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追求学问，学习知识

疑问

  1. 为啥有的FTP搭建完成后，有的电信网络无法连接？
  2. commons-codec加密解密失败，base64错误，只能换成低版本codec1.10？
1
IllegalArgumentException: Last encoded character (before the paddings if any) is a valid base 64 alphabet but not a possible value
  1. 消息 javax.servlet.ServletException: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

描述 服务器遇到一个意外的情况，阻止它完成请求。

Exception

org.apache.jasper.JasperException: javax.servlet.ServletException: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:598)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:499)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    com.hbbc.global.UserRightChecker.doFilter(UserRightChecker.java:69)
Root Cause

javax.servlet.ServletException: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    org.apache.jasper.runtime.PageContextImpl.doHandlePageException(PageContextImpl.java:909)
    org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:838)
    org.apache.jsp.global.login_jsp._jspService(login_jsp.java:471)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    com.hbbc.global.UserRightChecker.doFilter(UserRightChecker.java:69)

  2. 地址栏HTTP，ajax请求https，会跨域？？必须ajax使用自动协议//