java.net.SocketException: Unexpected end of file from server

今天访问远程服务器的数据的时候返回Unexpected end of file from server异常，异常信息为：

java.net.SocketException: Unexpected end of file from server
    at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:851)
    at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:678)
    at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:848)
    at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:678)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1569)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)

在stackoverflow找到答案，如下：
“Unexpected end of file” implies that the remote server accepted and closed the connection without sending a response. It’s possible that the remote system is too busy to handle the request, or that there’s a network bug that randomly drops connections.

With the information available it’s impossible to say what’s going wrong. If you have access to the servers in question you can use packet sniffing tools to find what exactly is sent and received, and look at logs to of the server process to see if there are any error messages.
意思就是说“意外的文件结束”意味着远程服务器接受并关闭连接，而不发送响应。远程系统可能太忙，无法处理请求，或者有网络错误随机丢弃连接。
有了可用的信息，不可能说出了什么问题。如果您有权访问有问题的服务器，您可以使用数据包嗅探工具来查找发送和接收的内容，并查看服务器进程的日志，以查看是否有任何错误消息。