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POdatasource vs simple connection database
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copied!<p>What would be the best approach?, I need to connect many remote databases to resolve many requests from a Restful web service. I was thinking two solutions:</p> <ol> <li><p>One datasource per remote database, and the connection to each datasource will be like a singleton pattern.</p></li> <li><p>One simple connection per remote database, well just a singleton pattern to connect with each database.</p></li> </ol> <p>One example of the first approach is like this (vía msdn):</p> <pre><code>import java.sql.*; import com.microsoft.sqlserver.jdbc.*; public class connectDS { public static void main(String[] args) { // Declare the JDBC objects. Connection con = null; CallableStatement cstmt = null; ResultSet rs = null; try { // Establish the connection. SQLServerDataSource ds = new SQLServerDataSource(); ds.setUser("UserName"); ds.setPassword("*****"); ds.setServerName("localhost"); ds.setPortNumber(1433); ds.setDatabaseName("AdventureWorks"); con = ds.getConnection(); // Execute a stored procedure that returns some data. cstmt = con.prepareCall("{call dbo.uspGetEmployeeManagers(?)}"); cstmt.setInt(1, 50); rs = cstmt.executeQuery(); // Iterate through the data in the result set and display it. while (rs.next()) { System.out.println("EMPLOYEE: " + rs.getString("LastName") + ", " + rs.getString("FirstName")); System.out.println("MANAGER: " + rs.getString("ManagerLastName") + ", " + rs.getString("ManagerFirstName")); System.out.println(); } } // Handle any errors that may have occurred. catch (Exception e) { e.printStackTrace(); } finally { if (rs != null) try { rs.close(); } catch(Exception e) {} if (cstmt != null) try { cstmt.close(); } catch(Exception e) {} if (con != null) try { con.close(); } catch(Exception e) {} System.exit(1); } } } </code></pre> <p>For the second approach the singleton example could be:</p> <pre><code>public java.sql.Connection conn; private static Statement statement; public static MysqlConnect db; private MysqlConnect() { String url= "jdbc:mysql://localhost:3306/"; String dbName = "Banco"; String driver = "com.mysql.jdbc.Driver"; String userName = "root"; String password = "123456"; try { Class.forName(driver).newInstance(); this.conn = (java.sql.Connection)DriverManager.getConnection(url+dbName,userName,password); System.out.println("Connected to DataBase: " + dbName); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | SQLException sqle) { System.out.println("Error Inesperado en MysqlConnect" + sqle.toString()); } } /** *Method for connect to a database * @return MysqlConnect Database connection object */ public static synchronized MysqlConnect getDbCon() { if ( db == null ) { try { db = new MysqlConnect(); statement = db.conn.createStatement(); } catch (SQLException ex) { Logger.getLogger(MysqlConnect.class.getName()).log(Level.SEVERE, null, ex); } } System.out.println("Connection to DB: OK"); return db; } </code></pre>

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