Java Reference
In-Depth Information
If the report we are exporting contains images, then there are a couple of extra steps
we need to take to make sure the images are displayed correctly in the browser. We
must attach the
JasperPrint
instance to the HTTP session. The session attribute
name is defined in the
DEFAULT_JASPER_PRINT_SESSION_ATTRIBUTE
constant
defined in
net.sf.jasperreports.j2ee.servlets.ImageServlet
.
We also need to set the
JRHtmlExporterParameter.IMAGES_URI
parameter as an
instance of
JRHtmlExporter
. Its corresponding value must be a string indicating
the location of the images. In practice, this value is almost always set to the URL
mapped to the
net.sf.jasperreports.j2ee.servlets.ImageServlet
included
with JasperReports. In our example, we set its value to
"image?image="
, which is a
typical value. Of course, the
ImageServlet
must be included in
web.xml
for reports
with images to render properly. The
web.xml
corresponding to the previous servlet
deployment is as follows:
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<servlet>
<servlet-name>webreport</servlet-name>
<servlet-class>
net.ensode.jasperbook.HtmlReportServlet
</servlet-class>
</servlet>
<servlet>
<servlet-name>ImageServlet</servlet-name>
<servlet-class>
net.sf.jasperreports.j2ee.servlets.ImageServlet
</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>webreport</servlet-name>
<url-pattern>/webreport</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>ImageServlet</servlet-name>
<url-pattern>/image</url-pattern>
</servlet-mapping>
</web-app>
