Servlet 所处的是什么环境呢？其实是tomcat。
ServletContext application = this.getServletContext();
application 这个篮子比Session大。webapp 下所有的 servlet 访问的都是这同一个篮子。
示例程序 : TestServletContext.java
import javax.servlet.http.*;
import javax.servlet.*;
import java.io.*;
import java.util.Date;
public class TestServletContext extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=gb2312");
PrintWriter out = response.getWriter();
ServletContext application = this.getServletContext();
Integer accessCount = (Integer) application.getAttribute("accessCount");
if (accessCount == null) {
accessCount = new Integer(0);
} else {
accessCount = new Integer(accessCount.intValue() + 1);
}
// Use setAttribute instead of putValue in version 2.2.
application.setAttribute("accessCount", accessCount);
out.println("<html><head><title>Session追踪</title></head>"
+ "<BODY BGCOLOR="#FDF5E6">
" + "<H1 ALIGN="CENTER">"
+ accessCount + "
" + "</TABLE>
" + "</BODY></HTML>"
+ "</H1>
");
}
}