我正在研究JAVAFX应用程序.在我的应用程序中,单击一个按钮后,它会打开一个窗口,其中包含一个TableView,其中包含一个“应用并保存”按钮.单击“应用”按钮时,它将保留TableView的当前状态(如果我们添加/删除表行并单击“应用”并重新打开表,则应显示先前更新的TableView). “保存”按钮用于将表记录保存到数据库.假设表中有两行(来自数据库),如果我添加第三行并单击Apply,我的TableView窗口将被关闭.如果我重新打开表格,则第三行不存在.
如何保留以前添加的第三行,而不将其插入数据库？
最佳答案 您可以尝试将TableView的项(或者可选地只是TableView的添加项的列表)存储为打开窗口的类中的成员.
我创建了一个例子：
应用程序TableViewSample可用于打开第二个窗口.此应用程序存储TablePopUp的一个实例,该类可以显示第二个模态阶段,同时维护一个“缓冲区” – 一个Person列表(TableView上显示的数据模型)对象,它们被添加到TableView并被“应用” “但尚未存储在数据库中.
public class TableViewSample extends Application {
// Stores the state of the TableView and opens the second window
TablePopUp popUp = new TablePopUp();
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage stage) {
Scene scene = new Scene(new BorderPane());
stage.setTitle("Table View Sample");
stage.setWidth(450);
stage.setHeight(550);
BorderPane root = (BorderPane) scene.getRoot();
Button button = new Button("Open window");
button.setOnAction((e) -> popUp.showTable());
root.setCenter(button);
stage.setScene(scene);
stage.show();
}
class TablePopUp {
// Stores the Person object which were added and applied but not stored
// in DB
ObservableList<Person> bufferAdd = FXCollections.observableArrayList();
// Simulate the items coming from the DV
private ObservableList<Person> dataFromDB = FXCollections.observableArrayList(
new Person("Jacob", "Smith", "jacob.smith@example.com"),
new Person("Isabella", "Johnson", "isabella.johnson@example.com"),
new Person("Ethan", "Williams", "ethan.williams@example.com"),
new Person("Emma", "Jones", "emma.jones@example.com"),
new Person("Michael", "Brown", "michael.brown@example.com"));
void showTable() {
// Temporary buffer for the added Persion objects
ObservableList<Person> tempBuffer = FXCollections.observableArrayList();
// Temporary buffer to store persons to be deleted on apply
ObservableList<Person> bufferRemoveFromBuffer = FXCollections.observableArrayList();
// Data what the TableView displays
ObservableList<Person> tableData = FXCollections.observableArrayList();
// Stores the person objects that will be removed from the DB if Save is pressed
ObservableList<Person> bufferRemoveFromDB = FXCollections.observableArrayList();
// The Table displays elements from the DB + the applied buffer
tableData.addAll(dataFromDB);
tableData.addAll(bufferAdd);
// Create the table
TableView<Person> table = new TableView<Person>();
table.setItems(tableData);
Scene scene = new Scene(new BorderPane());
final Label label = new Label("Address Book");
label.setFont(new Font("Arial", 20));
TableColumn firstNameCol = new TableColumn("First Name");
firstNameCol.setMinWidth(100);
firstNameCol.setCellValueFactory(new PropertyValueFactory<Person, String>("firstName"));
TableColumn lastNameCol = new TableColumn("Last Name");
lastNameCol.setMinWidth(100);
lastNameCol.setCellValueFactory(new PropertyValueFactory<Person, String>("lastName"));
TableColumn emailCol = new TableColumn("Email");
emailCol.setMinWidth(200);
emailCol.setCellValueFactory(new PropertyValueFactory<Person, String>("email"));
table.getColumns().addAll(firstNameCol, lastNameCol, emailCol);
TextField addFirstName = new TextField();
addFirstName.setPromptText("First Name");
addFirstName.setMaxWidth(firstNameCol.getPrefWidth());
TextField addLastName = new TextField();
addLastName.setMaxWidth(lastNameCol.getPrefWidth());
addLastName.setPromptText("Last Name");
TextField addEmail = new TextField();
addEmail.setMaxWidth(emailCol.getPrefWidth());
addEmail.setPromptText("Email");
// Button to add a new Person
