在Servlet的配置文件中，可以使用一个或多个<init-param>标签为servlet配置一些初始化参数。当servlet配置了初始化参数后，web容器在创建servlet实例对象时，会自动将这些初始化参数封装到ServletConfig对象中，并在调用servlet的init方法时，ServletConfig对象传递给servlet。进而，程序员通过ServletConfig对象就可以得到当前servlet的初始化参数信息。
示例代码如下：

复制代码 代码如下:
package com.yyz.servletconfig;
import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ServletConfigDemo1 extends HttpServlet {
ServletConfig config;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获取指定的初始化参数
String value = config.getInitParameter("xxx");
response.getOutputStream().write(value.getBytes());
//获取所有的初始化参数
Enumeration e = cofig.getInitParameterNames();
while(e.hasMoreElements()){
String name = (String) e.nextElement();
value = config.getInitParameter(name);
response.getOutputStream().write((name+"="+value+"<br/>").getBytes());
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}
@Override
public void init(ServletConfig config) throws ServletException {
this.config = config;
}
}

相应的web.xml如下：

复制代码 代码如下:
<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://.yyz.servletconfig.ServletConfigDemo2</servlet-class>
<init-param>
<param-name>name</param-name>
<param-value>yyz</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>ServletConfigDemo2</servlet-name>
<url-pattern>/servlet/ServletConfigDemo2</url-pattern>
</servlet-mapping>
</web-app>