向JSF 2.0 UIInput组件添加自定义属性(HTML5)支持

Question

我正在尝试编写一个渲染器来处理组件placeholder上的属性<h:inputText>.在阅读了JSF 2.0之后,我走向了这条路径,剥离了所需的HTML5属性,看起来是正确的.这是我的自定义渲染器

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);
    }
}

此渲染器在faces config中注册为

 <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>

这个注册很好,没有问题.

我的目的是处理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,因为我将属性插入错误的地方.它必须在writer.startElement('input')执行后插入.但是,startElement必须在super的encodeBegin()方法中的某个地方发生.那么如何插入自定义属性(在这种情况下为"占位符")然后继续执行流程？

注意:上面的代码确实添加了一个placeholder属性,但没有添加到我想要的输入组件,它将它写入Input的父级(因为我试图在组件本身实际写入流之前编写一个属性,它将属性应用于当前组件)

Answer 1

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attributes数组即可.

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);

    }

}

您应该将此添加到faces-config.xml文件中.

 <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>

Answer 2

您可以只覆盖ResponseWriters startElement方法,该方法只调用一次,然后您可以还原到原始的响应编写器对象.

import javax.faces.context.*;
import java.io.IOException;

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

      // Put all of the attributes you want to render here...
      private static final String[] ATTRIBUTES = {"required","placeholder"};

    @Override
    protected void getEndTextToRender(FacesContext context,
            UIComponent component, String currentValue) throws IOException {
        final ResponseWriter originalResponseWriter = context.getResponseWriter();
        context.setResponseWriter(new ResponseWriterWrapper() {

            @Override
// As of JSF 1.2 this method is now public.
            public ResponseWriter getWrapped() {
                return originalResponseWriter;
            }   

            @Override
            public void startElement(String name, UIComponent component)
                    throws IOException {
                super.startElement(name, component);
if ("input".equals(name)) {
  for (String attribute : ATTRIBUTES)
  {
    Object value = component.getAttributes().get(attribute);
    if (value != null)
    {
      super.writeAttribute(attribute,value,attribute);
} 
  }
}   
        });
        super.getEndTextToRender(context, component, currentValue);
        context.setResponseWriter(originalResponseWriter); // Restore original writer.
    }



}