我正在开发一个程序,使用该程序可以搜索数据库并显示结果。
我现在被困在展示部分了。我的SQL查询已经工作并返回结果。我正在使用PreparedStatement来填充我的ResultSet。然而,我不知道如何将ResultSet的数据返回到我想要用来显示数据的JTable。有人能向我详细解释如何做到这一点吗?或者是否有更好的方法来代替我看不到的JTable?
我正在使用MVC模型和DAO模式,但我对编程还是很陌生。到目前为止,在研究它的过程中,我发现最好的解决方案是创建一个自定义表类,但从那时起,我不知道如何前进。
我的自定义表类:
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.Vector;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
public class ResultSetTable {
public static TableModel resultSetToTableModel(ResultSet rs) {
try {
ResultSetMetaData metaData = rs.getMetaData();
int numberOfColumns = metaData.getColumnCount();
Vector columnNames = new Vector();
//Spaltennamen
for (int column = 0; column < numberOfColumns; column++) {
columnNames.addElement(metaData.getColumnLabel(column + 1));
}
//Alle Zeilen
Vector rows = new Vector();
while (rs.next()) {
Vector newRow = new Vector();
for (int i = 1; i <= numberOfColumns; i++) {
newRow.addElement(rs.getObject(i));
}
rows.addElement(newRow);
}
return new DefaultTableModel(rows, columnNames);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
}
我的View类的相关部分:
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTable;
import javax.swing.JTextField;
import dbconnect.dao.impl.BTRDaoImpl;
public class View extends JFrame{
public View() {
JTable table = new JTable(new ResultSetTable(BTRDaoImpl.resultset);
this.setSize(600, 400);
setResizable(false);
}
我的BTRDaoImpl类带有sql查询和结果集:
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collection;
import mvc.View;
import dao.BTRbDao;
import business.BTRBean;
public class BTRDaoImpl extends AbstractDao implements BTRDao {
private Connection dbConnection = null;
private PreparedStatement preparedStatement = null;
public void sqlquery() {
try {
String btrname = View.searchbbtrname.getText();
String btrplz = View.searchbtrplz.getText();
btrname = btrname.trim().toUpperCase();
btrplz = btrplz.trim().toUpperCase();
if (btrplz.isEmpty()) {
String btrResult = "SELECT BBSTBBNR, BBSTNABE, BBSTPLZ FROM BP.TBBBST WHERE BBSTNABEG = ?";
dbConnection = AbstractDao.getConnection();
preparedStatement = dbConnection.prepareStatement(btrResult);
preparedStatement.setString(1, btrname);
} else {
String btrResult = "SELECT BBSTBBNR, BBSTNABE, BBSTPLZ FROM BP.TBBBST WHERE BBSTNABEG = ? AND BBSTPLZ = ?";
dbConnection = AbstractDao.getConnection();
preparedStatement = dbConnection.prepareStatement(btrResult);
preparedStatement.setString(1, btrname);
preparedStatement.setString(2, btrplz);
}
} catch (SQLException e1) {
System.out.println("An error with the SQL query occured: ");
e1.printStackTrace();
}
}
public Collection<BtrBean> getBTR() throws SQLException,
IOException {
sqlquery();
final Collection<BtrBean> result = new ArrayList<BtrBean>();
ResultSet resultset = null;
try {
resultset = preparedStatement.executeQuery();
// while loop to get data
while (resultset.next()) {
BtrBean btr = new BtrBean();
int btrid = resultset.getInt(1);
String btrplz = resultset.getString(3);
String btrname = resultset.getString(2);
btr.setBetriebnr(btrid);
btr.setBetriebplz(btrplz);
btr.setBetriebname(btrname);
result.add(btr);
// System.out.println("BTR-ID: " + btrid + " BTR PLZ: " + btrplz + " BTR: " + btrname);
}
} catch (SQLException e) {
e.printStackTrace();
System.out.println("An error processing the SQL occured: ");
e.printStackTrace();
} catch (NullPointerException npe) {
System.out.println("NullPointerException: ");
npe.printStackTrace();
} finally {
if (preparedStatement != null) preparedStatement.close();
closeConnection(resultset);
}
return result;
}
}
我的BTRBean类:
public class BetriebBean {
private String betriebname;
private int betriebnr;
private String betriebplz;
public BetriebBean() {
}
public BetriebBean(String betriebname, int betriebnr, String betriebplz) {
super();
this.betriebname = betriebname;
this.betriebnr = betriebnr;
this.betriebplz = betriebplz;
}
public String getBetriebname() {
return betriebname;
}
public void setBetriebname(String betriebname) {
this.betriebname = betriebname;
}
public int getBetriebnr() {
return betriebnr;
}
public void setBetriebnr(int betriebnr) {
this.betriebnr = betriebnr;
}
public String getBetriebplz() {
return betriebplz;
}
public void setBetriebplz(String betriebplz) {
this.betriebplz = betriebplz;
}
}
//编辑:
我的整个视图类:
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTable;
import javax.swing.JTextField;
public class View extends JFrame{
private static final long serialVersionUID = 1L;
public static final String SEARCH = "SEARCH";
private JLabel searchbtrlabel = new JLabel("BTR name:");
public static JTextField searchbtrname = new JTextField(10);
