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JDBI からQuandl Data のデータアクセスオブジェクトを作成

JDBI でQuandl 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 Quandl は、Java アプリケーションとリアルタイムQuandl 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、Quandl 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Quandl 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。

Quandl AAPL 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 MyAAPLDAO { //insert new data into Quandl @SqlUpdate("INSERT INTO AAPL (Collapse, Volume) values (:collapse, :volume)") void insert(@Bind("collapse") String collapse, @Bind("volume") String volume); //request specific data from Quandl (String type is used for simplicity) @SqlQuery("SELECT Volume FROM AAPL WHERE Collapse = :collapse") String findVolumeByCollapse(@Bind("collapse") String collapse); /* * close with no args is used to close the connection */ void close(); }

Quandl への接続を開く

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

Quandl uses an API key for authentication. See the help documentation for a guide to obtaining the APIKey property.

Additionally, set the DatabaseCode connection property to the code identifying the Database whose Datasets you want to query with SQL. You can search the available Databases by querying the Databases view.

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 Quandl JDBC Driver.Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.quandl.jar

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

A connection string for Quandl will typically look like the following:

jdbc:quandl:APIKey=abc123;DatabaseCode=WIKI;

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:quandl:APIKey=abc123;DatabaseCode=WIKI;"); MyAAPLDAO dao = dbi.open(MyAAPLDAO.class); //do stuff with the DAO dao.close();

Quandl Data について

With the connection open to Quandl, simply call the previously defined method to retrieve data from the AAPL entity in Quandl.

//disply the result of our 'find' method String volume = dao.findVolumeByCollapse("Daily"); System.out.println(volume);

Quandl Data の書き方

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

//add a new entry to the AAPL entity dao.insert(newCollapse, newVolume);

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

 
 
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