Template Methods

dbVisitor supports the following template method usage patterns:

• Get a Connection
• Get a Statement
• Custom PreparedStatement Setup
• Call Stored Procedures

Get a Connection

ConnectionCallback gives you direct access to java.sql.Connection. JdbcTemplate acquires/releases the connection and handles exceptions.

T resultList = jdbcTemplate.execute((ConnectionCallback<T>) con -> {
    return ...;
});

Get a Statement

StatementCallback exposes java.sql.Statement. JdbcTemplate manages connection acquisition, statement creation/closure, and exception handling.

T resultList = jdbcTemplate.execute((StatementCallback<T>) stmt -> {
    return ...;
});

Custom PreparedStatement Setup

Template methods let you customize PreparedStatement creation.

• Set arguments, read results via ResultSetExtractor

  T result = jdbc.executeCreator(con -> {
      PreparedStatement ps = con.prepareStatement("select * from users where id > ?");
      ps.setInt(1, 2);
      return ps;
  }, (ResultSetExtractor) rs -> {
      return ...;
  });

• Set arguments, read results via RowMapper

  List<User> result = jdbc.executeCreator(con -> {
      PreparedStatement ps = con.prepareStatement("select * from users where id > ?");
      ps.setInt(1, 2);
      return ps;
  }, (RowMapper<User>) (rs, rowNum) -> {
      return ...;
  });

• Set arguments, process rows via RowCallbackHandler

  jdbc.executeCreator(con -> {
      PreparedStatement ps = con.prepareStatement("select * from users where id > ?");
      ps.setInt(1, 2);
      return ps;
  }, (RowCallbackHandler) (rs, rowNum) -> {
      // process one row
  });

Call Stored Procedures

List<Object> objectMap = new JdbcTemplate(conn).call("{call proc_select_table(?,?)}", cs -> {
    cs.setString(1, "dative");
    cs.registerOutParameter(2, Types.VARCHAR);
}, cs -> {
    // Receive all results using MultipleResultSetExtractor
    List<Object> objects = new MultipleResultSetExtractor().doInCallableStatement(cs);
    // Get output parameter
    objects.add(cs.getString(2));
    return objects;
});