htm/xmconxmldomuserguide.asp上也有DOM的详细技术信息。

   DOM的设计为了适用于不同的语言，它保留了不同语言中非常相似的API。但是它并不适合于Java编程者的习惯。而JDOM作为一种轻量级API被制定，它最核心的要求是以Java为中心，只适合于Java语言，它遵循DOM的接口主要规则，除去了DOM中为了兼容各语言而与Java习惯的不同。

二、使用JDOM的前提条件
   须要有SAX、DOM解析器的类文件，JDOM只是一种适合Java程序员来使用的Java XML解析器，目前流行的Java XML解析器还有：Apache Xerces Java、JAXP。
Xerces Java解析器是完全用Java编写的XML解析器，最新版本是2.5，它支持以下标准和API：
（1） XML1.0规范（第二版本）
（2） XML命名空间规范
（3） DOM2核心标准规范
（4） SAX2核心扩展
（5） JAXP1.2 ：是Sun提供的使用Java处理XML的接口API。
（6） XML Schema结构和数据类型标准

      还有最好的是它开放源代码，我们可以在http://xml.apache.org/dist/xerces-j/ 处去下载。下载文件Xerces-J-bin.2.5.0.zip。
解压下载文件，得到四个压缩包加到项目的路径中（其实不要全加，但不熟的情况下考虑这么做）。
JDOM的二进制版本下载：http://www.jdom.org/downloads/index.html
把解压后的jdom.jar文件加到项目的类路径中，另外便于调试，还要下载它的源代码。

三、使用JDOM解析XML
     好了，现在该是正题了。下面通过一个简单的例子说明一下怎么用JDOM这一适合Java程序员习惯的工具包来解析XML文档。
为了简单，我用了如下XML作为要解析的XML文件：
<?xml version="1.0" encoding="gb2312"?>
<books>
   <book email="zhoujunhui">
     <name>rjzjh</name>
     <price>60.0</price>
  </book>
</books>
够简单的吧，但它对于我们关心的东西都有了，子节点，属性。
下面是用于解析这个XML文件的Java文件：

1 public class JDomParse {
2	public JDomParse(){
3		String xmlpath="library.xml";
4		SAXBuilder builder=new SAXBuilder(false);
5		try {
6			Document doc=builder.build(xmlpath);
7			Element books=doc.getRootElement();
8			List booklist=books.getChildren("book");
9			for (Iterator iter = booklist.iterator(); iter.hasNext();) {
10				Element book = (Element) iter.next();
11				String email=book.getAttributeValue("email");
12				System.out.println(email);
13				String name=book.getChildTextTrim("name");
14				System.out.println(name);
15				book.getChild("name").setText("alterrjzjh");
16
17			}
18
19			XMLOutputter outputter=new XMLOutputter();
20			outputter.output(doc,new FileOutputStream(xmlpath));
21
22		} catch (JDOMException e) {
23			e.printStackTrace();
24		} catch (IOException e) {
25			e.printStackTrace();
26		}
27	}
28	public static void main(String[] args) {
29		new JDomParse();
30	}
31}

首先要了解java默认的序列化行为，java将一切关于对象的信息都保存了下了，也就是说，有些时候那些不需要保存的也被保存了下来。一般情况下，我们仅仅需要保存逻辑数据就可以了。不需要保存的数据我们可以用关键字transient标出。

例如：

import java.io.*;

public class Serial implements Serializable {

　int company_id;

　String company_addr;

　transient boolean company_flag;

}


其中的company_flag字段将不会参与序列化与反序列化，但同时也增加了为它初始值的责任。这也是序列化常常导致的问题之一。因为序列化相当于一个只接受数据流的public构造函数，这种对象构造方法是语言之外的。但他仍然是一种形式上的构造函数。如若你的类不能够通过其他方面来保证初始化，则你需要额外的提供readObject方法，首先正常的反序列化，然后对transient标示的字段进行初始化。

在不适合的时候，使用java默认的序列化行为可能会带来速度上的影响，最糟糕的情况是，可能导致溢出。在某些数据结构的实现中，经常会充斥着各种的循环引用，而java的默认序列化行为，并不了解你的对象结构，其结果就是java试图通过一种昂贵的“图遍历”来保存对象状态。可想而知，不但慢而且可能溢出。这时候你就要提供自己的readObject，来代替默认的行为。

note: http://developer.51cto.com/art/200601/20017.htm

• JNDI 名称：jdbc/blue
• 数据源 URL：jdbc:mysql://localhost/home
• JDBC 驱动程序类：org.gjt.mm.mysql.Driver
• 用户名：root
• 口令： ×××

2、在conf/catalina/localhost下找到与“项目名.xml”文件，程序名是webapps目录下的项目文件夹名称。在此文件中的 <context> 标记之间添加以下资源链接：

   <ResourceLink name="jdbc/blue" type="javax.sql.DataSource" global="jdbc/blue"/>

注意：一定要加在这个文件中，而不是在项目文件夹里的web.xml中。至少我这样做时结果不对。

3、 接下来就是测试了。测试程序很重要，尽量用简单的了。以下是我的测试程序：





<%@ page contentType="text/html; charset=GBK"%>
<%@ page import="java.sql.*,javax.sql.DataSource,javax.naming.*"%>
<html>
<head><title>test.jsp</title></head>
<body bgcolor="#ffffff">

<% 
Context initCtx=new InitialContext();
DataSource ds = (DataSource)initCtx.lookup("java:comp/env/jdbc/blue");

try
{
out.println("test! <br>");
Connection conn=ds.getConnection();
out.println("data from database:<br>");
Statement stmt=conn.createStatement();
ResultSet rs =stmt.executeQuery("select * from dept");
while(rs.next())
{

out.println(rs.getString(1));
out.println(rs.getString(2));

}
rs.close();
stmt.close();
}
catch(Exception e)
{
e.printStackTrace();
}
%>
</body>
</html>





























































Good Luck!

