Simplifying JDBC Operations with the SimpleJdbc Classes

The SimpleJdbcInsert and SimpleJdbcCall classes provide a simplified configuration by taking advantage of database metadata that can be retrieved through the JDBC driver. This means that you have less to configure up front, although you can override or turn off the metadata processing if you prefer to provide all the details in your code.

Inserting Data by Using SimpleJdbcInsert

We start by looking at the SimpleJdbcInsert class with the minimal amount of configuration options. You should instantiate the SimpleJdbcInsert in the data access layer’s initialization method. For this example, the initializing method is the setDataSource method. You do not need to subclass the SimpleJdbcInsert class. Instead, you can create a new instance and set the table name by using the withTableName method. Configuration methods for this class follow the fluid style that returns the instance of the SimpleJdbcInsert, which lets you chain all configuration methods. The following example uses only one configuration method (we show examples of multiple methods later):

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcInsert insertActor;

	public void setDataSource(DataSource dataSource) {
		this.insertActor = new SimpleJdbcInsert(dataSource).withTableName("t_actor");
	}

	public void add(Actor actor) {
		Map<String, Object> parameters = new HashMap<>(3);
		parameters.put("id", actor.getId());
		parameters.put("first_name", actor.getFirstName());
		parameters.put("last_name", actor.getLastName());
		insertActor.execute(parameters);
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

	private val insertActor = SimpleJdbcInsert(dataSource).withTableName("t_actor")

	fun add(actor: Actor) {
		val parameters = mutableMapOf<String, Any>()
		parameters["id"] = actor.id
		parameters["first_name"] = actor.firstName
		parameters["last_name"] = actor.lastName
		insertActor.execute(parameters)
	}

	// ... additional methods
}

The execute method used here takes a plain java.util.Map as its only parameter. The important thing to note here is that the keys used for the Map must match the column names of the table, as defined in the database. This is because we read the metadata to construct the actual insert statement.

Retrieving Auto-generated Keys by Using SimpleJdbcInsert

The next example uses the same insert as the preceding example, but, instead of passing in the id, it retrieves the auto-generated key and sets it on the new Actor object. When it creates the SimpleJdbcInsert, in addition to specifying the table name, it specifies the name of the generated key column with the usingGeneratedKeyColumns method. The following listing shows how it works:

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcInsert insertActor;

	public void setDataSource(DataSource dataSource) {
		this.insertActor = new SimpleJdbcInsert(dataSource)
				.withTableName("t_actor")
				.usingGeneratedKeyColumns("id");
	}

	public void add(Actor actor) {
		Map<String, Object> parameters = new HashMap<>(2);
		parameters.put("first_name", actor.getFirstName());
		parameters.put("last_name", actor.getLastName());
		Number newId = insertActor.executeAndReturnKey(parameters);
		actor.setId(newId.longValue());
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

	private val insertActor = SimpleJdbcInsert(dataSource)
			.withTableName("t_actor").usingGeneratedKeyColumns("id")

	fun add(actor: Actor): Actor {
		val parameters = mapOf(
				"first_name" to actor.firstName,
				"last_name" to actor.lastName)
		val newId = insertActor.executeAndReturnKey(parameters);
		return actor.copy(id = newId.toLong())
	}

	// ... additional methods
}

The main difference when you run the insert by using this second approach is that you do not add the id to the Map, and you call the executeAndReturnKey method. This returns a java.lang.Number object with which you can create an instance of the numerical type that is used in your domain class. You cannot rely on all databases to return a specific Java class here. java.lang.Number is the base class that you can rely on. If you have multiple auto-generated columns or the generated values are non-numeric, you can use a KeyHolder that is returned from the executeAndReturnKeyHolder method.

