我对Java很新，我对sql也不是很熟悉。我正在开发一个程序，它接受地板订单并将它们存储在SQL数据库中。名称和地址将存储正常，但其余信息不会。信息检索也不起作用。我也不确定我做错了什么。我出于显而易见的原因从Connection对象中删除了信息，但我可以向您保证，我的程序中有正确的信息..任何帮助都将不胜感激。
import java.awt.event.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.text.*;
import javax.swing.*;
public class FlooringOrders extends JFrame implements ActionListener {
private JLabel lblFloorType, lblRoomSize, lblLength, lblWidth, lblName,
lblAddress, lblOrderInfo, lblTotal;
private JRadioButton rbtnWood, rbtnCarpet;
private JButton btnCalculate, btnSubmit, btnOrders;
private ButtonGroup grpType;
private JTabbedPane tab;
private JTextField txtLength, txtWidth, txtArea, txtName, txtAddress;
private JTextArea txtOrderInfo, txtTotal, txtCustomer;
private JPanel p1, p2, p3, p4;
private double Length, Width, Area, Total;
private String sLength, sWidth, sArea, sTotal, fType, insertQuery;
private PreparedStatement myQuery;
private ResultSet rs;
private DecimalFormat df;
public FlooringOrders() {
super("Flooring Orders");
df = new DecimalFormat("#,###,###.00");
tab = new JTabbedPane();
p1 = new JPanel();
p2 = new JPanel();
p3 = new JPanel();
p4 = new JPanel();
lblFloorType = new JLabel("Choose Floor Type: ");
lblRoomSize = new JLabel("Enter Room Size: ");
lblLength = new JLabel("Length (ft): ");
lblWidth = new JLabel("Width (ft): ");
lblName = new JLabel("Enter Name: ");
lblAddress = new JLabel("Enter Address: ");
lblOrderInfo = new JLabel("Order Info: ");
lblTotal = new JLabel("Total: ");
rbtnWood = new JRadioButton("Wood - $20/sq. ft.");
rbtnCarpet = new JRadioButton("Carpet - $10/sq. ft.");
grpType = new ButtonGroup();
btnCalculate = new JButton("Calculate Area");
btnSubmit = new JButton("Submit");
btnOrders = new JButton("Customer Orders");
txtLength = new JTextField(10);
txtWidth = new JTextField(10);
txtArea = new JTextField(10);
txtName = new JTextField(10);
txtAddress = new JTextField(10);
txtOrderInfo = new JTextArea(15, 15);
txtTotal = new JTextArea(15, 15);
txtCustomer = new JTextArea(15, 15);
grpType.add(rbtnCarpet);
grpType.add(rbtnWood);
getContentPane().add(tab);
p1.add(lblFloorType);
p1.add(rbtnWood);
p1.add(rbtnCarpet);
p1.add(lblRoomSize);
p1.add(lblLength);
p1.add(txtLength);
p1.add(lblWidth);
p1.add(txtWidth);
p1.add(btnCalculate);
p1.add(txtArea);
tab.add("Flooring", p1);
p2.add(lblName);
p2.add(txtName);
p2.add(lblAddress);
p2.add(txtAddress);
p2.add(btnSubmit);
tab.add("Customer Info", p2);
p3.add(lblOrderInfo);
p3.add(txtOrderInfo);
p3.add(lblTotal);
p3.add(txtTotal);
tab.add("Total", p3);
p4.add(btnOrders);
p4.add(txtCustomer);
tab.add("Order List", p4);
btnCalculate.addActionListener(this);
btnSubmit.addActionListener(this);
btnOrders.addActionListener(this);
} //end constructor
public void actionPerformed(ActionEvent a) {
sLength = txtLength.getText();
sWidth = txtWidth.getText();
fType = "";
Length = Double.parseDouble(sLength);
Width = Double.parseDouble(sWidth);
Area = 0;
Total = 0;
if(a.getSource().equals(btnCalculate)) {
Area = Length * Width;
if(rbtnWood.isSelected()) {
Total = Area * 20;
fType.equals("Wood");
} else if(rbtnCarpet.isSelected()) {
Total = Area * 10;
fType.equals("Carpet");
} //end if/else
sArea = String.valueOf(df.format(Area));
sTotal = String.valueOf(df.format(Total));
