通過ServletContext擷取應用級配置參數

通過ServletContext擷取應用級配置參數：

web.xml檔案中：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
  
  <context-param>
  	<param-name>encoding</param-name>
  	<param-value>UTF-8</param-value>
  </context-param>
  <context-param>
  	<param-name>XXX</param-name>
  	<param-value>yyy</param-value>
  </context-param>
  
  <servlet>
    <servlet-name>ServletContextDemo1</servlet-name>
    <servlet-class>com.neu.ServletContextDemo1</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>ServletContextDemo1</servlet-name>
    <url-pattern>/servlet/ServletContextDemo1</url-pattern>
  </servlet-mapping>

</web-app>
           

ServletContextDemo.java檔案：

package com.neu;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletContextDemo1 extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		//擷取應用結級配置參數
		ServletContext sc = getServletContext();
		//得到一個參數
//		String value = sc.getInitParameter("encoding");
//		response.getWriter().write(value);
		//得到所有的參數
		Enumeration<String> context = sc.getInitParameterNames();
		while(context.hasMoreElements()){
			String paramName = context.nextElement();
			response.getWriter().write(paramName+"="+sc.getInitParameter(paramName));
			response.getWriter().write("   ");
		}
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
	
	}

}
           

運作及結果：

運作：http://localhost:8080/ServletDemo/servlet/ServletContextDemo1

結果：XXX=yyyencoding=UTF-8