JavaFX Alert对话框

1. 标准对话框

消息对话框

Alert alert = new Alert(AlertType.INFORMATION);
alert.setTitle("Information Dialog");
alert.setHeaderText("Look, an Information Dialog");
alert.setContentText("I have a great message for you!");

alert.showAndWait();

没有标题的消息对话框

Alert alert = new Alert(AlertType.INFORMATION);
alert.setTitle("Information Dialog");
alert.setHeaderText(null);
alert.setContentText("I have a great message for you!");

alert.showAndWait();

2. 警告对话框

Alert alert = new Alert(AlertType.WARNING);
alert.setTitle("Warning Dialog");
alert.setHeaderText("Look, a Warning Dialog");
alert.setContentText("Careful with the next step!");

alert.showAndWait();

3. 错误对话框

Alert alert = new Alert(AlertType.ERROR);
alert.setTitle("Error Dialog");
alert.setHeaderText("Look, an Error Dialog");
alert.setContentText("Ooops, there was an error!");

alert.showAndWait();

4. 异常对话框
这不是一个完整的异常对话框。但我们可以很容易地将 TextArea 作为可扩展的内容。

Alert alert = new Alert(AlertType.ERROR);
alert.setTitle("Exception Dialog");
alert.setHeaderText("Look, an Exception Dialog");
alert.setContentText("Could not find file blabla.txt!");

Exception ex = new FileNotFoundException("Could not find file blabla.txt");

// Create expandable Exception.
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
ex.printStackTrace(pw);
String exceptionText = sw.toString();

Label label = new Label("The exception stacktrace was:");

TextArea textArea = new TextArea(exceptionText);
textArea.setEditable(false);
textArea.setWrapText(true);

textArea.setMaxWidth(Double.MAX_VALUE);
textArea.setMaxHeight(Double.MAX_VALUE);
GridPane.setVgrow(textArea, Priority.ALWAYS);
GridPane.setHgrow(textArea, Priority.ALWAYS);

GridPane expContent = new GridPane();
expContent.setMaxWidth(Double.MAX_VALUE);
expContent.add(label, 0, 0);
expContent.add(textArea, 0, 1);

// Set expandable Exception into the dialog pane.
alert.getDialogPane().setExpandableContent(expContent);

alert.showAndWait();

5. 确认对话框

Alert alert = new Alert(AlertType.CONFIRMATION);
alert.setTitle("Confirmation Dialog");
alert.setHeaderText("Look, a Confirmation Dialog");
alert.setContentText("Are you ok with this?");

Optional<ButtonType> result = alert.showAndWait();
if (result.get() == ButtonType.OK){
    // ... user chose OK
} else {
    // ... user chose CANCEL or closed the dialog
}

6. 自定义确认对话框

Alert alert = new Alert(AlertType.CONFIRMATION);
alert.setTitle("Confirmation Dialog with Custom Actions");
alert.setHeaderText("Look, a Confirmation Dialog with Custom Actions");
alert.setContentText("Choose your option.");

ButtonType buttonTypeOne = new ButtonType("One");
ButtonType buttonTypeTwo = new ButtonType("Two");
ButtonType buttonTypeThree = new ButtonType("Three");
ButtonType buttonTypeCancel = new ButtonType("Cancel", ButtonData.CANCEL_CLOSE);

alert.getButtonTypes().setAll(buttonTypeOne, buttonTypeTwo, buttonTypeThree, buttonTypeCancel);

Optional<ButtonType> result = alert.showAndWait();
if (result.get() == buttonTypeOne){
    // ... user chose "One"
} else if (result.get() == buttonTypeTwo) {
    // ... user chose "Two"
} else if (result.get() == buttonTypeThree) {
    // ... user chose "Three"
} else {
    // ... user chose CANCEL or closed the dialog
}

7. 可输入的对话框

TextInputDialog dialog = new TextInputDialog("walter");
dialog.setTitle("Text Input Dialog");
dialog.setHeaderText("Look, a Text Input Dialog");
dialog.setContentText("Please enter your name:");

