Closing the Connection

You must close your connection to the database once you finish your work. Use the close method of the Connection object to do this: 
   conn.close( );
Typically, you should put close( ) statements in a final clause. The steps in the preceding slides are summarized in the following example, which performs the following tasks:
  1. Import packages.
  2. Open an OracleDataSource.
  3. Connect to the database xe.
  4. Create a Statement object.
  5. Execute an SQL statement.
  6. Process the result set.
  7. Close the result set, statement, and connection.

SQL (p2.txt) =

                       
view source
print?
01/*********************************************************
02 
03  This program shows how to close connections.
04 
05  To use this program, you need to create a table
06    emp_tbl by using the following command:
07 
08  SQL> create table  emp_tbl (
09    2    empno   integer  primary key,
10    3    ename   varchar(64)  not null );
11 
12  Table created.
13 
14*********************************************************/
15 
16// Import the following packages to use JDBC.
17import  java.sql.*;
18import  java.io.*;
19import  oracle.sql.*;
20import  oracle.jdbc.*;
21import  oracle.jdbc.pool.OracleDataSource;
22 
23class  CloseConnection {
24  public static void  main( String args[ ] ) throws SQLException {
25    String user     = "C##user_id";
26    String password = "password";
27    String database = "20.185.147.112:1521/xe";
28 
29    // Open an OracleDataSource and get a connection.
30    OracleDataSource ods = new OracleDataSource( );
31    ods.setURL     ( "jdbc:oracle:thin:@" + database );
32    ods.setUser    ( user );
33    ods.setPassword( password );
34    Connection conn = ods.getConnection( );
35 
36    try {
37      // Read the parameter, sql.
38      FileInputStream    stream     = new FileInputStream  ( "p2.txt" );
39      InputStreamReader  iStrReader = new InputStreamReader( stream );
40      BufferedReader     reader     = new BufferedReader   ( iStrReader );
41      String  sql = reader.readLine( );
42      if ( sql == null )  sql = "";
43      else  sql = sql.trim( );
44  
45      try {
46        // Query the employee names.
47        Statement  stmt = conn.createStatement( );
48        System.out.println( "<font color='#3366CC'><h4>" + sql + "</h4></font>" );
49        if ( stmt.execute( sql ) ) {
50          ResultSet  rset = stmt.getResultSet( );
51          // Print the names.
52          while ( rset.next( ) )
53            System.out.println( rset.getString( 1 ) ); 
54          // Close the result set.
55          rset.close( );
56        }
57        // Close the statement.
58        stmt.close( );
59      }
60      catch( SQLException e ) {
61        System.out.println( e );
62      }
63    }
64    catch( IOException e ) { System.out.println( e ); }
65    // Close the connection.
66    conn.close( );
67  }
68}