I'm trying to display image bytes which is saved in database as a StreamedContent in the <p:graphicImage> as follows:
<p:graphicImage value="#{item.imageF}" width="50" id="grpImage" height="80"/>
private StreamedContent content; // getter and setter
public StreamedContent getImageF() {
if (student.getImage() != null) {
InputStream is = new ByteArrayInputStream(student.getImage());
System.out.println("Byte :"+student.getImage());
content = new DefaultStreamedContent(is, "", student.getStuID());
System.out.println("ddd ------------------------------- " + content);
return content;
}
return content;
}
This returns a blank image. How is this caused and how can I solve it?
The stdout prints the following:
INFO: Byte :[B#a2fb48
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#b0887b
INFO: Byte :[B#a2fb48
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#1d06a92
INFO: Byte :[B#d52f0b
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#39a60
INFO: Byte :[B#d52f0b
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#8c3daa
INFO: Byte :[B#124728a
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#1dbe05b
INFO: Byte :[B#124728a
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#66a266
INFO: Byte :[B#a2fb48
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#1293976
INFO: Byte :[B#a2fb48
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#17b7399
INFO: Byte :[B#d52f0b
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#1e245a5
INFO: Byte :[B#d52f0b
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#4a7153
INFO: Byte :[B#124728a
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#1561bfd
INFO: Byte :[B#124728a
INFO: ddd ------------------------------- org.primefaces.model.DefaultStreamedContent#47a8c2
The <p:graphicImage> requires a special getter method. It will namely be invoked twice per generated image, each in a completely different HTTP request.
The first HTTP request, which has requested the HTML result of a JSF page, will invoke the getter for the first time in order to generate the HTML <img> element with the right unique and auto-generated URL in the src attribute which contains information about which bean and getter exactly should be invoked whenever the webbrowser is about to request the image. Note that the getter does at this moment not need to return the image's contents. It would not be used in any way as that's not how HTML works (images are not "inlined" in HTML output, but they are instead requested separately).
Once the webbrowser retrieves the HTML result as HTTP response, it will parse the HTML source in order to present the result visually to the enduser. Once the webbrowser encounters an <img> element during parsing the HTML source, then it will send a brand new HTTP request on the URL as specified in its src attribute in order to download the content of that image and embed it in the visual presentation. This will invoke the getter method for the second time which in turn should return the actual image content.
In your particular case PrimeFaces was apparently either unable to identify and invoke the getter in order to retrieve the actual image content, or the getter didn't return the expected image content. The usage of #{item} variable name and the lot of calls in the log suggests that you were using it in an <ui:repeat> or a <h:dataTable>. Most likely the backing bean is request scoped and the datamodel isn't properly preserved during the request for the image and JSF won't be able to invoke the getter during the right iteration round. A view scoped bean would also not work as the JSF view state is nowhere available when the browser actually requests the image.
To solve this problem, your best bet is to rewrite the getter method as such so that it can be invoked on a per-request basis wherein you pass the unique image identifier as a <f:param> instead of relying on some backing bean properties which may go "out of sync" during subsequent HTTP requests. It would make completely sense to use a separate application scoped managed bean for this which doesn't have any state. Moreover, an InputStream can be read only once, not multiple times.
In other words: never declare StreamedContent nor any InputStream or even UploadedFile as a bean property; only create it brand-new in the getter of a stateless #ApplicationScoped bean when the webbrowser actually requests the image content.
E.g.
<p:dataTable value="#{bean.students}" var="student">
<p:column>
<p:graphicImage value="#{studentImages.image}">
<f:param name="studentId" value="#{student.id}" />
</p:graphicImage>
</p:column>
</p:dataTable>
Where the StudentImages backing bean can look like this:
#Named // Or #ManagedBean
#ApplicationScoped
public class StudentImages {
#EJB
private StudentService service;
public StreamedContent getImage() throws IOException {
FacesContext context = FacesContext.getCurrentInstance();
if (context.getCurrentPhaseId() == PhaseId.RENDER_RESPONSE) {
// So, we're rendering the HTML. Return a stub StreamedContent so that it will generate right URL.
return new DefaultStreamedContent();
}
else {
// So, browser is requesting the image. Return a real StreamedContent with the image bytes.
String studentId = context.getExternalContext().getRequestParameterMap().get("studentId");
Student student = studentService.find(Long.valueOf(studentId));
return new DefaultStreamedContent(new ByteArrayInputStream(student.getImage()));
}
}
}
Please note that this is a very special case wherein performing business logic in a getter method is completely legit, considering how the <p:graphicImage> works under the covers. Invoking business logic in getters is namely usually frowned upon, see also Why JSF calls getters multiple times. Don't use this special case as excuse for other standard (non-special) cases. Please also note that you can't make use of EL 2.2 feature of passing method arguments like so #{studentImages.image(student.id)} because this argument won't end up in the image URL. Thus you really need to pass them as <f:param>.
