桌面应用程序中英文资料外文翻译文献Binding Beans and Data in a Desktop Application This guide is an introduction to the support in NetBeans IDE 6.0 for beans binding and data binding in Java desktop applications.Software and Files Needed for the TutorialFor this tutorial you need to have the following software installed on your computer:NetBeans IDE 6.0 (download).Java Standard Development Kit (JDK) version 5.0 or 6.0 (download)Introduction: Beans Binding in NetBeans IDE 6.0Until the release of the beans binding library, it was somewhat cumbersome to connect UI components to databases or to keep values of component properties in sync. For example, displaying data from a standard database in a JTable required the manual creation of utility classes to handle the connection between the database and the JTable. And keeping values of different bean properties in sync (such as the value of a JTextField with the rendering of a visual bean) required hand-coding of listeners and event handlers.The beans binding library simplifies and standardizes all of this. You can merely write a few lines of code to establish which properties of which components need to be kept in sync, and the beans binding library handles the rest. In the NetBeans IDE, beans binding features are integrated in the GUI Builder, so you can quickly get the behavior of your application coded soon after you have established the visual design.This guide is an overview of the main aspects of beans binding in the IDE. For aconcrete example of many of these features, you can try the Building a Java Desktop Database Application tutorial.Binding Properties to Other PropertiesAt its most basic, beans binding is a way to connect bean properties without using event listening and handling code.To illustrate the concept of beans binding and how the IDE supports it, we will do a simple example where a user can adjust a slider to change a numerical value in a text field.To set up the example:In the IDE, choose, File > New Project.Select the Java category and select the Java Application template. Click Next.In the Name and Location page of the wizard, perform the following operations: Type NumberSlider as the project name.Leave the Set As Main Project checkbox selected.Clear the Create Main Class checkbox.Click Finish to exit the wizard and set up the project.In the Projects window, right-click the NumberSlider project node and choose New > JFrame Form.(If JFrame Form is not available in the New menu, choose Other. Then in theNew File wizard, select the Swing GUI Forms category and select the JFrame Form template.)In the Name and Location page of the wizard, perform the following operations: Type NumberSliderFrame for the class name.Type numberslider for the package name.Click Finish to exit the wizard and create the form.NumberSliderForm.java should open in design mode in the editing area.From the Swing Controls section of the Palette, drag a slider component into the design area. (If the Palette window is not open, choose Window > Palette.) From the Palette, drag a text field component to the design area.The resulting form might look something like the screenshot below. However, positioning is not important for purposes of this example.Source and TargetNow that we have set up the example, we are ready to create the binding. However, first we need to determine which component will be the source of the binding and which will be the target. The binding source component is where a value for the property first originates.When binding in the GUI Editor, you initiate a binding on the target and then you declare the source in the Bind dialog box.In this case, since the JSlider comes with a default range of values, we will use it as the source.Note: Bindings can be two-way (read/write), so that changes in the target are automatically reflected in the source. However, the direction of the initial binding is always from the source to the target. See the information on Update Mode in the Advanced Binding Configuration section.To bind the slider to the text field:Right-click the text field component and choose Bind > text to open the Bind dialog box.From the Binding Source combo box, select jSlider1.From the Binding Expression combo box, select value int as shown in the image below.Click OK.You have just bound the value bean property of the slider to the text value of the text field.In the design area, the text field should show the value 50. This value reflects the fact that the slider is in the middle position and the default range of values for the slider is from 0 to 100.You can now run the application and see the binding in action.To run the project:Choose Run > Run Main Project.In the Run Project dialog box, click OK to accept numberslider.NumberSliderForm as the main class.The applications should start in a separate window. Adjust the slider in the running application and watch the value change in the text field.Advanced Binding ConfigurationThe example above shows a straightforward binding with some default behaviors. But sometimes you might want or need to configure your binding differently. If that is the case, you can use the Advanced tab of the Binding dialog box.The Advanced tab of the dialog box contains the following fields:Name. Enables you to create a name for the binding, which gives you more flexibility for managing your bindings. The name is added to the constructor of the binding and can be referenced with the binding's getName() method.Update Mode. Specifies the way that the properties are kept synchronized. The possible values are:Always sync (read/write). Whenever a change is made to either the source or the target, the other is updated.Only read from source (read only). The target is only updated the first time the source value is set. Changes that are made to the source are updated in the target. Changes made to the target are not updated in the source.Read from source once (read once). The target is only updated when the target and source are initially bound.Update Source When (available only to the text property of JTextField and JTextArea components). Enables you to select the frequency with which the properties are synchronized.Ignore Adjusting (available to the value property of JSlider; to the selectedElement property of JTable and JList; and to the selectedElements property ofJTable and JList). If this