实现一个flink sql connector websocket 连接器

要实现一个Flink SQL WebSocket连接器，需要遵循以下步骤：

1. 创建一个WebSocket连接器类，继承Flink SQL的TableSource接口，用于从WebSocket中读取数据。

   public class WebSocketTableSource implements StreamTableSource<Row> {
       private final String url;
       private final String[] fieldNames;
       private final TypeInformation<?>[] fieldTypes;
   
       public WebSocketTableSource(String url, String[] fieldNames, TypeInformation<?>[] fieldTypes) {
           this.url = url;
           this.fieldNames = fieldNames;
           this.fieldTypes = fieldTypes;
       }
   
       @Override
       public DataStream<Row> getDataStream(StreamExecutionEnvironment env) {
           // 创建WebSocket连接
           WebSocketClient client = new WebSocketClient();
           final List<Row> rows = new ArrayList<>();
           client.connect(new WebSocketAdapter() {
               @Override
               public void onTextMessage(WebSocket websocket, String message) throws Exception {
                   // 从WebSocket中读取数据
                   ObjectMapper objectMapper = new ObjectMapper();
                   JsonNode jsonNode = objectMapper.readTree(message);
                   Object[] values = new Object[fieldTypes.length];
                   for (int i = 0; i < fieldTypes.length; i++) {
                       values[i] = objectMapper.convertValue(jsonNode.get(fieldNames[i]), fieldTypes[i].getTypeClass());
                   }
                   rows.add(Row.of(values));
               }
           }, new URI(url));
   
           // 将数据转换为数据流
           TypeInformation<Row> rowType = Types.ROW_NAMED(fieldNames, fieldTypes);
           return env.fromCollection(rows, rowType);
       }
   
       @Override
       public TableSchema getTableSchema() {
           return new TableSchema(fieldNames, fieldTypes);
       }
   
       @Override
       public String explainSource() {
           return "WebSocket(" + url + ")";
       }
   }

2. 在Flink SQL中使用WebSocket连接器，例如：

   CREATE TABLE websocket_table (
     field1 STRING,
     field2 INT,
     field3 BOOLEAN
   ) WITH (
     'connector' = 'websocket',
     'url' = 'ws://localhost:8080',
     'format' = 'json'
   );
   
   SELECT * FROM websocket_table;

这将创建一个WebSocket连接器，并将从WebSocket中读取的数据作为Flink SQL的表。需要注意的是，WebSocket连接器需要异步处理事件，因此需要使用非阻塞式的WebSocket客户端库，例如Jetty WebSocket客户端库。同时，需要指定数据的格式，例如JSON格式，以便正确解析数据。