Creating Your First Report - JasperReports for Java Developers - page 38

response.setContentType("application/pdf");
servletOutputStream.flush();
servletOutputStream.close();
}
catch (JRException e)
{
// display stack trace in the browser
StringWriter stringWriter = new StringWriter();
PrintWriter printWriter = new PrintWriter(stringWriter);
e.printStackTrace(printWriter);
response.setContentType("text/plain");
response.getOutputStream().print(stringWriter.toString());
}
}
}
Since web browsers are incapable of displaying reports in JasperReports' native
format (at least without the help of an applet), we must export the report to a format
that the browser can understand. JasperReports allows us to export reports to PDF
and many other formats. Since the PDF format is widely used, we chose to export to
this format in this example.
The servlet in the above example calls the static JasperRunManager.
runReportToPdfStream() method. The signature for this method is:
runReportToPdfStream(java.io.InputStream inputStream ,
java.io.OutputStream outputStream ,
java.util.Map parameters ,
JRDataSource dataSource)
To display the report on the browser, we need to pass the binary report template,
or Jasper file, in the form of a stream, as the first argument of this method.
We can accomplish this by calling the javax.servlet.ServletContext.
getResourceAsStream() method, passing a String containing the location
of the Jasper file as a parameter. This method will return an instance of java.
io.InputStream that we can use as the first argument for the JasperRunManager.
runReportToPDFStream() method.
The JasperRunManager.runReportToPDFStream() method needs an instance of
java.io.OutputStream() to write the compiled report. We can simply use the
default output stream for the servlet, which can be obtained by calling the javax.
servlet.http.HttpServletResponse.getOutputStream() method.