Java SQL结果集异常

我正在使用JSF和PrimeFaces开发一个Web应用程序。我有两个类&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循环条件内调用ResultSet对象上的next（）方法来打印结果

这工作很好，给了我一个输出

但是，当我尝试调用结果集对象以使用上面相同的场景（在输入类中使用该while循环）获得输出时，会出现以下异常

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)

然后我假设在第一次使用next（）方法之后，光标仍然在最后，尽管我在输入类中再次使用了next（）方法

因此，在转到第二个while循环之前，我尝试使用.beforeFirst（）方法将光标重置回顶部。但它又给了我同样的错误

然后我尝试在DBConn类中对我访问的第一个while循环进行注释，因此光标肯定位于顶部。但是它给了我以下的错误

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)

我如何解决这个问题？这是我第一次开发数据库应用程序。 很抱歉这些sys.prints，我用它们来调试

以下是与本案例相关的两类：

输入类

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");
}

}

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("<user>");
        dataSource.setPassword("<pass>");

        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;
}

}

DBConn类

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");
}

}

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("<user>");
        dataSource.setPassword("<pass>");

        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;
}

}

导入java.sql.ResultSet；
导入java.sql.SQLException；
导入java.sql.Statement；
导入oracle.jdbc.OracleConnection；
导入oracle.jdbc.pool.OracleDataSource；
公共类DBConn{
私有字符串sql；
私人结果集；
公共结果集getResultSet（）{
试一试{
OracleDataSource dataSource=新的OracleDataSource（）；
setURL（“jdbc:oracle:thin:@172.16.20.45:1521:ABS”）；
dataSource.setUser（“”）；
dataSource.setPassword（“”）；
OracleConnection con=（OracleConnection）dataSource.getConnection（）；
con.setAutoCommit（假）；
语句stmnt=con.createStatement（）；
rs=stmnt.executeQuery（sql）；
System.out.println（“--------------”；
系统输出打印项次（rs）；
System.out.println（“--------------”；
系统输出打印项次（rs）；
System.out.println（“--------------”；
while（rs.next（））{
System.out.println（“****************”）；
System.out.println（rs.getString（1））；
System.out.println（“****************”）；
}
}捕获（SQLE异常）{
e、 printStackTrace（）；
}
返回rs；
}
公共void setSQL（字符串sql）{
this.sql=sql；
}
}

您的getResultMethod（）将光标放在结果集的末尾。发生此异常是因为您没有调用next（）并尝试在下面的方法中访问ResultSet

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)); //here rs.next() should be called first
        //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");
}

解决方案

try{

    while(rs.next()){
         System.out.println(nCon.getResultSet().getString(1));
    }
......
}

---

我认为问题在于你得到结果集的方式。每次调用nCon.getResultSet（）时，它都会返回一个新的resultset。这意味着您调用一个resultset对象的下一个方法，并在另一个对象中调用getString（1）。这是我的解决办法

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");
}

---

只是一个观察，

REQUEST_DATE='1-AUG-2014'

这是一种处理日期的错误方式。由于隐式数据转换，您将很快遇到性能问题。如果请求日期是日期数据类型，则使用

到日期（2014年8月1日）

@LalitKumarB我这样做是为了测试目的。我只是想看看它是否有效。顺便说一句，谢谢你的提醒。这就是我做的对吗？我的getResultSet（）返回rs对象。但是在getResultSet（）方法中，您迭代所有结果集，然后返回结果集，光标位于末尾。因此，当您调用nCon.getResultSet（）.getString（）时，光标位于末尾，当您调用时，它不会给出任何输出。是的，但是我省略了while循环，因此光标位于顶部的原始位置。然后它给了我上面提到的第二个错误。