txtArea.setText(sArea);
txtTotal.setText(sTotal);
System.out.println("Calculate Area pressed");
} //end if
if(a.getSource().equals(btnSubmit)) {
newOrder();
System.out.println("Submit pressed");
} //end if
if(a.getSource().equals(btnOrders)) {
orderList();
System.out.println("Customer Orders pressed");
} //end if
} //end actionPerformed
public void newOrder() {
insertQuery = "INSERT into CustomerOrders(CustomerName, CustomerAddress,
FloorType, RoomSize, Total) values(?, ?, ?, ?, ?)";
try {
Connection conn = DriverManager.getConnection();
myQuery = conn.prepareStatement(insertQuery);
myQuery.setString(1, txtName.getText());
myQuery.setString(2, txtAddress.getText());
myQuery.setString(3, fType);
myQuery.setDouble(4, Area);
myQuery.setDouble(5, Total);
myQuery.execute();
JOptionPane.showMessageDialog(null, "Thank you for your order!");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} //end try/catch
} //end newOrder
public void orderList() {
try {
rs = myQuery.executeQuery("SELECT * from CustomerOrders");
ResultSetMetaData md = rs.getMetaData();
int columns = md.getColumnCount();
while (rs.next()) {
for(int i = 1; i < columns; i++) {
txtCustomer.setText(rs.getString(i) + " ");
System.out.print(rs.getString(i) + " ");
System.out.println();
} //end for
}// end while
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} //end try/catch
} //end orderList
} //end class
答案 0 :(得分：1)
在 public void orderList（）{中，您应该在执行之前创建一个语句。
myQuery = conn.createStatement( );
rs = myQuery.executeQuery("SELECT * from CustomerOrders");
让我知道它是否对你有所帮助。
我已经重构了一些代码。希望它能帮助你进步。
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.text.DecimalFormat;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JTabbedPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
public class FlooringOrders extends JFrame implements ActionListener {
private JLabel lblFloorType, lblRoomSize, lblLength, lblWidth, lblName,
lblAddress, lblOrderInfo, lblTotal;
private JRadioButton rbtnWood, rbtnCarpet;
private JButton btnCalculate, btnSubmit, btnOrders;
private ButtonGroup grpType;
private JTabbedPane tab;
private JTextField txtLength, txtWidth, txtArea, txtName, txtAddress;
private JTextArea txtOrderInfo, txtTotal, txtCustomer;
private JPanel p1, p2, p3, p4;
private double Length, Width, Area, Total;
private String sLength, sWidth, sArea, sTotal, fType, insertQuery;
private PreparedStatement myQuery;
private ResultSet rs;
private DecimalFormat df;
public FlooringOrders() {
super("Flooring Orders");
df = new DecimalFormat("#,###,###.00");
tab = new JTabbedPane();
p1 = new JPanel();
p2 = new JPanel();
p3 = new JPanel();
p4 = new JPanel();
lblFloorType = new JLabel("Choose Floor Type: ");
lblRoomSize = new JLabel("Enter Room Size: ");
lblLength = new JLabel("Length (ft): ");
lblWidth = new JLabel("Width (ft): ");
lblName = new JLabel("Enter Name: ");
lblAddress = new JLabel("Enter Address: ");
lblOrderInfo = new JLabel("Order Info: ");
lblTotal = new JLabel("Total: ");
rbtnWood = new JRadioButton("Wood - $20/sq. ft.");
rbtnCarpet = new JRadioButton("Carpet - $10/sq. ft.");
grpType = new ButtonGroup();
btnCalculate = new JButton("Calculate Area");
btnSubmit = new JButton("Submit");
btnOrders = new JButton("Customer Orders");
