JasperReports (http://jasperreports.sourceforge.net) is a powerful open-source reporting engine that supports the creation of report designs using an easily understood XML file format. JasperReports is capable of rendering reports output into four different formats: CSV, Excel, HTML and PDF.
Your application will need to include the latest release of JasperReports, which at the time of writing was 0.6.1. JasperReports itself depends on the following projects:
BeanShell
Commons BeanUtils
Commons Collections
Commons Digester
Commons Logging
iText
POI
JasperReports also requires a JAXP compliant XML parser.
To configure JasperReports views in your Spring container
configuration you need to define a
ViewResolver
to map view names to the
appropriate view class depending on which format you want your report
rendered in.
Typically, you will use the
ResourceBundleViewResolver
to map view names to
view classes and files in a properties file.
<bean id="viewResolver" class="org.springframework.web.servlet.view.ResourceBundleViewResolver"> <property name="basename" value="views"/> </bean>
Here we've configured an instance of the
ResourceBundleViewResolver
class that will look
for view mappings in the resource bundle with base name
views
. (The content of this file is described in
the next section.)
The Spring Framework contains five different
View
implementations for JasperReports,
four of which correspond to one of the four output formats supported
by JasperReports, and one that allows for the format to be determined
at runtime:
Table 16.2. JasperReports View
classes
Class Name | Render Format |
---|---|
JasperReportsCsvView | CSV |
JasperReportsHtmlView | HTML |
JasperReportsPdfView | |
JasperReportsXlsView | Microsoft Excel |
JasperReportsMultiFormatView | The view is decided upon at runtime |
Mapping one of these classes to a view name and a report file is a matter of adding the appropriate entries into the resource bundle configured in the previous section as shown here:
simpleReport.class=org.springframework.web.servlet.view.jasperreports.JasperReportsPdfView simpleReport.url=/WEB-INF/reports/DataSourceReport.jasper
Here you can see that the view with name
simpleReport
is mapped to the
JasperReportsPdfView
class, causing the output
of this report to be rendered in PDF format. The
url
property of the view is set to the location of
the underlying report file.
JasperReports has two distinct types of report file: the design
file, which has a .jrxml
extension, and the
compiled report file, which has a .jasper
extension. Typically, you use the JasperReports Ant task to compile
your .jrxml
design file into a
.jasper
file before deploying it into your
application. With the Spring Framework you can map either of these
files to your report file and the framework will take care of
compiling the .jrxml
file on the fly for you. You
should note that after a .jrxml
file is compiled by
the Spring Framework, the compiled report is cached for the lifetime
of the application. To make changes to the file you will need to
restart your application.
The JasperReportsMultiFormatView
allows
for report format to be specified at runtime. The actual rendering of
the report is delegated to one of the other JasperReports view classes
- the JasperReportsMultiFormatView
class simply
adds a wrapper layer that allows for the exact implementation to be
specified at runtime.
The JasperReportsMultiFormatView
class
introduces two concepts: the format key and the discriminator key. The
JasperReportsMultiFormatView
class uses the
mapping key to lookup the actual view implementation class and uses
the format key to lookup up the mapping key. From a coding perspective
you add an entry to your model with the formay key as the key and the
mapping key as the value, for example:
public ModelAndView handleSimpleReportMulti(HttpServletRequest request, HttpServletResponse response) throws Exception { String uri = request.getRequestURI(); String format = uri.substring(uri.lastIndexOf(".") + 1); Map model = getModel(); model.put("format", format); return new ModelAndView("simpleReportMulti", model); }
In this example, the mapping key is determined from the
extension of the request URI and is added to the model under the
default format key: format
. If you wish to use a
different format key then you can configure this using the
formatKey
property of the
JasperReportsMultiFormatView
class.
By default the following mapping key mappings are configured in
JasperReportsMultiFormatView
:
Table 16.3. JasperReportsMultiFormatView
Default
Mapping Key Mappings
Mapping Key | View Class |
---|---|
csv | JasperReportsCsvView |
html | JasperReportsHtmlView |
JasperReportsPdfView | |
xls | JasperReportsXlsView |
So in the example above a request to URI /foo/myReport.pdf would
be mapped to the JasperReportsPdfView
class. You
can override the mapping key to view class mappings using the
formatMappings
property of
JasperReportsMultiFormatView
.
In order to render your report correctly in the format you have
chosen, you must supply Spring with all of the data needed to populate
your report. For JasperReports this means you must pass in all report
parameters along with the report datasource. Report parameters are
simple name/value pairs and can be added be to the
Map
for your model as you would add any
name/value pair.
