This is a general question about best practices for handling persisted data in JSF. My JSF page is going to have several fields that map to a managed bean. Upon a button click the fields of this bean are going to be persisted in a database. Is it better to use another bean with application scope to handle the JDBC code, or should I have a method in the bean itself to handle that? Similarly I'll need a method to retrieve the information upon a user request.
I'm trying to understand the concurrent model of each EJB session bean types.
The singleton is well documented and seems clear to me... Only one instance and many threads using it but each method by default is synchronized because @Lock is defaulted to WRITE. We can let multiple threads use on method with @Lock(READ).
The stateless beans are in a pool I think I read somewhere that the container will ensure only one thread is using one instance at a time but this instances are recycled/reused so many threads can use the same instance but one at a time.
Is this correct ? or is it possible that multi-threading occur in one instance of SLSB ?If in the client I obtain a single reference of a SLSB and share this "instance reference" in multiple threads is it true that all the threads could use different instances on the server side ?
The stateful instance I obtain in the client is linked to one server instance and any method call will target the same instace. If many threads are using the same reference, all method calls will be synchronized and waiting for a certain amount of time that can be defined in @AccessTimeout and if the timeout is reach will end with a ConcurrentAccessException.
Can we use @Lock(READ) and let many thread use the same method like in a singleton ?
I have a primefaces editable datatable with column filtering feature.The datatable has live scrolling feature.The problem that i am facing here is that both filtering and scrolling are happening correctly with Request scoped managed bean but when the scope of the same bean is changed to view scope(javax.faces.bean.ViewScoped) then the filtering happens but on removing the keyed in key word from filter box the table content is not reset to original state and also i am not able to scroll down to next set of records on reaching the end of scrolling.Cell editing feature is working perfectly.
One thing that i observed is ,currently i am querying 5000 odd records to load into datatable.But if the number of records is limited below 5000 scrolling is happening correctly but problem with filtering remains same.I even tested by upgrading to Primefaces 5.1 from 3.Code snippet of xhtml page
I am working on eclipse kepler, JSF 2.2 with PrimeFaces 4.0 / Mojarra 2.2 library.
actually there are 2 Problems:
I still get this server message no matter what I do.
(( javax.el.PropertyNotFoundException: /Order.xhtml @28,76 value="#{kk.refugee.id}": Target Unreachable, 'refugee' returned null))
and if I delete the input text puls the hidden, the message keeps pop up for 'material' selectOneMenu. -
I have no chance to examin : ((is this javascript code correct, to copy the value of one component to the other.)) these are my xhtml file and java calsses.
**kk.java** ----------- package khldqr.beans; import javax.faces.bean.ManagedBean; import javax.faces.bean.SessionScoped; @SessionScoped @ManagedBean public class kk {
I'm wondering if there's a way to build a template for managed beans which could be extended by a constructor instead of re-writing beans for each entity. I can do that quite easily for Dao objects by creating facades and using those facades to create Dao implementations for specific entities. Not sure if the same concept works for managed beans and haven't really come accross any searches.
I wrote the following but I'm not sure how to implement or even if the concept of generics and templating can be applied to managed beans in the same way it can be applied to Dao classes:
public class BeanTemplate<T> { private ListDataModel<T> listModel; @EJB private GenDao dao; private Class<T> entityClass;
[Code] .....
The above assumes there's only one method needed in the bean. I thought of extending like this:
public class EmployeeBean extends BeanTemplate<Employee> { public EmployeeBean() { super(Employee.class); }
// how can the methods be called??
Is the same concept for creating dao templates possible for managed beans?
In my Icefaces 3 application I have a ManagedBean ancestor that defines common attributes to those they spread it. Including CSS styles to be apply at the menu as icons depending on whether they are selected or not. Classes that extend the CommonMBean class define styles. My question is what do I have to put in the language experssion styleClass to tell him that the getter to use is that of the parent class.
CommonMBean.java package com.omb.view; public class CommonMBean private String menu1Css = ""; private String menu2Css = "";
If I have the next request scoped JSF bean for example:
public class UserBean { private String name; private String surname; public String saveUser(){ //service is called to save a user } public String updateUser(){ //service is called to update a user
[Code] ....
1.In struts for example the Action classes are singletons and I think is the way it has to be because they contain business logic and is the same logic for every user but in JSF because of you mix properties from a form and methods with business logic, these beans have to be request scoped like the above one but is very wierd that a bean which contains business logic(saveUser()....) be request scoped;I dont see it effective, is like creating a new servlet each time you want to save a user but I think is the way JSF works, right?
2 To avoid the mixing of form properties in a bean with business logic, some people say to have the form beans request scoped and actions beans session scoped.
- Is this right? - How then can you get the request form bean in the action bean? - The scopes in JSF are request, session and view so you cannot create singleton action beans, the best you can get is a session action bean, right?. Once again I dont see the point of creating action beans with session scoped,they should be application scoped if it existed
I am new to JSF and when i try to implement a sample application im getting this wierd error of page not found(.xhtml). Here is the code i have created..
Bean class :
package com.trail.beans; import javax.faces.bean.ManagedBean; import javax.faces.bean.SessionScoped; @ManagedBean @SessionScoped public class UserLoginBean {
And in the server getCustomerList() accessed to database, how many times getCustomerList() would be called from I request the xhtml page?. I have read this would be called several times because of JSF internals and It would be better to store it in a variable and access this variable.
