相同域名不同端口的两个应用，cookie名字、路径都相同的情况下，后面cookie会覆盖前面cookie吗

首先答案是：

会的。

本地测试流程：

两个相同的应用，代码完全相同；只是部署在两个不同的tomcat；域名都是localhost

应用A：部署在http://localhost:8087/

应用B：部署在http://localhost:8089/

在intelj idea中很简单，建立两个不同的运行配置即可：

步骤1：清空所有cookie

步骤2、在8087发送请求，用chrome开发工具查看

可以看到，生成了cookie。

用我的cookie扩展（名字叫editThisCookie），可以看到该cookie貌似没有区分端口号。

步骤3、在8089上测试一下

结论：可以看到，在请求8089端口的应用时，把8087应用返回的cookie带过去了，所以标题的答案就是：

同域名情况下，cookie同名同路径的话，会被覆盖（路径不同是否会覆盖没测试，有兴趣的同学自己测下）

参考资料
http://blog.csdn.net/wangjun5159/article/details/52399497

附项目文件如下：

web.xml

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
         http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <welcome-file-list>
        <welcome-file>login.jsp</welcome-file>
    </welcome-file-list>

    <!-- 登录过滤器 -->
    <filter>
        <filter-name>sessionFilter</filter-name>
        <filter-class>SessionFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>sessionFilter</filter-name>
        <url-pattern>*</url-pattern>
    </filter-mapping>
</web-app>


import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
 * Email: caokunliang@sgrcr.com
 * Date: 2017/4/6
 * desc:登录页面不进该filter
 */
public class SessionFilter extends OncePerRequestFilter {

    protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
        String uri = httpServletRequest.getRequestURI();
        System.out.println(uri);
        if (uri.contains("login.jsp") || uri.contains("index.jsp") || uri.contains("session")){
            filterChain.doFilter(httpServletRequest,httpServletResponse);
            return;
        }

        HttpSession session = httpServletRequest.getSession(false);
        if (session == null){
            //第一次访问，没带sessionid;下面的操作会默认创建一个session空间，并写cookie：jsessionid
            session = httpServletRequest.getSession(true);
        }else {
            //不是第一次访问的话，已经有session空间了
            System.out.println(session.getAttribute("SESSION"));
        }

        //判断session空间中有没有登录标识
        Boolean isLogin = (Boolean) session.getAttribute("isLogin");
        if (isLogin != null && isLogin.equals(Boolean.TRUE)){
            filterChain.doFilter(httpServletRequest,httpServletResponse);
        }else {
            //未登录
            httpServletResponse.sendRedirect("/login.jsp");
        }
    }

}

servlet:

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 javax.servlet.http.HttpSession;
import java.io.IOException;

// tag::class[]
@WebServlet("/session")
public class SessionServlet extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        String attributeName = req.getParameter("attributeName");
        String attributeValue = req.getParameter("attributeValue");
        HttpSession session = req.getSession(false);
        if (session == null){
            session = req.getSession(true);
        }
        System.out.println("SessionServlet" + session.getAttribute("SESSION"));
        if (attributeName.equals("ckl") && attributeValue.equals("123456")){
            session.setAttribute("isLogin", Boolean.valueOf(true));
            resp.sendRedirect(req.getContextPath() + "/index.jsp");
        }else {
            resp.sendRedirect(req.getContextPath() + "/login.jsp");
        }
    }

    private static final long serialVersionUID = 2878267318695777395L;
}

index.jsp

<!DOCTYPE html>
<html lang="en">
<title>Session Attributes</title>
<style type="text/css">
    body {
        padding: 1em;
    }
</style>

<head></head>
<body>
    <div class="container">
        <h1>Description</h1>
        <p>index.jsp</p>

        <h1>Try it</h1>

        <div>登录成功后主页</div>

        <hr/>

        <table class="table table-striped">
            <thead>
            <tr>
                <th>Attribute Name</th>
                <th>Attribute Value</th>
            </tr>
            </thead>
            <tbody>
            </tbody>
        </table>
    </div>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<title>Session Attributes</title>
<style type="text/css">
    body {
        padding: 1em;
    }
</style>

<head></head>
<body>
    <div class="container">
        <h1>Description</h1>
        <p>login.jsp</p>

        <h1>Try it</h1>

        <form class="form-inline" role="form" action="./session" method="post">
            <label for="attributeName">name</label>
            <input id="attributeName" type="text" name="attributeName"/>
            <label for="attributeValue">password</label>
            <input id="attributeValue" type="text" name="attributeValue"/>
            <input type="submit" value="Set Attribute"/>
        </form>

        <hr/>

        <table class="table table-striped">
            <thead>
            <tr>
                <th>name</th>
                <th>password</th>
            </tr>
            </thead>
            <tbody>
            </tbody>
        </table>
    </div>
</body>
</html>