Create a Data Access Object for OData Services using JDBI

JDBI is a SQL convenience library for Java that exposes two different style APIs, a fluent style and a SQL object style. The CData JDBC Driver for OData integrates connectivity to live OData services in Java applications. By pairing these technologies, you gain simple, programmatic access to OData services. This article explains how to build a basic Data Access Object (DAO) and the accompanying code to read and write OData services.

Getting Started

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Create a DAO for the OData Orders Entity

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 MyOrdersDAO {
 //insert new data into OData
 @SqlUpdate("INSERT INTO Orders (ShipCity, Freight) values (:shipCity, :freight)")
 void insert(@Bind("shipCity") String shipCity, @Bind("freight") String freight);

 //request specific data from OData (String type is used for simplicity)
 @SqlQuery("SELECT Freight FROM Orders WHERE ShipCity = :shipCity")
 String findFreightByShipCity(@Bind("shipCity") String shipCity);

 /*
 * close with no args is used to close the connection
 */
 void close();
}

Open a Connection to OData

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

The User and Password properties, under the Authentication section, must be set to valid OData user credentials. In addition, specify a URL to a valid OData server organization root or OData services file.

Built-in Connection String Designer

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

java -jar cdata.jdbc.odata.jar

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

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

jdbc:odata:URL=http://services.odata.org/V4/Northwind/Northwind.svc;UseIdUrl=True;OData Version=4.0;Data Format=ATOM;

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:odata:URL=http://services.odata.org/V4/Northwind/Northwind.svc;UseIdUrl=True;OData Version=4.0;Data Format=ATOM;");
MyOrdersDAO dao = dbi.open(MyOrdersDAO.class);

//do stuff with the DAO

dao.close();

Read OData Services

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

//disply the result of our 'find' method
String freight = dao.findFreightByShipCity("New York");
System.out.println(freight);

Write OData Services

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

//add a new entry to the Orders entity
dao.insert(newShipCity, newFreight);

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