javabeans

What is the advantage of using Java Beans?

由 送分小仙女□ 提交于 2019-11-29 23:03:29
I believe I understand what Java Beans are: Java class(es) which contain a no-arg constructor, are serializable, and expose their fields with getters and setters. Does a Java Bean have to expose all of its fields in order to qualify as a bean? If no, does it even have to expose any ? May Java Beans include constructors with arguments as well as a no-arg constructor? What is the purpose of Java Beans, other than to conform to a certain coding style? It seems there is a lot of talk about 'beans this' or 'beans that', but I don't know why they are advantageous, specifically. I can totally get

View all fields / properties of bean in JSP / JSTL

由 和自甴很熟 提交于 2019-11-29 20:27:50
I have a bean, ${product} . I would like to view all of the available fields / properties of this bean. So for instance, ${product.price} , ${product.name} , ${product.attributes.colour} etc. Is it possible to dynamically print out all names and values of these properties in JSP, using JSTL/EL? Something like: <c:forEach items="${product}" var="p"> ${p.key} - ${p.value} </c:forEach> Toby Replace object with the bean to determine. <c:set var="object" value="${product}" /> Display all declared fields and their values. <c:if test="${not empty object['class'].declaredFields}"> <h2>Declared fields

Copying one class's fields into another class's identical fields

由 孤人 提交于 2019-11-29 19:17:32
问题 I have this question. But it will be difficult for me to explain as I don't know exact terms to use. Hope someone will understand. I'll try to discribe to the best i can. I feel like this is much related to parsing Say there are two classes. And in both classes I have some variables, say strings (just for simplicity, variable type can be any), which have similar names . Eg: class ClassA{ String x,y,z; } class ClassB{ String x,y,z; } Now, what i need is, i need to copy the value of one class's

Java comparator for multi-column sorting?

由 久未见 提交于 2019-11-29 18:54:37
问题 Is there any Java open-source comparator for comparing beans by multiple fields for multi-column sorting? Each column can be sorted asceding or descending. For single-column sorting it can be achieved by using org.apache.commons.beanutils.BeanComparator together with org.springframework.util.comparator.InvertibleComparator . I'm aware that this functionality is quite trivial to write, but what's the benefit from reinventing the wheel, if it was already written and tested? 回答1: I wrote this a

Bean not instantiated

由 强颜欢笑 提交于 2019-11-29 17:59:28
Platform I am using : Fedora 20; mariadb-5.5.34-2.fc20.x86_64; Eclipse Kepler Service Release from www.eclipse.org; Apache TomEE plus 1.6.0. I am implementing example See here and I am trying to manage to work the login interface. My problem is that the Java Bean of Login.xhtml has not been instantiated. How is it possible? I am quite familiar with java Beans, I checked for errors and the example comes from an expert Java programmer. I found out this trouble because I did not manage to work the login, and the debugger showed no variables. Eclipse: no shown variables in debugging Java EE I

JSF - Problem with @ViewScope

由 孤者浪人 提交于 2019-11-29 17:57:00
I have a page that load (in a panelGroup) two different page, due to the login status (logged, not logged). This is the main switch : template.xhtml P.S. selector.page is "homepage" as default <h:panelGroup layout="block" styleClass="contenitore"> <h:panelGroup layout="block"> <h:panelGroup layout="block" styleClass="menu_table" id="login"> <ui:insert name="login_homepage" /> </h:panelGroup> <h:panelGroup layout="block" id="content"> <c:catch> <ui:include src="/#{selector.page}/#{selector.page}.xhtml" /> </c:catch> </h:panelGroup> </h:panelGroup> </h:panelGroup> homepage.xhtml <h:panelGroup

dynamically create class in scala, should I use interpreter?

由 走远了吗. 提交于 2019-11-29 17:38:27
问题 I want to create a class at run-time in Scala . For now, just consider a simple case where I want to make the equivalent of a java bean with some attributes, I only know these attributes at run time. How can I create the scala class? I am willing to create from scala source file if there is a way to compile it and load it at run time, I may want to as I sometimes have some complex function I want to add to the class. How can I do it? I worry that the scala interpreter which I read about is

Java Spring Recreate specific Bean

由 青春壹個敷衍的年華 提交于 2019-11-29 17:37:17
问题 I want to re-create (new Object) a specific bean at Runtime (no restarting the server) upon some DB changes. This is how it looks - @Component public class TestClass { @Autowired private MyShop myShop; //to be refreshed at runtime bean @PostConstruct //DB listeners public void initializeListener() throws Exception { //... // code to get listeners config //... myShop.setListenersConfig(listenersConfig); myShop.initialize(); } public void restartListeners() { myShop.shutdownListeners();

web.xml setup for facelets template and client

由 喜夏-厌秋 提交于 2019-11-29 17:36:17
I've looked at a few resources for JSF and facelets, but don't understand a few configuration points. What's the distinction between: <url-pattern>/faces/*</url-pattern> and: <url-pattern>*.jsf</url-pattern> While I understand it's possible to have several url-pattern elements, unless .jsf pages are explicitly being used, there's no actual need for this mapping, correct? If only faces templates and clients are being used, then it's extraneous? Furthermore, if the facelet template and client are inside WEB-INF , how are they accessed? With the latest releases for JSF and Facelets, there seems

When method marked with @PostConstruct called?

由 本小妞迷上赌 提交于 2019-11-29 16:25:12
问题 At which phase of the JSF request processing lifecycle, the backing bean method marked with @PostConstruct called? 回答1: Methods marked with the @PostConstruct will be invoked after the bean has been created, dependencies have been injected, all managed properties are set, and before the bean is actually set into scope. Found related SO thread, might not be exactly same but it answers your question. And a blog entry explaining the same. 来源： https://stackoverflow.com/questions/4061935/when
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