有谁知道空指向异常主要是什么原因造成的吗（jsp）？

Question

比如这个：

登陆失败

登陆失败:null

十二月 11, 2015 9:18:16 下午 org.apache.catalina.core.StandardWrapperValve invoke

严重: Servlet.service() for servlet jsp threw exception

java.lang.NullPointerException

at org.apache.jsp.register_005fcheck_jsp._jspService(register_005fcheck_jsp.java:113)

at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)

at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)

at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)

at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)

at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)

at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)

at java.lang.Thread.run(Thread.java:745)

Answer 1

你去取一个空对象的属性就会造成空指针错误呀。