I have below DBImporter class which is working fine and also inserting data correctly in database table. I am trying to fetch data from .CSV file and inserting into Oracle table.
Till now i was processing only one file in my directory and which is working fine. Now i want to process more than one file. So during run the first file process correctly and inserted data, in second file it started reading data and throw an error as :
java.lang.IllegalArgumentException: SQL array must not be empty
Below is my DBimporter class. I think the error is during final commit batch somewhere in line here but not sure
jdbcTemplate.batchUpdate(sqlBatch.toArray(new String[sqlBatch.size()]));
@Service
public class DBImporter {
private final static Logger log = LoggerFactory.getLogger(DBImporter.class);
private static final List<String> NULL_VALUES = Arrays.asList("", "N.A", "N.A", "UNKNOWN");
private static final List<String> COL_HEADERS = Arrays.asList("ID", "NM", "TYE", "SA");
private static final int BATCH_SIZE = 50;
private boolean eof = false;
private String tableName;
@Autowired
private JdbcTemplate jdbcTemplate;
public void setTableName(String tableName) {
this.tableName = tableName;
}
@Transactional(rollbackFor = IOException.class)
public void processFile(BufferedReader reader, String tableName) {
this.tableName = tableName;
List<String> sqlBatch = new ArrayList<String>(BATCH_SIZE);
log.info("Starte auslesen der Daten");
long t1 = System.currentTimeMillis();
log.info("Start time: " + t1);
jdbcTemplate.execute("DELETE FROM " + tableName);
while (!eof) {
try {
Map<String, ColumnData> dbColumns = getDBColumns();
// Get a list of db column data related to the column headers.
List<ColumnData> columnData = COL_HEADERS.stream().map(dbColumns::get).collect(toList());
// Get the next valid data row if its starts from "FRO" or "BO".
List<String> dataRow = findNextLineStartingWith(reader, "R", "T");
String query = createSql(columnData, dataRow);
sqlBatch.add(query);
// Process batch.
if (sqlBatch.size() >= BATCH_SIZE) {
jdbcTemplate.batchUpdate(sqlBatch.toArray(new String[sqlBatch.size()]));
sqlBatch.clear();
}
} catch (IllegalStateException e) {
break;
} catch (IOException e) {
log.error(e.getLocalizedMessage());
}
}
// Commit the final batch.
jdbcTemplate.batchUpdate(sqlBatch.toArray(new String[sqlBatch.size()]));
sqlBatch.clear();
long delta = System.currentTimeMillis() - t1;
log.info("Total runtime : " + delta / 1000 + " seconds");
}
/**
* Create a SQL insert query using the data row.
*
* @param tableName Name of the table.
* @param columnData Column data list.
* @param dataRow Data row to be inserted.
* @return Generated SQL query string.
*/
private String createSql(List<ColumnData> columnData, List<String> dataRow) {
List<String> values = new ArrayList<>(columnData.size());
for (int i = 0; i < columnData.size(); i++) {
if (NULL_VALUES.contains(dataRow.get(i))) {
values.add("NULL");
} else if (columnData.get(i).getType() >= Types.NUMERIC && columnData.get(i).getType() <= Types.DOUBLE) {
values.add(dataRow.get(i));
} else {
values.add("'" + dataRow.get(i).replace("'", "''") + "'");
}
}
return "INSERT INTO " + tableName + " (" +
columnData.stream().filter(Objects::nonNull).map(ColumnData::getName).collect(joining(", ")) +
", SYSTEM_INSERTED_AT) VALUES (" +
values.stream().collect(joining(", ")) +
", CURRENT_TIMESTAMP)";
}
/**
* Find the next line starting with the given string and split it into columns.
*
* @param reader BufferedReader object to be used.
* @param prefixes A list of prefixes to look for in the string.
* @return List of data objects.
* @throws IOException
*/
private List<String> findNextLineStartingWith(BufferedReader reader, String... prefixes) throws IOException {
while (true) {
String line = readLineOrThrow(reader);
for (String prefix : prefixes)
if (line.startsWith(prefix)) {
ArrayList<String> data = new ArrayList<>();
// Split the line using the delimiter.
data.addAll(Arrays.asList(line.split(";")));
// Build the row to be inserted.
List<String> row = Arrays.asList(data.get(1), data.get(2).trim(), "", "");
return row;
}
}
}
/**
* Read a single line in the file.
*
* @param reader BufferedReader object to be used.
* @return
* @throws IOException
*/
private String readLineOrThrow(BufferedReader reader) throws IOException {
String line = reader.readLine();
if (line == null) {
this.eof = true;
throw new IllegalStateException("Unexpected EOF");
}
return line.trim();
}
/**
* Read database column metadata.
*
* @param tableName Name of the table to process.
* @return A map containing column information.
*/
private Map<String, ColumnData> getDBColumns() {
Map<String, ColumnData> result = new HashMap<>();
try (Connection connection = jdbcTemplate.getDataSource().getConnection()) {
ResultSet rs = connection.getMetaData().getColumns(null, null, tableName, null);
while (rs.next()) {
String columnName = rs.getString(4).toUpperCase();
int type = rs.getInt(5);
result.put(columnName, new ColumnData(columnName, type));
}
return result;
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
