JSF核心标签:setPropertyActionListener vs属性vs param [英] JSF Core Tag :setPropertyActionListener vs attribute vs param
问题描述
setPropertyActionListener
vs attribute
vs param
有什么区别?
What is the difference between setPropertyActionListener
vs attribute
vs param
?
何时使用setPropertyActionListener
?
推荐答案
1. f:setPropertyActionListener:
使用此标签,您可以直接在支持bean中设置属性.示例:
With this tag, you can directly set property in you backing bean. Example:
xhtml:
<h:commandButton action="page.xhtml" value="OK">
<f:setPropertyActionListener target="#{myBean.name}" value="myname"/>
</h:commandButton>
支持bean:
@ManagedBean
@SessionScoped
public class MyBean{
public String name;
public void setName(String name) {
this.name= name;
}
}
这会将后备bean的name
属性设置为值 myname .
This will set name
property of backing bean to value myname.
2. f:param:
此标记简单地设置了请求参数.示例:
This tag simple sets the request parameter. Example:
xhtml:
<h:commandButton action="page.xhtml">
<f:param name="myparam" value="myvalue" />
</h:commandButton>
因此您可以在支持bean中获得此参数:
so you can get this parameter in backing bean:
FacesContext.getExternalContext().getRequestParameterMap().get("myparam")
3. f:属性:
使用此标记,您可以传递属性,以便可以从备用Bean的动作侦听器方法中获取该属性.
With this tag you can pass attribute so you can grab that attribute from action listener method of your backing bean.
xhtml:
<h:commandButton action="page.xhtml" actionListener="#{myBean.doSomething}">
<f:attribute name="myattribute" value="myvalue" />
</h:commandButton>
因此您可以从操作侦听器方法获取此属性:
so you can get this attribute from action listener method:
public void doSomething(ActionEvent event){
String myattr = (String)event.getComponent().getAttributes().get("myattribute");
}
无论何时要设置备用Bean的属性,都应使用f:setPropertyActionListener
.如果要将参数传递给支持Bean,请考虑f:param
和f:attribute
.同样,重要的是要知道,使用f:param
您可以传递String
值,而使用f:attribute
您可以传递对象.
You should use f:setPropertyActionListener
whenever you want to set property of the backing bean. If you want to pass parameter to backing bean consider f:param
and f:attribute
. Also, it is important to know that with f:param
you can just pass String
values, and with f:attribute
you can pass objects.
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