If you happen to use OmniFaces 2.0 or newer, then consider using its <o:graphicImage> instead which can be used more intuitively, with an application scoped getter method directly delegating to the service method and supporting EL 2.2 method arguments.
Thus so:
<p:dataTable value="#{bean.students}" var="student">
<p:column>
<o:graphicImage value="#{studentImages.getImage(student.id)}" />
</p:column>
</p:dataTable>
With
#Named // Or #ManagedBean
#ApplicationScoped
public class StudentImages {
#EJB
private StudentService service;
public byte[] getImage(Long studentId) {
return studentService.find(studentId).getImage();
}
}
See also the blog on the subject.
Try including a mime type. In your posted example, you have it as "". The blank image may be because it doesn't recognize the stream as a image file since you made that field an empty string. So add a mime type of image/png or image/jpg and see if that works:
String mimeType = "image/jpg";
StreamedContent file = new DefaultStreamedContent(bytes, mimeType, filename);
There's a couple possibilities here (and please post the entire class if this isn't it).
1) You're not initializing the image properly
2) Your stream is empty so you're getting nothing
I'm assuming student.getImage() has a signature of byte[] so first make sure that that data is actually intact and represents an image. Secondly--you're not specifying a content-type which should be "image/jpg" or whatever you're using.
Here's some boilerplate code to check it with, I'm using Primefaces 2 for this.
/** 'test' package with 'test/test.png' on the path */
#RequestScoped
#ManagedBean(name="imageBean")
public class ImageBean
{
private DefaultStreamedContent content;
public StreamedContent getContent()
{
if(content == null)
{
/* use your database call here */
BufferedInputStream in = new BufferedInputStream(ImageBean.class.getClassLoader().getResourceAsStream("test/test.png"));
ByteArrayOutputStream out = new ByteArrayOutputStream();
int val = -1;
/* this is a simple test method to double check values from the stream */
try
{
while((val = in.read()) != -1)
out.write(val);
}
catch(IOException e)
{
e.printStackTrace();
}
byte[] bytes = out.toByteArray();
System.out.println("Bytes -> " + bytes.length);
content = new DefaultStreamedContent(new ByteArrayInputStream(bytes), "image/png", "test.png");
}
return content;
}
}
and some markup...
<html
xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:p="http://primefaces.prime.com.tr/ui"
>
<h:head>
</h:head>
<h:body>
<p:graphicImage value="#{imageBean.content}" />
</h:body>
</html>
If that code works then you're set up properly. Despite the fact it is garbage code for the streams (don't use it in production) it should give you a point to troubleshoot from. My guess is that you might have something happening in your JPA or other Database framework where you're byte[] is empty or it is formatted wrong. Alternatively you could just have a content-type problem.
Lastly, I would clone the data from the bean so that student.getImage() would only be copied into a new array and then used. This way if you have something unknown going on (something else moving the object or changing the byte[] you're not messing with your streams.
Do something like:
byte[] data = new byte[student.getImage().length]
for(int i = 0; i < data.length; i++)
data[i] = student.getImage()[i];
so that your bean has a copy (or Arrays.copy()--whatever floats your boat). I can't stress enough how something simple like this/content type is usually what's wrong. Good luck with it.
The answer from BalusC is (as usual) the correct one.
But keep one thing (as already stated by him) in mind. The final request is done from the browser to get the URL from the constructed <img> tag. This is not done in a 'jsf context'.
So if you try to e.g. access the phaseId (logging or whatever reason)
context.getCurrentPhaseId().getName()
This will result in a NullPointerException and the somehow misleading error message you will get is:
org.primefaces.application.resource.StreamedContentHandler () - Error in streaming dynamic resource. Error reading 'image' on type a.b.SomeBean
It took me quite some time to figure out what was the problem.
Related
public class UserAction{
private UserData user;
//getter, setter
public String Load() {
user = UserDao.getInstance().getItem(getUserContext().getId());
request.getSession().setAttribute("item", user);
return super.Load();
}
}
public class PropertyAction {
private List <PropertyData> propertyList;
//getter, setter
#Override
public String execute() throws Exception {
propertyList=PropertyDao.getInstance().getItems();
return "list";
}
}
jsp:
<s:iterator value="propertyList" var="item">
${item.name}
${item.thema}
${item.desc}
</s:iterator>
I want to show very strange behaviour of Struts2.
