【发布时间】：2013-02-15 10:02:23
【问题描述】：
这是一个 JDBC 项目。来自 WAMP 服务器上的 mySql 数据库的数据显示在 jtable 中。现在我想要在我的 Spinnerbutton 上用户输入的 ID 并删除具有该 ID 的行。我做了一个 SQL 查询，一切正常，但是执行查询时 myjtable 上的数据不会刷新。我单击我的 JNazad 按钮（我的后退按钮），然后重新进入该窗口，以便我的 Jtable 显示刷新的数据。我想我没有在 NapraviTablicu 方法中正确实现 FireTableModel，但不知道我做错了什么：
public class GUIBDelete extends JFrame{
private SpinnerModel SM;
private JSpinner Spinner;
private JLabel LUnos;
private JButton BNazad, BIzvrsi;
private String ID, SqlQuery;
private Vector NaziviKolona = new Vector();
private Vector Podaci = new Vector();
private JTable Tablica=new JTable();
private JScrollPane ScrollPane;
private DefaultTableModel model;
private JTable NapraviTablicu(){
try {
String SqlQuery = "SELECT * FROM `nfc_baza`";
Podaci.clear();
NaziviKolona.clear();
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con = DriverManager.getConnection("jdbc:mysql://"
+ "localhost:3306/nfc", "root", "");
Statement Stat = con.createStatement();
ResultSet Rez = Stat.executeQuery(SqlQuery);
ResultSetMetaData md = Rez.getMetaData();
int columns = md.getColumnCount();
for (int i = 1; i <= columns; i++) {
NaziviKolona.addElement(md.getColumnName(i));
}
while (Rez.next()) {
Vector red = new Vector(columns);
for (int i = 1; i <= columns; i++) {
red.addElement(Rez.getObject(i));
}
Podaci.addElement(red);
}
Rez.close();
Stat.close();
con.close();
} catch (Exception e) {
System.out.println(e);
}
model = new DefaultTableModel(Podaci, NaziviKolona);
model.fireTableDataChanged();
JTable table = new JTable(model);
return table;
}
ActionListener a1 = new ActionListener() {
public void actionPerformed(ActionEvent a) {
dispose();
new GUIIzbornik();
}
};
ActionListener a2 = new ActionListener() {
public void actionPerformed(ActionEvent a) {
ID=null;
SqlQuery = "DELETE FROM `nfc`.`nfc_baza` WHERE `nfc_baza`.`ID` = ";
IzvrsiQuery();
model.fireTableDataChanged();
}
private void IzvrsiQuery() {
Object sp = Spinner.getValue();
ID = sp.toString();
SqlQuery=SqlQuery+ID;
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con2 = DriverManager.getConnection(
"jdbc:mysql://" + "localhost:3306/nfc", "root", "");
Statement Stat = con2.createStatement();
int Rez = Stat.executeUpdate(SqlQuery);
Stat.close();
con2.close();
JOptionPane.showMessageDialog(null, "Uspješno izvrseno!",
"Poruka!", JOptionPane.INFORMATION_MESSAGE);
} catch (Exception e) {
System.out.println(e);
}
}
};
GUIBDelete(){
setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
Tablica=NapraviTablicu();
ScrollPane = new JScrollPane(Tablica);
c.fill = GridBagConstraints.BOTH;
c.insets = new Insets(2, 2, 2, 2);
c.weightx = 0.1;
c.weighty = 0.1;
c.gridwidth = 4;
c.gridheight = 2;
c.gridx = 0;
c.gridy = 0;
add(ScrollPane, c);
LUnos= new JLabel("<html><br>Unesite ID elementa</br> kojeg želite obrisati:<html>");
c.gridx = 0;
c.gridy = 2;
c.gridwidth = 1;
c.gridheight = 1;
add(LUnos, c);
SM = new SpinnerNumberModel(1, 1, 1000, 1);
Spinner = new JSpinner(SM);
c.gridx = 2;
c.gridy = 2;
c.gridwidth = 1;
add(Spinner, c);
BNazad = new JButton("Nazad");
c.gridx = 0;
c.gridy = 3;
c.gridwidth = 1;
BNazad.addActionListener(a1);
add(BNazad, c);
BIzvrsi = new JButton("Izvrši");
c.gridx = 3;
c.gridy = 3;
BIzvrsi.addActionListener(a2);
add(BIzvrsi, c);
setSize(400, 500);
setTitle("Brisanje podataka");
setVisible(true);
setLocationRelativeTo(null);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
GUIBDelete i = new GUIBDelete();
}
});
}
}
首先，非常感谢您的回答！
当我使用PreparedStatement 时，我得到了这个异常：
java.lang.ClassCastException: com.mysql.jdbc.StatementImpl cannot be
cast to java.sql.PreparedStatement
..所以我必须使用经典的Statement
我也试过不每次都创建JTable，我只是在我的NapraviTablicu方法中创建模型，然后在我的构造函数中使用该模型，只需将它添加到表Tablica，但现在表是没有显示任何数据。我不知道我是否在我的代码中正确地实现了你的提示......