txtLength = new JTextField(10);
txtWidth = new JTextField(10);
txtArea = new JTextField(10);
txtName = new JTextField(10);
txtAddress = new JTextField(10);
txtOrderInfo = new JTextArea(15, 15);
txtTotal = new JTextArea(15, 15);
txtCustomer = new JTextArea(15, 15);
grpType.add(rbtnCarpet);
grpType.add(rbtnWood);
getContentPane().add(tab);
p1.add(lblFloorType);
p1.add(rbtnWood);
p1.add(rbtnCarpet);
p1.add(lblRoomSize);
p1.add(lblLength);
p1.add(txtLength);
p1.add(lblWidth);
p1.add(txtWidth);
p1.add(btnCalculate);
p1.add(txtArea);
tab.add("Flooring", p1);
p2.add(lblName);
p2.add(txtName);
p2.add(lblAddress);
p2.add(txtAddress);
p2.add(btnSubmit);
tab.add("Customer Info", p2);
p3.add(lblOrderInfo);
p3.add(txtOrderInfo);
p3.add(lblTotal);
p3.add(txtTotal);
tab.add("Total", p3);
p4.add(btnOrders);
p4.add(txtCustomer);
tab.add("Order List", p4);
btnCalculate.addActionListener(this);
btnSubmit.addActionListener(this);
btnOrders.addActionListener(this);
} // end constructor
private Connection getConnection() throws SQLException {
return DriverManager.getConnection("");
}
public void actionPerformed(ActionEvent a) {
if (a.getSource().equals(btnCalculate)) {
sLength = txtLength.getText();
sWidth = txtWidth.getText();
fType = "";
Length = sLength.isEmpty() ? 0.0 : Double.parseDouble(sLength);
Width = sWidth.isEmpty() ? 0.0 : Double.parseDouble(sWidth);
Area = 0;
Total = 0;
Area = Length * Width;
if (rbtnWood.isSelected()) {
Total = Area * 20;
fType.equals("Wood");
} else if (rbtnCarpet.isSelected()) {
Total = Area * 10;
fType.equals("Carpet");
} // end if/else
sArea = String.valueOf(df.format(Area));
sTotal = String.valueOf(df.format(Total));
txtArea.setText(sArea);
txtTotal.setText(sTotal);
System.out.println("Calculate Area pressed");
} // end if
if (a.getSource().equals(btnSubmit)) {
newOrder();
System.out.println("Submit pressed");
} // end if
if (a.getSource().equals(btnOrders)) {
orderList();
System.out.println("Customer Orders pressed");
} // end if
} // end actionPerformed
public void newOrder() {
insertQuery = "INSERT into CustomerOrders(CustomerName, CustomerAddress,FloorType, RoomSize, Total) values(?, ?, ?, ?, ?)";
PreparedStatement ps = null;
try {
Connection conn = DriverManager.getConnection("");
ps = conn.prepareStatement(insertQuery);
ps.setString(1, txtName.getText());
ps.setString(2, txtAddress.getText());
ps.setString(3, fType);
ps.setDouble(4, Area);
ps.setDouble(5, Total);
ps.execute();
JOptionPane.showMessageDialog(null, "Thank you for your order!");
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (ps != null) {
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
} // end newOrder
public void orderList() {
Statement stmt = null;
try {
stmt = getConnection().createStatement();
rs = stmt.executeQuery("SELECT * from CustomerOrders");
ResultSetMetaData md = rs.getMetaData();
int columns = md.getColumnCount();
while (rs.next()) {
for (int i = 1; i < columns; i++) {
txtCustomer.setText(rs.getString(i) + " ");
System.out.print(rs.getString(i) + " ");
System.out.println();
} // end for
}// end while
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (stmt != null) {
try {
stmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
} // end orderList
} // end class