I click property link -> then run PropertyAction.execute() and it display above jsp.
I click user link -> then run UserAction.Load()
I click property link -> then run PropertyAction.execute() and error has been shown "UserData has no property thema".
I spy what happened and I notice that I set setAttribute with name "item". So if I use var="item" in my iterator in jsp, it doesn not use value from propertyList but from session !
My question is it is correct behaviour ?
This is defined behavior; whether or not it's "correct" is debatable.
Because you're using JSP EL, the Struts request wrapper is responsible for resolving JSP EL expressions. The normal application scopes are searched first (e.g., application, session, request). If nothing is found, only then will the value stack be queried for matching expressions.
If you accessed item via non-JSP EL means, e.g., the <s:property> tag, only the value stack would be queried, and you'd get the expected behavior.
When you mix ELs results are not always what you'd expect, so you must be aware how the frameworks in question relate to each other.
This question already has answers here:
Conversion Error setting value for 'null Converter' - Why do I need a Converter in JSF?
(2 answers)
Closed 6 years ago.
I just tried to change a value of a select input box. Loading the page runs into my breakpoint for the getter method of the pubcategory property. Good so far. Changing the value, does NOT invoke the setter method. I trigger an Richfaces ajax processing. I confirm, that all JSF phases are walked through (I also see the JPA-SQL select queries, where I would expect an update statement for changing the value - well, can't be, if the setter method is not triggered). This is my selectOneMenu code
<h:selectOneMenu id="pubCategoryId" converter="#{pubCategoryConverter}" value="#{pubController.pubCategory}">
<f:selectItems value="#{listPubCategoryController.pubCategories}" var="category" itemLabel="#{category.name}" itemValue="#{category}" />
<a4j:ajax event="change" execute="#this" />
</h:selectOneMenu>
<h:message for="pubCategoryId" style="color:red" />
My converter is invoked on both times. the getAsString method, when I load the page and the getAsObject when the on-change action is triggered. From this I concluse, the change really goes back to the server. But - again - it never triggers the setter method.
#ManagedBean(name = "pubCategoryConverterController")
#FacesConverter(value = "pubCategoryConverter")
//#Named
public class PubCategoryConverter implements Converter {
#Inject
private PubCategoryRepository pubCategoryRepository;
public PubCategoryConverter() {
}
// from page to backing bean
#Override
public Object getAsObject(FacesContext ctx, UIComponent component,
String value) {
PubCategory pubCat = pubCategoryRepository.getPubCategoryById(new Long(
value));
return pubCat;
}
// from backing bean to page
#Override
public String getAsString(FacesContext fc, UIComponent uic, Object o) {
PubCategory pubCat = ((PubCategory) o);
return pubCat.getId().toString();
}
}
Same story if I annotate the converter with #Named instead of #FacesConverter/#ManagedBean. Any clue or hints anyone?
Using JBoss 7.1.1, Richfaces 4.3.3, JSF 2.0
The converter is called in the "Process Validations" phase of the JSF lifecycle whereas the setter is called later, during the "Update Model Values" phase. Each phase goes through the entire page which means a validation error in any component will prevent all model updates. If you're not seeing validation errors on the page try checking your message tags.
The skipping of lifecycle phases is done by calling FacesContext.renderResponse(). See UIInput.executeValidate() and LifeCycleImpl.execute() for details.
I hooked up the phase listener and printed the event.getFacesContext().getMessageList(). And, there is an error although not printed to the <h:Message for="pubCategoryId"/>. The error is msg j_idt18:pubFormE:pubCategoryId: Validation Error: Value is not valid
package com.foo;
import java.util.List;
import java.util.logging.Logger;
import javax.faces.event.PhaseEvent;
import javax.faces.event.PhaseListener;
import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
public class PhaseTracker implements PhaseListener {
private static final Logger logger = Logger.getLogger("org.exadel.helper");
public void beforePhase(PhaseEvent e) {
List<FacesMessage> msgs = e.getFacesContext().getMessageList();
for (FacesMessage msg : msgs) {
logger.info("before msg " + msg.getSummary() + " :: " + msg.getDetail());
}
logger.info("BEFORE " + e.getPhaseId());
}
public void afterPhase(PhaseEvent e) {
logger.info("AFTER " + e.getPhaseId());
}
}
The issue is with the equals(Object o) method within of the model object (some call that DTO). As stated in many forums, the values that you compare within this method must not look like e.g. this.id == o.id, because it compares instances not the inner state. Use equals instead this.id.equals(o.id). Once that is fixed the error Value is not valid will go away.
