我遇到了以下问题:
恢复视图后,字段验证会导致JSF跳转到渲染响应阶段(因为必填字段为空)。但即使呈现当前值(空字符串)以向用户显示他/她没有填充任何内容,也不会执行以下语句:
<c:if test="#{empty cc.attrs.fieldValue}">
<f:attribute name="style" value="background-color: yellow;"/>
</c:if>
是错误还是功能?请帮忙。
完整的测试示例(Netbeans 6.8项目)在这里:http://www.221b.cz/so/JSFTester.zip
从教程:“如果请求是回发并且在应用请求值阶段遇到错误,处理验证阶段或更新模型值阶段,则在渲染响应阶段期间呈现原始页面”({{3} })
是否意味着如果在“恢复视图”阶段恢复视图,然后任何应用请求/验证/更新模型阶段失败并跳到“渲染响应”,则渲染响应仅传递恢复的视图而不对客户端进行任何更改? / p>
Managed Bean(TesterBean.java):
package cz.test;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
@ManagedBean
@RequestScoped
public class TesterBean {
// Simple DataStore (in real world EJB)
private static String storedSomeValue = null;
private String someValue;
public TesterBean() {
}
public String storeValue() {
storedSomeValue = someValue;
return "index";
}
public String eraseValue() {
storedSomeValue = null;
return "index";
}
public String getSomeValue() {
someValue = storedSomeValue;
return someValue;
}
public void setSomeValue(String someValue) {
this.someValue = someValue;
}
}
复合组件(field-component.xhtml):
<?xml version='1.0' encoding='ISO-8859-1' ?>
<!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:f="http://java.sun.com/jsf/core"
xmlns:composite="http://java.sun.com/jsf/composite"
xmlns:c="http://java.sun.com/jsp/jstl/core">
<!-- INTERFACE -->
<composite:interface>
<composite:attribute name="currentBehaviour" type="java.lang.String" required="true"/>
<composite:attribute name="fieldValue" required="true"/>
</composite:interface>
<!-- IMPLEMENTATION -->
<composite:implementation>
<h:panelGrid columns="3">
<c:choose>
<c:when test="#{cc.attrs.currentBehaviour == 'READONLY'}" >
<h:outputText id="fieldValue" value="#{cc.attrs.fieldValue}">
</h:outputText>
</c:when>
<c:when test="#{cc.attrs.currentBehaviour == 'MANDATORY'}" >
<h:inputText id="fieldValue" value="#{cc.attrs.fieldValue}" required="true">
<f:attribute name="requiredMessage" value="Field is mandatory"/>
<c:if test="#{empty cc.attrs.fieldValue}">
<f:attribute name="style" value="background-color: yellow;"/>
</c:if>
</h:inputText> *
</c:when>
<c:when test="#{cc.attrs.currentBehaviour == 'OPTIONAL'}" >
<h:inputText id="fieldValue" value="#{cc.attrs.fieldValue}">
</h:inputText>
</c:when>
</c:choose>
<h:message for="fieldValue" style="color:red;" />
</h:panelGrid>
</composite:implementation>
Page(index.xhtml):
<?xml version='1.0' encoding='UTF-8' ?>
<!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:ez="http://java.sun.com/jsf/composite/components">
<h:head>
<title>Testing page</title>
</h:head>
<h:body>
<h:form>
<h:outputText value="Some value:"/>
<ez:field-component currentBehaviour="MANDATORY" fieldValue="#{testerBean.someValue}"/>
<h:commandButton value="Store" action="#{testerBean.storeValue}"/>
<h:commandButton value="Erase" action="#{testerBean.eraseValue}" immediate="true"/>
</h:form>
<br/><br/>
<b>Why is field's background color not set to yellow?</b>
<ol>
<li>NOTICE: Field has yellow background color (mandatory field with no value)</li>
<li>Fill in any value (eg. "Hello") and press Store</li>
<li>NOTICE: Yellow background disappeared (as mandatory field has value)</li>
<li>Clear text in the field and press Store</li>
<li><b>QUESTION: Why is field's background color not set to yellow?</b></li>
<li>Press Erase</li>
<li>NOTICE: Field has yellow background color (mandatory field with no value)</li>
</ol>
</h:body>
编辑,遵循Brian的建议(field-component.xhtml)
<?xml version='1.0' encoding='ISO-8859-1' ?>
<!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:f="http://java.sun.com/jsf/core"
xmlns:composite="http://java.sun.com/jsf/composite">
<!-- INTERFACE -->
<composite:interface>
<composite:attribute name="currentBehaviour" type="java.lang.String" required="true"/>
<composite:attribute name="fieldValue" required="true"/>
</composite:interface>
<!-- IMPLEMENTATION -->
<composite:implementation>
<h:panelGrid columns="3">
<h:outputText rendered="#{cc.attrs.currentBehaviour == 'READONLY'}" id="fieldValue1" value="#{cc.attrs.fieldValue}" />
<h:inputText rendered="#{cc.attrs.currentBehaviour == 'MANDATORY'}" id="fieldValue2" title="#{cc.attrs.fieldValue}" value="#{cc.attrs.fieldValue}" required="true" style="#{empty cc.attrs.fieldValue ? 'background-color: yellow;' : ''}">
