Tin*_*iny 5 jsf primefaces jsf-2.2
以下是一个简单的用例<f:viewAction>.
<f:metadata>
<f:viewParam name="id" value="#{testManagedBean.id}" maxlength="20"/>
<f:viewAction action="#{testManagedBean.viewAction}"/>
</f:metadata>
涉及的托管bean.
@ManagedBean
@ViewScoped
public final class TestManagedBean implements Serializable {
private static final long serialVersionUID = 1L;
private Long id; //Getter and setter.
public void viewAction() {
System.out.println("viewAction() called : " + id);
}
}
该参数id通过URL传递.当xxx通过相关URL传递非数字值并且未调用viewAction()与侦听器关联的方法时,存在转换错误<f:viewAction>.
的值id是null在这种情况下.我想重定向到另一个页面,当id不能转换为所需的目标类型(如本例中)或未id根据指定的验证标准进行验证,以避免可能在LazyDataModel#load()PrimeFaces或某处的方法中抛出的潜在异常只要在相应的托管bean中尝试访问这些参数,就会在关联的托管bean中执行else.为此,viewAction()应该调用该方法.
如何处理？我应该用吗？
<f:event type="preRenderView">
与<f:viewAction>？一起
这是指定的行为.当PROCESS_VALIDATIONS阶段以验证失败结束时,将跳过UPDATE_MODEL_VALUES和INVOKE_APPLICATION阶段.与"常规"形式完全一样<h:form>.把它想象<f:viewParam>成a <h:inputText>和a <f:viewAction>作为a <h:commandButton>,它会变得更加清晰.
对于您的特定要求,在转换/验证失败时执行重定向,至少有3个解决方案:
当你发现时,添加一个<f:event listener>.我宁愿挂钩postValidate事件而不是更好的自我可记录性.
<f:metadata>
<f:viewParam name="id" value="#{bean.id}" maxlength="20" />
<f:event type="postValidate" listener="#{bean.redirectIfNecessary}" />
<f:viewAction action="#{bean.viewAction}" />
</f:metadata>
public void redirectIfNecessary() throws IOException {
FacesContext context = FacesContext.getCurrentInstance();
if (!context.isPostback() && context.isValidationFailed()) {
context.getExternalContext().redirect("some.xhtml");
}
}
检查FacesContext#isPostback()可防止在同一视图(如果有)中对"常规"表单的验证失败执行重定向.
扩展内置函数,LongConverter从而执行重定向getAsObject()(验证器是不可或缺的,因为默认转换器Long已经在非数字输入上失败;如果转换器失败,验证器永远不会被触发).然而,这是糟糕的设计(紧耦合).
<f:metadata>
<f:viewParam name="id" value="#{bean.id}" converter="idConverter" />
<f:viewAction action="#{bean.viewAction}" />
</f:metadata>
@FacesConverter("idConverter")
public class IdConverter extends LongConverter {
@Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
if (value == null || !value.matches("[0-9]{1,20}")) {
try {
context.getExternalContext().redirect("some.xhtml");
return null;
}
catch (IOException e) {
throw new FacesException(e);
}
}
else {
return super.getAsObject(context, component, value);
}
}
}
如果需要,您可以在<f:attribute>内部<f:viewParam>使用"传递"参数到转换器.
<f:viewParam name="id" value="#{bean.id}" converter="idConverter">
<f:attribute name="redirect" value="some.xhtml" />
</f:viewParam>
String redirect = (String) component.getAttributes().get("redirect");
context.getExternalContext().redirect(redirect);
创建一个自定义标记处理程序,它与基本相同,<f:event listener>但不需要额外的辅助bean方法.
<html ... xmlns:my="http://example.com/ui">
<f:metadata>
<f:viewParam name="id" value="#{bean.id}" maxlength="20" />
<my:viewParamValidationFailed redirect="some.xhtml" />
<f:viewAction action="#{bean.viewAction}" />
</f:metadata>
com.example.taghandler.ViewParamValidationFailed
public class ViewParamValidationFailed extends TagHandler implements ComponentSystemEventListener {
private String redirect;
public ViewParamValidationFailed(TagConfig config) {
super(config);
redirect = getRequiredAttribute("redirect").getValue();
}
@Override
public void apply(FaceletContext context, UIComponent parent) throws IOException {
if (parent instanceof UIViewRoot && !context.getFacesContext().isPostback()) {
((UIViewRoot) parent).subscribeToEvent(PostValidateEvent.class, this);
}
}
@Override
public void processEvent(ComponentSystemEvent event) throws AbortProcessingException {
FacesContext context = FacesContext.getCurrentInstance();
if (context.isValidationFailed()) {
try {
context.getExternalContext().redirect(redirect);
}
catch (IOException e) {
throw new AbortProcessingException(e);
}
}
}
}
/WEB-INF/my.taglib.xml
<?xml version="1.0" encoding="UTF-8"?>
<facelet-taglib
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facelettaglibrary_2_0.xsd"
version="2.0"
>
<namespace>http://example.com/ui</namespace>
<tag>
<tag-name>viewParamValidationFailed</tag-name>
<handler-class>com.example.taghandler.ViewParamValidationFailed</handler-class>
</tag>
</facelet-taglib>
/WEB-INF/web.xml
<context-param>
<param-name>javax.faces.FACELETS_LIBRARIES</param-name>
<param-value>/WEB-INF/my.taglib.xml</param-value>
</context-param>
确实,这是一些代码,但它最终是干净和可重复使用的<my:viewParamValidationFailed>标签,实际上非常适合新的OmniFaces功能.
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