JdbcUtil

Lightweight, type-safe JDBC utility for Java 17+

A lightweight Java utility library, keeping you close to SQL while eliminating JDBC boilerplate. Write queries in pure SQL and map results directly to Java objects using modern type-safe method references.

Features

• **Java 17+
• Auto-close Statement, ResultSet
• Simple query/execute API with lambda mapping
• Type-safe mapping via method references, reflection, or tuples
• Fluent API with selectInto, execute, executeBatch
• Built-in support for scalars, tuples, maps, POJOs, records
• Parameter binding via StatementParameters
• Batch execution with executeBatch

Dependency

Gradle

implementation 'de.schaeuffelhut.jdbc:jdbc-util:1.0.0'

Maven

<dependency>
    <groupId>de.schaeuffelhut.jdbc</groupId>
    <artifactId>jdbc-util</artifactId>
    <version>1.0.0</version>
</dependency>

Quick Start

selectInto – Powerful Query Mapping

1. Scalar Value

String name = statementUtil.selectInto(
    "SELECT name FROM employees WHERE id = 1",
    ResultSetReaders.readOne(),
    ResultSetMappers.scalar(ResultTypes.String)
);

2. Tuple (List of values)

Object[] tuple = statementUtil.selectInto(
    "SELECT id, name FROM employees WHERE id = 1",
    ResultSetReaders.readOne(),
    ResultSetMappers.tuple(ResultTypes.Integer, ResultTypes.String)
);

3. Map (by column label)

Map<String, Object> map = statementUtil.selectInto(
    """
    SELECT id, name, COUNT(*) AS "count", SUM(id) AS "sum"
    FROM employees WHERE id = 1
    GROUP BY id, name
    """,
    ResultSetReaders.readOne(),
    ResultSetMappers.map(
        ResultTypes.Integer,   // id
        ResultTypes.String,   // name
        ResultTypes.Integer,  // count
        ResultTypes.Integer   // sum
    )
);

4. Object via Constructor (Record or Class)

record Employee(int id, String name) {}

Employee emp = statementUtil.selectInto(
    "SELECT id, name FROM employees WHERE id = 2",
    ResultSetReaders.readOne(),
    ResultSetMappers.object(Employee::new, ResultTypes.Integer, ResultTypes.String)
);

5. Object via Reflection (Mutable Class)

public static class EmployeeDto {
    public int id;
    public String name;
}

EmployeeDto dto = statementUtil.selectInto(
    "SELECT id AS \"id\", name AS \"name\" FROM employees WHERE id = 2",
    ResultSetReaders.readOne(),
    ResultSetMappers.objectViaReflection(
        EmployeeDto.class,
        ResultTypes.Integer,
        ResultTypes.String
    )
);

execute – Insert / Update / Delete

statementUtil.execute(
    """
    INSERT INTO employees (id, name) VALUES (?, ?)
    ON CONFLICT (id) DO UPDATE SET name = EXCLUDED.name
    """,
    StatementParameters.Integer(3),
    StatementParameters.String("Charlie")
);

executeBatch – Bulk Operations

record Employee(int id, String name){};
List<Employee> employees = List.of(new Employee(1, "Alice"), new Employee(2, "Bob"));

statementUtil.executeBatch(
        "INSERT INTO employees (id, name) VALUES (?, ?)",
        employees.stream()
                .map( e -> new StatementInParameter[]{
                        StatementParameters.String( e.id ),
                        StatementParameters.String( e.name )
                } )
                .toList()
);

Core Components

Class	Purpose
ResultSetReaders	readOne(), readMany(), readScalar()
ResultSetMappers	scalar(), tuple(), map(), object(), objectViaReflection()
ResultTypes	String, Integer, Long, Boolean, Object(UUID.class), Enum(MyEnum.class)
StatementParameters	Object(), String(), Integer(), EnumByName()

Real-World Example

record Realm(UUID uuid, String name) {}

List<Realm> realms = stmt.selectInto(
    """
    SELECT r.uuid, r.name
    FROM realm r
    JOIN realm_member rm ON r.uuid = rm.realm
    WHERE rm.user_account = ?
    """,
    ResultSetReaders.readMany(),
    ResultSetMappers.object(
        Realm::new,
        ResultTypes.Object(UUID.class),
        ResultTypes.String
    ),
    StatementParameters.Object(currentUserId)
);

License

MIT – Free for commercial and personal use.

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JdbcUtil – SQL First. Java Second. No Boilerplate.

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Maintained with love by @fschaeuffelhut