net.ucanaccess.jdbc.UcanaccessSQLException无效的游标状态

Question

我收到以下错误。 有人可以请求下面的协助吗？ 我在数据库中有2行。 问题是结果集光标没有移动我猜

控制台日志：

connection established...
rs execute...
rs is not null
rs is not next...
inside while....
inside do post catch 
**net.ucanaccess.jdbc.UcanaccessSQLException: invalid cursor state: identifier cursor not positioned on row in UPDATE, DELETE, SET, or GET statement: ; ResultSet is empty**
    at net.ucanaccess.jdbc.UcanaccessResultSet.getInt(UcanaccessResultSet.java:452)
    at com.test.myservlettest.doPost(myservlettest.java:93)
    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:504)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    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:421)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1074)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
    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)
Caused by: java.sql.SQLException: invalid cursor state: identifier cursor not positioned on row in UPDATE, DELETE, SET, or GET statement: ; ResultSet is empty**
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCUtil.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCResultSet.getCurrent(Unknown Source)
    at org.hsqldb.jdbc.JDBCResultSet$JDBCResultSetBasic.getColumnInType(Unknown Source)
    at org.hsqldb.jdbc.JDBCResultSet.getInt(Unknown Source)
    at net.ucanaccess.jdbc.UcanaccessResultSet.getInt(UcanaccessResultSet.java:450)
    ... 23 more
Caused by: org.hsqldb.HsqlException: invalid cursor state: identifier cursor not positioned on row in UPDATE, DELETE, SET, or GET statement: ; ResultSet is empty
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.error.Error.error(Unknown Source)
    ... 28 more
we are in service method of servlet

Myservlettest（servlet类）：

public void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException{
        System.out.println("Inside Servlet");

        Chintandatabase cd = new Chintandatabase();
        Connection con = null;
        String userid =null;
        String password = null;

        String un =req.getParameter("username") ;
        String pw =req.getParameter("userpass") ;
        String msg =null;

        System.out.println("username from UI: "+un);
        System.out.println("password from UI: "+pw);
        try {
            con = cd.getConnection();
            Statement s = con.createStatement();
            s.executeQuery("select SOE_ID,PASSWORD from User");
            ResultSet rs = s.getResultSet();
            System.out.println("rs execute...");
            if(rs==null){System.out.println("rs is null");}
            else {System.out.println("rs is not null");}

            if(rs.next()){System.out.println("rs is next");}
            else {System.out.println("rs is not next...");}

          while (rs.next() || rs!=null) {
                System.out.println("inside while....");
                System.out.println(rs.getInt(1));
                userid  = rs.getString("SOE_ID");
                password =  rs.getString("PASSWORD");
            }
            //s.close();
            //con.close();
        } catch (SQLException e) {
            System.out.println("inside do post catch ");
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        System.out.println("we are in service method of servlet");


        if ((un.equalsIgnoreCase(userid) && pw.equals(password))){

            msg="Hello " + un + "! your login is successfull...";
        }
        else{
            msg="Invalid Credentials...";

        }


        res.setContentType("text/html");
        PrintWriter out = res.getWriter();
        out.println("<font size='6' color=red>" + msg + "</font>");
    }

}

Chintandatabase类:(连接类）

package com.database;

import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.test.beans.*;


public class Chintandatabase {

    public Connection getConnection() throws SQLException {
        Connection con = null;
        try {
            Class.forName("net.ucanaccess.jdbc.UcanaccessDriver");
            con = DriverManager.getConnection("jdbc:ucanaccess://C:/ChintanDB/ChintanDB.accdb;memory=false");
            System.out.println("connection established...");

        } catch (Exception e) {
            System.out.println("inside get connection catch ");
            System.out.println("Exception : " + e);
            e.printStackTrace();
        }
        return con;

    }


}

Answer 1

问题是您已经将光标移动到以下行中：

 if(rs.next()){System.out.println("rs is next");}
 else {System.out.println("rs is not next...");}

只需将它们评论出来，您的问题就会得到解决

注意：在下面你只需要这个：

while (rs.next()) {
  ....
}

更新 Ohhh，还有我注意到的其他事情。 在ResultSet中获取数据的方法如下：

Statement s = con.createStatement();
ResultSet rs = s.executeQuery("select SOE_ID,PASSWORD from User");

请在此处查看完整示例