managed-bean

问题 I am building a JSF application. I defined the GUI and did the select statements query the database using select. Now I must do the insert statements, but I don\'t know how to read the value of a JSF input component like <h:inputText> and send it to my bean which performs the insert. Should <h:inputText> value be mapped through faces-config.xml , so I can have it in my Java code? 回答1: You need to put all <h:inputXxx> / <h:selectXxx> components in a <h:form> and bind their value attribute to a

问题 When trying to reference a managed bean in EL like so #{bean.entity.property} , sometimes a javax.el.PropertyNotFoundException: Target Unreachable exception is being thrown, usually when a bean property is to be set, or when a bean action is to be invoked. There seem to be five different kinds of messages: Target Unreachable, identifier \'bean\' resolved to null Target Unreachable, \'entity\' returned null Target Unreachable, \'null\' returned null Target Unreachable, \'\'0\'\' returned null

问题 I\'m trying to write a custom servlet (for AJAX/JSON) in which I would like to reference my @ManagedBeans by name. I\'m hoping to map: http://host/app/myBean/myProperty to: @ManagedBean(name=\"myBean\") public class MyBean { public String getMyProperty(); } Is it possible to load a bean by name from a regular servlet? Is there a JSF servlet or helper I could use for it? I seem to be spoilt by Spring in which all this is too obvious. 回答1: In a Servlet, you can get request scoped beans by: Bean

问题 What is the difference between defining View Params like this: <f:metadata> <f:viewParam name=\"id\" value=\"#{someBean.id}\"/> </f:metadata> And defining the property in the ManagedBean like this: @ManagedProperty(value = \"#{param.id}\") private Integer id; 回答1: <f:viewParam>: Sets the value during update model values phase only (since it extends UIInput). The set value is not available during @PostConstruct, so you need an additional <f:event type="preRenderView" listener="#{bean.init}" />

问题 I understand that a managed bean works like a controller, because your only task is \"link\" the View Layer with Model. To use a bean as a managed bean I must declare @ManagedBean annotation, doing that I can communicate JSF with bean directly. If I want to inject some component (from Spring) in this managedBean I have two possibles ways: Choose the property in ManagedBean (like \"BasicDAO dao\") and declare @ManagedProperty(#{\"basicDAO\"}) above the property. Doing it, i\'m injecting the

问题 I noticed that there are different bean scopes like: @RequestScoped @ViewScoped @FlowScoped @SessionScoped @ApplicationScoped What is the purpose of each? How do I choose a proper scope for my bean? 回答1: Introduction It represents the scope (the lifetime) of the bean. This is easier to understand if you are familiar with "under the covers" working of a basic servlet web application: How do servlets work? Instantiation, sessions, shared variables and multithreading. @Request/View/Flow/Session