我有一个显示罐头数据的非常简单的页面。我遇到了来自数据库的数据的这个问题,所以我做了这个简单的例子,仍然有问题。当此页面首次导航到会话时,第一行中的第一列不显示任何数据。JSF不显示第一行,第一列数据
如果我将范围更改为请求或会话,则无关紧要,如果我使用Firefox或IE,也没有什么不同。我所知道的是,如果我重新加载页面或导航离开并回来,它会突然显示我的数据 - 直到我关闭该浏览器的所有实例并加载一个新的浏览器。然后,再次,它不会显示我的数据,直到我重新加载页面。
问题是为什么直到我重新加载页面(“操作系统概念”不显示,但“Silberschatz”),我的第一本书的心爱的第一个标题才显示出来?
下面是相关的代码。
HomePage.java:
public class HomePage {
private Book[] books;
public HomePage() {
books = new Book[3];
books[0] = new Book("Operating System Concepts", "Silberschatz");
books[1] = new Book("Learning Sql", "Beaulieu");
books[2] = new Book("Effective Java", "Bloch");
}
public Book[] getBooks() {
return books;
}
public void setBooks(Book[] books) {
this.books = books;
}
}
Book.java
public class Book {
private String title;
private String author;
public Book() {}
public Book(String title, String author) {
this.title = title;
this.author = author;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
}
针对home.jsp:
<html>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<link href="../css/styles.css" rel="stylesheet" type="text/css" />
<f:loadBundle basename="omitted.for.anonymity.bundle.home" var="msgs"/>
<f:view>
<body>
<h:form>
<h:panelGrid columns="2" columnClasses="sideControlColumn,contentColumn">
<f:facet name="header">
<f:subview id="header">
<jsp:include page="header.jsp" />
</f:subview>
</f:facet>
<f:subview id="sideControl" >
<jsp:include page="sideControl.jsp" />
</f:subview>
<h:dataTable value="#{homePage.books}"
var="book"
styleClass="homeTable"
rowClasses="evenColumn,oddColumn"
>
<h:column>
<f:facet name="header">
<h:outputText value="#{msgs.columnHeader1}"/>
</f:facet>
<h:outputText value="#{book.title}" />
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="#{msgs.columnHeader2}"/>
</f:facet>
<h:outputText value="#{book.author}" />
</h:column>
</h:dataTable>
</h:panelGrid>
</h:form>
</body>
</f:view>
</html>
faces-config.xml中:
<?xml version="1.0"?>
<!DOCTYPE faces-config PUBLIC
"-//Sun Microsystems, Inc.//DTD JavaServer Faces Config 1.1//EN"
"http://java.sun.com/dtd/web-facesconfig_1_1.dtd">
<faces-config>
<navigation-rule>
<from-view-id>/pages/login.jsp</from-view-id>
<navigation-case>
<from-outcome>login</from-outcome>
<to-view-id>/pages/home.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<navigation-rule>
<from-view-id>/pages/home.jsp</from-view-id>
<navigation-case>
<from-outcome>searchForBooks</from-outcome>
<to-view-id>/pages/searchCriteria.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<navigation-rule>
<from-view-id>/pages/searchCriteria.jsp</from-view-id>
<navigation-case>
<from-outcome>searchForBooks</from-outcome>
<to-view-id>/pages/searchCriteria.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<navigation-rule>
<from-view-id>/pages/searchResults.jsp</from-view-id>
<navigation-case>
<from-outcome>searchForBooks</from-outcome>
<to-view-id>/pages/searchCriteria.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<navigation-rule>
<from-view-id>/pages/searchCriteria.jsp</from-view-id>
<navigation-case>
<from-outcome>search</from-outcome>
<to-view-id>/pages/searchResults.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<managed-bean>
<managed-bean-name>book</managed-bean-name>
<managed-bean-class>omitted.for.anonymity.beans.Book</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
<managed-bean>
<managed-bean-name>homePage</managed-bean-name>
<managed-bean-class>omitted.for.anonymity.beans.page.HomePage</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
<managed-bean>
<managed-bean-name>searchCriteriaPage</managed-bean-name>
<managed-bean-class>omitted.for.anonymity.beans.page.SearchCriteriaPage</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
<managed-bean>
<managed-bean-name>searchResultsPage</managed-bean-name>
<managed-bean-class>omitted.for.anonymity.beans.page.SearchResultsPage</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
</faces-config>
你是男人。我添加了该行,但它只将问题移至作者列。此外,向作者列添加相同的修复程序修复了一切。您假设EL中可能存在“bug” - 请详细说明requestScope的“前缀”是什么,以及为什么您认为这会修复它?投票和检查标记为正确答案 - 也将考虑升级JSF实现。我知道有很多依赖追逐,(必须匹配一个特定的jsp规范和类似的东西)。 – Russ 2009-12-17 14:21:22
JSP规范定义了变量如何解析的严格顺序。隐式变量(比如requestScope和sessionScope)总是首先被解析。使用这个前缀意味着EL不会通过作用域来解析你的对象。查看您的JSP规范版本,了解已定义的顺序和隐式变量列表(可能是JSR 245或JSR 152)。 – McDowell 2009-12-17 15:12:04