After all, I noticed the following. If you want to use the selectOneMenu with the tag attribute converter instead of <f:converter ../>, e.g. ...
<h:selectOneMenu value="#{pubController.pubCategory}" converter="#{pubCategoryConverterController}">
... you need to annotate your converter also as a #ManagedBean instance in addition to #FacesConverter, e.g.
#ManagedBean(name="pubCategoryConverterController")
#FacesConverter(value = "pubCategoryConverter")
On the other hand, if you want to use <f:converter converterId="pubCategoryConverter"> tag, you need to reference the faces converter name - NOT an instance of a managed bean. Notice, there is no EL #{...} around the converter name. However, in this case, you CANNOT inject a bean into your converter. As a consequence, in your converter bean, you need to instantiate a controller from the application context in order to use EJB services. e.g.
PubCategoryController pubCategoryController = ctx.getApplication().evaluateExpressionGet(ctx, "#{pubCategoryController}", PubCategoryController.class);
I use tomcat 7.0 and JSF 2.1 and I have problem when I call in my .xhtml page something like that: #{homePage.get("userName")}
I get javax.el.ELException: Caused by: java.lang.NullPointerException
at mainPacket.HomePageBean.get(HomePageBean.java:35)
I have ManagedBean like below:
#ManagedBean(name = "homePage")
#ViewScoped
public class HomePageBean {
private Map<String, Object> map;
public HomePageBean() {
map= FacesContext.getCurrentInstance().getExternalContext().getSessionMap();
//remove unnecessary values from sessionMap
FacesContext.getCurrentInstance().getExternalContext().getSessionMap().clear();
}
public String get(Object s){
return map.get(s).toString();
}
}
When I don't use clear, everything works ok. But I want to clear sessionMap. How to resolve it ?
Thanks
Java is an object oriented language. It doesn't give you a copy of the object everytime you request it. No, it gives you a reference to the object instance in memory. At the moment you invoke Map#clear() on the session map, then the map reference which you obtained just beforehand is basically also emptied, because it points to exactly the same map instance which you just emptied!
Your concrete functional requirement is nowhere mentioned in the question and the whole design in the code posted so far makes honestly no utter sense (I can't imagine any sensible real world use case for this), so it's hard to propose you the right solution. Best what you can get is the advice to add a nullcheck.
public String get(Object s){
Object value = map.get(s);
return (value != null) ? value.toString() : null;
}
You should by the way be very careful with abruptly emptying the session map this way. JSF stores view scoped and session scoped managed beans in there and it's also used by the flash scope.
When I access a JPA managed date value from JSF, it comes back with an javax.faces.component.UdateModelException saying
'Cannot convert 01.01.10 00:00 of type class java.util.Date to class org.apache.openjpa.util.java$util$Date$proxy
Using a JPA-managed date value (which means it is proxied) works fine when it is used directly from the EL likes this:
'<h:outputLabel value="MyDateValue" for="input"/>
'<h:inputText id="inputDate" value="#{bean.myDate}"/>
However, it causes trouble when trying to use it with composite components
and gives back the following converter exception and thus can't update the model...
The (simplified) JSF composite component inputDate.xhtml
<head>
<title>A date input field</title>
</head>
<composite:interface>
<composite:attribute name="dateValue"/>
</composite:interface>
<composite:implementation>
<h:outputLabel value="MyDateValue" for="input"/>
<h:inputText id="input" value="#{cc.attrs.dateValue}"/>
</composite:implementation>
Assumption:
It seems the proxy replacement in OpenJPA is handled differently when the value is being accessed from inside a composite. My guess is the EL-resolver handles calls to object values differently when it is passed to composites. Passing it to composites means it is first accessed within the composite, which is too late and the required replacement of the proxy is not accomplished (thus the converter exception)
So I tried to change the Expression Language for MyFaces, but it didn't work in Websphere, even though I changed the class loading to parent last and provided el-impl and el-api from glassfish in the lib folder and inserted the necessary context-param for MyFaces
How do you guys use JPA-managed dates (or other proxied entities) in composite components???
If you are using the sun EL implementation you might use the following ELResolver which works around this issue:
public class BugfixELResolver extends ELResolver {
//...
#Override
public Class<?> getType(ELContext anElContext, Object aBase, Object aProperty) {
if (aBase.getClass().getCanonicalName().equals("com.sun.faces.el.CompositeComponentAttributesELResolver.ExpressionEvalMap")){
Object tempProperty=((Map)aBase).get(aProperty);
if (tempProperty!=null&&tempProperty.getClass().getCanonicalName().equals("org.apache.openjpa.util.java.util.Date.proxy")) {
anElContext.setPropertyResolved(true);
return java.util.Date.class;
}
}
return null;
}
}
Add it to the faces-config this way:
<el-resolver>
xxx.BugfixELResolver
</el-resolver>
This workaround can also be used in environments where you can not change the EL implementation (like websphere etc.).
