elasticsearch：NoNodeAvailableException[None of the configured nodes are available异常

NoNodeAvailableException[None of the configured nodes are available: [{#transport#-1}{9L7K2EanQGSxD5aAmbzAIw}{localhost}{127.0.0.1:9200}]]

这里显示无可用节点异常，找了相关的博客，把elasticsearch.yaml文件中的cluster.name: my-application取消注释，并且在创建TransportClient时也设置了，原来设置为空；

Settings settings = Settings.builder().put("cluster.name","my-application")
                .put("client.transport.sniff", true)
                .build();
        TransportClient transportClient = new PreBuiltTransportClient(settings)
                .addTransportAddress(new TransportAddress(InetAddress.getByName("localhost"), Integer.valueOf(9200)))；

一步步Debug这里仍然报错；

由于前面也使用了

RestHighLevelClient

RestHighLevelClient restHighLevelClient = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http"))
        );

感觉有可能是端口的问题，把端口改为9300

Settings settings = Settings.builder().put("cluster.name","my-application")
                .put("client.transport.sniff", true)
                .build();
        TransportClient transportClient = new PreBuiltTransportClient(settings)
                .addTransportAddress(new TransportAddress(InetAddress.getByName("localhost"), Integer.valueOf(9300)));

重新运行，没有报错；

尝试在elasticsearch.yaml文件注释掉cluster.name，并且初始化时my-application也为空，重新运行，仍然没有报错！

Settings settings = Settings.builder().put("cluster.name","")
                .put("client.transport.sniff", true)
                .build();
        TransportClient transportClient = new PreBuiltTransportClient(settings)
                .addTransportAddress(new TransportAddress(InetAddress.getByName("localhost"), Integer.valueOf(9300)));