java.lang.StackOverflowError错误：

20-Mar-2020 00:07:33.707 严重 [http-nio-8080-exec-5] org.apache.catalina.core.ApplicationDispatcher.invoke Servlet[addUserServlet]的Servlet.service()抛出异常
	java.lang.StackOverflowError
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)
		at org.apache.catalina.core.ApplicationHttpRequest.setAttribute(ApplicationHttpRequest.java:304)

错误的原因，进行了递归调用，导致堆栈耗尽。

错误的web配置：
前台跳转时需要一个充满数据的页面，链接的地址:${pageContext.request.contextPath}/jsp/useradd.jsp，我直接在web配置直接写了/jsp/useradd.jsp，而转发的地址为/jsp/useradd.jsp，导致递归调用,可以修改前台的跳转页面解决问题。

 req.getRequestDispatcher("/jsp/useradd.jsp").forward(req,resp);

 <servlet>
        <servlet-name>addUserServlet</servlet-name>
        <servlet-class>com.smbms.servlet.addUserServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>addUserServlet</servlet-name>
        <url-pattern>/jsp/useradd.jsp</url-pattern>
    </servlet-mapping>