JDBC Utils

This project contains utilities to simplify JDBC data access code.

JdbcTemplate

The JdbcTemplate dramatically simplifies common JDBC usage and enforces the correct usage of the API. For example, performing a query to obtain a value can be done like this:

int value = jdbcTemplate.selectOne("SELECT value FROM table WHERE id = ?;",
    (rs, rowNum) -> rs.getInt("value"), JDBC.string("0101101011")).get();

This example makes use of the RowMapper interface, by which a row from a ResultSet can be converted to any arbitrary value as desired (such as mapping into an object).

The ResultSetHandler interface can be used if processing the ResultSet as a whole.

Query Parameters

The JdbcTemplate avoids SQL injection by recommending the use of query parameters and the ParameterValue interface. ParameterValue implementations are aware of how to apply themselves to a PreparedStatement. Implementations are provided in the JDBC utility class for many of the JDBC standard types.

Database-specifc extensions are also supported. The net.josephbeard.jdbc.postgres package includes several that are available when using a PostgreSQL JDBC driver.

Transaction Support

Multiple calls can be performed in the same transaction.

jdbcTemplate.doInTransaction(c -> {
    jdbcTemplate.insert(c, "INSERT INTO t1 (id, value) VALUES (?,?);", JDBC.string("0101101011"), JDBC.integer(5));
    jdbcTemplate.insert(c, "INSERT INTO t2 (id, value) VALUES (?,?);", JDBC.string("0101101011"), PostgreSQL.json("[1, \"2\", 3.14]"));
    
    throw new SQLException("Transaction will be automatically rolled back!");
});

This example also demonstrates the use of JDBC extensions (in this case, support for the PostgreSQL JSON datatype).