Specifying Columns for a SimpleJdbcInsert

You can limit the columns for an insert by specifying a list of column names with the usingColumns method, as the following example shows:

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcInsert insertActor;

	public void setDataSource(DataSource dataSource) {
		this.insertActor = new SimpleJdbcInsert(dataSource)
				.withTableName("t_actor")
				.usingColumns("first_name", "last_name")
				.usingGeneratedKeyColumns("id");
	}

	public void add(Actor actor) {
		Map<String, Object> parameters = new HashMap<>(2);
		parameters.put("first_name", actor.getFirstName());
		parameters.put("last_name", actor.getLastName());
		Number newId = insertActor.executeAndReturnKey(parameters);
		actor.setId(newId.longValue());
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

	private val insertActor = SimpleJdbcInsert(dataSource)
			.withTableName("t_actor")
			.usingColumns("first_name", "last_name")
			.usingGeneratedKeyColumns("id")

	fun add(actor: Actor): Actor {
		val parameters = mapOf(
				"first_name" to actor.firstName,
				"last_name" to actor.lastName)
		val newId = insertActor.executeAndReturnKey(parameters);
		return actor.copy(id = newId.toLong())
	}

	// ... additional methods
}

The execution of the insert is the same as if you had relied on the metadata to determine which columns to use.

Using SqlParameterSource to Provide Parameter Values

Using a Map to provide parameter values works fine, but it is not the most convenient class to use. Spring provides a couple of implementations of the SqlParameterSource interface that you can use instead. The first one is BeanPropertySqlParameterSource, which is a very convenient class if you have a JavaBean-compliant class that contains your values. It uses the corresponding getter method to extract the parameter values. The following example shows how to use BeanPropertySqlParameterSource:

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcInsert insertActor;

	public void setDataSource(DataSource dataSource) {
		this.insertActor = new SimpleJdbcInsert(dataSource)
				.withTableName("t_actor")
				.usingGeneratedKeyColumns("id");
	}

	public void add(Actor actor) {
		SqlParameterSource parameters = new BeanPropertySqlParameterSource(actor);
		Number newId = insertActor.executeAndReturnKey(parameters);
		actor.setId(newId.longValue());
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

	private val insertActor = SimpleJdbcInsert(dataSource)
			.withTableName("t_actor")
			.usingGeneratedKeyColumns("id")

	fun add(actor: Actor): Actor {
		val parameters = BeanPropertySqlParameterSource(actor)
		val newId = insertActor.executeAndReturnKey(parameters)
		return actor.copy(id = newId.toLong())
	}

	// ... additional methods
}

Another option is the MapSqlParameterSource that resembles a Map but provides a more convenient addValue method that can be chained. The following example shows how to use it:

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcInsert insertActor;

	public void setDataSource(DataSource dataSource) {
		this.insertActor = new SimpleJdbcInsert(dataSource)
				.withTableName("t_actor")
				.usingGeneratedKeyColumns("id");
	}

	public void add(Actor actor) {
		SqlParameterSource parameters = new MapSqlParameterSource()
				.addValue("first_name", actor.getFirstName())
				.addValue("last_name", actor.getLastName());
		Number newId = insertActor.executeAndReturnKey(parameters);
		actor.setId(newId.longValue());
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

	private val insertActor = SimpleJdbcInsert(dataSource)
			.withTableName("t_actor")
			.usingGeneratedKeyColumns("id")

	fun add(actor: Actor): Actor {
		val parameters = MapSqlParameterSource()
					.addValue("first_name", actor.firstName)
					.addValue("last_name", actor.lastName)
		val newId = insertActor.executeAndReturnKey(parameters)
		return actor.copy(id = newId.toLong())
	}

	// ... additional methods
}

As you can see, the configuration is the same. Only the executing code has to change to use these alternative input classes.

Calling a Stored Procedure with SimpleJdbcCall

The SimpleJdbcCall class uses metadata in the database to look up names of in and out parameters so that you do not have to explicitly declare them. You can declare parameters if you prefer to do that or if you have parameters that do not have an automatic mapping to a Java class. The first example shows a simple procedure that returns only scalar values in VARCHAR and DATE format from a MySQL database. The example procedure reads a specified actor entry and returns first_name, last_name, and birth_date columns in the form of out parameters. The following listing shows the first example:

CREATE PROCEDURE read_actor (
	IN in_id INTEGER,
	OUT out_first_name VARCHAR(100),
	OUT out_last_name VARCHAR(100),
	OUT out_birth_date DATE)
BEGIN
	SELECT first_name, last_name, birth_date
	INTO out_first_name, out_last_name, out_birth_date
	FROM t_actor where id = in_id;
END;

The in_id parameter contains the id of the actor that you are looking up. The out parameters return the data read from the table.

