我的名字是安德鲁，我是java的新手。所以，我的问题是，如果我的方法connection.register和connection.connect正确完成，我想打开一个基本窗口。怎么做到这个？我试图用布尔做一些事情，但它没有用。我看到了一种方法：
java.sql.Connection.isValid（int timeoutSeconds） 如果连接尚未关闭且仍然有效，则返回true。 驱动程序应提交有关连接的查询或使用其他一些查询 积极验证连接的机制仍然有效 这个方法叫做。驱动程序提交的查询以进行验证 连接应在当前环境中执行 事务。
我认为这是正确的，我的意思是我应该检查连接是否有效，如果是 - 打开基座（窗口）如果没有打印出一些错误或类似的东西。
package SYSTEM;
import java.awt.EventQueue;
import javax.swing.JFrame;
import java.awt.GridBagLayout;
import java.awt.Window.Type;
import javax.swing.JTextField;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JTextPane;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JLabel;
public class LogIn {
private String userName;
private String password;
private String DBAddress;
private JFrame frame;
private JTextField textFieldName;
private JTextField textFieldPassword;
private JLabel lblUsername;
private JLabel lblPassword;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
LogIn window = new LogIn();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public LogIn() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setAlwaysOnTop(true);
frame.setBounds(100, 100, 343, 295);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
textFieldName = new JTextField();
textFieldName.setBounds(93, 60, 148, 20);
frame.getContentPane().add(textFieldName);
textFieldName.setColumns(10);
textFieldPassword = new JTextField();
textFieldPassword.setBounds(93, 115, 148, 20);
textFieldPassword.setColumns(10);
frame.getContentPane().add(textFieldPassword);
JButton btnLogin = new JButton("Login");
btnLogin.addActionListener(new ActionListener() {
// po nacisnieciu klawisza biore w variables umieszczam stringi pobrane z tych pól
public void actionPerformed(ActionEvent arg0) {
String userName = textFieldName.getText();
String password = textFieldPassword.getText();
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (Exception ex) {
// handle the error
}
Connection con = new Connection();
con.register();
con.connect(userName, password);
Base bas = new Base();
bas.main(null);
}
});
btnLogin.setBounds(107, 146, 121, 23);
frame.getContentPane().add(btnLogin);
lblUsername = new JLabel("Username");
lblUsername.setBounds(132, 35, 71, 14);
frame.getContentPane().add(lblUsername);
lblPassword = new JLabel("Password");
lblPassword.setBounds(132, 91, 71, 14);
frame.getContentPane().add(lblPassword);
}
}
package SYSTEM;
import java.sql.DriverManager;
import java.sql.SQLException;
public class Connection {
public void register(){
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public void connect(String userName, String password){
java.sql.Connection conn = null;
String url = "jdbc:mysql://127.0.0.1:3306/cms";
try {
DriverManager.getConnection(url,userName,password);
} catch (SQLException ex) {
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
System.out.println("VendorError: " + ex.getErrorCode());
}
}
}
package SYSTEM;
import java.awt.EventQueue;
import javax.swing.JFrame;
import java.awt.GridLayout;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Base {
private JFrame frame;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Base window = new Base();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public Base() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 150, 178);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(null);
JButton btnNoweZamwienie = new JButton("Nowe zam\u00F3wienie");
btnNoweZamwienie.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
NewOrder no = new NewOrder();
no.main(null);
}
});
btnNoweZamwienie.setBounds(8, 22, 129, 23);
frame.getContentPane().add(btnNoweZamwienie);
JButton btnListaZamwie = new JButton("Lista zam\u00F3wie\u0144");
btnListaZamwie.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
List list = new List();
list.main(null);
}
});
btnListaZamwie.setBounds(8, 56, 129, 23);
frame.getContentPane().add(btnListaZamwie);
JButton btnWyjcie = new JButton("Wyj\u015Bcie");
btnWyjcie.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
frame.dispose();
}
});
btnWyjcie.setBounds(8, 124, 129, 23);
frame.getContentPane().add(btnWyjcie);
