when chart is not come then how to show message

[manish]

hi ,
I am facing a problem that when i entered my search criteria then x and y axis comes dinamicaly from database.
But when ther is no value then its x axis will not get any data
so i got
java.lang.IllegalStateException: getOutputStream() has already been called for this response
org.apache.catalina.connector.Response.getWriter(Response.java:596)
exception.
I have go through the posted topic but its not worth.
now i want to show the message when i will not get any data but unable to do so.
help me out>. i am using this code to send chart on jsp in my servlet>>>timeSeriesChart = createChart(sFromDate,sToDate,createDataset(sNDC,listPBM,sFromMonth,sFromYear,sToMonth,sToYear));

request.setAttribute("timeSeriesChart",timeSeriesChart);

response.setContentType( "image/png" );

BufferedImage buf = timeSeriesChart.createBufferedImage(600, 420, null);
PngEncoder encoder = new PngEncoder( buf, false, 0, 9 );
response.getOutputStream().write( encoder.pngEncode() );


RequestDispatcher requestDispatcher = getServletContext().getRequestDispatcher("/TimeSeriesReportResult.jsp");
requestDispatcher.forward(request,response);

[oacis]

The problem you are facing here is that you have already committed output to the response stream before you forward to the jsp.

Depending on what the /TimeSeriesReportResult.jsp does...

Firstly you are writing out a stream of data with the content type of image/png

Then you attempt to forward the request on to a jsp which will probably have the content type of txt/html (or something along those lines)

You will need to have a servlet/jsp that writes out the chart as a stream, and a second page which calls this page. I would recommend a servlet rather than a jsp, however if it is a jsp file it will look something like the following (pseudocode only)

so for chart.jsp

Code: Select all

<%
timeSeriesChart = createChart(sFromDate,sToDate,createDataset(sNDC,listPBM,sFromMonth,sFromYear,sToMonth,sToYear)); 

response.setContentType( "image/png" ); 

BufferedImage buf = timeSeriesChart.createBufferedImage(600, 420, null); 
PngEncoder encoder = new PngEncoder( buf, false, 0, 9 ); 
response.getOutputStream().write( encoder.pngEncode() ); 
%>

Note that you can have NO whitespace or anything else in the file - the servlet is a better option


in the /TimeSeriesReportResult.jsp

<img src="chart.jsp">

Hope this helps