JSF - 自定义标签 - 动态值在刷新后消失 [英] JSF - Custom Tags - Dynamic values disappear after refresh

问题描述

我遵循 此 教程在 JSF 2.1 中实现了一个marquee标签，并且部分成功。由于此标签支持动态数据，因此例如 。 ＃{bean.var} 作为一个值，我决定在组件内部弄脏它。然而，重新加载我的页面该值消失。

1. 您可以告诉我如何正确实施，以便我可以使用我的动态在$ value-attribute ？


2. 中的值也可以指向正确的方向，即代码导致我的元组类？

非常感谢！

http：// myjavabuddy.blogspot.de/2013/04/writing-custom-components-for-jsf-20.html

这是我的JSF

 < customJSF：marquee value =/> 
  

这是我的组件

  @FacesComponent（amelunxenfast.prog3.wissensmanagement.components.marquee）
 public class MarqueeComponent extends UIComponentBase {
 
 public static final字符串COMPONENT_TYPE =com.himanshu.jsf.custom.marquee; 
 
字符串值= null; 
 
 @EJB 
 FeedEJB ejb; 
 
 public String getValue（）{
返回值; 
} 
 
 @Override 
 public String getFamily（）{
 return COMPONENT_TYPE; 
 
 
 $ b @Override 
 public void encodeBegin（FacesContext context）throws IOException {
 ResponseWriter writer = context.getResponseWriter（）; 
 writer.startElement（marquee，this）; 
 writer.writeAttribute（scrollamount，10，）; 
 writer.write（ejb.getFeedString（））; 
 writer.endElement（marquee）; 
 
 
 $ b @Override 
 public void encodeEnd（FacesContext arg0）throws IOException {
 super.encodeEnd（arg0）; 
} 
 
 public void setValue（String value）{
 this.value = value; 
} 
  

}

解决方案

太长的评论...

我不认为注入 @EJB 里面 @FacesComponent ，我不认为这是一个好习惯，在这个特定情况下。





我认为一个更好的方法应该是用你自己的类扩展 TextRenderer ，在faces-config中声明一个新组件，并以与<$ c相同的方式使用它$ c> h：outputText （在 value 属性中传递 ValueExpression ）

I've followed this tutorial for implementing a marquee-tag in JSF 2.1 and succeeded partly. As this tag does NOT support dynamic data, e.g. #{bean.var} as a value, I've decided to do it dirty inside the component.

However, after reloading my page, the value disappears. The tag is still there, but the content is gone.

1. Could you show me how to implement is correctly, that I can use my dynamic value inside the value-attribute?
2. Or would you point me into the right direction which code is causing the error in my component class?

Thank you very much!

http://myjavabuddy.blogspot.de/2013/04/writing-custom-components-for-jsf-20.html

This is my JSF

<customJSF:marquee value="" />

This is my Component

@FacesComponent ("amelunxenfast.prog3.wissensmanagement.components.marquee")
public class MarqueeComponent extends UIComponentBase {

  public static final String COMPONENT_TYPE = "com.himanshu.jsf.custom.marquee";

    String value = null;

    @EJB
    FeedEJB ejb;

    public String getValue() {
        return value;
    }

    @Override
    public String getFamily() {
        return COMPONENT_TYPE;

}

@Override
public void encodeBegin(FacesContext context) throws IOException {
    ResponseWriter writer = context.getResponseWriter();
    writer.startElement("marquee", this);
    writer.writeAttribute("scrollamount", "10", "");
    writer.write(ejb.getFeedString());
    writer.endElement("marquee");
}


@Override
public void encodeEnd(FacesContext arg0) throws IOException {
    super.encodeEnd(arg0);
}

public void setValue(String value) {
    this.value = value;
}

}

解决方案

Too long for a comment...

I don't think it's legit to inject @EJB inside @FacesComponent and i don't think it's a good practice, in this specific case.

I think a better approach should be extending TextRenderer with your own class, declare a new component in faces-config and use it the same way you use h:outputText (passing ValueExpression in value attribute)

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