Java开发网 - [个人原创]工作中常用的J2EE技术

Topic: [个人原创]工作中常用的J2EE技术

1.[个人原创]工作中常用的J2EE技术

Posted by: jerryjerry123
Posted on: 2005-05-15 20:19

我是一名J2EE程序员，自己觉得对J2EE比较有经验：－）
我觉得要学习J2EE, 能找到一份好工作，掌握以下的技术要点是必须的：
(1) Java Basic syntax
(2) Memory manage in Java: 知道如何申请空间和释放空间
(3) JDBC: 知道如何访问数据库
(4) JSP: JSP在工作中最常用
(5) Servlet: JSP执行前是被翻译成Servlet,所以基本Servlet知识也是必须的

学习知识是为了工作，学习的最后方式也是在工作中学习，但是如何你不会，人家又会不雇用你，这是一个矛盾。

所以，我们必须自我学习上面的基本知识，以通过面试。

自我学习最好是找一本最简单的书，根据例子从粗到细耐心的学。

大家希望找些关于Java内存管理的资料，我想在绝大部分Java书籍中都会有简单介绍，但都可能不够深入。我个人觉得了解Java内存管理特别重要。所以我在这里作介绍一些点，我是从一个DevPartner Java™ Edition培训上学来的(那个培训对我影响深刻)，希望对大家有用。

New Memory Problems in Java
1. Temporary Objects
The GC works harder when objects are constantly being allocated, used for a short time and then unreferenced
For each object creation the following occurs:
*Memory is allocated on the heap
*Class constructors are called
*Fields are initialized
*The state of the object is tracked
Creating many short-lived objects is a common performance bottleneck on the Java platform
Temporary Objects
*Medium and Short lived objects
*Survive less than 2 garbage collections
String concatenation example…
String objects are immutable
Once created, cannot be changed
String abc = “a” + b + “c”;
Translates to –
String abc = new Stringbuffer().append(“a”)
.append Beer

             .append(“c”)
             .toString();
Two new objects are created
one StringBuffer and one String

String result = “”;
For (int i=0; i < 20; i++) {
  result += getNextString();
}

Better coded as:

String result = “”;
StringBuffer buffer = new StringBuffer();
For (int i=0; i < 20; i++) {
  buffer.append(getNextString())
}
Result = buffer.toString();

2. Java Memory Leaks

3. Memory Footprint

具体资料，大家可以查询www.compuware.com
我的理解是这个Java工具软件公司为了提供给Java开发者好的工具，所以对Java内存管理的日常问题和我们编程中常犯的内存错误进行研究，希望大家喜欢。

2.Re:[个人原创]工作中常用的J2EE技术 [Re: jerryjerry123]

Copy to clipboard

Posted by: ftang
Posted on: 2005-05-16 09:22

I think as a J2EE developer, you first have to be a Java Developer. Using Servlet/JSP/EJB is nothing...until you understand how application server works like JTA, JNDI, JDBC...when I say know how to works means you know every step how application server do...then you can be a J2EE developer...I saw too much J2EE developer only know JSP/Servlet...useless.

3.Re:[个人原创]工作中常用的J2EE技术 [Re: jerryjerry123]	Copy to clipboard
Posted by: javadd Posted on: 2005-05-18 11:00 如何申请空间和释放空间应该看什么资料？

4.Re:[个人原创]工作中常用的J2EE技术 [Re: ftang]

Copy to clipboard

Posted by: airport
Posted on: 2005-05-20 08:45

ftang wrote:
I think as a J2EE developer, you first have to be a Java Developer. Using Servlet/JSP/EJB is nothing...until you understand how application server works like JTA, JNDI, JDBC...when I say know how to works means you know every step how application server do...then you can be a J2EE developer...I saw too much J2EE developer only know JSP/Servlet...useless.

的确应该如你所说，

不过新手还是从jsp/servlet开始为好。否则因小失大，什么都不会了

5.Re:[个人原创]工作中常用的J2EE技术 [Re: jerryjerry123]	Copy to clipboard
Posted by: jigsaw Posted on: 2005-05-20 18:14 jerryjerry123显然是在灌水。。。。

6.Re:[个人原创]工作中常用的J2EE技术 [Re: jerryjerry123]	Copy to clipboard
Posted by: hcom Posted on: 2005-05-21 20:23 如何申请空间和释放空间应该看什么资料？同样的疑问

7.Re:[个人原创]工作中常用的J2EE技术 [Re: jerryjerry123]	Copy to clipboard
Posted by: jerryjerry123 Posted on: 2005-05-21 21:58 javaadd 和 hcom, 申请空间和释放空间应该看什么资料？我已在最上面更新了，希望对你们有帮助