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>
login.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>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>