不推荐使用richfaces javax.faces.el.MethodBinding替换使用

Question

我发现这段代码的工作原理是我可以通过编程方式创建一个richfaces下拉菜单.但有些代码已被弃用.谁能告诉我要放什么而不是弃用的电话？

谢谢

     public HtmlDropDownMenu getMyMenu()
 {
  HtmlDropDownMenu menu = new HtmlDropDownMenu();
  menu.setValue( "Node Select" );

  HtmlMenuItem menuItem = new HtmlMenuItem();
  // TODO programmatically pass from getNodes into a String[] rather than an ArrayList of SelectItems
  String subOption = "myBox";   
  menuItem.setValue( subOption );

  Application app = FacesContext.getCurrentInstance().getApplication();
  javax.faces.el.MethodBinding mb = app.createMethodBinding( "#{PrismBacking.onItemClick}", new Class[] { ActionEvent.class } );
  menuItem.setActionListener( mb );

  menu.getChildren().add( menuItem );
  return( menu );
 }

 public void onItemClick( ActionEvent event )
 {
  Object obj = event.getSource();

  if( obj instanceof HtmlMenuItem )
  {
   HtmlMenuItem item = (HtmlMenuItem)obj;
   if( item != null )
   {
    lastItem = item.getValue().toString();

   }
  }
 }

不推荐使用的代码行是:

   javax.faces.el.MethodBinding mb = app.createMethodBinding( "#{PrismBacking.onItemClick}", new Class[] { ActionEvent.class } );
  menuItem.setActionListener( mb );

Answer 1

像往常一样,所有弃用确实只是在API文档中描述,包括有关替换的详细信息.

要有一个清晰的概述,这里有前JSF 1.2和后JSF 1.2方法动态创建Action和ActionListener:

在JSF 1.0/1.1中创建Action绑定:

MethodBinding action = FacesContext.getCurrentInstance().getApplication()
    .createMethodBinding("#{bean.action}", new Class[0]);
uiCommandComponent.setAction(action);

在JSF 1.0/1.1中创建ActionListener绑定:

MethodBinding actionListener =  FacesContext.getCurrentInstance().getApplication()
    .createMethodBinding("#{bean.actionListener}", new Class[] {ActionEvent.class});
uiCommandComponent.setActionListener(actionListener);

在JSF 1.2或更新版本中创建Action表达式:

FacesContext context = FacesContext.getCurrentInstance();
MethodExpression action = context.getApplication().getExpressionFactory()
    .createMethodExpression(context.getELContext(), "#{bean.action}", String.class, new Class[0]);
uiCommandComponent.setActionExpression(action);

在JSF 1.2或更新版本中创建ActionListener表达式:

FacesContext context = FacesContext.getCurrentInstance();
MethodExpression actionListener = context.getApplication().getExpressionFactory()
    .createMethodExpression(context.getELContext(), "#{bean.actionListener}", null, new Class[] {ActionEvent.class});
uiCommandComponent.addActionListener(new MethodExpressionActionListener(actionListener));

为了避免大量的样板代码,你可以很好地将其包装在辅助方法中(如果需要在辅助/实用程序类中),例如:

public static MethodExpression createAction(String actionExpression, Class<?> returnType) {
    FacesContext context = FacesContext.getCurrentInstance();
    return context.getApplication().getExpressionFactory()
        .createMethodExpression(context.getELContext(), actionExpression, returnType, new Class[0]);
}

public static MethodExpressionActionListener createActionListener(String actionListenerExpression) {
    FacesContext context = FacesContext.getCurrentInstance();
    return new MethodExpressionActionListener(context.getApplication().getExpressionFactory()
        .createMethodExpression(context.getELContext(), actionListenerExpression, null, new Class[] {ActionEvent.class}));
}

所以你可以按如下方式使用它:

uiCommandComponent.setActionExpression(createAction("#{bean.action}", String.class);
uiCommandComponent.addActionListener(createActionListener("#{bean.actionListener}");

Answer 2

javadocs清楚地说明了这一点:

Application.createMethodBinding

不推荐.这已被替换为调用getExpressionFactory()然后调用ExpressionFactory.createMethodExpression(javax.el.E​​LContext,java.lang.String,java.lang.Class,java.lang.Class []).

以下是如何使用它:

MethodExpression methodExpression = 
    application.getExpressionFactory().createMethodExpression(
         FacesContext.getCurrentInstance().getELContext(), 
         "#{PrismBacking.onItemClick}", 
         null, 
         new Class[] { ActionEvent.class });
menuItem.setActionExpression(methodExpression);