www.pudn.com > SRS.rar > MainFrame.java
// MainFrame.java - Chapter 16 version.
// Copyright 2000 by Jacquie Barker - all rights reserved.
// A GUI class.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.util.*;
public class MainFrame extends JFrame {
// Define all of the components here as attributes of this class.
private JPanel leftPanel;
private JPanel topLeftPanel;
private JPanel labelPanel;
private JPanel fieldPanel;
private JPanel bottomLeftPanel;
private JPanel rightPanel;
private JPanel buttonPanel;
private JTextField ssnField;
private JTextField nameField;
private JLabel totalCoursesLabel;
private JButton dropButton;
private JButton addButton;
private JButton logoffButton;
private JButton saveScheduleButton;
private JLabel l1;
private JLabel l2;
private JLabel l3;
private JLabel l4;
private JList studentCourseList;
private JList scheduleOfClassesList;
// Maintain a handle on the Student who is logged in.
// (Whenever this is set to null, nobody is officially logged on.)
private Student currentUser;
// Constructor.
public MainFrame() {
// Initialize attributes.
currentUser = null;
String plaf = "";
// Note that using "this." as a prefix is unnecessary -
// any method calls that stand alone (without a dot notation
// prefix) are UNDERSTOOD to be invoked on THIS object.
this.setTitle("学生注册系统");
this.setSize(600, 350);
Container contentPane = this.getContentPane( );
// Set the style of the interface
plaf = "com.sun.java.swing.plaf.motif.MotifLookAndFeel";
try{
UIManager.setLookAndFeel(plaf);
SwingUtilities.updateComponentTreeUI(this);
} catch(Exception e){}
// Technique for centering a frame on the screen.
Dimension frameSize = this.getSize();
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
this.setLocation((screenSize.width - frameSize.width)/2,
(screenSize.height - frameSize.height)/2);
// Create a few panels.
leftPanel = new JPanel();
leftPanel.setLayout(new GridLayout(2, 1));
topLeftPanel = new JPanel();
topLeftPanel.setLayout(new GridLayout(1, 2));
labelPanel = new JPanel();
labelPanel.setLayout(new GridLayout(4, 1));
fieldPanel = new JPanel();
fieldPanel.setLayout(new GridLayout(4, 1));
bottomLeftPanel = new JPanel();
bottomLeftPanel.setLayout(new BorderLayout());
rightPanel = new JPanel();
rightPanel.setLayout(new BorderLayout());
buttonPanel = new JPanel();
buttonPanel.setLayout(new GridLayout(1, 4));
// We'll allow the main frame's layout to remain the
// default BorderLayout.
// Note that we are adding labels without maintaining
// handles on them!
JLabel l = new JLabel("学号: ");
l.setForeground(Color.black);
labelPanel.add(l);
l = new JLabel("姓名: ");
l.setForeground(Color.black);
labelPanel.add(l);
l = new JLabel("课程总汇: ");
l.setForeground(Color.black);
labelPanel.add(l);
// Add an empty label for padding/white space.
l = new JLabel("");
labelPanel.add(l);
// We DO maintain handles on the text fields, however, so
// that we can later go back and read their contents
// by name. Note our choice of descriptive names for these.
ssnField = new JTextField(10);
nameField = new JTextField(10);
// Because this next field is not editable, we are making it
// a JLabel. (I could have also made it a non-editable
// JTextField, but I wanted it to look like a label ...)
totalCoursesLabel = new JLabel();
totalCoursesLabel.setForeground(Color.lightGray);
fieldPanel.add(ssnField);
fieldPanel.add(nameField);
fieldPanel.add(totalCoursesLabel);
// Add an empty label for padding/white space.
l = new JLabel("");
fieldPanel.add(l);
// Create the buttons and add them to their panel. Again,
// note use of descriptive names.
dropButton = new JButton("弃选");
addButton = new JButton("添加");
logoffButton = new JButton("登出");
// Technique for creating a multi-line button label.
