我正在编辑JAVA中的图书馆管理系统，我遇到搜索功能问题。每本书都有BookID，Subject，Title，Author等，每个成员都有一个MemberID，Name等。
如果我选择按主题，标题或作者搜索，它会从数据库中返回正确的信息并显示它。但是当我尝试通过BookID搜索时，我收到错误。
这是表单和验证逻辑的代码，然后传递给ListSearchBooks.java和ListSearchMembers.java，它从数据库执行查询并显示它。
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class SearchBooksAndMembers extends JInternalFrame {
/***************************************************************************
*** declaration of the private variables used in the program ***
***************************************************************************/
//for creating the North Panel
private JPanel northPanel = new JPanel();
//for creating the label
private JLabel title = new JLabel("Search for Books and Members");
//for creating the center
private JPanel center = new JPanel();
//for creating the Center Panel
private JPanel centerBooksPanel = new JPanel();
//for creating an Internal Panel in the center panel
private JPanel searchBooksPanel = new JPanel();
//for creating an Internal Panel in the center panel
private JPanel searchBooksButtonPanel = new JPanel();
//for creating the table
private JLabel searchBooksLabel = new JLabel(" Search by: ");
//for creating JComboBox
private JComboBox searchBooksTypes;
//for creating String[]
private String[] booksTypes = {"BookID", "Subject", "Title", "Author", "Publisher", "ISBN"};
//for creating the label
private JLabel booksKey = new JLabel(" Write the Keyword: ");
//for cearting the text field
private JTextField booksKeyTextField = new JTextField();
//for creating the button
private JButton searchBooksButton = new JButton("Search");
//for creating the Center Panel
private JPanel centerMembersPanel = new JPanel();
//for creating an Internal Panel in the center panel
private JPanel searchMembersPanel = new JPanel();
//for creating an Internal Panel in the center panel
private JPanel searchMembersButtonPanel = new JPanel();
//for creating the table
private JLabel searchMembersLabel = new JLabel(" Search by: ");
//for creating JComboBox
private JComboBox searchMembersTypes;
//for creating String[]
private String[] membersTypes = {"MemberID", "Name", "E-Mail", "Major"};
//for creating the label
private JLabel membersKey = new JLabel(" Write the Keyword: ");
//for cearting the text field
private JTextField membersKeyTextField = new JTextField();
//for creating the button
private JButton searchMembersButton = new JButton("Search");
//for creating the south panel
private JPanel southPanel = new JPanel();
//for creating the button
private JButton cancelButton = new JButton("Cancel");
//for creating an array of string to store the data
private String[] booksData;
private String[] membersData;
//create objects from another classes for using them in the ActionListener
private ListSearchBooks listBooks;
private ListSearchMembers listMembers;
private Books book;
private Members member;
//for checking the information from the text field
public boolean isBooksDataCorrect() {
booksData = new String[2];
booksData[0] = searchBooksTypes.getSelectedItem().toString();
for (int i = 1; i < booksData.length; i++) {
if (!booksKeyTextField.getText().equals("")) {
if (searchBooksTypes.getSelectedItem().toString().equals("BookID")) {
booksData[i] = booksKeyTextField.getText();
}
else
booksData[i] = "'%" + booksKeyTextField.getText() + "%'";
}
else
return false;
}
return true;
}
//for checking the information from the text field
public boolean isMembersDataCorrect() {
membersData = new String[2];
membersData[0] = searchMembersTypes.getSelectedItem().toString();
for (int i = 1; i < membersData.length; i++) {
if (!membersKeyTextField.getText().equals("")) {
if (searchMembersTypes.getSelectedItem().toString().equals("MemberID")) {
membersData[i] = membersKeyTextField.getText();
}
else
membersData[i] = "'%" + membersKeyTextField.getText() + "%'";
}
else
return false;
}
return true;
}
//constructor of searchBooksAndMembers
public SearchBooksAndMembers() {
//for setting the title for the internal frame
super("Search", false, true, false, true);
