java登录系统，连接数据库，展示全部列表
三月 21, 2019 11:06:35 下午 org.apache.catalina.core.ApplicationDispatcher invoke严重: Servlet.service() for servlet [jsp] threw exceptionorg.apache.jasper.JasperException: /view/flats/list.jsp (line: [17], column: [61]) Unterminated [<c:url] tag at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:42) at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:291) at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:97) at org.apache.jasper.compiler.Parser.parseOptionalBody(Parser.java:1009) at org.apache.jasper.compiler.Parser.parseCustomTag(Parser.java:1294) at org.apache.jasper.compiler.Parser.parseElements(Parser.java:1473) at org.apache.jasper.compiler.Parser.parse(Parser.java:145) at org.apache.jasper.compiler.ParserController.doParse(ParserController.java:244) at org.apache.jasper.compiler.ParserController.parse(ParserController.java:105) at org.apache.jasper.compiler.Compiler.generatejava(Compiler.java:201) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:372) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:349) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:333) at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:600) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:368) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:385) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:329) at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:710) at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459) at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:384) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312) at com.zhiyou100.servlet.HouseListServlet.doGet(HouseListServlet.java:25) at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:475) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:498) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:796) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1368) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Unknown Source)
你要获取数据库的连接，然后写创建 statementString sql = "select * from users where account = '"+accountTextField.getText()+"' and password='"+passwordTextField.getText()+"'"；然后执行statement.excuseQuery(sql),饭回来的是个ResultSet然后boolean exist = false;//是否存在的标识while（rs.next）{//循环结果集（如果有下一个，那么说明用户存在）exist = true;//设置为存在这个用户break;//跳出循环}最后面判断exist是不是true ，如果是true就说明存在，如果为false就说明不存在‘伪代码，无法直接运行，但是过程是这样的。稍加修改即可