关于cas使用saml协议验证问题

Question

错误代码如下：
HTTP Status 500 – Internal Server Error
Type Exception Report

Message IO error sending HTTP request to /samlValidate

Description The server encountered an unexpected condition that prevented it from fulfilling the request.

Exception

java.lang.RuntimeException: IO error sending HTTP request to /samlValidate
org.jasig.cas.client.validation.Saml11TicketValidator.retrieveResponseFromServer(Saml11TicketValidator.java:212)
org.jasig.cas.client.validation.AbstractUrlBasedTicketValidator.validate(AbstractUrlBasedTicketValidator.java:193)
org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:204)
org.jasig.cas.client.session.SingleSignOutFilter.doFilter(SingleSignOutFilter.java:97)
Root Cause

java.io.IOException: Server returned HTTP response code: 500 for URL: http://localhost:9000/samlValidate?TARGET=http%3A%2F%2Flocalhost%3A8080%2F
sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1894)
sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)
org.jasig.cas.client.validation.Saml11TicketValidator.retrieveResponseFromServer(Saml11TicketValidator.java:210)
org.jasig.cas.client.validation.AbstractUrlBasedTicketValidator.validate(AbstractUrlBasedTicketValidator.java:193)
org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:204)
org.jasig.cas.client.session.SingleSignOutFilter.doFilter(SingleSignOutFilter.java:97)
Note The full stack trace of the root cause is available in the server logs.

cas server版本为4.0.7，关于saml协议的配置按照其官网的配置，不明白错误发生在哪里，求解答

Answer 1

https://blog.csdn.net/qq_28600087/article/details/81325344