//for setting the icon
setFrameIcon(new ImageIcon(ClassLoader.getSystemResource("images/Find16.gif")));
//for getting the graphical user interface components display area
Container cp = getContentPane();
//for setting the layout
northPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
//for setting the font
title.setFont(new Font("Tahoma", Font.BOLD, 14));
//for adding the label
northPanel.add(title);
//for adding the north panel to the container
cp.add("North", northPanel);
//for setting the layout
center.setLayout(new BorderLayout());
//for setting the layout
centerBooksPanel.setLayout(new BorderLayout());
//for setting the layout
searchBooksPanel.setLayout(new GridLayout(2, 2, 1, 1));
//for adding the label
searchBooksPanel.add(searchBooksLabel);
//for adding the JComboBos[]
searchBooksPanel.add(searchBooksTypes = new JComboBox(booksTypes));
//for adding the label
searchBooksPanel.add(booksKey);
//for adding the text field
searchBooksPanel.add(booksKeyTextField);
//for adding the internal panel to the panel
centerBooksPanel.add("North", searchBooksPanel);
//for setting the layout
searchBooksButtonPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));
//for adding the button
searchBooksButtonPanel.add(searchBooksButton);
//for adding the internal panel to the center panel
centerBooksPanel.add("South", searchBooksButtonPanel);
//for setting the border
centerBooksPanel.setBorder(BorderFactory.createTitledBorder("Search for a book:"));
//for adding center panel to the center
center.add("West", centerBooksPanel);
//for setting the layout
centerMembersPanel.setLayout(new BorderLayout());
//for setting the layout
searchMembersPanel.setLayout(new GridLayout(2, 2, 1, 1));
//for adding the label
searchMembersPanel.add(searchMembersLabel);
//for adding the JComboBos[]
searchMembersPanel.add(searchMembersTypes = new JComboBox(membersTypes));
//for adding the label
searchMembersPanel.add(membersKey);
//for adding the text field
searchMembersPanel.add(membersKeyTextField);
//for adding the internal panel to the panel
centerMembersPanel.add("North", searchMembersPanel);
//for setting the layout
searchMembersButtonPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));
//for adding the button
searchMembersButtonPanel.add(searchMembersButton);
//for adding the internal panel to the center panel
centerMembersPanel.add("South", searchMembersButtonPanel);
//for setting the border
centerMembersPanel.setBorder(BorderFactory.createTitledBorder("Search for a member:"));
//for adding center panel to the center
center.add("East", centerMembersPanel);
//for adding the center to the container
cp.add("Center", center);
/**
*for setting the font to the lables & buttons
*/
searchBooksLabel.setFont(new Font("Tahoma", Font.BOLD, 11));
searchBooksTypes.setFont(new Font("Tahoma", Font.BOLD, 11));
booksKey.setFont(new Font("Tahoma", Font.BOLD, 11));
booksKeyTextField.setFont(new Font("Tahoma", Font.PLAIN, 11));
searchBooksButton.setFont(new Font("Tahoma", Font.BOLD, 11));
cancelButton.setFont(new Font("Tahoma", Font.BOLD, 11));
searchMembersLabel.setFont(new Font("Tahoma", Font.BOLD, 11));
searchMembersTypes.setFont(new Font("Tahoma", Font.BOLD, 11));
membersKey.setFont(new Font("Tahoma", Font.BOLD, 11));
membersKeyTextField.setFont(new Font("Tahoma", Font.PLAIN, 11));
searchMembersButton.setFont(new Font("Tahoma", Font.BOLD, 11));
cancelButton.setFont(new Font("Tahoma", Font.BOLD, 11));
//for setting the layout
southPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));
//for adding the button
southPanel.add(cancelButton);
//for setting the border
southPanel.setBorder(BorderFactory.createEtchedBorder());
//for adding the south panel to the container
cp.add("South", southPanel);
/***********************************************************************
* for adding the action listener to the button,first the text will be *
* taken from the JTextField and passing them to listSearchBooks object*
