很杂的一些记录

1、jdk的安装和测试

windows下， 安装完java jdk后，并配置好合适的系统环境变量后，可以通过在cmd的终端中，输入java -version和javac -version查看jdk的版本号，如1.6.0对应的就是jdk 6，1.5.0对应的就是jdk 5。

 

2、Java Servlet Technology Overview (java servlet技术概述）

Java Servlet technology provides Web developers with a simple, consistent mechanism for extending the functionality of a Web server and for accessing existing business systems. A servlet can almost be thought of as an applet that runs on the server side--without a face. Java servlets make many Web applications possible

Servlets are the Java platform technology of choice for extending and enhancing Web servers. Servlets provide a component-based, platform-independent method for building Web-based applications, without the performance limitations of CGI programs. And unlike proprietary server extension mechanisms (such as the Netscape Server API or Apache modules), servlets are server- and platform-independent. This leaves you free to select a "best of breed" strategy for your servers, platforms, and tools.

Servlets have access to the entire family of Java APIs, including the JDBC API to access enterprise databases. Servlets can also access a library of HTTP-specific calls and receive all the benefits of the mature Java language, including portability, performance, reusability, and crash protection.

Today servlets are a popular choice for building interactive Web applications. Third-party servlet containers are available for Apache Web Server, Microsoft IIS, and others. Servlet containers are usually a component of Web and application servers, such as BEA WebLogic Application Server, IBM WebSphere, Sun Java System Web Server, Sun Java System Application Server, and others.

You might want to check out the latest information on JavaServer Pages (JSP) technology. JSP technology is an extension of the servlet technology created to support authoring of HTML and XML pages. It makes it easier to combine fixed or static template data with dynamic content. Even if you're comfortable writing servlets, there are several compelling reasons to investigate JSP technology as a complement to your existing work.

 

 3、windows下环境变量的配置

在windows下，设置系统环境变量PATH，添加号新安装bin可执行程序后，就可以在cmd终端中直接输入bin程序名称来执行了；这一点就类似与在Linux中通过设置PATH变量是一个原理。只是在windows下，很多情况下应用程序会自动帮用户向PATH添加好对应的bin路径。另外有时也需要通过手动增加lib对应的路径，这样写程序时就可以直接添加需要的头文件，而不需要考虑当前文件的目录位置，但大部分情况下，程序安装的时候都会做好这一步。

如果安装了不同版本的相同软件，在通过cmd终端使用bin目录下的可执行程序时，需要预先通过set进行路径的配置，以明确使用的是具体哪一个版本的bin程序。

例如，如果安装了ocaml的多个版本，则在使用它的bin程序之前，需要进行set：

set OCAMLWIN=D:/Program Files/Objective Caml
set OCAMLLIB=%OCAMLWIN%/lib
set PATH=%OCAMLWIN%/bin;%PATH%
set INCLUDE=%INCLUDE%;%OCAMLWIN%/inc
set LIB=%LIB%;%OCAMLWIN%/lib;obj/x86_WIN32

4、cygwin是什么？

在windows下安装了cygwin后，只要添加cygwin下的bin目录（里面包含了许多linux下的命令），就可以在win终端下使用linux的命令了，还是很爽的！

Cygwin is:

• a collection of tools which provide a Linux look and feel environment for Windows
• a DLL (cygwin1.dll) which acts as a Linux API layer providing substantial Linux API functionality.

Cygwin is not:

• a way to run native Linux apps on Windows.  You must rebuild your application from source if you want it to run on Windows.
• a way to magically make native Windows apps aware of UNIX®functionality like signals, ptys, etc.  Again, you need to build your apps from sourceif you want to take advantage of Cygwin functionality.

cygwin版本查询

 

cygcheck -c 是检查所有安装的软件的版本号。      cygcheck -c cygwin 就是当前Cygwin的版本号。      使用uname -a 也可以的Cygwin的版本号，还有内核的版本。      使用cat /proc/version的结果与uname -a一致。