在Servlet中，取得application

来源：互联网发布：imovie mac 教程编辑：程序博客网时间：2024/06/06 08:50

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:

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");
}
}

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:

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>

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