Button addButton = new Button("Add");
addButton.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent e) {
Person newPerson = new Person(addFirstName.getText(), addLastName.getText(), addEmail.getText());
// Add a new element to the temporary buffer and add it to
// the table data also
tempBuffer.add(newPerson);
tableData.add(newPerson);
addFirstName.clear();
addLastName.clear();
addEmail.clear();
}
});
// Button to remove a Person
Button removeButton = new Button("Remove");
removeButton.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent e) {
Person selectedItem = table.getSelectionModel().getSelectedItem();
if(selectedItem != null) {
// Remove the item from the list of the displayed persons
tableData.remove(selectedItem);
// Check the buffers: if one of the buffer contains the selected item, remove it from the buffer
if(tempBuffer.contains(selectedItem))
tempBuffer.remove(selectedItem);
else if(bufferAdd.contains(selectedItem))
bufferRemoveFromBuffer.add(selectedItem);
else {
// The item is not in the buffers -> remove the item from the DB
bufferRemoveFromDB.add(selectedItem);
}
}
}
});
HBox hb = new HBox();
hb.getChildren().addAll(addFirstName, addLastName, addEmail, addButton, removeButton);
hb.setSpacing(3);
VBox vbox = new VBox();
vbox.setSpacing(5);
vbox.setPadding(new Insets(10, 0, 0, 10));
vbox.getChildren().addAll(label, table, hb);
BorderPane root = (BorderPane) scene.getRoot();
root.setCenter(vbox);
Stage stage = new Stage();
HBox applySave = new HBox();
// On Save:
// Remove all elements from the buffer that were selected to be deleted
// Remove all elements from the BD that were selected to be deleted
// Add all the elements from the persistent buffer to the DB
// Add all the elements from the temporary buffer to the DB
// Clear both buffers
Button saveButton = new Button("Save to DB");
saveButton.setOnAction((e) -> {
bufferAdd.removeAll(bufferRemoveFromBuffer);
dataFromDB.removeAll(bufferRemoveFromDB);
dataFromDB.addAll(bufferAdd);
dataFromDB.addAll(tempBuffer);
bufferAdd.clear();
stage.close();
});
// On Apply:
// Add elements from the temporary buffer to the persistent buffer
// Remove elements from the buffer
Button applyButton = new Button("Apply");
applyButton.setOnAction((e) -> {
bufferAdd.addAll(tempBuffer);
bufferAdd.removeAll(bufferRemoveFromBuffer);
stage.close();
});
applySave.getChildren().addAll(saveButton, applyButton);
root.setBottom(applySave);
stage.initModality(Modality.APPLICATION_MODAL);
stage.setScene(scene);
stage.show();
}
}
public static class Person {
private final SimpleStringProperty firstName;
private final SimpleStringProperty lastName;
private final SimpleStringProperty email;
private Person(String fName, String lName, String email) {
this.firstName = new SimpleStringProperty(fName);
this.lastName = new SimpleStringProperty(lName);
this.email = new SimpleStringProperty(email);
}
public String getFirstName() {
return firstName.get();
}
public void setFirstName(String fName) {
firstName.set(fName);
}
public String getLastName() {
return lastName.get();
}
public void setLastName(String fName) {
lastName.set(fName);
}
public String getEmail() {
return email.get();
}
public void setEmail(String fName) {
email.set(fName);
}
}
}
TablePopUp类实际上有两个缓冲区：一个临时缓冲区,用于存储添加的元素;一个持久缓冲区,保存在不同的窗口之间.如果按下“应用”按钮,则临时缓冲区存储在持久缓冲区中.如果按下“保存”按钮,则两个缓冲区都存储在DB中,然后清除它们.
在示例中,还删除了删除.在删除时,它会发现,选择要从数据库中删除的Person对象是否来自数据库.如果它来自数据库,它将被放置到缓冲区,如果按下保存按钮,它只会从数据库中删除.相同的工作流程对于已添加但尚未放入数据库的人员有效：在删除时,如果按下“应用”按钮,则仅删除它们.