saveScheduleButton = new JButton();
saveScheduleButton.setLayout(new GridLayout(2, 1));
l1 = new JLabel("保存我的", JLabel.CENTER);
l1.setForeground(Color.black);
l2 = new JLabel("课程表！", JLabel.CENTER);
l2.setForeground(Color.black);
saveScheduleButton.add(l1);
saveScheduleButton.add(l2);
buttonPanel.add(dropButton);
buttonPanel.add(saveScheduleButton);
buttonPanel.add(new JLabel("")); // white space padding
buttonPanel.add(addButton);
buttonPanel.add(logoffButton);
studentCourseList = new JList();
studentCourseList.setFixedCellWidth(200);
bottomLeftPanel.add(studentCourseList, BorderLayout.CENTER);
l = new JLabel("已选课程:");
l.setForeground(Color.black);
bottomLeftPanel.add(l, BorderLayout.NORTH);
l = new JLabel("--- 课程表 ---", JLabel.CENTER);
l.setForeground(Color.black);
rightPanel.add(l, BorderLayout.NORTH);
scheduleOfClassesList = new JList(SRS.scheduleOfClasses.
getSortedSections());
scheduleOfClassesList.setFixedCellWidth(250);
rightPanel.add(scheduleOfClassesList, BorderLayout.EAST);
// Initialize the buttons to their proper enabled/disabled
// state.
resetButtons();
// Finally, attach all of the panels to one another
// and to the frame.
// Add in ascending row, then column, order.
topLeftPanel.add(labelPanel);
topLeftPanel.add(fieldPanel);
leftPanel.add(topLeftPanel);
leftPanel.add(bottomLeftPanel);
contentPane.add(leftPanel, BorderLayout.WEST);
contentPane.add(rightPanel, BorderLayout.CENTER);
contentPane.add(buttonPanel, BorderLayout.SOUTH);
// ------------------
// Add all behaviors.
// ------------------
// Different types of components require different types
// of listeners:
//
// o Text fields respond to an ActionListener
// whenever the Enter key is pressed.
//
// o Buttons respond to an ActionListener
// whenever the button is clicked.
//
// o JLists respond to a ListSelectionListener
// whenever an item is selected.
ActionListener aListener;
ListSelectionListener lListener;
WindowAdapter wListener;
// ssnField
aListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
// First, clear the fields reflecting the
// previous student's information.
clearFields();
// We'll try to construct a Student based on
// the ssn we read, and if a file containing
// Student's information cannot be found,
// we have a problem.
String id = ssnField.getText();
Student theStudent = new Student(id);
if (!theStudent.successfullyInitialized()) {
// Drat! The ID was invalid.
currentUser = null;
ssnField.setText("");
// Let the user know that login failed,
// UNLESS the ID typed was blank,
// signalling a successful log-off.
JOptionPane.showMessageDialog(null,
//"Invalid student ID; please try again.",
"学号非法，请重试！",
"Invalid Student ID",
JOptionPane.WARNING_MESSAGE);
}
else {
// Hooray! We found one! Now, we need
// to request and validate the password.
PasswordPopup pp = new PasswordPopup(
MainFrame.this);
String pw = pp.getPassword();
pp.dispose();
if (theStudent.validatePassword(pw)) {
currentUser = theStudent;
setFields(theStudent);
// Let the user know that the
// login succeeded.
JOptionPane.showMessageDialog(null,
theStudent.getName()+"登录成功！" + ".",
"Log In Succeeded",
JOptionPane.INFORMATION_MESSAGE);
}
else {
// Password validation failed;
// notify the user of this.
JOptionPane.showMessageDialog(null,
"密码错误！ " +
"请重试!",
"Invalid Password",
JOptionPane.WARNING_MESSAGE);
}
}
MainFrame.this.repaint();
// Check states of the various buttons.
resetButtons();
}
};
ssnField.addActionListener(aListener);
// addButton
aListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
// Determine which section is selected
// (note that we must cast it, as it
// is returned as an Object reference).