<f:attribute name="requiredMessage" value="Field is mandatory"/>
</h:inputText> *
<h:inputText rendered="#{cc.attrs.currentBehaviour == 'OPTIONAL'}" id="fieldValue3" value="#{cc.attrs.fieldValue}"/>
<h:message for="fieldValue" style="color:red;" />
</h:panelGrid>
</composite:implementation>
但是即使我摆脱了JSTL仍然无法工作:-(似乎只有值属性在h:inputText中使用来自http请求的新值更新,但其余属性未在阶段渲染响应中重新评估。
答案 0 :(得分:3)
您使用的<c:choose>
和<c:when>
标记是JSTL标记,而不是JSF标记。这意味着它们在构建时评估,而不是在渲染时评估。回发后,组件树不会重建,而是重新渲染,<c:
标签不会被重新评估。
使用<h:panelGroup rendered="#{}">
标记而不是<c:
标记再次尝试使用您的示例。
有关详细信息,请参阅此文章: http://drewdev.blogspot.com/2008/03/build-time-vs-render-time.html
请务必记住,您不能在JSF表单的帖子后面“重新显示”组件。这是因为在保存状态和恢复状态之间永远不应该更改JSF组件树。这非常重要,所以我再说一遍,JSF组件树在保存状态和恢复状态之间永远不应该被改变。
答案 1 :(得分:1)
我在过去两天做了一些调查和调试,这是我的结果。
首先,我简化了省略复合组件的示例,并使其尽可能简单。
托管bean(TesterBean2.java)
package cz.test;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
@ManagedBean
@RequestScoped
public class TesterBean2 {
// Simple DataStore (in real world EJB)
private static String storedSomeValue = null;
private String someValue;
public TesterBean2() {
}
public String storeValue() {
storedSomeValue = someValue;
return "index";
}
public String eraseValue() {
storedSomeValue = null;
return "index";
}
public String getSomeValue() {
someValue = storedSomeValue;
return someValue;
}
public void setSomeValue(String someValue) {
this.someValue = someValue;
}
}
测试页面(index.xhtml)
<?xml version='1.0' encoding='UTF-8' ?>
<!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">
<h:head>
<title>Testing page</title>
</h:head>
<h:body>
<h:form>
<h:inputText id="fieldValue" requiredMessage="Field is mandatory" title="#{testerBean2.someValue}" value="#{testerBean2.someValue}" required="true" style="#{empty testerBean2.someValue ? 'background-color: yellow;' : ''}"/>
<h:commandButton value="Store" action="#{testerBean2.storeValue}"/>
<h:commandButton value="Erase" action="#{testerBean2.eraseValue}"/>
</h:form>
</h:body>
问题出在哪里? 我认为这是com.sun.faces.renderkit_html_basic.TextRenderer及其方法getEndTextToRender的问题:
protected void getEndTextToRender(FacesContext context,
UIComponent component,
String currentValue)
throws IOException {
ResponseWriter writer = context.getResponseWriter();
assert(writer != null);
boolean shouldWriteIdAttribute = false;
boolean isOutput = false;
String style = (String) component.getAttributes().get("style");
String styleClass = (String) component.getAttributes().get("styleClass");
String dir = (String) component.getAttributes().get("dir");
String lang = (String) component.getAttributes().get("lang");
String title = (String) component.getAttributes().get("title");
if (component instanceof UIInput) {
writer.startElement("input", component);
writeIdAttributeIfNecessary(context, writer, component);
writer.writeAttribute("type", "text", null);
writer.writeAttribute("name", (component.getClientId(context)),
"clientId");
// only output the autocomplete attribute if the value
// is 'off' since its lack of presence will be interpreted
// as 'on' by the browser
if ("off".equals(component.getAttributes().get("autocomplete"))) {
writer.writeAttribute("autocomplete",
"off",
"autocomplete");
}
// render default text specified
if (currentValue != null) {
writer.writeAttribute("value", currentValue, "value");
}
// Rest of code omitted
}
currentValue 参数显式传递给此方法,该方法来自com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeEnd
@Override
public void encodeEnd(FacesContext context, UIComponent component)
throws IOException {
rendererParamsNotNull(context, component);
if (!shouldEncode(component)) {
return;
}
ResponseWriter writer = context.getResponseWriter();
assert(writer != null);
// NOTICE currentValue getter
String currentValue = getCurrentValue(context, component);
if (logger.isLoggable(Level.FINE)) {
logger.log(Level.FINE,
"Value to be rendered {0}",
currentValue);
}
// NOTICE currentValue
getEndTextToRender(context, component, currentValue);
}
如果我们仔细观察方法getCurrentValue()
/**
* @param context the FacesContext for the current request
* @param component the UIComponent whose value we're interested in
*
* @return the value to be rendered and formats it if required. Sets to
* empty string if value is null.
