我知道这个问题很常见，但我的选项已经用完了。试过每一个解决方案，没有什么对我有用。
我尝试做的只是将一些值从1个JFX窗口传递到另一个窗口。
这是login类
loginController方法
public void login(ActionEvent event){
try{
if(loginModel.isLogin(txtUsername.getText(), txtPassword.getText())){
try {
((Node)event.getSource()).getScene().getWindow().hide();
Stage primaryStage = new Stage();
FXMLLoader loader = new FXMLLoader();
mainViewController sendHello = loader.<mainViewController>getController();
sendHello.getUser(txtUsername.getText());
Pane root = loader.load(getClass().getResource("mainView.fxml").openStream());
primaryStage.setTitle("Kcalculator");
primaryStage.setScene(new Scene(root));
primaryStage.setResizable(false);
primaryStage.show();
} catch (IOException e) {
e.printStackTrace();
}
} else{
Alert alert1 = new Alert(Alert.AlertType.INFORMATION);
alert1.setTitle("Login failed");
alert1.setHeaderText(null);
alert1.setContentText("The username or password you have entered is invalid.");
alert1.showAndWait();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
这是我的mainViewController班级
public class mainViewController implements Initializable{
@FXML
private Label userLbl = new Label();
public void getUser(String user){
userLbl.setText("Welcome " + user);
}
@Override
public void initialize(URL location, ResourceBundle resources) {
}
}
在尝试了几个解决方案之后，在＆＃34;成功＆＃34;之后我仍然得到NullPointerException。登录。
答案 0 :(得分：0)
您需要在loader.getController之前加载fxml才能返回null以外的任何内容：
FXMLLoader loader = new FXMLLoader();
// load fxml
Pane root = loader.load(getClass().getResource("mainView.fxml").openStream());
// get controller created using fx:controller attribute in the fxml
mainViewController sendHello = loader.<mainViewController>getController();
// use controller
sendHello.getUser(txtUsername.getText());
请注意，fx:controller属性需要为此分配正确的值才能正常工作。
答案 1 :(得分：0)
我最近不得不为应用程序开发登录。此应用程序打开用户帐户类型的正确视图。它使用sqlite来存储和检索有关用户的信息，以及存储和检索加密密码。您可能会觉得这很有帮助。
控制器
import java.io.IOException;
import java.net.URL;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Arrays;
import java.util.ResourceBundle;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.stage.Stage;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
public class FXMLDocumentController implements Initializable {
@FXML private TextField tfUsername;
@FXML private PasswordField pfPassword;
@FXML private Button btnSignIn;
@FXML
void handlebtnSignIn(ActionEvent event){
int userID = 0;
String username = "", accountType = "";
byte[] encryptedPassword = null, salt = null;
if(tfUsername.getText().length() > 0 && pfPassword.getText().length() > 0)
{
try(Connection conn = DriverManager.getConnection("jdbc:sqlite:test.db");
PreparedStatement stmt = createPreparedStatement(conn, tfUsername.getText());
ResultSet rs = stmt.executeQuery())
{
while(rs.next())
{
userID = rs.getInt("user_id");
username = rs.getString("username");
encryptedPassword = rs.getBytes("password");
salt = rs.getBytes("salt");
accountType = rs.getString("account_type");
}
if(tfUsername.getText().equals(username) && authenticate(pfPassword.getText(), encryptedPassword, salt))
{
Stage stage = new Stage();
stage.setWidth(1080);
stage.setHeight(720);
Parent fxmlLoader = null;
switch(accountType)
{
case "administrator":
stage.setTitle("Tech Services Console");
System.out.println("I just signed in as an administrator");
fxmlLoader = FXMLLoader.load(getClass().getResource("AdminView.fxml"));
break;
case "collection":
stage.setTitle("Collection Console");
System.out.println("I just signed in as a collection member");
fxmlLoader = FXMLLoader.load(getClass().getResource("CollectionDevView.fxml"));
break;
case "selector":
stage.setTitle("Selector Console");
System.out.println("I just signed in as a selector member");
fxmlLoader = FXMLLoader.load(getClass().getResource("Selector.fxml"));
break;
}
stage.setScene(new Scene(fxmlLoader));
stage.show();
((Node)(event.getSource())).getScene().getWindow().hide();
tfUsername.setText("");
pfPassword.setText("");
}
else
{
Alert alert = new Alert(Alert.AlertType.INFORMATION);
alert.setHeaderText(null);
alert.setContentText("Incorrect username or password!");
alert.showAndWait();
}
}
catch (SQLException ex) {
Alert alert = new Alert(Alert.AlertType.INFORMATION);
alert.setHeaderText(null);
alert.setContentText("Incorrect username or password!");
alert.showAndWait();
System.out.println(ex.toString());
} catch (NoSuchAlgorithmException | InvalidKeySpecException | IOException ex) {
Logger.getLogger(FXMLDocumentController.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
@FXML
void handleEnterButtonPress(KeyEvent event)
{
if(event.getCode().equals(KeyCode.ENTER))
{
btnSignIn.fire();
}
}
@Override
public void initialize(URL url, ResourceBundle rb) {
// TODO
}
private PreparedStatement createPreparedStatement(Connection con, String username) throws SQLException {
String sql = "SELECT * FROM User WHERE username = ?";
PreparedStatement ps = con.prepareStatement(sql);
ps.setString(1, username);
return ps;
}