private JLabel searchbtrlabel = new JLabel("PLZ:");
public static JTextField searchbtrplz = new JTextField(10);
private JButton searchbutton = new JButton();
public View() {
this.setTitle("BTR search TBBBST");
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setLayout(new FlowLayout());
this.add(searchbtrlabel);
this.add(searchbtrname);
this.add(searchbtrplzlabel);
this.add(searchbtrplz);
searchbutton.setText("Search");
searchbutton.setActionCommand(View.SEARCH);
this.add(searchbutton);
JTable table = new JTable();
this.add(table);
this.setSize(600, 400);
setResizable(false);
//this.pack();
}
public JTextField getSearchbtrname() {
return searchbetriebname;
}
public JTextField getSearchbbtrplz() {
return searchbetriebplz;
}
public JButton getSearchbutton() {
return searchbutton;
}
}
我的控制器类:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Observable;
import java.util.Observer;
import mvc.Model;
import dbconnect.dao.impl.BTRDaoImpl;
public class Controller implements Observer, ActionListener{
private Model model;
@SuppressWarnings("unused")
private View view;
public Controller(Model model, View view) {
this.model = model;
this.view = view;
model.addObserver(this);
view.getSearchbutton().addActionListener(this);
view.setVisible(true);
}
@Override
public void actionPerformed(ActionEvent e) {
switch (e.getActionCommand()) {
case View.SEARCH:
model.search();
view.table.setModel(ResultSetToTable.buildTableModel(BTRDaoImpl.resultset));
break;
default:
System.out.println("Error : " + e.getActionCommand());
break;
}
}
@Override
public void update(Observable o, Object arg) {
// TODO Auto-generated method stub
}
}
首先,在库中包含rs2xml.jar
。你可以在这里找到
在JTable
中填充MySQL查询的任何操作中,都要使用以下总体思想:
public void sqlquery() {
try {
String btrResult = "SELECT BBSTBBNR, BBSTNABE, BBSTPLZ FROM BP.TBBBST WHERE BBSTNABEG = ?";
preparedStatement = dbConnection.prepareStatement(btrResult);
dbConnection.setString(1, btrname);
ResultSet rs =dbConnection.executeQuery();
Ur_table_name.setModel(DbUtils.resultSetToTableModel(DbUtils.resultSetToel(rs)); //this line of code will show it in your JTable
}catch(Exception e){
}
您的问题是什么?试着比"[…]"更具体,但从那以后我不知道如何进步。你想做什么?查询的结果在表中可见吗?
使用Paul Vargas在这里给出的答案从ResultSet中填充JTable的最简单的代码,您可以从以下内容开始(使用Java 8):
import java.sql.*;
import java.util.Vector;
import javax.swing.*;
import javax.swing.table.*;
public class ResultSetToTable {
public static void main(final String[] arguments) {
SwingUtilities.invokeLater(() -> {
try {
new ResultSetToTable().createAndShowGui();
} catch (SQLException e) {
e.printStackTrace();
}
});
}
private void createAndShowGui() throws SQLException {
final JFrame frame = new JFrame("Stack Overflow");
frame.setBounds(100, 100, 800, 600);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
final JPanel panel = new JPanel();
final TableModel tableModel = buildTableModel(getData("Audi"));
final JTable table = new JTable(tableModel);
panel.add(new JScrollPane(table));
frame.getContentPane().add(panel);
frame.setVisible(true);
}
private ResultSet getData(final String btrName) throws SQLException {
final String url = "jdbc:h2:/Freek/TBBBST";
final Connection connection = DriverManager.getConnection(url, "me", "123");
final String sql = "SELECT BBSTBBNR, BBSTNABE, BBSTPLZ " +
"FROM BP.TBBBST " +
"WHERE BBSTNABEG = ?";
final PreparedStatement preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, btrName);
return preparedStatement.executeQuery();
}
/**
* See https://stackoverflow.com/a/10625471/1694043
*/
public static TableModel buildTableModel(final ResultSet resultSet)
throws SQLException {
int columnCount = resultSet.getMetaData().getColumnCount();
// Column names.
Vector<String> columnNames = new Vector<>();
for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
columnNames.add(resultSet.getMetaData().getColumnName(columnIndex));
}
// Data of the table.
Vector<Vector<Object>> dataVector = new Vector<>();
while (resultSet.next()) {
Vector<Object> rowVector = new Vector<>();
for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
rowVector.add(resultSet.getObject(columnIndex));
}
dataVector.add(rowVector);
}
return new DefaultTableModel(dataVector, columnNames);
}
}
对于旧版本的Java,您应该能够使用以下版本的main
方法:
public static void main(final String[] arguments) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
try {
new ResultSetToTable().createAndShowGui();
} catch (SQLException e) {
e.printStackTrace();
}
}
});
}
编辑:连接控制器和表格
要使该表在视图之外可用,需要将View()
构造函数中的table
变量转换为字段(就像您对searchbtrname
所做的那样),并为其创建getTable
getter方法(就像对getSearchbtrname
所做的一样)。在Controller.actionPerformed
方法中,现在可以将view.table
更改为view.getTable()
。