我试图将此信息类型保存或删除到数据库中。当我运行这段代码时，我只是不断收到错误，而且我不能为我的生活弄清楚我做错了什么。框架打开，当您输入与您想要更改的代码相对应的ID时，它仍然没有变化。
import java.io.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.sql.*;
import java.util.*;
class Changeadd {
JFrame f;
JPanel p1, p2, p3;
JTabbedPane tp;
ImageIcon btnimg1, btnimg2;
JLabel l1, l2, l3, l4, l5, l6, l7, l8, l9, l10;
JTextField tf1, tf2, tf3, tf4, tf5, tf6, tf7, tf8, tf9, tf10;
JScrollPane sp1;
JButton savebtn, resetbtn, editbtn1, editbtn2, deletebtn;
Changeadd() {
f = new JFrame("Form");
p1 = new JPanel(new GridLayout(5, 2));
p2 = new JPanel(new GridLayout(5, 2));
p3 = new JPanel(new GridLayout(2, 2));
tp = new JTabbedPane();
l1 = new JLabel("MenuID");
l2 = new JLabel("Name");
l3 = new JLabel("Info");
l4 = new JLabel("Price");
l5 = new JLabel("Enter Menu ID to delete");
l7 = new JLabel("MenuID");
l8 = new JLabel("Name");
l9 = new JLabel("Info");
l10 = new JLabel("Price");
tf1 = new JTextField(12);
tf2 = new JTextField(12);
tf3 = new JTextField(12);
tf4 = new JTextField(12);
tf5 = new JTextField(12);
tf6 = new JTextField(12);
tf7 = new JTextField(12);
tf8 = new JTextField(12);
tf9 = new JTextField(12);
tf10 = new JTextField(12);
savebtn = new JButton(" Add ");
resetbtn = new JButton(" Reset");
editbtn1 = new JButton(" Edit ");
editbtn2 = new JButton(" Save");
deletebtn = new JButton("Delete");
p1.add(l1);
p1.add(tf1);
p1.add(l2);
p1.add(tf2);
p1.add(l3);
p1.add(tf3);
p1.add(l4);
p1.add(tf4);
p1.add(savebtn);
p1.add(resetbtn);
p2.add(l7);
p2.add(tf7);
p2.add(l8);
p2.add(tf8);
p2.add(l9);
p2.add(tf9);
p2.add(l10);
p2.add(tf10);
p2.add(editbtn1);
p2.add(editbtn2);
p3.add(l5);
p3.add(tf5);
p3.add(deletebtn);
resetbtn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
tf1.setText("");
tf2.setText("");
tf3.setText("");
tf4.setText("");
}
});
savebtn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
String value1 = tf1.getText();
String value2 = tf2.getText();
String value3 = tf3.getText();
String value4 = tf4.getText();
Connection con = null;
String url = "jdbc:mysql://localhost:3306/mydb";
String db = "myDB";
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String pass = "root";
System.out.println(value1 + value2 + value3 + value4);
try {
Class.forName(driver);
con = DriverManager.getConnection(url + db, user, pass);
PreparedStatement st = con
.prepareStatement("INSERT INTO menu(menu.menuID,menu.name,menu.info,menu.price) values(?,?,?,?)");
st.setString(1, value1);
st.setString(2, value2);
st.setString(3, value3);
st.setString(4, value4);
st.executeUpdate();
JOptionPane.showMessageDialog(p1,
"Data is successfully inserted into database.");
con.close();
} catch (Exception e) {
JOptionPane.showMessageDialog(p1,
"Error in submitting data!");
}
}
});
deletebtn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
String value1 = tf5.getText();
Connection con = null;
String url = "jdbc:mysql://localhost:3306/mydb";
String db = "myDB";
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String pass = "root";
try {
Class.forName(driver);
con = DriverManager.getConnection(url + db, user, pass);
PreparedStatement st = con
.prepareStatement("DELETE FROM menu WHERE menu.menuID = ?");
st.setString(1, value1);
st.executeUpdate();
JOptionPane.showMessageDialog(p3,
"Record is deleted successfully.");
con.close();
} catch (Exception exp3) {
JOptionPane.showMessageDialog(p3,
"Error in deleting record.");
}
}
});
editbtn1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
String value = tf7.getText();
Connection con = null;
String url = "jdbc:mysql://localhost:3306/mydb";
String db = "myDB";
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String pass = "root";
try {
Class.forName(driver);
con = DriverManager.getConnection(url + db, user, pass);
PreparedStatement st = con
.prepareStatement("SELECT FROM menu WHERE menu.menuID=?");
st.setString(1, value);
ResultSet res = st.executeQuery();
res.next();
tf7.setText(Integer.toString(res.getInt(1)));
tf8.setText(res.getString(2));
tf9.setText(res.getString(3));
tf10.setText(Integer.toString(res.getInt(4)));
con.close();
} catch (Exception e) {
JOptionPane.showMessageDialog(p2, "Can not edit data");
}
}
});
editbtn2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
Connection con = null;
String url = "jdbc:mysql://localhost:3306/mydb";
String db = "myDB";
String driver = "com.mysql.jdbc.Driver";
String user = "root";
String pass = "root";
try {
int x = JOptionPane.showConfirmDialog(p2,
"Confirm edit? All data will be replaced");
if (x == 0) {
try {
String value1 = tf7.getText();
String value2 = tf8.getText();
String value3 = tf9.getText();
String value4 = tf10.getText();
Class.forName(driver);
con = DriverManager.getConnection(url + db, user,
pass);
;
Statement st = con.createStatement();
st.executeUpdate("UPDATE menu set menu.name'"
+ value2 + "', menu.info'" + value3
+ "', menu.price'" + value4
+ "' where menu.menuID='" + value1 + "'");
JOptionPane.showMessageDialog(p2,
"Updated successfully");
con.close();
} catch (Exception ex) {
JOptionPane.showMessageDialog(p2,
"Error in updating edit fields");
}
}
} catch (Exception ex) {
JOptionPane.showMessageDialog(p2, "Error");
}
}
});
}
void dis() {
f.getContentPane().add(tp);
tp.addTab("Add Record", p1);
tp.addTab("Edit Record", p2);
tp.addTab("Delete Record", p3);
f.setSize(350, 180);
f.setVisible(true);
f.setResizable(true);
}
public static void main(String z[]) {
Changeadd pro = new Changeadd();
pro.dis();
}
}
答案 0 :(得分：2)
我认为你的网址错了
String url = "jdbc:mysql://localhost:3306/mydb";
已经包含附加的mydb
con = DriverManager.getConnection(url + db, user, pass);
将通过
"jdbc:mysql://localhost:3306/mydbmyDB"
也
您必须将mysql-connector-java-5.1.18-bin.jar文件放在文件夹中：
YOUR_WEBAPPS_FOLDER/YOUR_WEBAPP/WEB-INF/lib/
这样当你的servlet由web容器编译时，它将在类路径中可用。