public List nextBatch()

in hugegraph-loader/src/main/java/org/apache/hugegraph/loader/reader/jdbc/RowFetcher.java [126:170]

• 40 lines of code
• 10 McCabe index (conditional complexity)

    public List<Line> nextBatch() throws SQLException {
        if (this.fullyFetched) {
            return null;
        }

        String select = this.source.existsCustomSQL() ?
                        this.source.customSQL() :
                        this.source.vendor().buildSelectSql(this.source, this.nextStartRow);

        LOG.debug("The sql for select is: {}", select);

        List<Line> batch = new ArrayList<>(this.source.batchSize() + 1);
        try (Statement stmt = this.conn.createStatement();
             ResultSet result = stmt.executeQuery(select)) {
            if (this.source.existsCustomSQL()) {
                this.readHeader(result);
            }
            while (result.next()) {
                Object[] values = new Object[this.columns.length];
                for (int i = 1, n = this.columns.length; i <= n; i++) {
                    Object value = result.getObject(i);
                    if (value == null) {
                        value = Constants.NULL_STR;
                    }
                    values[i - 1] = value;
                }
                String rawLine = StringUtils.join(values, Constants.COMMA_STR);
                Line line = new Line(rawLine, this.columns, values);
                batch.add(line);
            }
        } catch (SQLException e) {
            this.close();
            throw e;
        }

        if (this.source.existsCustomSQL() || batch.size() != this.source.batchSize() + 1) {
            this.fullyFetched = true;
        } else {
            // Remove the last one
            Line lastLine = batch.remove(batch.size() - 1);
            lastLine.retainAll(this.primaryKeys);
            this.nextStartRow = lastLine;
        }
        return batch;
    }