How To Extract File From Oracle 10g Database Using Java

[Shun]

Hello, I am trying to extract the data from my Oracle 10g database using Java.

First, I tried to connect Oracle to Java using this code and it works.

import java.util.*;
import java.sql.*;
import java.io.*;
public class TestDBOracle {
 
  public static void main(String[] args) throws ClassNotFoundException, SQLException
  {
    Class.forName("oracle.jdbc.OracleDriver");
 
    String url = "jdbc:oracle:thin:@MY-PC:1521:XE";
 
    Connection conn = DriverManager.getConnection(url,"user", "pwd");
 
    conn.setAutoCommit(false);
    Statement stmt = conn.createStatement();
 
    ResultSet rset = stmt.executeQuery("select NC_ID from NC_TEST");
 
    while (rset.next()) {
         System.out.println (rset.getString(1));  
    }
    stmt.close();
    System.out.println ("Ok.");  
  }
}
 

Next, what I intend to do is to generate a text file from ORACLE. However I get this error.

Exception in thread "main" java.sql.SQLException: Io exception: The Network Adapter could not establish the connection
at oracle.jdbc.driver.DatabaseError.throwSqlException (DatabaseError.java:112)
at oracle.jdbc.driver.DatabaseError.throwSqlException (DatabaseError.java:146)
at oracle.jdbc.driver.DatabaseError.throwSqlException (DatabaseError.java:255)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnecti on.java:387)
at oracle.jdbc.driver.PhysicalConnection.<init>(Physi calConnection.java:414)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnect ion.java:165)
at oracle.jdbc.driver.T4CDriverExtension.getConnectio n(T4CDriverExtension.java:35)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriv er.java:801)
at java.sql.DriverManager.getConnection(DriverManager .java:582)
at java.sql.DriverManager.getConnection(DriverManager .java:185)
at ExtIndex.main(ExtIndex.java:26)

I used this code.

import java.sql.*;
import java.io.*;
import java.util.*;
 
public class ExtIndex {
 
public static void main(String[] args) throws ClassNotFoundException, SQLException, IOException
{
 
Class.forName("oracle.jdbc.OracleDriver");
String url = "jdbc:oracle:thin:@MY-PC:1512:XE";
 
Connection conn = DriverManager.getConnection(url,"user","pwd");
conn.setAutoCommit(false);
 
 
 
//------------------------------------------------------------------------//
Statement stmt = conn.createStatement();
ResultSet rset = stmt.executeQuery("select NC_ID from NC_TEST");
 
File file = new File("indexList.txt");
FileWriter outputFile = new FileWriter("indexList.txt");
BufferedWriter fos = new BufferedWriter(outputFile);
String writeOut;
 
try{
while (rset.next()) {
System.out.println (rset.getString(1));
writeOut = rset.getString(1) + "\n";
fos.write(writeOut);
}
}
catch (FileNotFoundException e) {
        System.err.println("FileStreamsTest: " + e);
    } 
catch (IOException e) {
        System.err.println("FileStreamsTest: " + e);
    }finally {
 
            try {
                if (fos != null) {
                    fos.flush();
                    fos.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
 
 
 
stmt.close();
System.out.println ("Index list generation successful");
 
ExtFile.ExtFile();
//--------------------------------------------------------------------------//
}
 
}
 

Thanks for any response.

[sanat]

Exception in thread "main" java.sql.SQLException: Io exception: The Network Adapter could not establish the connection.

I think there is a connection leak in your code.

Also I did not get any code which is closing the connection.