Jasper Reports is a Java reporting library that can be used to generate reports from templates in JRXML format. It includes methods to compile templates, fill them with data, and export the filled reports to file formats like HTML, PDF, and others. The viewReport method displays generated reports in the built-in JasperReport Viewer for previewing without opening exported files.

1. JASPER REPORTS - EXPLAINED

2. THE LIBRARY
 Can be downloaded at
 http://sourceforge.net/projects/jasperreports/?source=dir
ectory

3. LINKING THE LIBRARIES

4. CREATING A REPORTS STARTS
WITH A TEMPLATE

5. HELLO.JRXML

6. LINKING TO WINDOWS FORMS
[THE CODE]

7. CONNECT TO THE DATABASE

8. THE FORM

9. THE KOWD
 import net.sf.jasperreports.engine.*;
 import net.sf.jasperreports.view.*;
 import javax.sql.*;
 import java.util.HashMap;

10. ESSENTIAL METHODS
 JasperCompileManager.compileReport —
 The compileReport method takes the JasperReports
XML template and compiles it into byte code format
(a JasperReports instance), which you can serialize to
disk as a .jasper file. You can reuse the compiled
templates to generate reports without compiling
them unless you've changed the template source. This
is similar to the difference between a .jsp file and its
compiled servlet class counterpart.

11.  JasperFillManager.fillReport — The fillReport method takes the
compiled report (the JasperReports instance), a few user-
defined custom parameters, and a JasperReports datasource
(an empty instance—more on that later), and fills the report
instance with the parameters and data, if any. In this simple
static Hello Report World! example, the method fills in nothing
but returns an instance of JasperPrint instead.
The JasperPrint instance is an object representation of the
completed report. Now all you have to do is instruct
JasperReports to write it to disk in the desired and supported
formats.

12.  JasperExportManager.exportReportToHtmlFile
— The exportReport method takes the
JasperPrint instance and a destination file path
and creates an HTML file with the report content.
Besides HTML, the JasperReports framework
supports exporting to PDF, XML, CSV (comma-
separated values), XLS, RTF, and text file formats.
You can also create custom file formats for
export with the extensible JasperReports API.

13.  JasperExportManager.viewReport — The
viewReport method displays the generated
report in the built-in JasperReport Viewer. This is
an optional but handy display that enables you to
quickly see how a report looks without opening
the generated files.