Web.xml
接触
web.xml很长时间了，只是常用最简单的几项，还用不好。
Pebble自己实现了简单而实用的
MVC的框架，读源码时发现在
web.xml里设置比较多，如果不搞懂，朝下读会比较费力，今天决心找个全面的资料解读一下。
从[url]http://java.sun.com/developer/Books/javaserverpages/servlets_javaserver/[/url] 去下载 《More Servlets and JavaServer Pages》 第五章
Controlling Web Application Behavior with web.xml
Web.xml
里的各元素不仅大小写敏感，而且顺序敏感，所以我们必须按以下顺序来配置。
•
icon
. The
icon
element designates the location of either one or two image files that an IDE or GUI tool can use to represent the Web application. For details, see Section 5.11 (Documenting Web Applications).
•
display-name
. The
display-name
element provides a name that GUI tools might use to label this particular Web application. See Section 5.11.
•
description
. The
description
element gives explanatory text about the Web application. See Section 5.11.
•
distributable
. The
distributable
element tells the system that it is safe to distribute the Web application across multiple servers. See Section 5.15.
•
context-param
. The
context-param
element declares application-wide initialization parameters. For details, see Section 5.5 (Initializing and Preloading Servlets and JSP Pages).
•
filter
. The filter element associates a name with a class that implements the
javax.servlet.Filter
interface. For details, see Section 5.6 (Declaring Filters).
•
filter-mapping
. Once you have named a filter, you associate it with one or more servlets or JSP pages by means of the
filtermapping
element. See Section 5.6.
•
listener
. Version 2.3 of the servlet API added support for event listeners that are notified when the session or servlet context is created, modified, or destroyed. The
listener
element designates the event listener class. See Section 5.14 for details.
•
servlet
. Before you assign initialization parameters or custom URLs to servlets or JSP pages, you must first name the servlet or JSP page. You use the
servlet
element for that purpose. For details, see Section 5.3.
•
servlet-mapping
. Servers typically provide a default URL for servlets:
[url]http://host/webAppPrefix/servlet/ServletName[/url]
. However, you often change this URL so that the servlet can access initialization parameters (Section 5.5) or more easily handle relative URLs (Section 4.5). When you do change the default URL, you use the
servletmapping
element to do so. See Section 5.3.
•
session-config
. If a session has not been accessed for a certain period of time, the server can throw it away to save memory. You can explicitly set the timeout for individual session objects by using the
setMaxInactiveInterval
method of
HttpSession
, or you can use the
session-config
element to designate a default timeout.
For details, see Section 5.10.
•
mime-mapping
. If your Web application has unusual files that you want to guarantee are assigned certain MIME types, the
mimemapping
element can provide this guarantee. For more information, see Section 5.12.
•
welcome-file-list
. The
welcome-file-list
element instructs the server what file to use when the server receives URLs that refer to a directory name but not a filename. See Section 5.7 for details.
•
error-page
. The
error-page
element lets you designate the pages that will be displayed when certain HTTP status codes are returned or when certain types of exceptions are thrown. For details, see Section 5.8.
•
taglib
. The
taglib
element assigns aliases to Tag Library Descriptor files. This capability lets you change the location of the TLD files without editing the JSP pages that use those files. See Section 5.13 for more information.
•
resource-env-ref
. The
resource-env-ref
element declares an administered object associated with a resource. See Section 5.15.
•
resource-ref
. The
resource-ref
element declares an external resource used with a resource factory. See Section 5.15.
•
security-constraint
. The
security-constraint
element lets you designate URLs that should be protected. It goes hand-inhand with the
login-config
element. See Section 5.9 for details.
•
login-config
. You use the
login-config
element to specify how the server should authorize users who attempt to access protected pages. It goes hand-in-hand with the
security-constraint
element. See Section 5.9 for details.
•
security-role
. The
security-role
element gives a list of security roles that will appear in the
role-name
subelements of the
security-role-ref
element inside the
servlet
element. Declaring the roles separately could make it easier for advanced IDEs
to manipulate security information. See Section 5.9 for details.
•
env-entry
. The
env-entry
element declares the Web application’s environment entry. See Section 5.15.
•
ejb-ref
. The
ejb-ref
element declares a reference to the home of an enterprise bean. See Section 5.15.
•
ejb-local-ref
. The
ejb-local-ref
element declares a reference to the local home of an enterprise bean. See Section 5.15.
如果你down到这片材料，就会发现它讲得非常清楚明了，几乎无须翻译。把它配置好可以给我们工作带来很多方便和安全。常看些成熟的系统配置，争取慢慢达到灵活运用之。