Section selected = (Section)
scheduleOfClassesList.getSelectedValue();
// Check to see if this COURSE is already
// one that the student registered for,
// even if the SECTION is different.
// If so, warn them of this.
if (currentUser.isCurrentlyEnrolledInSimilar(
selected)) {
// Create a String array of TWO lines
// of messsage text, so that the popup
// window won't be too wide.
String[] message =
{ "你已经选过本课程！",
" " };
// Then, we can just hand the String
// array in to the showMessageDialog()
// call.
JOptionPane.showMessageDialog(null,
message,
"Request Denied",
JOptionPane.WARNING_MESSAGE);
}
else {
// Attempt to enroll the student, noting
// the status code that is returned.
int success =
selected.enroll(currentUser);
// Report the status to the user.
if (success == Section.SECTION_FULL) {
JOptionPane.showMessageDialog(
null,
"Sorry - that section is full.",
"Request Denied",
JOptionPane.WARNING_MESSAGE);
}
else if (success ==
Section.PREREQ_NOT_SATISFIED) {
JOptionPane.showMessageDialog(
null,
//"You haven't satisfied all " +
//"of the prerequisites for " +
//"this course.",
"你还有本课程的"+
"先行课程没有修过！",
"Request Denied",
JOptionPane.WARNING_MESSAGE);
}
else if (success ==
Section.PREVIOUSLY_ENROLLED) {
String[] message =
{ "You are already enrolled in " +
"(or have already",
"successfully completed) a " +
"section of this course.",
" " };
JOptionPane.showMessageDialog(
null,
message,
"Request Denied",
JOptionPane.WARNING_MESSAGE);
}
else { // success!
// Display a confirmation message.
JOptionPane.showMessageDialog(
null,
//"Seat confirmed in " +
selected.
getRepresentedCourse().
getCourseNo() +"已选中！" +".",
"Request Successful",
JOptionPane.INFORMATION_MESSAGE);
// Update the list of sections
// that this student is
// registered for.
studentCourseList.setListData(
currentUser.
getSectionsEnrolled());
// Update the field representing
// student's course total.
int total =
currentUser.getCourseTotal();
totalCoursesLabel.setText("" +
total);
// Clear the selection in the
// schedule of classes list.
scheduleOfClassesList.
clearSelection();
}
}
// Check states of the various buttons.
resetButtons();
}
};
addButton.addActionListener(aListener);
// dropButton
aListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
// Determine which section is selected
// (note that we must cast it, as it
// is returned as an Object reference).
Section selected = (Section)
studentCourseList.getSelectedValue();
// Drop the course.
selected.drop(currentUser);
// Display a confirmation message.
JOptionPane.showMessageDialog(null,
"Course " + selected.
getRepresentedCourse().
getCourseNo() + " 已弃选.",
"Request Successful",
JOptionPane.INFORMATION_MESSAGE);
// Update the list of sections that
// this student is registered for.
studentCourseList.setListData(
currentUser.
getSectionsEnrolled());
// Update the field representing
// student's course total.
int total = currentUser.getCourseTotal();
totalCoursesLabel.setText("" + total);
// Check states of the various buttons.
resetButtons();
}
};
dropButton.addActionListener(aListener);
// saveScheduleButton
aListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
boolean success = currentUser.persist();
if (success) {
// Let the user know that his/her
// schedule was successfully saved.
JOptionPane.showMessageDialog(null,
"成功保存课程表！",
"Schedule Saved",
JOptionPane.INFORMATION_MESSAGE);
}
else {
// Let the user know that there
// was a problem.
