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JDBI からApache Spark Data のデータアクセスオブジェクトを作成

JDBI でApache Spark data 用のSQL オブジェクトAPIを作成する方法を概説します。

JDBI は、Fluent スタイルとSQL オブジェクトスタイルという2つの異なるスタイルAPI を公開する、Java 用のSQL コンビニエンスライブラリです。CData JDBC Driver for Apache Spark は、Java アプリケーションとリアルタイムApache Spark data のデータ連携を実現します。これらの技術を組み合わせることによって、Apache Spark data へのシンプルなコードアクセスが可能になります。ここでは、基本的なDAO(Data Access Object )とそれに付随するApache Spark data の読み書きのためのコードの作成について説明します。

Apache Spark Customers Entity のDAO を作成

The interface below declares the desired behavior for the SQL object to create a single method for each SQL statement to be implemented.

public interface MyCustomersDAO { //insert new data into Apache Spark @SqlUpdate("INSERT INTO Customers (Country, Balance) values (:country, :balance)") void insert(@Bind("country") String country, @Bind("balance") String balance); //request specific data from Apache Spark (String type is used for simplicity) @SqlQuery("SELECT Balance FROM Customers WHERE Country = :country") String findBalanceByCountry(@Bind("country") String country); /* * close with no args is used to close the connection */ void close(); }

Apache Spark への接続を開く

Collect the necessary connection properties and construct the appropriate JDBC URL for connecting to Apache Spark.

Set the Server, Database, User, and Password connection properties to connect to SparkSQL.

ビルトイン接続文字列デザイナー

For assistance in constructing the JDBC URL, use the connection string designer built into the Apache Spark JDBC Driver.Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.sparksql.jar

Fill in the connection properties and copy the connection string to the clipboard.

A connection string for Apache Spark will typically look like the following:

jdbc:sparksql:Server=127.0.0.1;

Use the configured JDBC URL to obtain an instance of the DAO interface.The particular method shown below will open a handle bound to the instance, so the instance needs to be closed explicitly to release the handle and the bound JDBC connection.

DBI dbi = new DBI("jdbc:sparksql:Server=127.0.0.1;"); MyCustomersDAO dao = dbi.open(MyCustomersDAO.class); //do stuff with the DAO dao.close();

Apache Spark Data について

With the connection open to Apache Spark, simply call the previously defined method to retrieve data from the Customers entity in Apache Spark.

//disply the result of our 'find' method String balance = dao.findBalanceByCountry("US"); System.out.println(balance);

Apache Spark Data の書き方

It is also simple to write data to Apache Spark, using the previously defined method.

//add a new entry to the Customers entity dao.insert(newCountry, newBalance);

Since the JDBI library is able to work with JDBC connections, you can easily produce a SQL Object API for Apache Spark by integrating with the CData JDBC Driver for Apache Spark.Download a free trial and work with live Apache Spark data in custom Java applications today.

 
 
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