1. Is this true this would be called several times? why?
2. If the previous statement was true, how to avoid it, I mean not call the method from a service?
I've spent almost 3 hours on googling about java beans and where it is usable. What I've figured out is that a bean has a public non-arg constructor, properties and getters/setters to manipulate them. I also know that a bean contains no logic, only fields. However, I don't fully understand why I need to use beans instead of normal classes even if a class can do the same things like a bean? Are beans used to store data or what?
I have seen in some examples like URL... a good design is to have the model and the action methods in one just single bean and the model not to be a separated class but a few properties like this:
public class CustomerBean implements Serializable{ //DI via Spring CustomerBo customerBo; [b]public String name;[/b] [b]public String address;[/b] //getter and setter methods
[code]...
Some questions:
1. If you are using hibernate or any other ORM like the above example(URL...), why not to use the hibernate pojo bean directly like it represented the form instead of using properties?:
public class CustomerBean implements Serializable{ //DI via Spring CustomerBo customerBo; [b]Customer customer;[/b] //represents the properties of a form //getter and setter methods public void setCustomerBo(CustomerBo customerBo) { this.custom
2. Why is it said that JSF represents the purest MVC? Spring separates the model from the view too and Struts does too. I dont really understand it
My project consists of a web app where a user can select a area from a picture and f.e. if it is a office layout he can input the worker name and any peace of hardware that the area might have. In this case there are two categories: Hardware and Computer. Hardware - it has 5 dropdown lists consisting of printer, scanner and etc. Computer - like Hardware consists of many dropdown lists which add up to components such as processor, motherboard and etc. For me, considering this is my first ever web app project, is a huge step towards web development, I have used various mixes of Java, javascript and primefaces code.
My current problem: When a user selects an area he gets a dialog box where he is prompted to select his desired input, afterwards the user clicks the 'save' button and get's another dialogbox which has a resume of what he has selected so he could check out his input and save it by clicking the 'save' button in the resume box. My problem is that when the user clicks the save button the button calls a method which takes all the input and creates an Area object (Area object consists of various objects such as: Coordinates, Dimensions, Employee, ComputerList and HardwareList) and sends a query to the database, but all the values I get is null.
XHTML code:
<!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:ui="http://java.sun.com/jsf/facelets" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core" xmlns:p="http://primefaces.org/ui">
I have an in-cell editable data table with a viewscoped managed bean.I found that the control never goes to the ajax event method onCellEdit when the scope of the bean is @Viewscoped but it works when the scope is changed to request scope.how to get this feature work with viewscope.Below is my code snippet
1. All jsf tags like datatable, form, etc.. will generate UIComponents in server side, right?
2. All non JSF tags will not generate UIComponents in server side, right?
3. If you want something in a view that will be the same across users and requests, I mean, It will not change like a label tag, it doesn't make any sense to create it with a JSF tag in order to save memory in server side, right?
private String displayFormat = "%02d:%02d:%02d";// produces 00:00:00 hour:min:seconds public void timerHasChanged() { currentTime = System.currentTimeMillis(); // How long has been taken so far? long secsTaken = (currentTime - startTime) / 1000; long minsTaken = secsTaken / 60; secsTaken %= 60; long hoursTaken = minsTaken/60; minsTaken %= 60;
Formatter fmt = new Formatter(); fmt.format(displayFormat, hoursTaken, minsTaken, secsTaken); timerJbl.setText(fmt.toString());
How would i code the get and set method for format, so in property tab a user can choose if they want the timer shown in seconds, or minutes or hours or seconds&minutes
I am developing a web application using JSF-2.0 on weblogic 10.3.6. I am using Facelets as VDL. I have 5 different machine. They are different according to their OS and their geographical location. On my first xhtml page server (machine) is decided. Then on next page file upload and rest of processing takes place. My restriction is that SSO configuration can be done on only one machine.
So I am restricted to using xhtml files from only my primary server where SSO configuration is done. But I have to connect to servlets or managed-bean of different machine as requests are machine specific and file needs to be uploaded to those machines for processing. So I cannot use redirectUrl as I need to be only on one machine. Is it possible that xhtml on one server can talk to managed-bean on other server(different machine)?.
We can have attributes in different scopes in a JSP page. Suppose there is an attribute named 'name' with values in different scopes as below:
request - A session - B application - C page - D
Suppose I print ${name} in a JSP page, then what will be the value printed on the JSP? And, what will be the preference order of attributes search in different scopes?
I am new to Java and I am doing an assignment to identify Class and Attributes from below example. How to identify 7 classes and its attributes from this scenario:
ABC Maps Maker produces electronic maps for global positioning systems. Every map needs to define the latitude and longitude of the centre of the map, together with the length and breadth of the map. A map also has a name, and a set of geographical features.
A geographical feature is something noticeable in a a map; e.g., a hill, or valley. Among the types of features are the following: trace features, track features and tract features.
All features have a name that is displayed on the map next to the feature. A trace feature has a coordinate point to indicate its location relative to the centre of the map. Broadcasting stations, mountain peaks, and transmission towers, are examples of trace features. Every trace feature has a description associated with it.
Examples of track features include roads, railways and rivers. Each track feature has a list of points that define its course, and a line pattern. The line pattern specifies the colour, and the thickness.
Like a track feature, a tract feature also has set of points, except that when drawn on the map, the last point is linked to the first point to enclose a complete region. Additionally, it has a fill pattern which incorporates essentially a colour.
Recall that there is a class, Point, in the java.awt package – this can be used to hold the co-ordinate of a point
