Java 错误：连接关闭后不允许任何操作_Java_Mysql_Jsp_Jdbc

Java 错误：连接关闭后不允许任何操作

java mysql jsp jdbc

Java 错误：连接关闭后不允许任何操作,java,mysql,jsp,jdbc,Java,Mysql,Jsp,Jdbc,我知道将SQL代码或任何与数据库相关的代码放在JSP中是个坏主意。但是我想试试这种方法，请帮忙。在retrieve.jsp中的以下代码中，我必须输入empid、datefrom和dateto，然后它将在dispaly.jsp页面上以表格的形式显示结果，显示员工的所有详细信息、总工作时间和加班时间 retrieve.jsp %@page contentType="text/html" pageEncoding="UTF-8"%> <%@page import="com.eis.bea

我知道将SQL代码或任何与数据库相关的代码放在JSP中是个坏主意。但是我想试试这种方法，请帮忙。在retrieve.jsp中的以下代码中，我必须输入empid、datefrom和dateto，然后它将在dispaly.jsp页面上以表格的形式显示结果，显示员工的所有详细信息、总工作时间和加班时间

retrieve.jsp

%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@page import="com.eis.bean.Provider"%>
<%@page import="com.eis.bean.ConnectionProvider"%>
<%@page import="java.sql.*" %>

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>JSP Page</title>
</head>
<body>
    <h4>Enter Employee ID and the dates</h4>
    <form name="retrieve form" action="display1.jsp" method="POST">
        <table border="0">

            <tbody>
                <tr>
                    <td>Employee ID</td>
                    <td><input type="text" name="Emp_id" required="required"/></td>
                </tr>
                <tr>
                    <td>From Date:</td>
                    <td><input type="date" name="From" value="yyyy/MM/dd" required="required"/></td>
                </tr>
                <tr>
                    <td>To Date:</td>
                    <td><input type="date" name="To" value="yyyy/MM/dd" required="required"/></td>
                </tr>
            </tbody>
        </table>
        <input type="reset" value="Clear" name="clear" />
        <input type="submit" value="Submit" name="submit" />
    </form>
</body>
</html>

以下是错误：

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:400)
at com.mysql.jdbc.Util.getInstance(Util.java:383)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:958)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:937)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:872)
at com.mysql.jdbc.ConnectionImpl.throwConnectionClosedException(ConnectionImpl.java:1236)
at com.mysql.jdbc.ConnectionImpl.checkClosed(ConnectionImpl.java:1231)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4140)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4109)
at org.apache.jsp.display_jsp._jspService(display_jsp.java:113)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2503)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2492)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

您的连接是使用

ConnectionProvider.getConn（）获得的
该函数必须确保返回的连接仍处于打开状态，否则必须返回新连接
我猜现在它总是返回只创建一次的连接的同一个实例
编辑：将您的ConnectionProvider更改为：
public class ConnectionProvider {  
  public static Connection getConn(){  
    try {  
      Class.forName("com.mysql.jdbc.Driver");
      return DriverManager.getConnection("jdbc:mysql://localhost:3306/timsheetdb","root","lion");  
    } catch(Exception e){}  

    return null;  
  }  
}

这不是一个好代码，我个人不会这样使用它，但它应该可以解决您的问题。现在，每次都会创建到数据库的新连接。
听起来似乎有道理。除此之外，您应该始终确保在使用后关闭结果集
和语句。@f1sh感谢您的快速回复。。。你能告诉我怎么做吗？@hendrik我做了，但忘了写密码。。。现在我确实编辑了代码，请检查。
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:400)
at com.mysql.jdbc.Util.getInstance(Util.java:383)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:958)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:937)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:926)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:872)
at com.mysql.jdbc.ConnectionImpl.throwConnectionClosedException(ConnectionImpl.java:1236)
at com.mysql.jdbc.ConnectionImpl.checkClosed(ConnectionImpl.java:1231)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4140)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4109)
at org.apache.jsp.display_jsp._jspService(display_jsp.java:113)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2503)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2492)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

public class ConnectionProvider {  
  public static Connection getConn(){  
    try {  
      Class.forName("com.mysql.jdbc.Driver");
      return DriverManager.getConnection("jdbc:mysql://localhost:3306/timsheetdb","root","lion");  
    } catch(Exception e){}  

    return null;  
  }  
}