JSF页面传参数到后台bean的四种方式

有四种方法可以把JSF页面的参数传到后台Bean：

• Method expression (JSF 2.0)
• f:param
• f:attribute
• f:setPropertyActionListener

我们一个一个的来看例子

1. Method expression

JSF 2.0后的版本允许你通过方法表达式(Method expression)的方式来传参数，像这样{bean.method(param)}.

JSF page…

<h:commandButton action="#{user.editAction(delete)}" />

Backing bean…

@ManagedBean(name="user")@SessionScopedpublic class UserBean{public String editAction(String id) {  //id = "delete"}}

2. f:param

用f:param标签传参数，backing bean通过request parameter获取传过来的参数。

JSF page…

<h:commandButton action="#{user.editAction}"><f:param name="action" value="delete" /></h:commandButton>

Backing bean…

@ManagedBean(name="user")@SessionScopedpublic class UserBean{public String editAction() {  Map<String,String> params =                FacesContext.getExternalContext().getRequestParameterMap();  String action = params.get("action");          //...}}

 

3. f:atribute

用f:atribute标签，后台通过action listener获取.

JSF page…

<h:commandButton action="#{user.editAction}" actionListener="#{user.attrListener}"><f:attribute name="action" value="delete" /></h:commandButton>

Backing bean…

@ManagedBean(name="user")@SessionScopedpublic class UserBean{  String action;  //action listener event  public void attrListener(ActionEvent event){action = (String)event.getComponent().getAttributes().get("action");  }  public String editAction() {//...  }}

4. f:setPropertyActionListener

 

通过f:setPropertyActionListener标签传参数,它会直接把参数值设置到backing bean对应的属性。

JSF page…

<h:commandButton action="#{user.editAction}" >    <f:setPropertyActionListener target="#{user.action}" value="delete" /></h:commandButton>

Backing bean…

@ManagedBean(name="user")@SessionScopedpublic class UserBean{public String action;public void setAction(String action) {this.action = action;}public String editAction() {   //now action property contains "delete"}}