jface databinding:输入无效数值时强制恢复初始值-updateModelToTarget

    /**
     * Updates the target's state from the model's state at the next reasonable
     * opportunity. There is no guarantee that the state will have been updated
     * by the time this call returns.
     * 在合适的机会将model状态更新到target,因为是异步更新，所以不保证当方法返回时target更新完成。
     */
    public abstract void updateModelToTarget();

package testwb;

import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Text;
import org.eclipse.core.databinding.Binding;
import org.eclipse.core.databinding.DataBindingContext;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.databinding.observable.value.WritableValue;
import org.eclipse.jface.databinding.swt.WidgetProperties;
import org.eclipse.swt.widgets.Display;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.jface.databinding.fieldassist.ControlDecorationSupport;
import org.eclipse.jface.databinding.swt.DisplayRealm;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;

public class TestPojoBinding5 extends Dialog {

    private DataBindingContext m_bindingContext;
    // floatValue 初始值0.5f
    private final WritableValue<Float> floatValue = new WritableValue<Float>(Float.valueOf(0.5f), Float.class);
    // Text文本框对象
    private Text floatValueText;
    private Binding bindValue;

    /**
     * Create the dialog.
     * @param parentShell
     */
    public TestPojoBinding5(Shell parentShell) {
        super(parentShell);
    }

    /**
     * Create contents of the dialog.
     * @param parent
     */
    @Override
    protected Control createDialogArea(Composite parent) {
        Composite container = (Composite) super.createDialogArea(parent);
        container.setLayout(null);

        Button btnNewButton = new Button(container, SWT.NONE);
        // 点击“恢复初始值”按钮时，将floatValue重新设置为初始值
        btnNewButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                floatValue.setValue(Float.valueOf(0.5f));
            }
        });
        btnNewButton.setBounds(38, 154, 80, 27);
        btnNewButton.setText("恢复初始值");

        floatValueText = new Text(container, SWT.BORDER);
        floatValueText.setBounds(38, 27, 80, 23);

        return container;
    }

    /**
     * Create contents of the button bar.
     * @param parent
     */
    @Override
    protected void createButtonsForButtonBar(Composite parent) {
        createButton(parent, IDialogConstants.OK_ID, IDialogConstants.OK_LABEL, true);
        createButton(parent, IDialogConstants.CANCEL_ID, IDialogConstants.CANCEL_LABEL, false);
        m_bindingContext = initDataBindings();
    }

    /**
     * Return the initial size of the dialog.
     */
    @Override
    protected Point getInitialSize() {
        return new Point(362, 298);
    }
    public static void main(String[] args) {
        Display display = Display.getDefault();
        Realm.runWithDefault(DisplayRealm.getRealm(display), new Runnable() {
            public void run() {
                try {
                    TestPojoBinding5 setting = new TestPojoBinding5(null);
                    setting.open();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
    protected DataBindingContext initDataBindings() {
        DataBindingContext bindingContext = new DataBindingContext();
        //
        IObservableValue observeTextFloatValueTextObserveWidget = WidgetProperties.text(SWT.Modify).observe(floatValueText);
        //　将floatValueText和floatValue进行数据绑定
        bindValue=bindingContext.bindValue(observeTextFloatValueTextObserveWidget, floatValue, null, null);
        // 创建验证错误提示组件(就是Text文本框左上角的红X号，数据验证出错时显示)，
        ControlDecorationSupport.create(bindValue, SWT.TOP | SWT.LEFT);
        return bindingContext;
    }
}

        // 点击“恢复初始值”按钮时，将floatValue重新设置为初始值
        btnNewButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                floatValue.setValue(Float.valueOf(0.5f));
                // 强制更新Text组件内容
                bindValue.updateModelToTarget();
            }
        });

        // 点击“恢复初始值”按钮时，将floatValue重新设置为初始值
        btnNewButton.addSelectionListener(new SelectionAdapter() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                // 判断floatValue是否等于初始值(0.5f)，如果是的话，只做强制更新
                if(floatValue.getValue()==0.5f)
                    bindValue.updateModelToTarget();
                else// 否则就更新floatValue，Text会自动更新。
                    floatValue.setValue(Float.valueOf(0.5f));               
            }
        });