As in the accepted answer provided by Daniel, Primefaces' charts are not available at the server side. I add an answer here only to show a possible workaround.
At the client side, we assign the base64 PNG encoded string to a hidden field value, an example modified from Primefaces demo source code for export charts:
<h:form id="hform">
<p:lineChart value="#{testBean.linearModel}" legendPosition="e"
zoom="true" title="Linear Chart" minY="0" maxY="10"
style="width:500px;height:300px" widgetVar="chart" />
<p:commandButton id="exp" value="Export" icon="ui-icon-extlink"
onclick="exportChart();"
actionListener="#{testBean.submittedBase64Str}" />
<h:inputHidden id="b64" value="#{testBean.base64Str}" />
<script type="text/javascript">
function exportChart() {
// exportAsImage() will return a base64 png encoded string
img = chart.exportAsImage();
document.getElementById('hform:b64').value = img.src;
}
</script>
</h:form>
At the backing bean, we need to decode the string, a simple example as below:
public void submittedBase64Str(ActionEvent event){
// You probably want to have a more comprehensive check here.
// In this example I only use a simple check
if(base64Str.split(",").length > 1){
String encoded = base64Str.split(",")[1];
byte[] decoded = org.apache.commons.codec.binary.Base64.decodeBase64(encoded);
// Write to a .png file
try {
RenderedImage renderedImage = ImageIO.read(new ByteArrayInputStream(decoded));
ImageIO.write(renderedImage, "png", new File("C:\\out.png")); // use a proper path & file name here.
} catch (IOException e) {
e.printStackTrace();
}
}
}
The PNG file is now stored in the server, and you can continue to make use of that file in other parts of your codes.
