向 JSF 2.0 UIInput 组件添加自定义属性 (HTML5) 支持 [英] Adding custom attribute (HTML5) support to JSF 2.0 UIInput component

问题描述

我正在尝试编写一个渲染器来处理 组件上的 placeholder 属性.在阅读了 JSF 2.0 去除了所需的 HTML5 属性后，我走向了这条道路a> 似乎是正确的.这是我的自定义渲染器

I am trying to write a renderer which would process the placeholder attribute on an <h:inputText> component. I headed to this path after reading JSF 2.0 strips out needed HTML5 attributes and it seems correct. Here's my custom renderer

public class InputRenderer extends com.sun.faces.renderkit.html_basic.TextRenderer{

    @Override
    public void encodeBegin(FacesContext context, UIComponent component) 
    throws IOException {
        System.out.println("Rendering :"+component.getClientId());

        String placeholder = (String)component.getAttributes().get("placeholder");
        if(placeholder != null) { 
            ResponseWriter writer = context.getResponseWriter();
            writer.writeAttribute("placeholder", placeholder, "placeholder");
        }

        super.encodeBegin(context, component);

    }


    @Override
    public void decode(FacesContext context, UIComponent component) {
        super.decode(context, component);
    }

    @Override
    public void encodeEnd(FacesContext context, UIComponent component) 
    throws IOException {
        super.encodeEnd(context, component);
    }
}

这个渲染器在faces config中注册为

And this renderer is registered in faces config as

 <render-kit>
    <renderer>
        <component-family>javax.faces.Input</component-family>
        <renderer-type>javax.faces.Text</renderer-type>
        <renderer-class>com.example.renderer.InputRenderer</renderer-class>
    </renderer>
</render-kit>

注册成功，没有问题.

我的意图是处理 placeholder 属性，插入它，然后将处理委托给 super.我上面的代码不起作用，因为我在错误的地方插入了属性.它必须在 writer.startElement('input') 执行后插入.但是，startElement 必须发生在 super 的 encodeBegin() 方法中的某处.那么如何插入自定义属性(在本例中为占位符")，然后继续执行流程?

My intention is to process the placeholder attribute, insert it, and then delegate the processing to super. My above code doesn't work because I'm inserting the attribute at a wrong place. It must be inserted after writer.startElement('input') has executed. However, the startElement must be happening somewhere in the super's encodeBegin() method. So how do I insert a custom attribute ('placeholder' in this case) and then continue the execution flow?

注意:上面的代码确实添加了一个 placeholder 属性，但没有添加到我打算添加的输入组件中，它将它写入输入的父级(因为我正在尝试编写一个属性在组件本身实际写入流之前，它会将属性应用于当前组件)

NB: The above code does add a placeholder attribute but not to the input component that I intend to, It writes it to the parent of the Input (since I'm trying to write an attribute before the component itself is actually written in the stream, it applies the attribute to the current component)

推荐答案

这是我的方式.我添加了占位符和数据主题属性.如果要添加更多属性，只需将其名称添加到属性数组中即可.

This is my way. I added placeholder and data-theme attributes. If you want to add more attributes, you should just add its name to attributes array.

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;

import com.sun.faces.renderkit.html_basic.TextRenderer;

public class InputRender extends TextRenderer {

    @Override
    protected void getEndTextToRender(FacesContext context,
            UIComponent component,
            String currentValue)
     throws java.io.IOException{

        String [] attributes = {"placeholder","data-theme"};

        ResponseWriter writer = context.getResponseWriter();

        for(String attribute : attributes)
        {
            String value = (String)component.getAttributes().get(attribute);
            if(value != null) {                             
                writer.writeAttribute(attribute, value, attribute);
            }
        }

        super.getEndTextToRender(context, component, currentValue);

    }

}

您应该将其添加到 faces-config.xml 文件中.

You should add this to faces-config.xml file.

 <render-kit>
    <renderer>
        <component-family>javax.faces.Input</component-family>
        <renderer-type>javax.faces.Text</renderer-type>
        <renderer-class>your.package.InputRenderer</renderer-class>
    </renderer>
</render-kit>

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