一 获取初始化参数
在web.xml中配置Servlet时，可以配置一些初始化参数。
而在Servlet中可以通过ServletConfig接口提供方法来取得这些参数。
二 界面
<%@
page
language
=
"java"
import
=
"java.util.*"
contentType
=
"text/html; charset=utf-8"
%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+
"://"
+request.getServerName()+
":"
+request.getServerPort()+path+
"/"
;
%>
DOCTYPE
HTML
PUBLIC
"-//W3C//DTD HTML 4.01 Transitional//EN">
<
html
>
<
head
>
<
base
href
=
"
<%=
basePath
%>
"
>
<
title
>
My JSP 'index.jsp' starting page
title
>
<
meta
http-equiv
=
"pragma"
content
=
"no-cache"
>
<
meta
http-equiv
=
"cache-control"
content
=
"no-cache"
>
<
meta
http-equiv
=
"expires"
content
=
"0"
>
<
meta
http-equiv
=
"keywords"
content
=
"keyword1,keyword2,keyword3"
>
<
meta
http-equiv
=
"description"
content
=
"This is my page"
>
head
>
<
body
>
<
h1
>
获取初始化参数演示案例
h1
>
<
hr
>
<
a
href
=
"servlet/GetInitParameterServlet"
>
获取初始化参数
Servlet
a
>
body
>
html
>
三 配置文件
xml
version
=
"1.0"
encoding
=
"UTF-8"
?>
<
web-app
xmlns:xsi
=
" http://www.w3.org/2001/XMLSchema-instance"
;
xmlns
=
" http://java.sun.com/xml/ns/javaee"
;
xmlns:web
=
" http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
;
xsi:schemaLocation
=
" http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
;
version
=
"2.5"
>
<
display-name
>
display-name
>
<
servlet
>
<
description
>
This is the description of my J2EE component
description
>
<
display-name
>
This is the display name of my J2EE component
display-name
>
<
servlet-name
>
GetInitParameterServlet
servlet-name
>
<
servlet-class
>
servlet.GetInitParameterServlet
servlet-class
>
<
init-param
>
<
param-name
>
username
param-name
>
<
param-value
>
admin
param-value
>
init-param
>
<
init-param
>
<
param-name
>
password
param-name
>
<
param-value
>
123456
param-value
>
init-param
>
servlet
>
<
servlet-mapping
>
<
servlet-name
>
GetInitParameterServlet
servlet-name
>
<
url-pattern
>
/
servlet
/GetInitParameterServlet
url-pattern
>
servlet-mapping
>
<
welcome-file-list
>
<
welcome-file
>
index.jsp
welcome-file
>
welcome-file-list
>
web-app
>
四 Servlet
package servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class GetInitParameterServlet extends HttpServlet {
private String username;//用户名
private String password; //密码
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
/**
* Constructor of the object.
*/
public GetInitParameterServlet() {
super();
}
/**
* Destruction of the servlet.
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet.
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
/**
* The doPost method of the servlet.
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.println("");
out.println("");
out.println(" A Servlet ");
out.println(" ");
out.println("
"+"用户名："+this.getUsername()+"
");
out.println("
"+"密码："+this.getPassword()+"
");
out.println(" ");
out.println("");
out.flush();
out.close();
}
/**
* Initialization of the servlet.
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
this.setUsername(this.getInitParameter("username"));
this.setPassword(this.getInitParameter("password"));
}
}
五 测试
