mysql - Jsp页面与数据库的通信
问题描述
我正在学习编程,并且正在尝试在页面中创建用户已完成的预订列表。特别是,我想恢复用户使用他的电子邮件所做的所有预订,我创建了一个 JSP 页面:
<body>
<%=session.getAttribute("Nome") +" "+ session.getAttribute("Cognome") + " "+ session.getAttribute("Email") %>
<br>
Prenotazioni Effettuate:
<%
try{
String email=(String)session.getAttribute("Email");
// out.print("Hello "+n);
Class.forName("com.mysql.cj.jdbc.Driver");
// out.println("driver loaded");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/Hotel","root" ,"123456789");
// out.println("Connect");
Statement stmt = con.createStatement();
// out.println("conncetion successfull");
String query="";
String emailp = "";
String arrivdate = "";
query="select * from reservation where email = "+email;
ResultSet r = stmt.executeQuery(query);
while (r.next())
{
emailp = r.getString("email");
arrivdate = r.getString("arrivalDate");
%>
Email: <%= emailp %>
Arrival date: <%= arrivdate %>
<% }}
catch(Exception e)
{
}
out.close();
%>
我不明白为什么什么都没有打印。是查询问题还是代码问题出错了?你知道怎么帮我吗?
GRAVE: Servlet.service() for servlet [jsp] in context with path
> [/Apartment] threw exception [java.lang.IllegalStateException:
> Exception occurred when flushing data] with root cause
> java.io.IOException: Stream closed at
> org.apache.jasper.runtime.JspWriterImpl.ensureOpen(JspWriterImpl.java:187)
> at
> org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:105)
> at
> org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:180)
> at
> org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:120)
> at
> org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:75)
> at
> org.apache.jsp.Prenotazionieffettuate_jsp._jspService(Prenotazionieffettuate_jsp.java:198)
> at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) at
> org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:444)
> at
> org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:386)
> at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:330)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) 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:494)
> at
> org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
> at
> org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
> at
> org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651)
> at
> org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
> at
> org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
> at
> org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:412)
> at
> org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
> at
> org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:754)
> at
> org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1385)
> at
> org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
> at
> org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
> at java.lang.Thread.run(Thread.java:748)
解决方案
我用这种方式解决了:
String query="SELECT * FROM reservation WHERE email= '" + session.getAttribute("Email") + "'";
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