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有异常，求解决

五月 15, 2017 10:38:46 上午 org.apache.catalina.core.StandardWrapperValve invoke

严重: Servlet.service() for servlet [UploadServlet] in context with path [/scxz] threw exception

java.lang.StringIndexOutOfBoundsException: String index out of range: -1

at java.lang.String.substring(Unknown Source)

at com.imooc.servlet.UploadServlet.doPost(UploadServlet.java:46)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)

at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:313)

at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

at java.lang.Thread.run(Unknown Source)

qq_柒分醉_03927370

2017-05-15

源自：Java中的文件上传下载 2-5

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1 回答

qq_莫非
2017-05-15

需要有个地方设置 request.setAttribute("vector" , vector对象）；
然后才能取值，一般是在 session 中 setAttribute 和 getAttribute.
request.getAttribute("vector"); 没有取到 vector 值，
可以改成 if( request.getAttribute("vector") != null) {
vector = (Vector) request.getAttribute("vector");

Vector news = (Vector) vector.get(0);
Vector hot = (Vector) vector.get(1);
Vector placard = (Vector) vector.get(2);

}