我正在使用JSF和PrimeFaces开发Web应用程序。我有两个类Inputs和DBConn。我正在执行这样的SQL命令

SQL="SELECT COUNT(*) FROM TXN_HEADER WHERE REQUEST_DATE='01-AUG-2014'"


然后在DBConn类中,我在while循环条件内在ResultSet对象上调用next()方法以打印结果。

这工作正常,并给了我一个输出。

但是,当我尝试使用上述相同场景(在Inputs类中使用while循环)调用ResultSet对象以获取输出时,它给了我以下异常。

java.sql.SQLException: Result set after last row
at oracle.jdbc.driver.GeneratedScrollableResultSet.getString(GeneratedScrollableResultSet.java:879)
at Inputs.commandButton(Inputs.java:41)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.el.parser.AstValue.invoke(AstValue.java:245)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:277)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
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:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:655)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1566)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1523)
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)


然后我假设,尽管我在那个Inputs类中再次使用了next()方法,但是在第一次使用next()方法之后,光标仍然位于最后。

所以我尝试使用.beforeFirst()方法,然后转到第二个while循环,将游标重设回顶部。但这又给了我同样的错误。

然后,我尝试注释我在DBConn类中访问的第一个while循环,因此游标肯定在顶部。但是,这给了我以下错误。

java.sql.SQLException: ResultSet.next was not called
at oracle.jdbc.driver.GeneratedScrollableResultSet.getString(GeneratedScrollableResultSet.java:874)
at Inputs.commandButton(Inputs.java:41)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.el.parser.AstValue.invoke(AstValue.java:245)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:277)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
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:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:655)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1566)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1523)
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)


我该如何解决?这是我第一次开发数据库应用程序。
对于这些sys.prints感到抱歉,我将它们用于调试。

这是与此案例相关的两个类:

输入类别

import java.sql.SQLException;

import javax.annotation.ManagedBean;

@ManagedBean
public class Inputs {
private String date;
private String showRes;

public String getDate() {
    return date;
}

public void setDate(String date) {
    this.date = date;
}

public String getShowRes() {
    return showRes;
}

public void setShowRes(String showRes) {
    this.showRes=showRes;
}

public void commandButton(){

    DBConn nCon=new DBConn();

    Calculations nCalc=new Calculations();
    nCalc.setPieChartSQL(getDate());
    nCon.setSQL(nCalc.getPieChartSQL());

    System.out.println("............");
    System.out.println(nCon.getResultSet());
    System.out.println("............");
    System.out.println(nCon.getResultSet());
    System.out.println("............");

    try {
        System.out.println(nCon.getResultSet().getString(1));
        //nCon.getResultSet().beforeFirst();
        while(nCon.getResultSet().next()){
            System.out.println("++++++++++++");
            System.out.println(nCon.getResultSet().getString(1));
            System.out.println("++++++++++++");
            setShowRes(nCon.getResultSet().getString(1));
        }
    } catch (SQLException e) {
        e.printStackTrace();
    }
    System.out.println("777777777777777777777");
}

}


DBConn类

import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import oracle.jdbc.OracleConnection;
import oracle.jdbc.pool.OracleDataSource;

public class DBConn {

private String sql;
private ResultSet rs;

public ResultSet getResultSet(){

    try {
        OracleDataSource dataSource=new OracleDataSource();
        dataSource.setURL("jdbc:oracle:thin:@172.16.20.45:1521:ABS");
        dataSource.setUser("ABS_INP");
        dataSource.setPassword("b2a6b224");

        OracleConnection con = (OracleConnection)dataSource.getConnection();
        con.setAutoCommit(false);

        Statement stmnt = con.createStatement();
        rs = stmnt.executeQuery(sql);
        System.out.println("-----------");
        System.out.println(rs);
        System.out.println("-----------");
        System.out.println(rs);
        System.out.println("-----------");

        while(rs.next()){
            System.out.println("*************");
            System.out.println(rs.getString(1));
            System.out.println("*************");
        }


    } catch (SQLException e) {
        e.printStackTrace();
    }

    return rs;
}

public void setSQL(String sql) {
    this.sql=sql;
}

}

最佳答案

我认为问题出在获取结果集的方式上。每次调用nCon.getResultSet()时,它都会返回一个新的结果集。这意味着您调用一个结果集对象的next方法,并在另一个结果集对象中调用getString(1)。这是我的解决方案。

public void commandButton(){

     DBConn nCon=new DBConn();

     Calculations nCalc=new Calculations();
     nCalc.setPieChartSQL(getDate());
     nCon.setSQL(nCalc.getPieChartSQL());

     System.out.println("............");
     System.out.println(nCon.getResultSet());
     System.out.println("............");
     System.out.println(nCon.getResultSet());
     System.out.println("............");

     try {
         ResultSet rst=nCon.getResultSet();
         rst.beforeFirst();
         while(rst.next()){
             System.out.println("++++++++++++");
             String str=rst.getString(1);
             System.out.println("++++++++++++");
             setShowRes(str);
        }
    } catch (SQLException e) {
        e.printStackTrace();
    }
    System.out.println("777777777777777777777");
}

08-27 15:19