Backing bean property that should return a string with html code returns empty string

问题

I have a property in my backing bean that returns html code:

public String getHtmlPrevisualizar() {
    return "<html><head><title></title></head><body>Hello world.</body></html>";
}

What I want to do is show this html code in a iframe. I do this with javascript. This is the xhtml page:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:a4j="http://richfaces.org/a4j"
      xmlns:rich="http://richfaces.org/rich"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:ui="http://java.sun.com/jsf/facelets">

    <f:loadBundle basename="resources" var="msg" />
<head>
    <title>#{msg['pageTitle']}</title>
</head>
<body>
<ui:composition template="/WEB-INF/facelets/templates/sqa/plantilla.xhtml">  
    <ui:define name="title">#{msg['pageTitle']}</ui:define>
    <ui:define name="javascript">
        <script type="text/javascript">
            function showPreview() {
                var doc = document.getElementById('iframePreview').contentWindow.document;
                doc.open();
                doc.write('#{nuevoEditarEstructura.htmlPrevisualizar}');
                doc.close();
                return false;
            }
            function showPreview2() {
                var doc = document.getElementById('iframePreview').contentWindow.document;
                doc.open();
                doc.write('<html><head><title></title></head><body>Hello world.</body></html>');
                doc.close();
                return false;
            }
        </script>
    </ui:define>
    <ui:define name="content">
        <h:form>
            <a4j:commandLink value="Preview" styleClass="boton" onclick="showPreview();"/>
            <a4j:commandLink value="Preview2" styleClass="boton" onclick="showPreview2();"/>
            <br/>
            <br/>
            <h:outputText value="#{nuevoEditarEstructura.htmlPrevisualizar}" />
            <br/>
            <br/>
            #{nuevoEditarEstructura.htmlPrevisualizar}
            <br/>
            <br/>
        </h:form>
        <iframe id="iframePreview">
        </iframe>
    </ui:define>  
</ui:composition>
</body>
</html>

There are two commandLinks. The first one gets the html code from the backing bean, the second one has the html code written in a string in javascript. The first commandLink doesn't work. If I view the source code of the page, the value thas should have returned from the backing bean is empty.

I have printed the value from the property in the backing bean also with this:

        <h:outputText value="#{nuevoEditarEstructura.htmlPrevisualizar}" />
        <br/>
        <br/>
        #{nuevoEditarEstructura.htmlPrevisualizar}

But nothig is shown. I have called getHtmlPrevisualizar() and printed its content in the eclipse console, and it returns the right html code.

I know that there can be some problems with escaped characters and facelets, I was expecting to have to deal with the characters in the html being escaped, but I don't get anything.

回答1:

Set escape="false" in your <h:outputText /> tag component

<h:outputText value="#{nuevoEditarEstructura.htmlPrevisualizar}" escape="false" />

回答2:

Well, this is embarrassing. The problem was that the backing bean name was misspelled, nothing else. I wish that we could get some kind of warning for this, instead of just silently fail.

来源：https://stackoverflow.com/questions/11020438/backing-bean-property-that-should-return-a-string-with-html-code-returns-empty-s

标签

java

html

jsf

facelets

jsf-1.2