我想从java gui到数据库获取startTime和endTime的值。
ComputerSeats课程
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
public class SeatMonitoringDesign extends JFrame
{
public JLabel LStation, LID, LFirstName, LLastName, LTimeIn;
public JLabel[] Astation,Aid, Afirstname, Alastname, Atime;
public JRadioButton[] seat = new JRadioButton[10];
private String str = "";
private int station, occupiedSeatCounter;
private JLabel studNum, seatNum;
private ButtonGroup seatGroup = new ButtonGroup();
private boolean[] seatOccupied = new boolean[10];
private SimpleDateFormat dateFormatter = new SimpleDateFormat("hh:mm:ss");
private JTextField studNumTF;
private JButton logIn, logOut;
private ButtonHandler logInB;
private ButtonHandler logOutB;
private ButtonHandler radioB;
public SeatMonitoringDesign()
{
studNum = new JLabel("Enter Your Student Number: ");
studNum.setLocation(30,20);
studNum.setSize(200,100);
studNumTF = new JTextField(7);
studNumTF.setLocation(50,80);
studNumTF.setSize(120,30);
seatNum = new JLabel("Station Numbers: ");
seatNum.setLocation(60,90);
seatNum.setSize(600,400);
setTitle("Computer Seat Registration");
Container pane = getContentPane();
pane.setLayout(null);
pane.add(studNum);
pane.add(studNumTF);
setSize(1130,500);
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(EXIT_ON_CLOSE);
int x=50,y=150;
for(int i=0 ; i<10 ; i++)
{
switch(i)
{
case 0: str = "1"; break;
case 1: str = "2"; break;
case 2: str = "3"; break;
case 3: str = "4"; break;
case 4: str = "5"; break;
case 5: str = "6"; break;
case 6: str = "7"; break;
case 7: str = "8"; break;
case 8: str = "9"; break;
case 9: str = "10"; break;
}
seat[i] = new JRadioButton(str);
seat[i].setSize(60,40);
seat[i].setLocation(x,y);
radioB = new ButtonHandler();
seat[i].addItemListener(radioB);
seat[i].setBackground(Color.green);
seatGroup.add(seat[i]);
pane.add(seat[i]);
x=110;
if((i+1)%2==0)
{
x=50;
y=y+30;
}
}
for(int i=0 ; i<10 ; i++)
{
seatOccupied[i] = false;
}
logIn = new JButton("Log In");
logIn.setSize(100,30);
logIn.setLocation(15,350);
logIn.setBackground(Color.orange);
logInB = new ButtonHandler();
logIn.addActionListener(logInB);
pane.add(logIn);
logOut = new JButton("Log Out");
logOut.setSize(100,30);
logOut.setLocation(125,350);
logOut.setBackground(Color.orange);
logOutB = new ButtonHandler();
logOut.addActionListener(logOutB);
pane.add(logOut);
LStation = new JLabel("Station #", SwingConstants.CENTER);
LStation.setSize(100,20);
LStation.setLocation(280,60);
pane.add(LStation);
LID = new JLabel("Student Number");
LID.setSize(100,20);
LID.setLocation(450,60);
pane.add(LID);
LFirstName = new JLabel("First Name");
LFirstName.setSize(100,20);
LFirstName.setLocation(630,60);
pane.add(LFirstName);
LLastName = new JLabel("Last Name");
LLastName.setSize(100,20);
LLastName.setLocation(810,60);
pane.add(LLastName);
LTimeIn = new JLabel("Time In");
LTimeIn.setSize(100,20);
LTimeIn.setLocation(990,60);
pane.add(LTimeIn);
Astation = new JLabel[10];
Aid = new JLabel[10];
Afirstname = new JLabel[10];
Alastname = new JLabel[10];
Atime = new JLabel[10];
y=85;
for(int i=0 ; i<10 ; i++)
{
switch(i)
{
case 0: str = "1"; break;
case 1: str = "2"; break;
case 2: str = "3"; break;
case 3: str = "4"; break;
case 4: str = "5"; break;
case 5: str = "6"; break;
case 6: str = "7"; break;
case 7: str = "8"; break;
case 8: str = "9"; break;
