GWT:从FormPanel/VerticalPanel中检索动态添加的组件 [英] GWT: retrieve Components from FormPanel/VerticalPanel which are added dynamically

问题描述

我正在使用GWT 2.5.0创建一个网页，在此我使用了许多复合组件.并且该网页是基于XML开发的.

I am creating a web page using GWT 2.5.0, in this I used lots of composite component. And the web page is developed based on XML .

因此，在这里我们解析XML，并根据每个元素将componnet添加到VerticalPanel，最后将其添加到FormPanel，然后将其返回以添加到RootPanel.在该组件对应于XML的旁边，我添加了一个Button，将其称为提交"按钮，在其click事件上，我想获取该表单中每个组件的值. 为了明确我的想法，下面是我的工作的伪代码:

So here we parse the XML and according to each element add componnet to a VerticalPanel and finally add it to a FormPanel and then return it to add to RootPanel. Beside the Component corresponds to XML I add a Button, call it submit button, on its click event I want to get the values of every component in that form. To clear what my idea is , below is the pseudo code of my work:

public FormPanel createFormWithComponents(){

    FormPanel fp = new FormPanel();
    vp = new VerticalPanel();
    //these are creatred based on the xml
    ABC coutn = new ABC (null,"pressure count",true);
    PI propotion =  new PI(12.5,"HR percentage");

    vp.add(coutn);
    vp.add(propotion);
    //a common button to every form created here
    Button submit = new Button("submit");
    vp.add(submit);
    submit.addClickHandler(new ClickHandler() {

        @Override
        public void onClick(ClickEvent event) {

已更新

                String values = "";
                Iterator<Widget> vPanelWidgets =  vp.iterator();
                while (vPanelWidgets.hasNext()){
                    Widget childWidget = vPanelWidgets.next();
                    if(childWidget instanceof ABC){
                        ABC xx = (ABC )childWidget;
                        values = String.valueOf(xx.getMagnitude());
                    }
                }
                Window.alert(values);
            }
        });

        fp.add(vp);
        return fp;
    }

任何见识将不胜感激. 更新: 这里是将每个子窗口小部件组件与我的Composite组件之一进行比较，与所有Composite组件相比，我是否必须这样做?我有什么简单或优化的方法吗? 我想要一个很好的解决方案，因为那里有很多复合组件:

Any insight would be appreciated. UPDATED: Here am comparing each of child widget component with one of my Composite component , do i have to do like this comparing to all Composite component? I there any kind of simple or optimized way to do it? I want good solution for doing this process as there are so many composite component over there:

if(childWidget instanceof ABC ){
    ABC xx = (ABC )childWidget;
    values = String.valueOf(xx.getMagnitude());
}

推荐答案

您可以使所有Composite组件实现具有单个getValue()方法的接口:

You could make all you Composite components implement an interface having a single getValue() method:

public interface HasValue {
    public String getValue();
}

然后，您可以轻松提取实现该接口的所有小部件的值:

Then you can easilly extract the value of all widgets implementing that interface:

    while (vPanelWidgets.hasNext()){
        Widget childWidget = vPanelWidgets.next();
        if(childWidget instanceof HasValue){
            HasValue xx = (HasValue) childWidget;
            values = xx.getValue();
        }
    }

如果需要返回字符串以外的值，则可以使用泛型.看一下GWT的com.google.gwt.user.client.ui.HasValue作为示例(您也可以使用该接口而不是创建自己的接口).

If you need to return values other than strings, you could use generics. Take a look at GWT's com.google.gwt.user.client.ui.HasValue for an example of that (you could also use that interface instead of creating your own).

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