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Template Methods

dbVisitor supports the following template method usage patterns:

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.setString(1, "Bob");
        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.setString(1, "Bob");
        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.setString(1, "Bob");
        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;
});