import org.apache.kafka.clients.admin.AdminClient; import org.apache.kafka.clients.admin.AdminClientConfig; import org.apache.kafka.clients.admin.DescribeClusterResult; import org.apache.kafka.clients.admin.ListTopicsResult; import java.util.Properties; import java.util.concurrent.TimeUnit; public class JavaAdminClientTest { public static void main(String[] args) { // Set uncaught exception handler to catch AdminClient thread errors Thread.setDefaultUncaughtExceptionHandler((t, e) -> { System.err.println("UNCAUGHT EXCEPTION in thread " + t.getName() + ":"); e.printStackTrace(); }); String bootstrapServers = args.length > 0 ? args[0] : "localhost:9093"; System.out.println("Testing Kafka wire protocol with broker: " + bootstrapServers); Properties props = new Properties(); props.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers); props.put(AdminClientConfig.REQUEST_TIMEOUT_MS_CONFIG, 10000); props.put(AdminClientConfig.DEFAULT_API_TIMEOUT_MS_CONFIG, 10000); props.put(AdminClientConfig.CLIENT_ID_CONFIG, "java-admin-test"); props.put(AdminClientConfig.CONNECTIONS_MAX_IDLE_MS_CONFIG, 120000); props.put(AdminClientConfig.SOCKET_CONNECTION_SETUP_TIMEOUT_MS_CONFIG, 10000); props.put(AdminClientConfig.SOCKET_CONNECTION_SETUP_TIMEOUT_MAX_MS_CONFIG, 30000); props.put(AdminClientConfig.SECURITY_PROTOCOL_CONFIG, "PLAINTEXT"); props.put(AdminClientConfig.RECONNECT_BACKOFF_MS_CONFIG, 50); props.put(AdminClientConfig.RECONNECT_BACKOFF_MAX_MS_CONFIG, 1000); System.out.println("Creating AdminClient with config:"); props.forEach((k, v) -> System.out.println(" " + k + " = " + v)); try (AdminClient adminClient = AdminClient.create(props)) { System.out.println("AdminClient created successfully"); Thread.sleep(2000); // Give it time to initialize // Test 1: Describe Cluster (uses Metadata API internally) System.out.println("\n=== Test 1: Describe Cluster ==="); try { DescribeClusterResult clusterResult = adminClient.describeCluster(); String clusterId = clusterResult.clusterId().get(10, TimeUnit.SECONDS); int nodeCount = clusterResult.nodes().get(10, TimeUnit.SECONDS).size(); System.out.println("Cluster ID: " + clusterId); System.out.println("Nodes: " + nodeCount); } catch (Exception e) { System.err.println("Describe Cluster failed: " + e.getMessage()); e.printStackTrace(); } // Test 2: List Topics System.out.println("\n=== Test 2: List Topics ==="); try { ListTopicsResult topicsResult = adminClient.listTopics(); int topicCount = topicsResult.names().get(10, TimeUnit.SECONDS).size(); System.out.println("Topics: " + topicCount); } catch (Exception e) { System.err.println("List Topics failed: " + e.getMessage()); e.printStackTrace(); } System.out.println("\nAll tests completed!"); } catch (Exception e) { System.err.println("AdminClient creation failed: " + e.getMessage()); e.printStackTrace(); System.exit(1); } } }