I am relatively new to java and database and therefore asking your help for my code optimization. I have around 20 text files with comma separated values.Each text files has around 10000 lines Based on the the 3rd value in each line, I insert the data into different tables. Each time I check the 3rd value and use different methods to save this data. My code is as follows. Could someone please tell me if this is the proper way to do this operation. Thanks in advance.
public void readSave() throws SQLException
{
File dir = new File("C:\\Users\\log");
String url = Config.DB_URL;
String user= Config.DB_USERNAME;
String password= Config.DB_PASSWORD;
con= DriverManager.getConnection(url, user, password);
con.setAutoCommit(false);
String currentLine;
if (!dir.isDirectory())
throw new IllegalStateException();
for (File file : dir.listFiles()) {
BufferedReader br;
try {
br = new BufferedReader(new FileReader(file));
while ((currentLine = br.readLine()) != null) {
List<String> values = Arrays.asList(currentLine.split(","));
if (values.get(2).contentEquals("0051"))
save0051(values,con);
else if(values.get(2).contentEquals("0049"))
save0049(values,con);
else if(values.get(2).contentEquals("0021"))
save0021(values,con);
else if(values.get(2).contentEquals("0089"))
save0089(values,con);
if(statement!=null)
statement.executeBatch();
}
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try {
con.commit();
statement.close();
con.close();
}
catch (Exception e) {}
}
private void save0051(List<String> values, Connection connection) throws SQLException {
// TODO Auto-generated method stub
String WRITE_DATA = "INSERT INTO LOCATION_DATA"
+ "(loc_id, timestamp, message_id" +
) VALUES (?,?,?)";
try {
statement = connection.prepareStatement(WRITE_DATA);
statement.setString(1, values.get(0));
statement.setLong(2, Long.valueOf(values.get(1)));
statement.setInt(3, Integer.valueOf(values.get(2)));
statement.addBatch();
} catch (SQLException e) {
e.printStackTrace();
System.out.println("Could not save to DB, error: " + e.getMessage());
}
return;
}
PreparedStatement
in the loop. Create it once and reuse it. If this is going to be performance critical I'd suggest a few changes.
刚刚发现已经提到了批处理插入, 但这是我遇到的一个不错的教程页面,我认为他解释得很好
Use JDBC Batch INSERT, executeBatch() is faster as insert is made in one shot as a list. see http://javarevisited.blogspot.com/2013/01/jdbc-batch-insert-and-update-example-java-prepared-statement.html Efficient way to do batch INSERTS with JDBC http://www.java2s.com/Code/Java/Database-SQL-JDBC/BatchUpdateInsert.htm
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