You can declare SimpleJdbcCall in a manner similar to declaring SimpleJdbcInsert. You should instantiate and configure the class in the initialization method of your data-access layer. Compared to the StoredProcedure class, you need not create a subclass and you need not to declare parameters that can be looked up in the database metadata. The following example of a SimpleJdbcCall configuration uses the preceding stored procedure (the only configuration option, in addition to the DataSource, is the name of the stored procedure):

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcCall procReadActor;

	public void setDataSource(DataSource dataSource) {
		this.procReadActor = new SimpleJdbcCall(dataSource)
				.withProcedureName("read_actor");
	}

	public Actor readActor(Long id) {
		SqlParameterSource in = new MapSqlParameterSource()
				.addValue("in_id", id);
		Map out = procReadActor.execute(in);
		Actor actor = new Actor();
		actor.setId(id);
		actor.setFirstName((String) out.get("out_first_name"));
		actor.setLastName((String) out.get("out_last_name"));
		actor.setBirthDate((Date) out.get("out_birth_date"));
		return actor;
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

	private val procReadActor = SimpleJdbcCall(dataSource)
			.withProcedureName("read_actor")


	fun readActor(id: Long): Actor {
		val source = MapSqlParameterSource().addValue("in_id", id)
		val output = procReadActor.execute(source)
		return Actor(
				id,
				output["out_first_name"] as String,
				output["out_last_name"] as String,
				output["out_birth_date"] as Date)
	}

		// ... additional methods
}

The code you write for the execution of the call involves creating an SqlParameterSource containing the IN parameter. You must match the name provided for the input value with that of the parameter name declared in the stored procedure. The case does not have to match because you use metadata to determine how database objects should be referred to in a stored procedure. What is specified in the source for the stored procedure is not necessarily the way it is stored in the database. Some databases transform names to all upper case, while others use lower case or use the case as specified.

The execute method takes the IN parameters and returns a Map that contains any out parameters keyed by the name, as specified in the stored procedure. In this case, they are out_first_name, out_last_name, and out_birth_date.

The last part of the execute method creates an Actor instance to use to return the data retrieved. Again, it is important to use the names of the out parameters as they are declared in the stored procedure. Also, the case in the names of the out parameters stored in the results map matches that of the out parameter names in the database, which could vary between databases. To make your code more portable, you should do a case-insensitive lookup or instruct Spring to use a LinkedCaseInsensitiveMap. To do the latter, you can create your own JdbcTemplate and set the setResultsMapCaseInsensitive property to true. Then you can pass this customized JdbcTemplate instance into the constructor of your SimpleJdbcCall. The following example shows this configuration:

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcCall procReadActor;

	public void setDataSource(DataSource dataSource) {
		JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
		jdbcTemplate.setResultsMapCaseInsensitive(true);
		this.procReadActor = new SimpleJdbcCall(jdbcTemplate)
				.withProcedureName("read_actor");
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

	private var procReadActor = SimpleJdbcCall(JdbcTemplate(dataSource).apply {
		isResultsMapCaseInsensitive = true
	}).withProcedureName("read_actor")

	// ... additional methods
}

By taking this action, you avoid conflicts in the case used for the names of your returned out parameters.

Explicitly Declaring Parameters to Use for a SimpleJdbcCall

Earlier in this chapter, we described how parameters are deduced from metadata, but you can declare them explicitly if you wish. You can do so by creating and configuring SimpleJdbcCall with the declareParameters method, which takes a variable number of SqlParameter objects as input. See the next section for details on how to define an SqlParameter.

