jface databinding(数据挷定)中的数据转换(IConverter)和数据验证(IValidator )

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.UpdateValueStrategy;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.databinding.validation.IValidator;
import org.eclipse.core.databinding.validation.ValidationStatus;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.jface.databinding.swt.WidgetProperties;
import org.eclipse.core.databinding.beans.PojoProperties;
import org.eclipse.core.databinding.conversion.StringToNumberConverter;
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;

public class TestBinding extends Dialog {
    /**
     * 数据对象定义
     * @author guyadong
     *
     */
    public class Configuration {
        private Float globalAspectRatio;

        public Float getGlobalAspectRatio() {
            return globalAspectRatio;
        }

        public void setGlobalAspectRatio(Float globalAspectRatio) {
            this.globalAspectRatio = globalAspectRatio;
            System.out.printf("updated %f\n",globalAspectRatio);
        }

        public Configuration(Float globalAspectRatio) {
            super();
            this.globalAspectRatio = globalAspectRatio;
        }
    }
    private DataBindingContext m_bindingContext;
    /**
     * 成员变量：数据对象
     */
    protected Configuration editorConfig=new Configuration(0.5f);
    /**
     * Text组件
     */
    private Text globalAspectRatioValue;

    /**
     * Create the dialog.
     * @param parentShell
     */
    public TestBinding(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);
        globalAspectRatioValue = new Text(container, SWT.BORDER);
        globalAspectRatioValue.setBounds(38, 28, 73, 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);
    }
    @Override
    protected void configureShell(Shell newShell) {
        newShell.setText("设置");  
        super.configureShell(newShell);
    }
    public static void main(String[] args) {
        Display display = Display.getDefault();
        Realm.runWithDefault(DisplayRealm.getRealm(display), new Runnable() {
            public void run() {
                try {
                    TestBinding setting = new TestBinding(null);
                    setting.open();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    protected DataBindingContext initDataBindings() {
        DataBindingContext bindingContext = new DataBindingContext();
        IObservableValue observeTextGlobalAspectRatioValueObserveWidget = WidgetProperties.text(SWT.Modify).observe(globalAspectRatioValue);
        IObservableValue globalAspectRatioEditorConfigObserveValue = PojoProperties.value("globalAspectRatio").observe(editorConfig);
        // 创建String 到 Float的转换器
        StringToNumberConverter converter = StringToNumberConverter.toFloat(false);
        // 更新策略对象(Text内容改变时更新)
        UpdateValueStrategy updateStrategy = new UpdateValueStrategy(UpdateValueStrategy.POLICY_UPDATE).setConverter(converter);
        // 设置Set方法验证器(Set方法修改Text文本内容之前验证)
        // Lambda表达式实现，验证失败返回错误信息
        updateStrategy.setBeforeSetValidator((value) -> {
                // 这里value的类型是数据对象的属性类型 (Float)
                if ((Float)value<100) {
                    return ValidationStatus.ok();
                }
                return ValidationStatus.error("globalAspectRatio must <100");
        });
        // 设置Get方法验证器(Get方法获取Text文本内容之后验证)
        // 传统匿名类实现，验证失败返回错误信息
        updateStrategy.setAfterGetValidator(new IValidator() {
            @Override
            public IStatus validate(Object value) {         
                // 这里value的类型是Text对象的text属性类型(String)   
                boolean ok=false;
                try{
                    Float s = (Float) converter.convert(value);
                    if (s<100) {
                        ok=true;
                        return ValidationStatus.ok();
                    }
                    return ValidationStatus.error("globalAspectRatio must <100");
                }catch(Exception e){
                    return ValidationStatus.error("无效数字");
                }finally{
                    // 数据无效时 disable OK按钮
                    getButton(IDialogConstants.OK_ID).setEnabled(ok);
                }}
        });
        // 调用bindValue完成Text.text到数据对象的globalAspectRatio属性的绑定
        Binding bindValue = bindingContext.bindValue(observeTextGlobalAspectRatioValueObserveWidget, globalAspectRatioEditorConfigObserveValue, 
                updateStrategy,
                null);
        // 创建错误提示组件，当验证失败时显示提示信息
        ControlDecorationSupport.create(bindValue, SWT.TOP | SWT.LEFT);
        return bindingContext;
    }
}