Display different images within the portlet, liferay introduction, add portlet liferay

anu 86	:	Display different images within the portlet
		I'm developing JSR-168 compatible portlet for Liferay using the Netbeans portal pack. The purpose of my portlet is to display a pie chart according to some values in a database. In the edit mode (myportlet_edit.jsp)of the portlet I gave a form for the user to fill the text value in order to retrieve the data from the database. (Eg: Month of the year)
		Then in the view.jsp file, I connected to the database and retrieved the required details for the month selected by the user, to generate the pie chart.Then I generated the pie chart using JFree and stored it as an .png image within the folder liferay-portal-5.2.3\tomcat-6.0.18\webapps\myportlet. Every thing is fine up to that point and I get the correct piechart image within the folder everytime I change the month.
		But the problem is it is not correctly displayed at the portlet. In the view.jsp file of my portlet I used the following code to display the generated pie chart.
		When I deploy the portlet for the first time, it displayed the correct image according to the selected month and which is stored in the folder. But when I set the month again and refresh the page,correct chart is generated at the folder, but the chart is not changed at the portlet.
		Can someone please help me to solve this issue. Since this is urgent matter, any help would be highly appreciated.
Mazhar Anwar	:	Hi,
		Rather than storing to file system, you can directly send image to browser by using any Servlet or serveResource method of
		PortletAPI and by using Java Script or ajax you can change the src of your image <img> tag.
		something like
		document.getElementById('<portlet:namespace />chartImage').src = url;
		where url will be your Servlet call or serveResource Method call which will return you an image and this will solve your problem.
		Regards
Ankur Srivastava	:	Are you doing a form submit upon month change event.. ?
anu 86	:	Thanks lot for your immediate replies. Yes I'm using a form to get the month from the user. It is in myportlet_edit.jsp file as below
		Then in the processAction method of the myportlet.java file I did the following.
		Then in the do_view method of the myportlet.java file I did the following.
		Finally in the myportlet_view.jsp file I did the following.
		Then based on this filterValue I queried my database and created the jfree pie chart with those retrieved values as below.
		Then at the end of <% %> tags of the above java codes, I did the following to view this saved chart.
		Although the correct chart is displayed for the first time in the porltet, next times when I submit a new month the chart doesn't changed in the portlet. (But the correct chart is created and saved within the folder /webapps/myportlet/piechart.png)
Babu Janarthanan	:	Hi,
		I Guess this is due to hard coding the file name as "piechart.png". instead you can create file name using ServletUtilities.saveChartAsPNG(chart, 280, 180, null, null). you can also take a look at admin portlet for JFree chart implementation(server.jspf)
		hope it helps you.
		Thx,
		Babu
anu 86	:	Hi Babu,
		Although it is sometimes back, thanks lot for your guide. But I still have problems in it. First I added the following to my WEB-INF/web.xml file of the portlet.
		Then I changed the previous view.jsp file of my portlet and now it has the following code to create the chart.
		But now it doesn't display the chart within my portlet. There is only a small red dot in the chart area.
		So can anyone please help me on this...Since I'm new to this area, any help would be really helpful.
		Thanks,