Explicit declarations are necessary if the database you use is not a Spring-supported database. Currently, Spring supports metadata lookup of stored procedure calls for the following databases: Apache Derby, DB2, MySQL, Microsoft SQL Server, Oracle, and Sybase. We also support metadata lookup of stored functions for MySQL, Microsoft SQL Server, and Oracle.

You can opt to explicitly declare one, some, or all of the parameters. The parameter metadata is still used where you do not explicitly declare parameters. To bypass all processing of metadata lookups for potential parameters and use only the declared parameters, you can call the method withoutProcedureColumnMetaDataAccess as part of the declaration. Suppose that you have two or more different call signatures declared for a database function. In this case, you call useInParameterNames to specify the list of IN parameter names to include for a given signature.

The following example shows a fully declared procedure call and uses the information from the preceding example:

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcCall procReadActor;

	public void setDataSource(DataSource dataSource) {
		JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
		jdbcTemplate.setResultsMapCaseInsensitive(true);
		this.procReadActor = new SimpleJdbcCall(jdbcTemplate)
				.withProcedureName("read_actor")
				.withoutProcedureColumnMetaDataAccess()
				.useInParameterNames("in_id")
				.declareParameters(
						new SqlParameter("in_id", Types.NUMERIC),
						new SqlOutParameter("out_first_name", Types.VARCHAR),
						new SqlOutParameter("out_last_name", Types.VARCHAR),
						new SqlOutParameter("out_birth_date", Types.DATE)
				);
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

		private val procReadActor = SimpleJdbcCall(JdbcTemplate(dataSource).apply {
			isResultsMapCaseInsensitive = true
		}).withProcedureName("read_actor")
				.withoutProcedureColumnMetaDataAccess()
				.useInParameterNames("in_id")
				.declareParameters(
						SqlParameter("in_id", Types.NUMERIC),
						SqlOutParameter("out_first_name", Types.VARCHAR),
						SqlOutParameter("out_last_name", Types.VARCHAR),
						SqlOutParameter("out_birth_date", Types.DATE)
	)

		// ... additional methods
}

The execution and end results of the two examples are the same. The second example specifies all details explicitly rather than relying on metadata.

How to Define SqlParameters

To define a parameter for the SimpleJdbc classes and also for the RDBMS operations classes (covered in Modeling JDBC Operations as Java Objects) you can use SqlParameter or one of its subclasses. To do so, you typically specify the parameter name and SQL type in the constructor. The SQL type is specified by using the java.sql.Types constants. Earlier in this chapter, we saw declarations similar to the following:

  • Java

  • Kotlin

new SqlParameter("in_id", Types.NUMERIC),
new SqlOutParameter("out_first_name", Types.VARCHAR),
SqlParameter("in_id", Types.NUMERIC),
SqlOutParameter("out_first_name", Types.VARCHAR),

The first line with the SqlParameter declares an IN parameter. You can use IN parameters for both stored procedure calls and for queries by using the SqlQuery and its subclasses (covered in Understanding SqlQuery).

The second line (with the SqlOutParameter) declares an out parameter to be used in a stored procedure call. There is also an SqlInOutParameter for InOut parameters (parameters that provide an IN value to the procedure and that also return a value).

Only parameters declared as SqlParameter and SqlInOutParameter are used to provide input values. This is different from the StoredProcedure class, which (for backwards compatibility reasons) lets input values be provided for parameters declared as SqlOutParameter.

For IN parameters, in addition to the name and the SQL type, you can specify a scale for numeric data or a type name for custom database types. For out parameters, you can provide a RowMapper to handle mapping of rows returned from a REF cursor. Another option is to specify an SqlReturnType that provides an opportunity to define customized handling of the return values.

