PrimeFaces - MeterGauge with Ajax Polling Example

In this example, we will learn how to use MeterGaugeChartModel to display a meter gauge which updates with ajax polling.

JSF page

src/main/webapp/index.xhtml

<h:form>
    <p:chart id="cpu_gauge" type="metergauge" model="#{cpuUsageBean.meterGaugeModel}"
             style="width:400px;height:250px"/>
    <p:poll interval="1" update="cpu_gauge"/>
</h:form>

The managed bean

@ManagedBean
@ViewScoped
public class CpuUsageBean {
  private AtomicInteger cpuUsage;
  private MeterGaugeChartModel gaugeModel;

  @PostConstruct
  public void init() {
      initCpuGaugeModel();
      initCpuSimulator();
  }

  private void initCpuGaugeModel() {
      gaugeModel = new MeterGaugeChartModel();
      gaugeModel.setIntervals(Arrays.asList(20, 40, 60, 80, 100));
      gaugeModel.setTitle("CPU Usage %");
      gaugeModel.setSeriesColors("aa6666,bb6666,cc6666,dd6666,ee6666");
  }

  private void initCpuSimulator() {
      cpuUsage = new AtomicInteger(50);
      ExecutorService es = Executors.newFixedThreadPool(1);
      es.execute(() -> {
          while (true) {
              int i = ThreadLocalRandom.current()
                                       .nextInt(-15, 16);
              int usage = cpuUsage.get();
              usage += i;
              if (usage < 0) {
                  usage = 0;
              } else if (usage > 100) {
                  usage = 100;
              }
              cpuUsage.set(usage);
              try {
                  TimeUnit.MILLISECONDS.sleep(500);
              } catch (InterruptedException e) {
              }
          }
      });
  }


  public MeterGaugeChartModel getMeterGaugeModel() {
      gaugeModel.setValue(cpuUsage.get());
      return gaugeModel;
  }
}

mvn tomcat7:run-war

Output

Example Project

Dependencies and Technologies Used:

• primefaces 6.1 primefaces
• jsf-api 2.2.14: This is the master POM file for Oracle's Implementation of the JSF 2.2 Specification.
• jsf-impl 2.2.14: This is the master POM file for Oracle's Implementation of the JSF 2.2 Specification.
• JDK 1.8
• Maven 3.3.9