case 9: str = "10"; break;
}
Astation[i] = new JLabel(str, SwingConstants.CENTER);
Astation[i].setSize(100,30);
Astation[i].setLocation(280,y);
pane.add(Astation[i]);
Aid[i] = new JLabel("Vacant Station");
Aid[i].setSize(100,30);
Aid[i].setLocation(450,y);
pane.add(Aid[i]);
Afirstname[i] = new JLabel("---------");
Afirstname[i].setSize(100,30);
Afirstname[i].setLocation(630,y);
pane.add(Afirstname[i]);
Alastname[i] = new JLabel("---------");
Alastname[i].setSize(100,30);
Alastname[i].setLocation(810,y);
pane.add(Alastname[i]);
Atime[i] = new JLabel("00:00:00--");
Atime[i].setSize(100,30);
Atime[i].setLocation(990,y);
pane.add(Atime[i]);
y = y+30;
}
setVisible(true);
}
public class ButtonHandler implements ActionListener, ItemListener
{
public void itemStateChanged(ItemEvent e)
{
for(int i=0 ; i<10 ; i++)
{
if(e.getSource() == seat[i])
station = (i+1);
}
}
public void actionPerformed(ActionEvent e)
{
LogicalChecker lc = new LogicalChecker();
cobadatabase cb = new cobadatabase(studNumTF.getText());
String output;
Date now1 = new Date();
Date now2 = new Date();
//long secs = (now2.getTime() - now1.getTime()) / 1000;
//long diffSeconds = diff / 1000 % 60;
//long diffMinutes = diff / (60 * 1000) % 60;
// long diffHours = diff / (60 * 60 * 1000) % 60;
//long startTime = System.currentTimeMillis();
//long finishTime = System.currentTimeMillis();
//long elapsedTime = finishTime - startTime;
long diff = (now2.getTime() - now1.getTime());
cobadatabase cb2 = new cobadatabase(studNumTF.getText(),dateFormatter.format(now1),dateFormatter.format(now2), diff);
if("Log In".equals(e.getActionCommand()))
{
if(station == 0)
{
lc.StationCheck(0);
}
else if(seatOccupied[station-1] == true)
{
lc.StationCheck(2);
}
else if(!studNumTF.getText().equals(cb.getStudentNumber()))
{
studNumTF.setText("");
lc.StationCheck(3);
}
else
{
seatOccupied[station-1] = true;
Aid[station-1].setText(cb.getStudentNumber());
Afirstname[station-1].setText(cb.getFirstName());
Alastname[station-1].setText(cb.getLastName());
seat[station-1].setBackground(Color.red);
Atime[station-1].setText(dateFormatter.format(now1));
occupiedSeatCounter++;
}
}
if("Log Out".equals(e.getActionCommand()))
{
if(station == 0)
{
lc.StationCheck(0);
}
else if(Aid[station-1].getText() == "Vacant Station")
{
lc.StationCheck(1);
}
else
{
Aid[station-1].setText("Vacant Station");
Afirstname[station-1].setText("---------");
Alastname[station-1].setText("---------");
seat[station-1].setBackground(Color.green);
Atime[station-1].setText("00:00:00");
seatOccupied[station-1] = false;
studNumTF.setText("");
output = "Time Check-Out "+dateFormatter.format(now2)+"\n Total Time: " +diff;
JOptionPane.showMessageDialog(null,output, "Check- Out.",JOptionPane.INFORMATION_MESSAGE);
}
}
}
}
}
cobadatabase类
import java.sql.*;
import java.util.*;
import java.text.*;
public class cobadatabase{
protected String sn,fn,ln,srt, sn2, srt2, et;
protected Long tt;
private Connection conn;
private PreparedStatement st;
public cobadatabase(){
try{
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://localhost/studentrecords","root","");
}
catch(Exception e){}
}
public cobadatabase(String sn2, String str2, String et, long tt)
{
this();
try
{
st = conn.prepareStatement("Insert into time(StudentNumber,StartTime,EndTime,TotalTime) values(?,?,?,?)");
st.setString(1,sn2);
st.setString(2,str2);