  <!-- The mapping for the invoker servlet -->

<!--

  <servlet-mapping>

    <servlet-name>invoker</servlet-name>

    <url-pattern>/servlet/*</url-pattern>

  </servlet-mapping>

-->

When you edit web.xml in the Tomcat conf directory, the servlet is ready to go。

例如，after saving Ch09_06.java and building the project, start Tomcat with the Tomcat plug-in's buttons and navigate to http://localhost:8080/Ch09_06/servlet/org.eclipsebook.ch09.Ch09_06.

2、就是编辑每个项目中的web.xml文件：

lternatively, if you don't want to edit web.xml in the Tomcat conf directory to enable anonymous servlets, you can create a local web.xml for each project you create with the Tomcat plug-in.

Your Java Programming Questions

There are several people who have kindly offered to answer Java questions. So please send all questions to:

1. Sun has a "New To Java" Programming Information Center to help get you started.
   
   
2. Bill Venners, who teaches with me, has created the Java Answers Forum. He said: "I wanted to create a place where programmers could ask and answer each other questions, where the questions and answers would remain indefinitely and be searchable."
   
   
3. The forums at TechInterviews have many people asking and answering Java questions.
   
   
4. IBM DeveloperWorks contains some nice introductory material.
   
   
5. Kathy Kozel has created http://www.javaranch.com/ for the same reason. You can send programming questions to kathykozel@javaranch.com
   
   
6. Marcus Green maintains the Java Certification Exam Discussion Forum
   
   
7. Another page about certification www.levteck.com.
   
   
8. Raymond Blum is available to answer Java questions. He has several years experience in Java and other O-O languages and is currently consulting as an OO mentor and Java instructor. You can send him questions at raytrace@thebyteboard.com
   
   
9. David Reilly has a web site devoted to answering Java questions, which seems well-targeted to beginners. You can go directly to his FAQ.
   
   
10. JFind keeps a list of answers and snippets.
    
    
11. The JavaFAQ specializes in Java questions and answers, including Java Daily Tips, many online Java books, a weekly newsletter, and they provide a free "Java Tips" e-book.
    
    
12. Charles Bell says he will be happy to try to answer questions; he also has a web site at http://www.quantumhyperspace.com.
    
    
13. jGuru.com http://www.jguru.com maintains a set of community-driven, topical FAQs where developers can pose questions or answer those already posed.
    
    
14. Kevin Brown has created an egroup "For those who are working through and would like to discuss the book."
    
    
15. Here's another study group for TIJ: http://groups.yahoo.com/group/JavaThink/.
    
    
16. For JSP (Java Server Pages) questions, JSPInsider claims to have "a refreshing take on JSP." JSPInsider is based upon a group of developers sharing information to help the JSP community make the most out of JSP. They also have a newsletter.
    
    
17. From a bulletin from Sun: "HotDispatch, Inc. and Sun Microsystems, Inc. are helping to bring people together in a real-time marketplace for Java technology support ... [if] you like the idea of getting technical help at competitive prices, visit: http://developer.java.sun.com/developer/support/Hotdispatch/"
    
    
18. Dr. Heinz Max Kabutz publishes an Advanced Java newsletter. Not for the uninitiated, but I find something fascinating in every issue. To subscribe, either send an email here or do it via the web here. He has back issues here.
    
    
19. Programmer's Heaven provides a Java Message Board for Q & A.
    
    

1、 在 tomcat/conf/sever.xml 中添加项目，例如 myapp 项目：

                <Context path="/myapp" docBase="myapp" debug="0"

                              reloadable="true" crossContext="true">

            </Context>

2 ．每编制一个 servlet ，就需要在项目的 web-inf /web.xml 中添加这个 servlet 的配置，例如要新增ContexrServlet，其结构如下：

<servlet>

  <servlet-name>ContextServlet</servlet-name>

  <servlet-class>ContextServlet</servlet-class>

  </servlet>

<servlet-mapping>

<servlet-name>ContextServlet</servlet-name>

<url-pattern>/servlet/*</url-pattern>

</servlet-mapping>

3 ．编译 servlet ，拷贝 class 文件到项目的 /web-inf/classes 下。

4 ．重启 tomcat ，运行。 例如，输入 ocalhost:8080/myapp/servlet/ContextServlet 即可运行

注意：   修改了 web.xml 以及新加了和修改了 class ，都要重启 Tomcat (Just to clarify u need to redeploy your application if you make ANY change in ur classes. This is not the case with jsp files or html files. )

JavaBean 注意事项：

1. 同上；
2. 建立自己的 Bean ，一定注意： javabean 文件必须带包名 ，即在 javabean 文件开头要有 package pname 。 (注意： 这可是个小trick呀，开始的时候我是根本没有注意到问题出在这里呀。)
3. 编译 javabean ，拷贝 class 文件到项目的 /web-inf/classes 下
4. 重启 tomcat ，运行关联的 jsp，即可。