用java通过Prometheus HTTP API获取主机CPU情况举例-Go服务器开发

以下是使用Java通过Prometheus HTTP API获取主机CPU情况的示例代码：

import io.prometheus.client.Counter;
import io.prometheus.client.Gauge;
import io.prometheus.client.exporter.HTTPResponse;
import io.prometheus.client.exporter.HttpConnectionFactory;
import io.prometheus.client.exporter.PushGateway;
import io.prometheus.client.hotspot.DefaultExports;
import io.prometheus.client.spring.boot.SpringBootMetricsCollector;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

@Component
public class MetricsExporter {
    private static final String PUSHGATEWAY_HOST = "localhost";
    private static final String PUSHGATEWAY_PORT = "9091";
    private static final String JOB_NAME = "example-job";
    private static final String INSTANCE_NAME;

    @Autowired
    private SpringBootMetricsCollector springBootMetricsCollector;

    static {
        String hostname = "";
        try {
            hostname = InetAddress.getLocalHost().getHostName();
        } catch (UnknownHostException e) {
            // handle exception
        }
        INSTANCE_NAME = hostname;
    }

    @Bean
    public void start() throws InterruptedException, ExecutionException {
        DefaultExports.initialize();

        // register Spring Boot metrics collector
        springBootMetricsCollector.register();

        // define Prometheus Metrics
        Gauge cpuUsage = Gauge.build()
                .name("cpu_usage")
                .help("Current CPU usage")
                .register();

        // create a PushGateway instance with HTTP connection factory
        PushGateway pushGateway = new PushGateway(PUSHGATEWAY_HOST + ":" + PUSHGATEWAY_PORT,
                                                  new HttpConnectionFactory());

        // push metrics to the PushGateway every 10 seconds
        while (true) {
            try {
                HTTPResponse response = pushGateway.pushAdd(cpuUsage, JOB_NAME, INSTANCE_NAME);
                System.out.println("Pushed metrics to PushGateway. Status code: " + response.getStatus());
            } catch (Exception e) {
                // handle exception
            }
            TimeUnit.SECONDS.sleep(10);
        }
    }
}

在上面的代码中，我们首先使用DefaultExports.initialize()方法初始化Prometheus Java客户端的默认指标（例如JVM内存使用情况、线程数等）。然后，我们使用SpringBootMetricsCollector实例将Spring Boot应用程序的度量收集器注册到Prometheus客户端。接下来，我们定义了一个名为cpu_usage的计量器，该计量器会记录当前主机的CPU使用情况。

然后，我们创建了一个PushGateway实例，并使用pushAdd()方法将CPU使用率指标推送到PushGateway。我们还定义了一个作业名（example-job）和一个实例名（使用主机名）。最后，我们使用TimeUnit.SECONDS.sleep(10)方法设置了一个10秒的循环周期，周期性地将CPU使用率指标推送到PushGateway。