checkbox is selected, any changes made to one property are not propagated to the other property until the user is finished making the change. For example, when the application's user drags a slider, the value of the property to which the slider's value property is bound is only updated once the user releases the mouse button.Converter. If your binding involves properties with different data types, you can specify code that converts values between the types. The beans binding library handles many commonly needed conversions, but you might need to provide your own converters for other combinations of property types. Such converters need to extend the org.jdesktop.beansbinding.Converter class.The Converter drop-down list is populated with any converters that have been added as beans to your form. You can also add the conversion code directly by clicking the ellipsis (...) button, and selecting Custom Code from the Select Converter Property Using drop-down list.Validator. Enables you to specify code to validate a change in the target property value before propagating that change back to the source property. For example, you can use a validator to make sure that an integer property value is within a specific range.Validators need to extend the org.jdesktop.beansbinding.Validator class.The Validator drop-down list is populated with any validators that have been added as beans to your form. You can also add the validation code directly by clicking the ellipsis (...) button, and selecting Custom Code from the Select Validator Property Using drop-down list.Null Source Value. Enables you to specify a different value to use if the source property has a null value when the binding is attempted. This field corresponds with the setSourceNullValue() method of the org.jdesktop.beansbinding.Binding class.Unreadable Source Value. Enables you to specify a different value to use if the binding expression cannot be resolved when the binding is attempted. This field corresponds with the setSourceUnreadableValue() method of the org.jdesktop.beansbinding.Binding class.Note: To better understand the classes and methods mentioned above, you can access the beans binding Javadoc documentation directly from the IDE. Choose Help > Javadoc References > Beans Binding. In the browser window that opens, click the org.jdesktop.beansbinding link to access documentation for those classes.Binding Data to ComponentsOnce you have created a new Java form and added components to the form, you can generate code to bind those components to data. The IDE makes it easy to bind data to Swing JTable, JList, and JComboBox components.Before binding a component to data from a database, you need to have done the following things:Connected to a database in the IDE.Added the component to a form in the GUI Builder.Created classes that represent the database tables to which you want to bind. Steps on creating the entity classes for binding data to a component are given below.Creating Entity ClassesTo create entity classes to represent the database that is to be bound to the JTable: In the Projects window, right-click your project and choose New > Other, select the Persistence category, and select the Entity Classes from Database template.In the Database Tables page of the wizard, select the database connection.Once the Available Tables column is populated, select the tables that you want to use in your application and click Add to move them to the Selected Tables column. Click Next.In the Entity Classes page of the wizard, make sure the Generate Named QueryAnnotations for Persistent Fields dialog box is selected.Make any customizations that you want to make to the names of the generated classes and their location.Click Create Persistence Unit.In the Create Persistence Unit dialog box, make sure of the following things:That the selected Persistence Library is TopLink.That the selected Table Generation Strategy is "None".Click Finish.You should see nodes for the entity classes in the Projects window.Binding Components to the Beans That Represent the DataTo bind the data to a JTable component:Right-click the component in the GUI Builder and choose Bind > elements.Click Import Data to Form. From the Import Data to Form dialog box, select the database table to which you want to bind your components. Click OK.From the Binding Source combo box, select the item that represents the result list of the entity class. For example, if the entity class is called, Customer.java, the list object would be generated as customerList.Leave the Binding Expression value as null.If there are any database columns that you want to appear in the JTable, select those columns in the Selected list and move them to the Available list.Select the Advanced tab to further configure the binding. For example, you can specify a validator or converter, or you can specify behavior if the binding source is null or unreadable.Click OK.To bind the data to a JList component:Right-click the component in the GUI Builder and choose Bind > elements.Click Import Data to Form. From the Import Data to Form dialog box, select the database table to which you want to bind your components. Click OK.From the Binding Source combo box, select the item that represents the result list of the entity class. For example, if the entity class is called, Customer.java, the list object would be generated as customerList.Leave the Binding Expression value as null.In the Display Expression drop-down list, select the property that represents the database column that contains the values that you want to display in the list.Select the Advanced tab to further configure the binding.Click OK.Note: You can also use the New Java Desktop Application wizard to quickly create a whole working application that has CRUD (create, read, update, and delete) features. However, it is better to generate all the entity classes in advance to ensure that all relations among the entities are correctly covered by the generated classes.Special Binding PropertiesWhere necessary, the beans binding library provides special synthetic properties for some Swing components that are missing from the components themselves. Theseproperties represent things, such as a table's selected row, that are useful to bind to other properties.在桌面应用程序中Bean和数据的绑定这个向导是一个在java桌面应用程序中对于NetBeans IDE 6.0中支持bean 绑定以及数据绑定的介绍。