在Servlet中，取得application有两种方法：
1.通过无参初始化方法，直接取得；
2.通过有参初始化方法，必须使用config对象取得。

实例：
1.无参初始化方法：
Application.java:
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  1. package mgc.servlet.test;   
  2.   
  3. import java.io.*;   
  4. import javax.servlet.*;   
  5. import javax.servlet.http.*;   
  6.   
  7. public class Application extends HttpServlet {   
  8.        
  9.     public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {   
  10.         this.doPost(request,response);   
  11.     }   
  12.        
  13.     public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {   
  14.         //取得Application对象   
  15.         ServletContext application=this.getServletContext();   
  16.         //设置Application属性   
  17.         application.setAttribute("name", "Magci");   
  18.         //跳转到接收页面   
  19.         response.sendRedirect("application.jsp");   
  20.     }   
  21. }  
package mgc.servlet.test;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Application extends HttpServlet {
    
    public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {
        this.doPost(request,response);
    }
    
    public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {
        //取得Application对象
        ServletContext application=this.getServletContext();
        //设置Application属性
        application.setAttribute("name", "Magci");
        //跳转到接收页面
        response.sendRedirect("application.jsp");
    }
}


web.xml:
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  1.   <servlet>  
  2.     <servlet-name>Application</servlet-name>  
  3.     <servlet-class>mgc.servlet.test.Application</servlet-class>  
  4.   </servlet>  
  5.   
  6.   <servlet-mapping>  
  7.     <servlet-name>Application</servlet-name>  
  8.     <url-pattern>/servlet/application</url-pattern>  
  9.   </servlet-mapping>  
  <servlet>
    <servlet-name>Application</servlet-name>
    <servlet-class>mgc.servlet.test.Application</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>Application</servlet-name>
    <url-pattern>/servlet/application</url-pattern>
  </servlet-mapping>


application.jsp:
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  1. <%@page contentType="text/html;charset=GB2312" %>  
  2. <html>  
  3.   <head>  
  4.     <title>application</title>  
  5.   </head>  
  6.      
  7.   <body>  
  8.       <h1><%=getServletContext().getAttribute("name") %></h1>  
  9.   </body>  
  10. </html>  
<%@page contentType="text/html;charset=GB2312" %>
<html>
  <head>
    <title>application</title>
  </head>
  
  <body>
      <h1><%=getServletContext().getAttribute("name") %></h1>
  </body>
</html>



2.有参初始化方法:

Config.java:
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  1. package mgc.servlet.test;   
  2.   
  3. import java.io.*;   
  4. import javax.servlet.*;   
  5. import javax.servlet.http.*;   
  6.   
  7. public class Config extends HttpServlet {   
  8.        
  9.     private ServletConfig conf=null;   
  10.        
  11.     public void init(ServletConfig conf) throws ServletException {   
  12.         //实例化config对象   
  13.         this.conf=conf;   
  14.     }   
  15.        
  16.     public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {   
  17.         this.doPost(request,response);   
  18.     }   
  19.        
  20.     public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {   
  21.         //通过config对象取得Application对象   
  22.         ServletContext application=this.conf.getServletContext();   
  23.         //设置Application属性   
  24.         application.setAttribute("name", "Magci");   
  25.         //跳转到接收页面   
  26.         response.sendRedirect("config.jsp");   
  27.     }   
  28. }  
package mgc.servlet.test;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Config extends HttpServlet {
    
    private ServletConfig conf=null;
    
    public void init(ServletConfig conf) throws ServletException {
        //实例化config对象
        this.conf=conf;
    }
    
    public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {
        this.doPost(request,response);
    }
    
    public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException,ServletException {
        //通过config对象取得Application对象
        ServletContext application=this.conf.getServletContext();
        //设置Application属性
        application.setAttribute("name", "Magci");
        //跳转到接收页面
        response.sendRedirect("config.jsp");
    }
}


web.xml:
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  1.   <servlet>  
  2.     <servlet-name>Config</servlet-name>  
  3.     <servlet-class>mgc.servlet.test.Config</servlet-class>  
  4.   </servlet>  
  <servlet>
    <servlet-name>Config</servlet-name>
    <servlet-class>mgc.servlet.test.Config</servlet-class>
  </servlet>


config.jsp:
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  1. <%@page contentType="text/html;charset=GB2312" %>  
  2. <html>  
  3.   <head>  
  4.     <title>config</title>  
  5.   </head>  
  6.      
  7.   <body>  
  8.       <h1><%=getServletContext().getAttribute("name") %></h1>  
  9.   </body>  
  10. </html>  
<%@page contentType="text/html;charset=GB2312" %>
<html>
  <head>
    <title>config</title>
  </head>
  
  <body>
      <h1><%=getServletContext().getAttribute("name") %></h1>
  </body>
</html>