線程安全問題:

Servlet的service方法,每次被請求是,調用.

這個調用很特殊,是在新的子線程中調用的,當service方法執行完畢,子線程死亡了.

可以簡單的理解為:service方法每次執行都是一個新的線程.

package cn.xdl.demo1;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;/*** @author victor* @site https://victorfengming.github.io/* @company XDL* @project xdl_javaweb* @package cn.xdl.demo1* @created 2019-11-15 13:30* @function "線程鎖測試"*/
@WebServlet("/s1")
public class Servlet1 extends HttpServlet {// 剩余票數private int count = 10;protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 創建線程鎖對象,用于作為標記Object ob = new Object();// 這個地方寫什么對象都行,別瞎傳遞就行!synchronized (ob) {if (count > 0) {System.out.println("恭喜你,有票");System.out.println("正在出票");count--;System.out.println("出票完成,剩余票數:" + count);} else {System.out.println("很遺憾,沒票了!");}}}
}