驗證Servlet單例多線程

建立測試Servlet

package handler;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestSingletonHandler
 */
@WebServlet("/TestSingletonHandler")
public class TestSingletonHandler extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	
	private int requestCount=0;
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestSingletonHandler() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		requestCount++;
		System.out.println("requestCount:"+requestCount);
		System.out.println("hashCode:"+this.hashCode());
		PrintWriter pw=response.getWriter();
		pw.write("ok");
		pw.close();
		pw.flush();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	}

}

瀏覽器發出兩次請求

控制檯輸出以下:

requestCount:1
hashCode:21867369
requestCount:2
hashCode:21867369

requestCount能夠累積請求次數，兩次hashCode輸出一致，說明該Servlet爲單例