ResultSet关闭Part2后，不允许操作

Question

有人能解释一下为什么我在以下代码中得到" ResultSet关闭后不允许操作"错误;

我的数据库由两个表、控制台和硬件组成。控制台表有3列(id，名称和成本)，而硬件有4列(id, CPU，内存和HDD)。

当我到达:

while(rs1.next())  
{
    a1 = rs1.getString(1);    
    b1 = rs1.getString(2);
    c1 = rs1.getString(3);    
    model1.addRow(new Object[]{a1,b1,c1});
}

错误弹出，我不知道为什么。

代码:

try
{    
    add = true;
    conn1 = DriverManager.getConnection("jdbc:mysql://localhost/test1?user=me&password=12345");
    conn3 = DriverManager.getConnection("jdbc:mysql://localhost/test1?user=me&password=12345");
    stmt1 = conn1.createStatement();
    stmt3 = conn3.createStatement();
    rs1 = stmt1.executeQuery("SELECT * FROM consoles");
    rs3 = stmt1.executeQuery("SELECT * FROM hardware");
    conn_pr1 = DriverManager.getConnection("jdbc:mysql://localhost/test1?user=me&password=12345");
    conn_pr3 = DriverManager.getConnection("jdbc:mysql://localhost/test1?user=me&password=12345");
    String sql1 = "INSERT INTO consoles (name,cost) VALUES (?,?)";
    String sql3 = "INSERT INTO hardware (CPU,Memory,HDD) VALUES (?,?,?)";
    ps1 =conn_pr1.prepareStatement(sql1);
    ps3 = conn_pr3.prepareStatement(sql3);
    str1 = JOptionPane.showInputDialog(null,"Console name : ");
    if(!(str1 == null))
    {
        ps1.setString(1,str1);
        str2 = JOptionPane.showInputDialog(null,"Cost : ");
    }
    if(!(str2 == null))
    {
        int2 = Integer.parseInt(str2); 
        ps1.setLong(2,int2);
        str3 = JOptionPane.showInputDialog(null,"CPU : ");
    }
    if(!(str3 == null))
    {
        str4 = JOptionPane.showInputDialog(null,"Memory : ");
        ps3.setString(1,str3);
    }
    if(!(str4 == null))
    {
        str5 = JOptionPane.showInputDialog(null,"HDD : ");
        ps3.setString(2,str4);
    }
    if(!(str5 == null))
    {
        int3 = Integer.parseInt(str5); 
        ps3.setLong(3,int3);
    }
    if((!(str1 == null)) && (!(str2 == null)) && (!(str3 == null)) &&
       (!(str4 == null)) && (!(str5 == null)))
    {  //start if
        ps1.executeUpdate();
        ps3.executeUpdate();
        model1 = new DefaultTableModel();
        model3 = new DefaultTableModel();
        table1 = new JTable(model1);
        table3 = new JTable(model3);
        model1.addColumn("id");
        model1.addColumn("name");
        model1.addColumn("cost");
        model3.addColumn("id");
        model3.addColumn("CPU");
        model3.addColumn("Memory");
        model3.addColumn("HDD");
        while(rs1.next())  
        {
            a1 = rs1.getString(1);    
            b1 = rs1.getString(2);
            c1 = rs1.getString(3);    
            model1.addRow(new Object[]{a1,b1,c1});
        }
        while(rs3.next())  
        {
            a3 = rs3.getString(1);
            if (a3 != a)
                a3 = a;
            b3 = rs3.getString(2);
            c3 = rs3.getString(3);
            d3 = rs3.getString(4);  
            model3.addRow(new Object[]{a3,b3,c3,d3});
        }
        model1.fireTableDataChanged();
        table1.setCellSelectionEnabled(true);
        table1.setColumnSelectionAllowed(true);
        table1.setFillsViewportHeight(true);
        table1.setSurrendersFocusOnKeystroke(true);
        table1.setBounds(10,45,461,360);
        frame.getContentPane().remove(tablecons);
        frame.getContentPane().add(table1);
        model1.fireTableDataChanged();
        model3.fireTableDataChanged();
        table3.setCellSelectionEnabled(true);
        table3.setColumnSelectionAllowed(true);
        table3.setFillsViewportHeight(true);
        table3.setSurrendersFocusOnKeystroke(true);
        table3.setBounds(488,45,430,360);
        frame.getContentPane().remove(tablehard);
        frame.getContentPane().add(table3);
        model3.fireTableDataChanged();
        conn1.close();
        conn3.close();
        conn_pr3.close();
        conn_pr1.close();
        stmt1.close();
        stmt3.close();
        ps1.close();
        rs1.close();
        rs3.close();
        ps3.close();
    }  // end if
    else
        JOptionPane.showMessageDialog(null,"Cancelled!!!");
} catch ( SQLException case1){case1.printStackTrace();
} catch ( Exception case2){case2.printStackTrace();}}}); 

Answer 1

错误似乎出现在假数字列表stmt1/3中。

先关闭ResultSets，再关闭Statements，再关闭Connections。

可以分四部分遍历四个表。更好的可读性，并且您可能受益于使用资源进行尝试(从Java 7开始):

try (ResultSet rs = stmt.executeQuery()) {
    while (rs.next()) {
        ...
    }
} // Automatically closes rs