Reporting the Open Way

Jasper Reports is a popular open source reporting solution

in use. It is written completely in Java and can be integrated into any Java or

Java EE project. We know about its ability to create reports in multi-formats

and its ability to integrate with web pages. However, this product  is not

well documented. In this article, we look into Jasper Reports and associated

tools and their applicability to various scenarios.

How it works



Jasper Reports uses XML to define its report files. The format used is

rather conventional and the definition files are saved with a JRXML extension.

This definition file contains all the information about the report such as

title, headers and footers, and of course, the report details. All this

information is characterized and defined within respective tags. After the

report has been defined, it needs to be compiled into a binary format to view

the report in an existing Java application. You can even integrate it with web

pages such as those from JSP or even JSF pages. To use it, you simply need to

download the package from http://jasperreports. sourceforge.net and make sure

you have the JARs in the DIST folder of the Jasper Reports package folder and

the path included in the CLASSPATH variable.

The Jasper Assistant plugin for Eclipse allows visual configuration of data source and designs the report from the 'Jasper Assistant Perspective'

Sample report



The first step in using Jasper Reports is to write the report definition

file. You can use any text or WYSIWYG editor. We will design a simple report

that displays 'Hello World' in a PDF document. The report definition

invariably includes the following definitions.

-- >






 


   


     


        y="0" width="200" height="20"/>


        World!>>>


     






   




 





 

For the sake of simplicity, we have omitted the and tags that define the header and footer respectively. All

the report data is displayed under the



tag, ie, after all formatting information (such as headers and

title) has been defined. The content of report is defined under the detail tag.

The tag used here displays static text in the report. The

tag defines a report section; all of the elements contain a

'band' element as its only child element. Next, we need to compile this into

a binary file. This can be achieved by calling the compileReport() method on the

'net.sf.jasperreports.engine. JasperCompileManager' class. Of many methods

available, in this example, we will use the one that takes a single String

parameter. The following code handles report display in the Java class.

// import the library







import net.sf.jasperreports.engine.*;







...







JasperReport jasRep;







JasperPrint jasPrnt;







Try {







      jasRep = JasperCompileManager.compileReport(







          "reports/demo.jrxml");







      jasPrnt = JasperFillManager.fillReport(







          jasRep, new HashMap(),
new JREmptyDataSource());







      JasperExportManager.exportReportToPdfFile(







          jasPrnt, "reports/demo.pdf");







} catch (JRException exp) {







      exp.printStackTrace();







}

Use any text editor to write the XML file that creates the report. Jasper then pulls required data from a data source and saves it

The first statement compiles the report into a binary

format. The binary skeletal framework of the report then needs some data,

(static “Hello World!” text in our case) which is provided by the fillReport()

method in the code. Lastly, we have exported the report to a PDF file using the

exportReportToPdfFile() as seen in the preceeding code snippet. For this example

to compile and run, you need the following string in your CLASSPATH:

jasperreports-1.2.1.jar; commons-beanutils-1.5.jar; commons-collections-2.1.jar;

commons-digester- 1.7.jar; commons-logging-1.0.2.jar; commons-logging-api-1.0.2.

jar; itext-1.3.1.jar.

The version numbers can be different depending on the

version of jasper reports being used. Also note that you need to import

'poi-2.0-final-20040126.jar' instead of 'itext-1.3.x.jar' if you intend

to export to an Excel file.

Jasper tools



The above example was a demonstration of Jasper



Reports, which in any case is more capable than what we made it to do. For more

advanced scenarios, you can use the GUI based Jasper Assistant, which helps you

visually build the report, saving your time and effort. Jasper Assistant can be

downloaded from www.jasperassistant.com.

The Assistant is based on Eclipse's plug-in architecture.

So all you need to do is download the package and extract it to the Eclipse

installation folder and start IDE. However, you need also plug-ins such as EMF

(Eclipse Modeling Framework) SDK and GEF (Graphical Editing Framework) SDK

installed in your Eclipse IDE before you can use the Jasper Assistant. The

plug-ins are available at Eclipse's website for free.

Once all the plug-ins are installed, you can simply add a

report to your application. First, create a data source for your report through

the Data Sources section available in 'Window>Preferences>Jasper

Assistant'. Switch to new perspective from Window>Open

Perspective>Other>Jasper Assistant and then choose the File>

New>Report menu to create new Report.

The New Report Wizard then guides you through the initial

steps of report creation, where it connects to the database over a data source

and lets you specify the query or select the fields that will be displayed in

the report. To design the report, you can drag the fields you need to show into

the design editor. Also, you can add bands such as title, page header and column

headers and also format them from the 'Properties' window in the Jasper

Assistant Perspective.

Tweaking app servers for Jasper reports



Jasper Reports can also be displayed from Web pages.



However, you need to make following changes in your app server for that. For

Sun's application server, add the below line in the D:\Sun\ AppServer\domains\domain1\config\server.policy

file, assuming that 'domain1' is the currently used domain in the

application server.

grant{ permission

java.lang.RuntimePermission "createClassLoader"};

Similarly, for Tomcat, add the following line to the

startup script (startup.bat for Windows and startup.sh for Linux):

CATALINA_OPTS="$CATALINA_OPTS

-Djava.awt.headless=true"

So, whenever you have to make complex reports, you know

which way you have to head.

Anadi Misra