public class GUIBDelete extends JFrame{
private SpinnerModel SM;
private JSpinner Spinner;
private JLabel LUnos;
private JButton BNazad, BIzvrsi;
private String ID, SqlQuery;
private Vector NaziviKolona = new Vector();
private Vector Podaci = new Vector();
private JTable Tablica=new JTable();
private JScrollPane ScrollPane;
private DefaultTableModel model;
private void NapraviTablicu(){
try {
String SqlQuery = "SELECT * FROM `nfc_baza`";
Podaci.clear();
NaziviKolona.clear();
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://"
+ "localhost:3306/nfc", "root", "");
Statement Stat = con.createStatement();
ResultSet Rez = Stat.executeQuery(SqlQuery);
ResultSetMetaData md = Rez.getMetaData();
int columns = md.getColumnCount();
for (int i = 1; i <= columns; i++) {
NaziviKolona.addElement(md.getColumnName(i));
}
while (Rez.next()) {
Vector red = new Vector(columns);
for (int i = 1; i <= columns; i++) {
red.addElement(Rez.getObject(i));
}
Podaci.addElement(red);
}
Rez.close();
Stat.close();
con.close();
} catch (Exception e) {
System.out.println(e);
}
model = new DefaultTableModel(Podaci, NaziviKolona);
//model.fireTableDataChanged();
}
ActionListener a1 = new ActionListener() {
public void actionPerformed(ActionEvent a) {
dispose();
new GUIIzbornik();
}
};
ActionListener a2 = new ActionListener() {
public void actionPerformed(ActionEvent a) {
ID=null;
SqlQuery = "DELETE FROM `nfc`.`nfc_baza` WHERE `nfc_baza`.`ID` = ";
IzvrsiQuery();
//model.fireTableDataChanged();
}
private void IzvrsiQuery() {
Object sp = Spinner.getValue();
ID = sp.toString();
SqlQuery=SqlQuery+ID;
try {
Class.forName("com.mysql.jdbc.Driver");
Connection con2 = DriverManager.getConnection(
"jdbc:mysql://" + "localhost:3306/nfc", "root", "");
PreparedStatement Stat = (PreparedStatement) con2.createStatement();
int Rez = Stat.executeUpdate(SqlQuery);
Stat.close();
con2.close();
JOptionPane.showMessageDialog(null, "Uspješno izvrseno!",
"Poruka!", JOptionPane.INFORMATION_MESSAGE);
} catch (Exception e) {
System.out.println(e);
}
}
};
GUIBDelete(){
setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
Tablica=new JTable(model);
ScrollPane = new JScrollPane(Tablica);
c.fill = GridBagConstraints.BOTH;
c.insets = new Insets(2, 2, 2, 2);
c.weightx = 0.1;
c.weighty = 0.1;
c.gridwidth = 4;
c.gridheight = 2;
c.gridx = 0;
c.gridy = 0;
add(ScrollPane, c);
LUnos= new JLabel("<html><br>Unesite ID elementa</br> kojeg želite obrisati:<html>");
c.gridx = 0;
c.gridy = 2;
c.gridwidth = 1;
c.gridheight = 1;
add(LUnos, c);
SM = new SpinnerNumberModel(1, 1, 1000, 1);
Spinner = new JSpinner(SM);
c.gridx = 2;
c.gridy = 2;
c.gridwidth = 1;
add(Spinner, c);
BNazad = new JButton("Nazad");
c.gridx = 0;
c.gridy = 3;
c.gridwidth = 1;
BNazad.addActionListener(a1);
add(BNazad, c);
BIzvrsi = new JButton("Izvrši");
c.gridx = 3;
c.gridy = 3;
BIzvrsi.addActionListener(a2);
add(BIzvrsi, c);
setSize(400, 500);
setTitle("Brisanje podataka");
setVisible(true);
setLocationRelativeTo(null);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
GUIBDelete i = new GUIBDelete();
}
});
}
}
【问题讨论】：
-
请学习java命名约定并遵守它们。
标签： java mysql swing jdbc jtable