boolean authenticate(String attemptedPassword, byte[] encryptedPassword, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException
{
byte[] encryptedAttmeptedPassword = getEncryptedPassword(attemptedPassword, salt);
return Arrays.equals(encryptedPassword, encryptedAttmeptedPassword);
}
public byte[] getEncryptedPassword(String password, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException
{
String algorithm = "PBKDF2WithHmacSHA1";
int derivedKeyLength = 160;
int iterations = 2000;
KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, iterations, derivedKeyLength);
SecretKeyFactory f = SecretKeyFactory.getInstance(algorithm);
return f.generateSecret(spec).getEncoded();
}
public byte[] generateSalt() throws NoSuchAlgorithmException
{
SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
byte[] salt = new byte[8];
random.nextBytes(salt);
return salt;
}
}
FXML
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.PasswordField?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.text.Text?>
<AnchorPane id="apMain" onKeyReleased="#handleEnterButtonPress" prefHeight="350.0" prefWidth="425.0" stylesheets="@../css/log_in_stylesheet.css" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1" fx:controller="planningchart3.FXMLDocumentController">
<children>
<GridPane alignment="CENTER" hgap="10.0" layoutX="45.0" layoutY="69.0" prefHeight="284.0" prefWidth="448.0" vgap="10.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
<columnConstraints>
<ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
<ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
<ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
<ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
<ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
</columnConstraints>
<rowConstraints>
<RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
<RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
<RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
<RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
<RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
<RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
</rowConstraints>
<padding>
<Insets bottom="25.0" left="25.0" right="25.0" top="25.0" />
</padding>
<children>
<TextField fx:id="tfUsername" promptText="username" text="sedj601" GridPane.columnIndex="2" GridPane.columnSpan="2" GridPane.rowIndex="3" />
<PasswordField fx:id="pfPassword" prefHeight="25.0" prefWidth="107.0" promptText="password" text="hello" GridPane.columnIndex="2" GridPane.columnSpan="2" GridPane.rowIndex="4" />
<Button fx:id="btnSignIn" alignment="CENTER" contentDisplay="CENTER" mnemonicParsing="false" onAction="#handlebtnSignIn" prefHeight="30.0" prefWidth="92.0" text="Sign in" wrapText="true" GridPane.columnIndex="3" GridPane.rowIndex="5" />
<Text id="welcomeText" strokeType="OUTSIDE" strokeWidth="0.0" text="Welcome" GridPane.columnIndex="1" GridPane.rowIndex="2">
<font>
<Font name="Tahoma" size="20.0" />
</font>
</Text>
<Label styleClass="outline" text="User name: " textFill="#03244d" GridPane.columnIndex="1" GridPane.columnSpan="2" GridPane.rowIndex="3">
<font>
<Font name="Cambria Bold" size="14.0" />
</font></Label>
<Label styleClass="outline" text="Password: " textFill="#03244d" GridPane.columnIndex="1" GridPane.columnSpan="2" GridPane.rowIndex="4">
<font>
<Font name="Cambria Bold" size="14.0" />
</font></Label>
</children>
</GridPane>
</children>
</AnchorPane>
我将用户名设置为sedj601，将密码设置为hello。你可能想要摆脱这一部分。
这是有用的here。
这部分可能会对您的问题更有帮助。
try
{
if(tfUsername.getText().equals(username) && authenticate(pfPassword.getText(), encryptedPassword, salt))
{
Stage stage = new Stage();
stage.setWidth(1080);
stage.setHeight(720);
Parent fxmlLoader = null;
switch(accountType)
{
case "administrator":
stage.setTitle("Tech Services Console");
System.out.println("I just signed in as an administrator");
fxmlLoader = FXMLLoader.load(getClass().getResource("AdminView.fxml"));
break;
case "collection":
stage.setTitle("Collection Console");
System.out.println("I just signed in as a collection member");
fxmlLoader = FXMLLoader.load(getClass().getResource("CollectionDevView.fxml"));
break;
case "selector":
stage.setTitle("Selector Console");
System.out.println("I just signed in as a selector member");
fxmlLoader = FXMLLoader.load(getClass().getResource("Selector.fxml"));
break;
}
stage.setScene(new Scene(fxmlLoader));
stage.show();
((Node)(event.getSource())).getScene().getWindow().hide();
tfUsername.setText("");
pfPassword.setText("");
}
else
{
Alert alert = new Alert(Alert.AlertType.INFORMATION);
alert.setHeaderText(null);
alert.setContentText("Incorrect username or password!");
alert.showAndWait();
}
}
catch (SQLException ex) {
Alert alert = new Alert(Alert.AlertType.INFORMATION);
alert.setHeaderText(null);
alert.setContentText("Incorrect username or password!");
alert.showAndWait();
System.out.println(ex.toString());
}
catch (NoSuchAlgorithmException | InvalidKeySpecException | IOException ex)
{
Logger.getLogger(FXMLDocumentController.class.getName()).log(Level.SEVERE, null, ex);
}