JOptionPane.showMessageDialog(null,
"Problem saving your " +
"schedule; please contact " +
"the SRS Support Staff for " +
"assistance.",
"Problem Saving Schedule",
JOptionPane.WARNING_MESSAGE);
}
}
};
saveScheduleButton.addActionListener(aListener);
// logoffButton
aListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
clearFields();
ssnField.setText("");
currentUser = null;
// Clear the selection in the
// schedule of classes list.
scheduleOfClassesList.clearSelection();
// Check states of the various buttons.
resetButtons();
}
};
logoffButton.addActionListener(aListener);
// studentCourseList
lListener = new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
// When an item is selected in this list,
// we clear the selection in the other list.
if (!(studentCourseList.isSelectionEmpty()))
scheduleOfClassesList.clearSelection();
// Check states of the various buttons.
resetButtons();
}
};
studentCourseList.addListSelectionListener(lListener);
// scheduleOfClassesList
lListener = new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
// When an item is selected in this list,
// we clear the selection in the other list.
if (!(scheduleOfClassesList.isSelectionEmpty()))
studentCourseList.clearSelection();
// Check states of the various buttons.
resetButtons();
}
};
scheduleOfClassesList.addListSelectionListener(lListener);
wListener = new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
};
this.addWindowListener(wListener);
this.setVisible(true);
try {
jbInit();
}
catch(Exception e) {
e.printStackTrace();
}
}
// Because there are so many different situations in which one or
// more buttons need to be (de)activated, and because the logic is
// so complex, we centralize it here and then just call this method
// whenever we need to check the state of one or more of the buttons.
// It is a tradeoff of code elegance for execution efficiency:
// we are doing a bit more work each time (because we don't need to
// reset all four buttons every time), but since the execution time
// is minimal, this seems like a reasonable tradeoff.
private void resetButtons() {
// There are four conditions which collectively govern the
// state of each button:
//
// o Whether a user is logged on or not.
boolean isLoggedOn;
if (currentUser != null) isLoggedOn = true;
else isLoggedOn = false;
// o Whether the user is registered for at least one course.
boolean atLeastOne;
if (currentUser != null && currentUser.getCourseTotal() > 0)
atLeastOne = true;
else atLeastOne = false;
// o Whether a registered course has been selected.
boolean courseSelected;
if (studentCourseList.isSelectionEmpty())
courseSelected = false;
else courseSelected = true;
// o Whether an item is selected in the Schedule of Classes.
boolean catalogSelected;
if (scheduleOfClassesList.isSelectionEmpty())
catalogSelected = false;
else catalogSelected = true;
// Now, verify the conditions on a button-by-button basis.
// Drop button:
if (isLoggedOn && atLeastOne && courseSelected)
dropButton.setEnabled(true);
else dropButton.setEnabled(false);
// Add button:
if (isLoggedOn && catalogSelected)
addButton.setEnabled(true);
else addButton.setEnabled(false);
// Save My Schedule button:
if (isLoggedOn) {
saveScheduleButton.setEnabled(true);
// Because of the way that we created the latter two
// buttons, we have do a bit of extra work to make them
// APPEAR to be turned on or off.
l1.setEnabled(true);
l2.setEnabled(true);
}
else {
saveScheduleButton.setEnabled(false);
l1.setEnabled(false);
l2.setEnabled(false);
}
// Log Off button:
if (isLoggedOn) logoffButton.setEnabled(true);
else logoffButton.setEnabled(false);
}
// Called whenever a user is logged off.
private void clearFields() {
nameField.setText("");
totalCoursesLabel.setText("");
studentCourseList.setListData(new Vector());
}
// Set the various fields, lists, etc. to reflect the information
// associated with a particular student. (Used when logging in.)
private void setFields(Student theStudent) {
nameField.setText(theStudent.getName());
int total = theStudent.getCourseTotal();
totalCoursesLabel.setText("" + total);
// If the student is registered for any courses, list these, too.
if (total > 0) {
// Because we already have a vector containing the
// sections that the student is registered for,
// and because these objects have defined a toString()
// method, we can merely hand the vector to the JList.
studentCourseList.setListData(theStudent.
getSectionsEnrolled());
}
}
private void jbInit() throws Exception {
}
}