这是一个很大的代码，但请帮助我！我正在做一个关于人脸识别（OpenCV Libraries）的项目，用它来标记项目认可的学生的出勤率！我的项目已准备就绪但只能从我的JFrame中使用的JTextField中检索文本...我正在使用MYSql和Netbeans！
这是代码！
import static cern.jet.math.Bessel.i1;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
import facedetection.*;
import com.googlecode.javacv.*;
import com.googlecode.javacv.cpp.*;
import com.googlecode.javacpp.Loader;
import com.mysql.jdbc.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;
public class FaceRecognizer extends JFrame
{
// GUI components
private FaceRecogPanel facePanel;
private JButton recogBut;
private JTextField nameField; // where the name (and distance info) appears
private JButton done;
private JButton exit;
public FaceRecognizer()
{
super("Face Recognizer");
FaceRecognizer fac;
Container c = getContentPane();
c.setLayout( new BorderLayout() );
// Preload the opencv_objdetect module to work around a known bug.
Loader.load(opencv_objdetect.class);
facePanel = new FaceRecogPanel(this); // the sequence of pictures appear here
c.add( facePanel, BorderLayout.CENTER);
// button for recognizing a highlighted face
done = new JButton("Done");
recogBut = new JButton("Recognize Face");
recogBut.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent e)
{ nameField.setText("");
recogBut.setEnabled(false);
facePanel.setRecog();
}
});
done.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
WelcomeStaffs wc = new WelcomeStaffs();
Connection con = null;
try{
String url = "jdbc:mysql://localhost:3306/facedetection";
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Conncection Success");
con = (Connection) DriverManager.getConnection(url, "root", "2204");
System.out.println("Database Connected");
System.out.println(nameField.getText());
}
catch(Exception ex)
{
System.out.println("Exception = "+ex);
}
String nm = nameField.getText().toUpperCase();
String name ="",course="";
String subject = wc.subject_txt.getText();
String staff = wc.staff_txt.getText();
String day = wc.day_txt.getText();
// String tempd = wc.date_txt.getText().trim();
// String tempt = wc.time_txt.getText().trim();
int roll_no = 0;
// int date = Integer.parseInt(tempd);
// int time = Integer.parseInt(tempt);
String sql = "select roll_no,name,course from students where name= ? ";
try {
PreparedStatement ps = con.prepareStatement(sql);
ps.setString(1,nm);
ResultSet rs = ps.executeQuery(sql);
while(rs.next()) //retrieving values from database and storing it!
{
roll_no = rs.getInt("roll_no");
name = rs.getString("name");
course = rs.getString("course");
System.out.println("Retrieved Data!!!!!!!"+name+course);
}
} catch (SQLException ex) {
Logger.getLogger(FaceRecognizer.class.getName()).log(Level.SEVERE, null, ex);
}
try{
if(roll_no == 0 && name.equals("") && course.equals(""))
{
System.out.println("EMPTY");
}
else
{
sql = "INSERT INTO attendance(roll_no, name, course, subject, staff, day) VALUES(?,?,?,?,?,?)";
PreparedStatement ps1 = con.prepareStatement(sql);
ps1.setInt(1,roll_no);
ps1.setString(2,name);
ps1.setString(3,course);
ps1.setString(4,subject);
ps1.setString(5,staff);
ps1.setString(6,day);
// ps1.setInt(7,date);
// ps1.setInt(8,time);
int i1 = ps1.executeUpdate();
System.out.println("Data Inserted"+i1);
}
}
catch(Exception ec)
{
System.out.println(""+ec);
}
}
});
nameField = new JTextField(20); // for the name of the recognized face
nameField.setEditable(false);
JPanel p = new JPanel();
p.add(recogBut);
p.add( new JLabel("Name: "));
p.add( nameField);
p.add(done);
c.add(p, BorderLayout.SOUTH);
addWindowListener( new WindowAdapter() {
public void windowClosing(WindowEvent e)
{ facePanel.closeDown(); // stop snapping pics
/*Attendance_Chart ac = new Attendance_Chart();
ac.setVisible(true);*/
System.exit(0);
}
});
pack();
setResizable(false);
setVisible(true);
} // end of FaceRecognizer()
public void setRecogName(final String faceName, final String dist)
// update face name and its distance in the nameField; called from panel
{
SwingUtilities.invokeLater(new Runnable() {
public void run()
{ nameField.setText( faceName);
recogBut.setEnabled(true);
}
});
} // end of setRecogName()
// -------------------------------------------------------
public static void main( String args[] )
{ new FaceRecognizer();
}
} // end of FaceRecognizer class
我得到的例外就是这个！按下完成按钮！
Mar 22, 2016 10:04:49 PM FaceRecognizer$2 actionPerformed
SEVERE: null
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?' at line 1
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1053)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4120)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4052)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2664)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2788)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2738)
at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1617)
at FaceRecognizer$2.actionPerformed(FaceRecognizer.java:89)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6525)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6290)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4881)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Window.dispatchEventImpl(Window.java:2750)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
答案 0 :(得分：2)
更改行
ResultSet rs = ps.executeQuery();
到
select roll_no,name,course from students where name= ?（否则你正在执行{{1}}作为静态SQL语句 - 而且Mysql抱怨参数通配符。）