I am using taglib.
I have the following java code.
int i=0;
public void doTag() throws JspException, IOException {
i= 1; //I do some process and get a value for i
super.doTag();
}
I have defined a tld file for accessing the code in jsp file.
My doubt is that how do i access the value i in my jsp file.
I dont want to use the getJspContext().getOut().print(i) which will print the value of i.
Thanks.
Related
Is it possible to pass a variable to the data-sly-use statement using HTL Sightly Use API while also specifying a bundle?
For example
<sly data-sly-use.help="${'com.company.service.Helper' # myVar='hello!'}"></sly>
with the helper
package com.company.service;
import com.adobe.cq.sightly.WCMUsePojo;
public class Helper extends WCMUsePojo {
#Override
public void activate() throws Exception {
String myVar = getProperties().get("myVar", String.class);
// why is myVar is null?
}
}
If it makes a difference, this is in AEM 6.4.3.0
When extending WCMUsePojo you need to use the get (https://helpx.adobe.com/experience-manager/6-2/sites/developing/using/reference-materials/javadoc/com/adobe/cq/sightly/WCMUsePojo.html#get(java.lang.String,%20java.lang.Class) ) method to be able to obtain the obiects passed as expression options.
Also have a look at the Passing Parameters section in https://docs.adobe.com/content/help/en/experience-manager-htl/using/htl/use-api-java.html
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.
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.
I'm using Grails 2.3.7 and have a controller method which binds the request to a command class. One of the fields in the command class is a String array, as it expects multiple params with the same name to be specified - e.g. ?foo=1&foo=2&foo=3&bar=0.
This works fine most of the time. The one case where it fails is if the param value contains a comma - e.g. ?foo=val1,val2&foo=val3,val4. In this case I'm getting an array with 4 values: ["val1","val2","val3","val4"], not the intended output of ["val1,val2","val1,val2"]. URL escaping/encoding the comma does not help and in my cases the param value is surrounded by quote characters as well (foo=%22a+string+with+commas,+etc%22).
I had a similar problem with Spring 3.x which I was able to solve: How to prevent parameter binding from interpreting commas in Spring 3.0.5?. I've attempted one of the answers by adding the following method to my controller:
#InitBinder
public void initBinder(WebDataBinder binder) {
binder.registerCustomEditor(String[].class, new StringArrayPropertyEditor(null));
}
However this didn't work.
I also tried specifying a custom conversion service, based on the comment in https://jira.grails.org/browse/GRAILS-8997.
Config/spring/resources.groovy:
beans = {
conversionService (org.springframework.context.support.ConversionServiceFactoryBean) {
converters = [new CustomStringToArrayConverter()]
}
}
and
import org.springframework.core.convert.converter.Converter
import org.springframework.util.StringUtils
class CustomStringToArrayConverter implements Converter<String, String[]> {
#Override
public String[] convert(String source) {
return StringUtils.delimitedListToStringArray(source, ";");
}
}
but I couldn't get this to work either.
For now, I've come up with a work around. My Controller method has an extra line to set the troublesome field explicitly with:
commandObj.foo = params.list('foo') as String[]
I'm still open to suggestions on how to configure grails to not split on a comma...
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.