*/
protected String getCurrentValue(FacesContext context,
UIComponent component) {
if (component instanceof UIInput) {
Object submittedValue = ((UIInput) component).getSubmittedValue();
if (submittedValue != null) {
// value may not be a String...
return submittedValue.toString();
}
}
String currentValue = null;
Object currentObj = getValue(component);
if (currentObj != null) {
currentValue = getFormattedValue(context, component, currentObj);
}
return currentValue;
}
getSubmittedValue()返回的属性在“恢复视图”阶段填写(如果“处理验证阶段”跳到“渲染”响应阶段)。因此,我们获得了“更新”值,该值仅从用户传递给值属性,其余值保持不变。
如果成功进行流程验证阶段,这不会导致直接跳转到渲染响应阶段(如果用户填写任何非空值),则会调用HtmlInputText的新构造函数,并且样式,标题等。属性从头开始填充。这些属性由托管bean填充,托管bean在阶段更新模型值中使用适当的数据进行更新。
好的,这不是错误,而是功能。它只是肯定了我的论点,句子中有一些气味:“如果请求是回发并且在应用请求值阶段遇到错误,过程验证阶段或更新模型值阶段,则在渲染响应阶段期间呈现原始页面”
如果我真的渴望强制字段的黄色背景,那么如何解决这种情况?
更新的项目在此处:http://www.221b.cz/so/JSFTester2.zip
答案 2 :(得分:1)
我终于设法让验证工作了。
我使用了有权访问UIComponent的验证器。如果验证失败,则会对组件应用特殊样式。在渲染响应阶段也会考虑这种风格。
那它的表现如何?
我已经实现了自己的必需验证器(受到来自http://www.codereye.com/2009/12/validating-empty-text-field-using-jsf.html的Bashan验证器的启发)。
RequiredValidator.java
package cz.test;
import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.validator.Validator;
import javax.faces.validator.ValidatorException;
import org.apache.el.ValueExpressionLiteral;
public class RequiredValidator implements Validator {
public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
if (value == null || "".equals(value.toString().trim())) {
FacesMessage message = new FacesMessage();
String messageStr = (String) component.getAttributes().get("message");
if (messageStr == null) {
messageStr = "Please enter data";
}
message.setDetail(messageStr);
message.setSummary(messageStr);
message.setSeverity(FacesMessage.SEVERITY_ERROR);
component.setValueExpression("style", new ValueExpressionLiteral("background-color: yellow;", String.class));
throw new ValidatorException(message);
} else {
component.setValueExpression("style", new ValueExpressionLiteral("", String.class));
}
}
}
我添加的行: component.setValueExpression(“style”,new ValueExpressionLiteral(“background-color:yellow;”,String.class));
强制对空字段(web.xml)进行JSF触发器验证:
....
<context-param>
<param-name>javax.faces.VALIDATE_EMPTY_FIELDS</param-name>
<param-value>true</param-value>
</context-param>
....
使用JSF注册验证器(faces-config.xml):
<validator>
<validator-id>RequiredValidator</validator-id>
<validator-class>cz.test.RequiredValidator</validator-class>
</validator>
和使用所需验证器和TesterBean2(index.xhtml)的网页:
<?xml version='1.0' encoding='UTF-8' ?>
<!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:f="http://java.sun.com/jsf/core">
<h:head>
<title>Testing page</title>
</h:head>
<h:body>
<h:form>
<h:messages/>
<h:inputText id="fieldValue"
title="#{testerBean2.someValue}"
value="#{testerBean2.someValue}"
style="#{empty testerBean2.someValue ? 'background-color: yellow;' : ''}">
<f:validator validatorId="RequiredValidator"/>
<f:attribute name="message" value="Field is mandatory"/>
</h:inputText>
<h:commandButton value="Store" action="#{testerBean2.storeValue}"/>
<h:commandButton value="Erase" action="#{testerBean2.eraseValue}"/>
</h:form>
</h:body>
</html>
注意:h:inputText中不能使用required属性。它将超过所需的验证器。