JButton button = new JButton("Lista zam\u00F3wie\u0144");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Archives arch = new Archives();
arch.main(null);
}
});
button.setBounds(8, 90, 129, 23);
frame.getContentPane().add(button);
}
}
答案 0 :(得分：0)
所有框架（或窗口）似乎都是使用自己的main()方法的独立应用程序。这不是必要的。创建一个控制器类作为应用程序，让您的Base，NewOrder，Archives和LogIn窗口扩展JFrame。
例如：
public class Application {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
LogIn window = new LogIn();
window.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
}
您的LogIn类现在扩展了JFrame，并且成功注册并连接后会打开一个Base窗口：
public class LogIn extends JFrame {
private String userName;
private String password;
private String DBAddress;
private JTextField textFieldName;
private JTextField textFieldPassword;
private JLabel lblUsername;
private JLabel lblPassword;
public LogIn() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
setAlwaysOnTop(true);
setBounds(100, 100, 343, 295);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
getContentPane().setLayout(null);
textFieldName = new JTextField();
textFieldName.setBounds(93, 60, 148, 20);
getContentPane().add(textFieldName);
textFieldName.setColumns(10);
textFieldPassword = new JTextField();
textFieldPassword.setBounds(93, 115, 148, 20);
textFieldPassword.setColumns(10);
getContentPane().add(textFieldPassword);
JButton btnLogin = new JButton("Login");
btnLogin.addActionListener(new ActionListener() {
// po nacisnieciu klawisza biore w variables umieszczam stringi
// pobrane z tych pól
public void actionPerformed(ActionEvent arg0) {
String userName = textFieldName.getText();
String password = textFieldPassword.getText();
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (Exception ex) {
// handle the error
}
Connection con = new Connection();
if (con.register() && con.connect(userName, password)) {
Base bas = new Base();
bas.setVisible(true);
dispose();
}
}
});
btnLogin.setBounds(107, 146, 121, 23);
getContentPane().add(btnLogin);
lblUsername = new JLabel("Username");
lblUsername.setBounds(132, 35, 71, 14);
getContentPane().add(lblUsername);
lblPassword = new JLabel("Password");
lblPassword.setBounds(132, 91, 71, 14);
getContentPane().add(lblPassword);
}
}
这是Connection类。这些方法应该根据成功或失败返回一个布尔值：
public class Connection {
public boolean register() {
try {
Class.forName("com.mysql.jdbc.Driver");
return true;
} catch (ClassNotFoundException e) {
e.printStackTrace();
return false;
}
}
public boolean connect(String userName, String password) {
java.sql.Connection conn = null;
String url = "jdbc:mysql://127.0.0.1:3306/cms";
try {
DriverManager.getConnection(url, userName, password);
return true;
} catch (SQLException ex) {
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
System.out.println("VendorError: " + ex.getErrorCode());
return false;
}
}
}
以此为例，您的Base类现在也扩展了JFrame：
public class Base extends JFrame {
public Base() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
setBounds(100, 100, 150, 178);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
getContentPane().setLayout(null);
JButton btnNoweZamwienie = new JButton("Nowe zam\u00F3wienie");
btnNoweZamwienie.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
NewOrder no = new NewOrder(); //rewrite your code accordingly; make New Order extend JFrame
no.main(null);
}
});
btnNoweZamwienie.setBounds(8, 22, 129, 23);
getContentPane().add(btnNoweZamwienie);
JButton btnListaZamwie = new JButton("Lista zam\u00F3wie\u0144");
btnListaZamwie.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
List list = new List(); //rewrite your code accordingly; make List extend JFrame
list.main(null);
}
});
btnListaZamwie.setBounds(8, 56, 129, 23);
getContentPane().add(btnListaZamwie);
JButton btnWyjcie = new JButton("Wyj\u015Bcie");
btnWyjcie.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
dispose();
}
});
btnWyjcie.setBounds(8, 124, 129, 23);
getContentPane().add(btnWyjcie);
JButton button = new JButton("Lista zam\u00F3wie\u0144");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Archives arch = new Archives(); //rewrite your code accordingly; make Archives extend JFrame
arch.main(null);
}
});
button.setBounds(8, 90, 129, 23);
getContentPane().add(button);
}
}