Here is the workaround. The problem seems to be WebSpheres' ExpressionLanguage Implementation or rather the order resolvers are executed. Registering the JBoss EL implementation works and resolves the date proxies before calling the composite component. I also tried the Glassfish EL, but it didn't work either...
Registering a alternative EL is quite strange: The setting in web.xml for MyFaces is
<context-param>
<param-name>org.apache.myfaces.EXPRESSION_FACTORY</param-name>
<param-value>org.jboss.el.ExpressionFactoryImpl</param-value>
</context-param>
Additionally under WebContent/META-INF/services/ a file named javax.el.expressionFactory is needed with this single line org.jboss.el.ExpressionFactoryImpl. The class comes from jboss-el-2.0.2.CR1.jar
(sorry, couldn't find the link to a maven repo)
I will keep you updated once I find a better solution...
I was wondering if I can capture the result of an action after the result returns and the JSP is rendered. I want to be able to take the entire result (generated HTML) and push it into memcached so I can bring it via Nginx with-out hitting the application server. Any ideas?
PS: I know I can run the interceptor after the action executes but before the result returns and the JSP is rendered, but not after the JSP is rendered.
I haven't found a way to do this inside of struts2, your best bet it to create a servlet Filter and have it modify the OutputStream.
http://onjava.com/pub/a/onjava/2003/11/19/filters.html
Hey I know its quite late now to answer you might have already found out the answer, however for others to benefit I am posting the answer.
One thing that is very similar to what you are doing is done by sitemesh filter.
Yes, filter comes before and after the Struts2 filter itself, so you can mess with the inputs and outputs easily.
But struts does evaluate JSP/freemarker/velocity and generate the final html which is passed to the user. JSP is a bit trickey because internally a servlet is called but check out org.apache.struts2.views.freemarker.FreemarkerResult class, you can see the actual html getting generated in template.process(model, writer);. This writer is actually ServletActionContext.getResponse().getWriter();
Now to get the html all you need to do is
ServletActionContext.getResponse().getWriter().toString() //This does not work out of box. To get the toString() to work you need to use a ResponseWrapper - which is the same method to get result html in Filters. See- Programming Customized Requests and Responses.
Listing to modify resulting html in struts 2. This is not tested, but it is extracted from my code I have written earlier for custom template engine. I will probably post full description in Custom template engine for struts2
public class DecoratorInterceptor implements Interceptor {
public String intercept(ActionInvocation invocation) throws Exception {
final ActionContext context = invocation.getInvocationContext ();
HttpServletResponse responseParent = (HttpServletResponse)
context.get(ServletActionContext.HTTP_RESPONSE);
CharResponseWrapper wrapper = new CharResponseWrapper(responseParent);
ServletActionContext.setResponse(wrapper);
//Actual Action called
String result = invocation.invoke();
String htmlReturned = wrapper.toString();
//play with htmlReturned ...
String modifiedhtml = pushintoMemCache(htmlReturned );
CharArrayWriter car = new CharArrayWriter();
car.write(modifiedhtml );
PrintWriter out = responseParent.getWriter();
out.write(car.toString());
out.flush();
}
#Override
public void destroy() {
// TODO Auto-generated method stub
}
#Override
public void init() {
// TODO Auto-generated method stub
}
}
Read this article - http://struts.apache.org/2.0.6/docs/interceptors.html
SUMMARY:When you request a resource
that maps to an "action", the
framework invokes the Action object.
But, before the Action is executed,
the invocation can be intercepted by
another object. After the Action
executes, the invocation could be
intercepted again. Unsurprisingly, we
call these objects "Interceptors."
Question: How do you determine if the view has been generated? Do you set a request header or an some sort of a flag to determine if the view has been generated?
You could try throwing a MemCachedException to indicate that it is time to load into a mem cache. Your interceptor code could read
try {
return invocation.invoke();
} catch (MemCachedException mce) {
// Your code to upload to MemCache.
} finally {
// blah blah clean up.
}
Within your interceptor's intercept() method, the ActionInvocation parameter has a getResult() method which returns null before Action execution (i. e. before you call invocation.invoke() in your intercept() method) and contains an implementation of Result afterwards. That object should give you some way to access the data you need, but how this is done probably depends on the class that is actually used.
See also my somewhat related question and the answer I posted after figuring it out.