Servlet实现页面访问量统计实例
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2024-03-19 22:40:28
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我们知道一个Web应用程序只有一个ServletContext对象，而且该对象可以被Web应用程序中所有Servlet所访问。因此使用ServletContext对象来保存一些需要在Web应用程序*享的信息再合适不过了。
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet(name = "CounterServlet",
urlPatterns = "/counterServlet")
public class CounterServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext context = this.getServletContext();
Integer count = null;
//为避免线程安全问题，使用synchronized关键字进行同步
synchronized (context){
count = (Integer) context.getAttribute("counter");
if(count == null){
count = new Integer(1);
}else {
count = new Integer(count.intValue() + 1);
}
context.setAttribute("counter",count);
}
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.print("<html><head>");
out.print("<title>页面访问统计</title>");
out.print("</html><body>");
out.println("<h2>页面已被访问了</h2>" + "<b>"+count+"</b>" +"次");
out.println("</body></html>");
}
}
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