***********************************************************************/
searchBooksButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
//for checking if there is a missing information
if (isBooksDataCorrect() == true) {
book = new Books();
String bookQuery = "SELECT BookID, Subject, Title, Author, Publisher," +
"Copyright, Edition, Pages, NumberOfBooks,ISBN,Library,Availble,ShelfNo FROM Books" +
" WHERE " + booksData[0] + " LIKE " + booksData[1];
book.connection(bookQuery);
int bookID = book.getBookID();
if (bookID != 0) {
listBooks = new ListSearchBooks(bookQuery);
getParent().add(listBooks);
try {
listBooks.setSelected(true);
}
catch (java.beans.PropertyVetoException e) {
}
dispose();
}
else {
JOptionPane.showMessageDialog(null, "No Match(es)", "Error", JOptionPane.ERROR_MESSAGE);
booksKeyTextField.setText(null);
}
}
else
JOptionPane.showMessageDialog(null, "Please enter a keyword", "Warning", JOptionPane.WARNING_MESSAGE);
}
});
/***********************************************************************
* for adding the action listener to the button,first the text will be *
* taken from the JTextField and passing them to listSearchBooks object*
***********************************************************************/
searchMembersButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
if (isMembersDataCorrect()) {
member = new Members();
String memberQuery = "SELECT MemberID, ID, Name, EMail, Major, Expired" +
" FROM Members WHERE " + membersData[0] + " LIKE " + membersData[1];
member.connection(memberQuery);
int memberID = member.getMemberID();
if (memberID != 0) {
listMembers = new ListSearchMembers(memberQuery);
getParent().add(listMembers);
try {
listMembers.setSelected(true);
}
catch (java.beans.PropertyVetoException e) {
}
dispose();
}
else {
JOptionPane.showMessageDialog(null, "No Match(es)", "Error", JOptionPane.ERROR_MESSAGE);
membersKeyTextField.setText(null);
}
}
else
JOptionPane.showMessageDialog(null, "Please enter a keyword", "Warning", JOptionPane.WARNING_MESSAGE);
}
});
//for adding the action listener for the button to dispose the frame
cancelButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
dispose();
}
});
//for setting the visible to true
setVisible(true);
//show the internal frame
pack();
}
}
这是ListBooks.Java的代码
import javax.swing.*;
import javax.swing.table.TableColumn;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.print.PrinterException;
import java.awt.print.PrinterJob;
import java.sql.SQLException;
public class ListSearchBooks extends JInternalFrame {
/***************************************************************************
*** declaration of the private variables used in the program ***
***************************************************************************/
//for creating the North Panel
private JPanel northPanel = new JPanel();
//for creating the Center Panel
private JPanel centerPanel = new JPanel();
//for creating the label
private JLabel label = new JLabel("List of Searched Books");
//for creating the button
private JButton printButton;
//for creating the table
private JTable table;
//for creating the TableColumn
private TableColumn column = null;
//for creating the JScrollPane
private JScrollPane scrollPane;
//for creating an object for the ResultSetTableModel class
private ResultSetTableModel tableModel;
//constructor of listSearchBooks
public ListSearchBooks(String query) {
//for setting the title for the internal frame
super("Searched Books", false, true, false, true);
//for setting the icon
setFrameIcon(new ImageIcon(ClassLoader.getSystemResource("images/List16.gif")));
//for getting the graphical user interface components display area
Container cp = getContentPane();
/***********************************************************************
*for setting the required information for the ResultSetTableModel class*
************************************************************************/
final String JDBC_DRIVER ="net.ucanaccess.jdbc.UcanaccessDriver";
final String DATABASE_URL = "jdbc:ucanaccess://JLibrary.mdb";