When adding the datasource to the model you have two approaches to
choose from. The first approach is to add an instance of
JRDataSource
or a
Collection
type to the model
Map
under any arbitrary key. Spring will
then locate this object in the model and treat it as the report
datasource. For example, you may populate your model like so:
private Map getModel() { Map model = new HashMap(); Collection beanData = getBeanData(); model.put("myBeanData", beanData); return model; }
The second approach is to add the instance of
JRDataSource
or Collection
under a
specific key and then configure this key using the
reportDataKey
property of the view class. In both
cases Spring will instances of Collection
in a
JRBeanCollectionDataSource
instance. For
example:
private Map getModel() { Map model = new HashMap(); Collection beanData = getBeanData(); Collection someData = getSomeData(); model.put("myBeanData", beanData); model.put("someData", someData); return model; }
Here you can see that two Collection
instances
are being added to the model. To ensure that the correct one is used, we
simply modify our view configuration as appropriate:
simpleReport.class=org.springframework.web.servlet.view.jasperreports.JasperReportsPdfView simpleReport.url=/WEB-INF/reports/DataSourceReport.jasper simpleReport.reportDataKey=myBeanData
Be aware that when using the first approach, Spring will use the
first instance of JRDataSource
or
Collection
that it encounters. If you need to place
multiple instances of JRDataSource
or
Collection
into the model then you need to use the
second approach.
JasperReports provides support for embedded sub-reports within your master report files. There are a wide variety of mechanisms for including sub-reports in your report files. The easiest way is to hard code the report path and the SQL query for the sub report into your design files. The drawback of this approach is obvious - the values are hard-coded into your report files reducing reusability and making it harder to modify and update report designs. To overcome this you can configure sub-reports declaratively and you can include additional data for these sub-reports directly from your controllers.
To control which sub-report files are included in a master report using Spring, your report file must be configured to accept sub-reports from an external source. To do this you declare a parameter in your report file like so:
<parameter name="ProductsSubReport" class="net.sf.jasperreports.engine.JasperReport"/>
Then, you define your sub-report to use this sub-report parameter:
<subreport> <reportElement isPrintRepeatedValues="false" x="5" y="25" width="325" height="20" isRemoveLineWhenBlank="true" backcolor="#ffcc99"/> <subreportParameter name="City"> <subreportParameterExpression><![CDATA[$F{city}]]></subreportParameterExpression> </subreportParameter> <dataSourceExpression><![CDATA[$P{SubReportData}]]></dataSourceExpression> <subreportExpression class="net.sf.jasperreports.engine.JasperReport"> <![CDATA[$P{ProductsSubReport}]]></subreportExpression> </subreport>
This defines a master report file that expects the sub-report to
be passed in as an instance of
net.sf.jasperreports.engine.JasperReports
under the
parameter ProductsSubReport
. When configuring your
Jasper view class, you can instruct Spring to load a report file and
pass into the JasperReports engine as a sub-report using the
subReportUrls
property:
<property name="subReportUrls"> <map> <entry key="ProductsSubReport" value="/WEB-INF/reports/subReportChild.jrxml"/> </map> </property>
Here, the key of the Map
corresponds to the name of the sub-report parameter in th report
design file, and the entry is the URL of the report file. Spring will
load this report file, compiling it if necessary, and will pass into
the JasperReports engine under the given key.
This step is entirely optional when using Spring configure your
sub-reports. If you wish, you can still configure the data source for
your sub-reports using static queries. However, if you want Spring to
convert data returned in your ModelAndView
into
instances of JRDataSource
then you need to specify
which of the parameters in your ModelAndView
Spring
should convert. To do this configure the list of parameter names using
the subReportDataKeys
property of the your chosen
view class:
<property name="subReportDataKeys" value="SubReportData"/>
Here, the key you supply MUST
correspond to both the key used in your
ModelAndView
and the key used in your report design
file.
If you have special requirements for exporter configuration -
perhaps you want a specific page size for your PDF report, then you can
configure these exporter parameters declaratively in your Spring
configuration file using the exporterParameters
property of the view class. The exporterParameters
property is typed as Map
and in your
configuration the key of an entry should be the fully-qualified name of
a static field that contains the exporter parameter definition and the
value of an entry should be the value you want to assign to the
parameter. An example of this is shown below:
<bean id="htmlReport" class="org.springframework.web.servlet.view.jasperreports.JasperReportsHtmlView"> <property name="url" value="/WEB-INF/reports/simpleReport.jrxml"/> <property name="exporterParameters"> <map> <entry key="net.sf.jasperreports.engine.export.JRHtmlExporterParameter.HTML_FOOTER"> <value>Footer by Spring! </td><td width="50%">&nbsp; </td></tr> </table></body></html> </value> </entry> </map> </property> </bean>
Here you can see that the
JasperReportsHtmlView
is being configured with an
exporter parameter for
net.sf.jasperreports.engine.export.JRHtmlExporterParameter.HTML_FOOTER
which will output a footer in the resulting HTML.