Spring JdbcTemplate Example

Spring JdbcTemplate is the most important class in Spring JDBC package.

Spring JdbcTemplate

  • JDBC produces a lot of boiler plate code, such as opening/closing a connection to a database, handling sql exceptions etc. It makes the code extremely cumbersome and difficult to read.
  • Implementing JDBC in the Spring Framework takes care of working with many low-level operations (opening/closing connections, executing SQL queries, etc.).
  • Thanks to this, when working with the database in the Spring Framework, we only need to define the connection parameters from the database and register the SQL query, the rest of the work for us is performed by Spring.
  • JDBC in Spring has several classes (several approaches) for interacting with the database. The most common of these is using the JdbcTemplate class. This is the base class that manages the processing of all events and database connections.
  • The JdbcTemplate class executes SQL queries, iterates over the ResultSet, and retrieves the called values, updates the instructions and procedure calls, “catches” the exceptions, and translates them into the exceptions defined in the org.springframwork.dao package.
  • Instances of the JdbcTemplate class are thread-safe. This means that by configuring a single instance of the JdbcTemplate class, we can then use it for several DAO objects.
  • When using JdbcTemplate, most often, it is configured in the Spring configuration file. After that, it is implemented using bean in DAO classes.

Spring JdbcTemplate Example

Let’s look at Spring JdbcTemplate example program. I am using Postgresql database here, but you can use any other relational database too, such as MySQL and Oracle. All you need is to change the database configurations and it should work.

First of all we need some sample data to work on. Below SQL queries will create a table and populate it with some data for us to use.

Below image shows the final project structure in Eclipse.

Spring-JDBCTemplate-Example-Project

Spring JDBC Maven Dependencies

We need following dependencies – spring-core, spring-context, spring-jdbc and postgresql. If you are using any other relational database such as MySQL, then add it’s corresponding java driver dependencies. Here is our final pom.xml file.

Spring DataSource Configuration

Next step is to create spring configuration class to define DataSource bean. I am using java based configuration, you can also do this using spring bean configuration xml file.

  • @Configuration – says that this class is configuration for Spring context.
  • @ComponentScan(“com.journaldev.spring”)- specifies the package to scan for component classes.
  • @PropertySource(“classpath:database.properties”)- says that properties will be read from database.properties file.

Content of database.properties file is shown below.

If you are using MySQL or some other relational database, change above configurations accordingly.

Spring JDBC Model Classes

Next step is to create model classes to map our database table.

For fetching data from database we need to implement interface RowMapper. This interface has only one method mapRow(ResultSet resultSet, int i), which will return one instance of our model class (i.e. Person).

Spring JDBC DAO Classes

Final step is to create DAO classes to map our model class to database table using sql queries. We will also configure DataSource using @Autowired annotation and expose some APIs.

PersonDAOImpl class is annotated with @Component annotation and in this class we have field with type JdbcTemplate.

When constructor of this class will be invoked, an instance of DataSource will be injected into it and we can create an instance of JdbcTemplate. After that we can use in in our methods.

Spring JdbcTemplate Test Program

Our Spring JdbcTemplate example project is ready, let’s test this with a test class.

Below image shows the output produced when we execute above program. Output will vary based on sample data and on multiple executions, idea is to learn here how to use Spring JdbcTemplate through example program.

Spring JDBC, Spring JdbcTemplate Example

That’s all about Spring JdbcTemplate, you can download the final project from below link.

Reference: API Doc

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