一、使用Servlet2.5初始化参数
Servlet2.5是基于 xml 配置的,所以在xml中配置。
Servlet3.0开始支持 注解 配置。
配置分两种情况:在当前 Servlet有效 和在 整个web容器 中有效。
对于整个web容器有效的情况下,无论是2.5还是3.0(及以上)都必须在xml中配置。
配置整个web容器有效时使用 <context-param></context-param>
配置当前Servlet有效时在对应的<servlet></servlet>
使用<init-param></init-param>
配置文件如下:
<?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" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<context-param>
<param-name>globalParamName</param-name>
<param-value>globalParamValue</param-value>
</context-param>
<servlet>
<description></description>
<display-name>TestServlet</display-name>
<servlet-name>TestServlet</servlet-name>
<servlet-class>TestServlet</servlet-class>
<init-param>
<param-name>servletParamName</param-name>
<param-value>servletParamValue</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>TestServlet</servlet-name>
<url-pattern>/TestServlet</url-pattern>
</servlet-mapping>
</web-app>
读取:
public class TestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public TestServlet() {
}
@Override
public void init() throws ServletException {
super.init();
String value = super.getInitParameter("servletParamName");
System.out.println("当前Servlet的servletParam值为"+value);
ServletContext sc = super.getServletContext();
String gValue = sc.getInitParameter("globalParamName");
System.out.println("当前Web容器的gobalValue为"+gValue);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.getWriter().append("Served at: ").append(request.getContextPath());
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
二、使用Servlet3.0初始化参数
initParams= {@WebInitParam(name="servletnameParam30",value="servletValue30")}
name和value分别对应
<param-name>
<param-value>
@WebServlet(value="/TestServlet",loadOnStartup=1,initParams= {@WebInitParam(name="servletnameParam30",value="servletValue30")})
public class TestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public TestServlet() {
// TODO Auto-generated constructor stub
}
@Override
public void init() throws ServletException {
super.init();
String value = super.getInitParameter("servletnameParam30");
System.out.println("当前Servlet的servletParam30值为"+value);
ServletContext sc = super.getServletContext();
String gValue = sc.getInitParameter("globalParamName");
System.out.println("当前Web容器的gobalValue为"+gValue);
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}