Calling a Stored Function by Using SimpleJdbcCall

You can call a stored function in almost the same way as you call a stored procedure, except that you provide a function name rather than a procedure name. You use the withFunctionName method as part of the configuration to indicate that you want to make a call to a function, and the corresponding string for a function call is generated. A specialized call (executeFunction) is used to run the function, and it returns the function return value as an object of a specified type, which means you do not have to retrieve the return value from the results map. A similar convenience method (named executeObject) is also available for stored procedures that have only one out parameter. The following example (for MySQL) is based on a stored function named get_actor_name that returns an actor’s full name:

CREATE FUNCTION get_actor_name (in_id INTEGER)
RETURNS VARCHAR(200) READS SQL DATA
BEGIN
	DECLARE out_name VARCHAR(200);
	SELECT concat(first_name, ' ', last_name)
		INTO out_name
		FROM t_actor where id = in_id;
	RETURN out_name;
END;

To call this function, we again create a SimpleJdbcCall in the initialization method, as the following example shows:

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcCall funcGetActorName;

	public void setDataSource(DataSource dataSource) {
		JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
		jdbcTemplate.setResultsMapCaseInsensitive(true);
		this.funcGetActorName = new SimpleJdbcCall(jdbcTemplate)
				.withFunctionName("get_actor_name");
	}

	public String getActorName(Long id) {
		SqlParameterSource in = new MapSqlParameterSource()
				.addValue("in_id", id);
		String name = funcGetActorName.executeFunction(String.class, in);
		return name;
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

	private val jdbcTemplate = JdbcTemplate(dataSource).apply {
		isResultsMapCaseInsensitive = true
	}
	private val funcGetActorName = SimpleJdbcCall(jdbcTemplate)
			.withFunctionName("get_actor_name")

	fun getActorName(id: Long): String {
		val source = MapSqlParameterSource().addValue("in_id", id)
		return funcGetActorName.executeFunction(String::class.java, source)
	}

	// ... additional methods
}

The executeFunction method used returns a String that contains the return value from the function call.

Returning a ResultSet or REF Cursor from a SimpleJdbcCall

Calling a stored procedure or function that returns a result set is a bit tricky. Some databases return result sets during the JDBC results processing, while others require an explicitly registered out parameter of a specific type. Both approaches need additional processing to loop over the result set and process the returned rows. With the SimpleJdbcCall, you can use the returningResultSet method and declare a RowMapper implementation to be used for a specific parameter. If the result set is returned during the results processing, there are no names defined, so the returned results must match the order in which you declare the RowMapper implementations. The name specified is still used to store the processed list of results in the results map that is returned from the execute statement.

The next example (for MySQL) uses a stored procedure that takes no IN parameters and returns all rows from the t_actor table:

CREATE PROCEDURE read_all_actors()
BEGIN
 SELECT a.id, a.first_name, a.last_name, a.birth_date FROM t_actor a;
END;

To call this procedure, you can declare the RowMapper. Because the class to which you want to map follows the JavaBean rules, you can use a BeanPropertyRowMapper that is created by passing in the required class to map to in the newInstance method. The following example shows how to do so:

  • Java

  • Kotlin

public class JdbcActorDao implements ActorDao {

	private SimpleJdbcCall procReadAllActors;

	public void setDataSource(DataSource dataSource) {
		JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
		jdbcTemplate.setResultsMapCaseInsensitive(true);
		this.procReadAllActors = new SimpleJdbcCall(jdbcTemplate)
				.withProcedureName("read_all_actors")
				.returningResultSet("actors",
				BeanPropertyRowMapper.newInstance(Actor.class));
	}

	public List getActorsList() {
		Map m = procReadAllActors.execute(new HashMap<String, Object>(0));
		return (List) m.get("actors");
	}

	// ... additional methods
}
class JdbcActorDao(dataSource: DataSource) : ActorDao {

		private val procReadAllActors = SimpleJdbcCall(JdbcTemplate(dataSource).apply {
			isResultsMapCaseInsensitive = true
		}).withProcedureName("read_all_actors")
				.returningResultSet("actors",
						BeanPropertyRowMapper.newInstance(Actor::class.java))

	fun getActorsList(): List<Actor> {
		val m = procReadAllActors.execute(mapOf<String, Any>())
		return m["actors"] as List<Actor>
	}

	// ... additional methods
}

The execute call passes in an empty Map, because this call does not take any parameters. The list of actors is then retrieved from the results map and returned to the caller.