// Traditional way to get the response value.
Optional<String> result = dialog.showAndWait();
if (result.isPresent()){
    System.out.println("Your name: " + result.get());
}

// The Java 8 way to get the response value (with lambda expression).
result.ifPresent(name -> System.out.println("Your name: " + name));

说明：如果用户点击了取消按钮result.isPresent()将会返回false

8. 可选择的对话框

List<String> choices = new ArrayList<>();
choices.add("a");
choices.add("b");
choices.add("c");

ChoiceDialog<String> dialog = new ChoiceDialog<>("b", choices);
dialog.setTitle("Choice Dialog");
dialog.setHeaderText("Look, a Choice Dialog");
dialog.setContentText("Choose your letter:");

// Traditional way to get the response value.
Optional<String> result = dialog.showAndWait();
if (result.isPresent()){
    System.out.println("Your choice: " + result.get());
}

// The Java 8 way to get the response value (with lambda expression).
result.ifPresent(letter -> System.out.println("Your choice: " + letter));

引用

说明：如果用户没有选择或点击了取消，result.isPresent()将会返回false

9. 自定义登录框

// Create the custom dialog.
Dialog<Pair<String, String>> dialog = new Dialog<>();
dialog.setTitle("Login Dialog");
dialog.setHeaderText("Look, a Custom Login Dialog");

// Set the icon (must be included in the project).
dialog.setGraphic(new ImageView(this.getClass().getResource("login.png").toString()));

// Set the button types.
ButtonType loginButtonType = new ButtonType("Login", ButtonData.OK_DONE);
dialog.getDialogPane().getButtonTypes().addAll(loginButtonType, ButtonType.CANCEL);

// Create the username and password labels and fields.
GridPane grid = new GridPane();
grid.setHgap(10);
grid.setVgap(10);
grid.setPadding(new Insets(20, 150, 10, 10));

TextField username = new TextField();
username.setPromptText("Username");
PasswordField password = new PasswordField();
password.setPromptText("Password");

grid.add(new Label("Username:"), 0, 0);
grid.add(username, 1, 0);
grid.add(new Label("Password:"), 0, 1);
grid.add(password, 1, 1);

// Enable/Disable login button depending on whether a username was entered.
Node loginButton = dialog.getDialogPane().lookupButton(loginButtonType);
loginButton.setDisable(true);

// Do some validation (using the Java 8 lambda syntax).
username.textProperty().addListener((observable, oldValue, newValue) -> {
    loginButton.setDisable(newValue.trim().isEmpty());
});

dialog.getDialogPane().setContent(grid);

// Request focus on the username field by default.
Platform.runLater(() -> username.requestFocus());

// Convert the result to a username-password-pair when the login button is clicked.
dialog.setResultConverter(dialogButton -> {
    if (dialogButton == loginButtonType) {
        return new Pair<>(username.getText(), password.getText());
    }
    return null;
});

Optional<Pair<String, String>> result = dialog.showAndWait();

result.ifPresent(usernamePassword -> {
    System.out.println("Username=" + usernamePassword.getKey() + ", Password=" + usernamePassword.getValue());
});

10. 修改对话框样式

自定义图标

// Get the Stage.
Stage stage = (Stage) dialog.getDialogPane().getScene().getWindow();

// Add a custom icon.
stage.getIcons().add(new Image(this.getClass().getResource("login.png").toString()));

说明：根据JavaFX 8u40最终版本的BUG报告，应该使用与它正在运行的应用程序相同的图标。在这种情况下，你还需要设置它的所有者，对话框会得到所有者的图标:

dialog.initOwner(otherStage);

不使用图标

dialog.initStyle(StageStyle.UTILITY);

11. 其他操作

设置拥有者

你可以为每一个对话框指定所有者。如果指定所有者或拥有者为null，那么它是一个顶级的、未拥有的对话框。

dialog.initOwner(parentWindow);

设置模式

你可以指定对话框的模式，包括Modality.NONE、WINDOW_MODAL或Modality.APPLICATION_MODAL。

dialog.initModality(Modality.NONE);