无法将数据从数据库导出到csv文件

Question

I'm trying to gather data off a database on the cloud and export every attribute and tuple onto a csv file.

static final String JBDC_DRIVER="com.mysql.jbdc.Driver";

public static void main(String[]args){
    String filename = "c:/users/myjbdcfile.csv";

    try{
        FileWriter fw = new FileWriter(filename);
        Connection conn = (Connection) DriverManager.getConnection(DB_URL,user,pass);
        String query  = "select * from allSavedSongs";
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(query);
        while(rs.next())
        {
            fw.append(rs.getString(1));
            fw.append(',');
            fw.append(rs.getString(2));
            fw.append(',');
            fw.append(rs.getString(3));
            fw.append(',');

        }
        fw.flush();
        fw.close();
        conn.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

I'm getting the error java.io.FileNotFoundException: c:\\users\\myjbdcfile.csv (Access is denied) I also tried doing String filename = "c:\\users\\myjdbcfile.csv";

Answer 1

Usually C:/Users will not have permissions to write, unless you modify the permissions. I would prefer not to modify the permissions and use different drive or folder.

       String filename = "D:/users/myjbdcfile.csv";
        File dbFile = new File(filename);
        dbFile.getParentFile().mkdirs();
        dbFile.createNewFile();
        FileWriter fw = new FileWriter(dbFile);

Also you are writing the data to file for each record which will impact the performance. Use StringBuilder and List and build the logic around it.

Answer 2

Have you consider approach without writing a java code at all? With IntelliJ IDEA Ultimate you can simply export sql results into a file :

of CSV or any custom format you want by creating a custom extractor script .