final String DEFAULT_QUERY = query;
//for bassing the required information to the ResultSetTableModel object
try {
tableModel = new ResultSetTableModel(JDBC_DRIVER, DATABASE_URL, DEFAULT_QUERY);
//for setting the Query
try {
tableModel.setQuery(DEFAULT_QUERY);
}
catch (SQLException sqlException) {
}
}
catch (ClassNotFoundException classNotFound) {
}
catch (SQLException sqlException) {
}
//for setting the table with the information
table = new JTable(tableModel);
//for setting the size for the table
table.setPreferredScrollableViewportSize(new Dimension(990, 200));
//for setting the font
table.setFont(new Font("Tahoma", Font.PLAIN, 12));
//for setting the scrollpane to the table
scrollPane = new JScrollPane(table);
//for setting the size for the table columns
for (int i = 0; i < 13; i++) {
column = table.getColumnModel().getColumn(i);
if (i == 0) //BookID
column.setPreferredWidth(20);
if (i == 1) //Subject
column.setPreferredWidth(100);
if (i == 2) //Title
column.setPreferredWidth(150);
if (i == 3) //Auther
column.setPreferredWidth(50);
if (i == 4) //Publisher
column.setPreferredWidth(70);
if (i == 5) //Copyright
column.setPreferredWidth(40);
if (i == 6) //Edition
column.setPreferredWidth(40);
if (i == 7) //Pages
column.setPreferredWidth(40);
if (i == 8) //NumberOfBooks
column.setPreferredWidth(80);
if (i == 9) //ISBN
column.setPreferredWidth(70);
if (i == 10) //Library
column.setPreferredWidth(30);
if (i == 11) //Availble
column.setPreferredWidth(30);
if (i == 12) //ShelfNo
column.setPreferredWidth(30);
}
//for setting the font to the label
label.setFont(new Font("Tahoma", Font.BOLD, 14));
//for setting the layout to the panel
northPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
//for adding the label to the panel
northPanel.add(label);
//for adding the panel to the container
cp.add("North", northPanel);
//for setting the layout to the panel
centerPanel.setLayout(new BorderLayout());
//for creating an image for the button
ImageIcon printIcon = new ImageIcon(ClassLoader.getSystemResource("images/Print16.gif"));
//for adding the button to the panel
printButton = new JButton("print the books", printIcon);
//for setting the tip text
printButton.setToolTipText("Print");
//for setting the font to the button
printButton.setFont(new Font("Tahoma", Font.PLAIN, 12));
//for adding the button to the panel
centerPanel.add(printButton, BorderLayout.NORTH);
//for adding the scrollpane to the panel
centerPanel.add(scrollPane, BorderLayout.CENTER);
//for setting the border to the panel
centerPanel.setBorder(BorderFactory.createTitledBorder("Books:"));
//for adding the panel to the container
cp.add("Center", centerPanel);
//for adding the actionListener to the button
printButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
Thread runner = new Thread() {
public void run() {
try {
PrinterJob prnJob = PrinterJob.getPrinterJob();
prnJob.setPrintable(new PrintingBooks(DEFAULT_QUERY));
if (!prnJob.printDialog())
return;
setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
prnJob.print();
setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
}
catch (PrinterException ex) {
System.out.println("Printing error: " + ex.toString());
}
}
};
runner.start();
}
});
//for setting the visible to true
setVisible(true);
//to show the frame
pack();
}
}
为什么问题仅适用于BookID？非常感谢任何帮助。
答案 0 :(得分：2)
正如问题评论中所述，您的空catch块正在吞噬异常并阻止您查看问题，即：
代码块
if (!booksKeyTextField.getText().equals("")) {
if (searchBooksTypes.getSelectedItem().toString().equals("BookID")) {
booksData[i] = booksKeyTextField.getText();
}
else
booksData[i] = "'%" + booksKeyTextField.getText() + "%'";
}
将最终导致类似以下的SQL查询，但
BookID
SELECT BookID, Subject, ... FROM Books WHERE Subject LIKE '%waffles%'
但是在搜索BookID时，您的代码将尝试执行
SELECT BookID, Subject, ... FROM Books WHERE BookID LIKE 1234
会导致UCanAccess抛出异常
net.ucanaccess.jdbc.UcanaccessSQLException：UCAExc ::: 3.0.6操作中不兼容的数据类型
您需要修复代码以为BookID搜索生成有效的SQL查询。该查询很可能使用相等（=）比较而不是LIKE。
在您熟悉它的同时，您还应该使用PreparedStatement和参数化查询来防止SQL注入问题，例如尝试搜索名为＆＃34的作者; O＆＃39;洛基＆＃34;