请问大家这个servlet是不是线程安全的，为什么。

Question

package com.hqit.action;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ThreadServlet extends HttpServlet
{
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException
{
int sum = 1;
try
{
Thread.sleep(2000);
} catch (InterruptedException e)
{
e.printStackTrace();
}
sum = sum + 10;
try
{
Thread.sleep(2000);
} catch (InterruptedException e)
{
e.printStackTrace();
}
sum = sum + 100;
try
{
Thread.sleep(2000);
} catch (InterruptedException e)
{
e.printStackTrace();
}
sum = sum + 1000;
System.out.println(sum);
resp.sendRedirect("show.jsp");
}
}

忘大家说说原因，谢谢。。。

Answer 1

[color=red]protected void doGet(HttpServletRequest req, HttpServletResponse resp)[/color]
throws ServletException, IOException
{
[color=red]int sum = 1; [/color]

sum变量在方法体内部，属于本地线程，当有多线程请求此Servlet时每个线程都会有此变量，所以不存在线程安全问题。