我的系统出了点问题。问题是：
如何根据用户名会话获取表数据。意味着，当用户登录时，他们可以在他们的个人资料表格中查看购买项目的历史记录（使用jTable）。提前谢谢。
这是我的代码：
public class Profile扩展了javax.swing.JFrame {
String username;
DefaultTableModel model;
public Profile() {
initComponents();
this.setLocationRelativeTo(null);
}
public Profile(String User) {
username = User;
initComponents();
this.setLocationRelativeTo(null);
}
public void retrieve(){
DefaultTableModel dth = new Cust_History().getData();
tblHistory.setModel(dth);
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jTabbedPane1 = new javax.swing.JTabbedPane();
jPanel1 = new javax.swing.JPanel();
jPanel2 = new javax.swing.JPanel();
jScrollPane1 = new javax.swing.JScrollPane();
tblHistory = new javax.swing.JTable();
jButton1 = new javax.swing.JButton();
jtfUser = new javax.swing.JLabel();
btnHistory = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Profile Information");
addWindowListener(new java.awt.event.WindowAdapter() {
public void windowOpened(java.awt.event.WindowEvent evt) {
formWindowOpened(evt);
}
});
jPanel1.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 430, Short.MAX_VALUE)
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 242, Short.MAX_VALUE)
);
jTabbedPane1.addTab("My Profile", jPanel1);
jPanel2.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
tblHistory.setModel(new javax.swing.table.DefaultTableModel(
new Object [][] {
{null, null, null, null},
{null, null, null, null},
{null, null, null, null},
{null, null, null, null}
},
new String [] {
"Title 1", "Title 2", "Title 3", "Title 4"
}
));
tblHistory.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
tblHistoryMouseClicked(evt);
}
});
jScrollPane1.setViewportView(tblHistory);
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 410, Short.MAX_VALUE)
.addContainerGap())
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGap(55, 55, 55)
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 121, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(66, Short.MAX_VALUE))
);
jTabbedPane1.addTab("Cart History", jPanel2);
jButton1.setText("Back");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jtfUser.setText("label username");
btnHistory.setText("Retrieve");
btnHistory.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnHistoryActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(41, 41, 41)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jTabbedPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 437, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addComponent(jButton1)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, `enter code here`javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(btnHistory))))
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jtfUser, javax.swing.GroupLayout.PREFERRED_SIZE, 129, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addContainerGap(52, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap(37, Short.MAX_VALUE)
.addComponent(jtfUser, javax.swing.GroupLayout.PREFERRED_SIZE, 15, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(12, 12, 12)
.addComponent(jTabbedPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 272, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jButton1)`enter code here`
.addComponent(btnHistory))
.addContainerGap())
);
pack();
}// </editor-fold>
private void tblHistoryMouseClicked(java.awt.event.MouseEvent evt) {
// TODO add your handling code here:
}
private void formWindowOpened(java.awt.event.WindowEvent evt) {
jtfUser.setText("Hello "+ username + " have a nice day!");
}
enter code here
private void btnHistoryActionPerformed(java.awt.event.ActionEvent evt) {
retrieve();
}
公共类Cust_History {
String User;
String conString = "jdbc:mysql://localhost:3306/softwaredesign";
String username = "root";
String password = "";
//CREATE TABLE
public DefaultTableModel getData(){
DefaultTableModel dth = new DefaultTableModel();
dth.addColumn("Artist");
dth.addColumn("SongTitle");
dth.addColumn("Price");
dth.addColumn("Qty");
try {
Connection con = DriverManager.getConnection(conString, username, password);
Profile pf = new Profile(User);
//SQL STATEMENT
String SQL = "SELECT Artist,SongTitle,Price,Qty FROM history WHERE Username LIKE '"+User+"'";
//PST
PreparedStatement s = con.prepareStatement(SQL);
ResultSet rs = s.executeQuery(SQL);
//LOOP
while (rs.next()){
//get value
String Artist = rs.getString(1);
String SongTitle = rs.getString(2);
String Price = rs.getString(3);
String Qty = rs.getString(4);
dth.addRow(new String[]{Artist, SongTitle, Price, Qty});
}
return dth;
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
}
为什么我不能像这样从个人资料表单中检索用户会话？
Profile pf = new Profile(User);
String SQL = "SELECT Artist,SongTitle,Price,Qty FROM history WHERE Username LIKE '"+pf.username+"'";
PreparedStatement s = con.prepareStatement(SQL);
ResultSet rs = s.executeQuery(SQL);