st.setString(3,et);
st.setLong(4,tt);
st.executeUpdate();
}
catch(Exception e){}
}
public cobadatabase(String StudentNumber)
{
this();
try{
st = conn.prepareStatement("SELECT * FROM student WHERE StudentNumber=?");
st.setString(1,StudentNumber);
ResultSet rs = st.executeQuery();
while (rs.next())
{
this.sn = rs.getString(1);
this.fn = rs.getString(2);
this.ln = rs.getString(3);
this.srt = rs.getString(4);
SimpleDateFormat ft = new SimpleDateFormat("kk:mm:ss");
ft.format(rs.getTime("TotalTime").getTime());
}
}
catch(Exception e){}
}
public cobadatabase(String StudentNumber2, String Start, String End)
{
this();
try{
st = conn.prepareStatement("SELECT * FROM time WHERE StudentNumber2=?");
st.setString(2,Start);
st.setString(3,End);
ResultSet rs = st.executeQuery();
while (rs.next())
{
this.sn2 = rs.getString(1);
this.srt2 = rs.getString(2);
this.et = rs.getString(3);
this.tt = rs.getLong(4);
}
}
catch(Exception e){}
}
public String getFirstName(){
return fn;
}
public String getLastName(){
return ln;
}
public String getStudentNumber(){
return sn;
}
public String getStart(){
return srt2;
}
public String getEnd(){
return et;
}
}
这里的问题是，当单击登录按钮时，开始时间同时显示在我的数据库的startTime和endTime列中。当单击注销按钮时，在数据库中创建另一行，其中包含startTime和endTime列的endTime。我想知道为什么会发生这种情况..
答案 0 :(得分：2)
查看以下网址 http://www.mkyong.com/java/java-how-to-get-current-date-time-date-and-calender/ 在应用程序的开头和最后使用它。
如果您正在测量应用程序执行时间的时间，上述情况并非我认为最佳。如果是这样，请尝试以下内容
import java.util.*;
public class VectorTest
{
Vector v = new Vector();
public VectorTest()
{
long startTime = System.currentTimeMillis(); // Get the start Time
long endTime = 0;
System.out.println( startTime);
for(int i=0;i<100000;i++)
{
v.add(i);
}
for(int i=0;i<v.size();i++)
{
System.out.println(v.get(i));
}
endTime = System.currentTimeMillis(); //Get the end Time
System.out.println(endTime);
System.out.println("Difference in mili seconds: "+ (endTime-startTime)); //Print the difference in mili seconds
System.out.println("Differencce in Seconds: "+ (endTime-startTime)/1000); // Print the difference in seconds
}
public static void main(String[]args)
{
new VectorTest();
}
}
为良好的编程实践提供额外建议
查看第3个重载的“CodeBase”构造函数。 SQL查询中有1个参数，但尝试在程序中设置2，即使是无效索引2和3
关闭finally块
不要将catch（）方法留空。打印堆栈跟踪
不要在任何地方使用相同的PreparedStament。把它们作为局部变量来作为全局变量。有时，数据库中的自动连接关闭方法存在延迟。在这种情况下，您的程序将以意想不到的方式执行。如果您在本地声明它们，那么只要方法不是
答案 1 :(得分：0)
您应该尝试设置单击正确按钮的时间，而不是设置同一按钮的开始和结束时间。我会为startTime设置一个全局变量并像这样计算
private long startTime = null;
public void actionPerformed(ActionEvent e) {
LogicalChecker lc = new LogicalChecker();
cobadatabase cb = new cobadatabase(studNumTF.getText());
String output;
//long secs = (now2.getTime() - now1.getTime()) / 1000;
//long diffSeconds = diff / 1000 % 60;
//long diffMinutes = diff / (60 * 1000) % 60;
// long diffHours = diff / (60 * 60 * 1000) % 60;
//long startTime = System.currentTimeMillis();
//long finishTime = System.currentTimeMillis();
//long elapsedTime = finishTime - startTime;
long diff = (now2.getTime() - now1.getTime());
cobadatabase cb2 = new cobadatabase(studNumTF.getText(),dateFormatter.format(now1),dateFormatter.format(now2), diff);
if("Log In".equals(e.getActionCommand())){
this.startTime = new Date().getTime(); // set start time
... do stuff
} else if("Log Out".equals(e.getActionCommand())){
long totalTime = new Date().getTime() - this.startTime(); // calculate total time
... do stuff
}
}