序本文主要研究一下flink TableEnvironment的scan操作实例//Scanning a directly registered tableval tab: Table = tableEnv.scan(“tableName”)//Scanning a table from a registered catalogval tab: Table = tableEnv.scan(“catalogName”, “dbName”, “tableName”)scan操作用于从schema读取指定的table，也可以传入catalogName及dbName从指定的catalog及db读取TableEnvironment.scanflink-table_2.11-1.7.0-sources.jar!/org/apache/flink/table/api/TableEnvironment.scalaabstract class TableEnvironment(val config: TableConfig) { private val internalSchema: CalciteSchema = CalciteSchema.createRootSchema(false, false) private val rootSchema: SchemaPlus = internalSchema.plus() //…… @throws[TableException] @varargs def scan(tablePath: String*): Table = { scanInternal(tablePath.toArray) match { case Some(table) => table case None => throw new TableException(s"Table ‘${tablePath.mkString(".")}’ was not found.") } } private[flink] def scanInternal(tablePath: Array[String]): Option[Table] = { require(tablePath != null && !tablePath.isEmpty, “tablePath must not be null or empty.”) val schemaPaths = tablePath.slice(0, tablePath.length - 1) val schema = getSchema(schemaPaths) if (schema != null) { val tableName = tablePath(tablePath.length - 1) val table = schema.getTable(tableName) if (table != null) { return Some(new Table(this, CatalogNode(tablePath, table.getRowType(typeFactory)))) } } None } private def getSchema(schemaPath: Array[String]): SchemaPlus = { var schema = rootSchema for (schemaName <- schemaPath) { schema = schema.getSubSchema(schemaName) if (schema == null) { return schema } } schema } //……}scan方法内部调用的是scanInternal，scanInternal首先读取catalog及db信息，然后调用getSchema方法来获取schemagetSchema是使用SchemaPlus的getSubSchema来按层次获取SchemaPlus，如果没有指定catalog及db，那么这里返回的是rootSchema获取到schema之后，就可以从tablePath数组获取tableName(数组最后一个元素)，调用SchemaPlus的getTable方法查找Table小结TableEnvironment的scan操作就是从Schema中查找Table，可以使用tableName，或者额外指定catalog及db来查找getSchema是使用SchemaPlus的getSubSchema来按层次获取SchemaPlus，如果没有指定catalog及db，那么这里返回的是rootSchema获取到schema之后，就可以从tablePath数组获取tableName(数组最后一个元素)，调用SchemaPlus的getTable方法查找TabledocTable API