[[jasper-reports-on-vaadin-sample]]
Jasper reports on Vaadin sample
------------------------------

[[introduction]]
Introduction
~~~~~~~~~~~~

I meet JasperReports some years ago and I liked this report library;
this year I did need to implement a report on a personal project using
Vaadin, but surprisingly I was not able to found a sample of this, so I
did this little sample and article.

First, you will need a JDK Maven and Mysql in order to try the sample,
and you can download the code here:
http://sourceforge.net/projects/jrtutorial/files/VaadinJRSample/

There is a README.txt file you can follow in order to run the sample,
basically you need to:

1.  Create database running resources/database.sql on Mysql or MariaDB
2.  Compile the entire project: run "mvn install”.
3.  Deploy the application in Jetty: run "mvn jetty:run"
4.  Go to http://localhost:8080/  in your browser

[[implementation]]
Implementation
~~~~~~~~~~~~~~

Let’s see the sample code step by step. +
The data is only a _person_ table with some data. +
The main class _MyUI.java_ has two UI components (the report generating
button and a list component used to show current data in database.):

[source,java]
....
final Button reportGeneratorButton = new Button("Generate report");
…
layout.addComponent(reportGeneratorButton);
layout.addComponent(new PersonList());
....

The list is implemented on _PersonList.java_, I am using a
_FilteringTable_ (https://vaadin.com/directory/component/filteringtable),
that loads the data using a Vaadin _SQLContainer_:

[source,java]
....
SQLContainer container=null;
…
TableQuery tq = new TableQuery("person", new ConnectionUtil().getJDBCConnectionPool());
container = new SQLContainer(tq);
filterTable = buildPagedTable(container);
....

And the _SQLContainer_ is provided with a _JDBCConnectionPool_ created
from a properties file (_resources/database.properties_):

[source,java]
....
Properties prop=PropertiesUtil.getProperties();
…
public JDBCConnectionPool getJDBCConnectionPool(){
JDBCConnectionPool pool = null;
try {
  pool = new SimpleJDBCConnectionPool(
      prop.getProperty("database.driver"),
      prop.getProperty("database.url"),
      prop.getProperty("database.userName"),
      prop.getProperty("database.password"));
} catch (SQLException e) {
  e.printStackTrace();
}
return pool;
....

The report generation is implemented on _ReportGenerator_ class, this
class loads the report template:

[source,java]
....
File templateFile=new File(templatePath);       
JasperDesign jasperDesign = JRXmlLoader.load(templateFile);
....

Compile report template:

[source,java]
....
jasperReport = JasperCompileManager.compileReport(jasperDesign);
....

Fill report with data:

[source,java]
....
HashMap fillParameters=new HashMap();       
JasperPrint jasperPrint = JasperFillManager.fillReport(   
    jasperReport,                   
    fillParameters,                   
    conn);
....

Export the _jasperPrint_ object to Pdf format:

[source,java]
....
JRPdfExporter exporter = new JRPdfExporter();
exporter.setExporterInput(new SimpleExporterInput(jasperPrint));
exporter.setExporterOutput(new SimpleOutputStreamExporterOutput(outputStream));
exporter.exportReport();
....

And finally execute all the logic to generate the report and sent it to
an _OutputStream_:

[source,java]
....
JasperDesign jasperDesign=loadTemplate(templatePath);
setTempDirectory(templatePath);       
JasperReport jasperReport=compileReport(jasperDesign);       
JasperPrint jasperPrint=fillReport(jasperReport, conn);       
exportReportToPdf(jasperPrint, outputStream);
....

But all the logic at _ReportGenerator.java_ is called from the
_ReportUtil_ class, this class is the responsible to connect Vaadin
layer with _ReportGenerator_ layer. There are two methods: the first one
is _prepareForPdfReport_, this method creates a database connection,
generates the report as a StreamResource (calling the another method)
and finally extends the source button with a _FileDownloader_ component
in order to upload the generated report stream, so all the uploading
magic is done by _FileDownloader_ extension
(https://vaadin.com/api/com/vaadin/server/FileDownloader.html):

[source,java]
....
Connection conn=new ConnectionUtil().getSQLConnection();
reportOutputFilename+=("_"+getDateAsString()+".pdf");       
StreamResource myResource =createPdfResource(conn,reportTemplate,reportOutputFilename);       
FileDownloader fileDownloader = new FileDownloader(myResource);       
fileDownloader.extend(buttonToExtend);
....

The second method _createPdfResource_, uses _ReportGenerator_ class in
order to return the generated report as a _StreamResource_:

[source,java]
....
return new StreamResource(new StreamResource.StreamSource() {
  @Override
  public InputStream getStream () {
    ByteArrayOutputStream pdfBuffer = new ByteArrayOutputStream();
    ReportGenerator reportGenerator=new ReportGenerator();
    try {
      reportGenerator.executeReport(baseReportsPath+templatePath, conn, pdfBuffer);
    } catch (JRException e) {
      e.printStackTrace();
    }
    return new ByteArrayInputStream(
        pdfBuffer.toByteArray());
  }
}, reportFileName);
....

So, in order to call the report generator process when only need to call
ReportUtil like we did in ‘MyUI.java’:

[source,java]
....
final Button reportGeneratorButton = new Button("Generate report");
new ReportsUtil().prepareForPdfReport("/reports/PersonListReport.jrxml",               
                                      "PersonList",               
                                      reportGeneratorButton);
....

Finally, the jasper report design can be found in the
_WEB-INF/personListReport.jrxml_ file

This is a picture of the sample running and the generated report:

image:img/VaadinJasperReportsSample_small.jpg[Running sample]

And that’s all, I expect to help someone with this sample, thanks for
reading.