Save et Open, méthodes – Exemple (VJ++)

S’applique à : Access 2013, Office 2013

Ces trois exemples montrent comment utiliser conjointement les méthodes Save et Open.

Supposons que vous partez en voyage d'affaires et que vous souhaitez emporter une table de la base de données. Avant de partir, vous accédez aux données sous la forme d'un objet Recordset et vous l'enregistrez dans un format transportable. Lorsque vous arrivez à destination, vous accédez à l'objet Recordset en tant qu'objet Recordset déconnecté, local. Vous modifiez l'objet Recordset avant de le réenregistrer ainsi que vos modifications. Enfin, un fois de retour, vous vous reconnectez à la base de données et vous la mettez à jour avec les modifications apportées au cours de votre voyage.

 
// BeginSaveJ 
import com.ms.wfc.data.*; 
import java.io.* ; 
 
public class SaveX 
{ 
 // The main entry point for the application. 
 
 public static void main (String[] args) 
 { 
 SaveX1(); 
 SaveX2(); 
 SaveX3(); 
 System.exit(0); 
 } 
 
 // First, access and save the Authors table. 
 
 // SaveX1 function 
 
 static void SaveX1() 
 { 
 // Define ADO Objects. 
 Recordset rstAuthors = null; 
 
 // Declarations. 
 String strCnn = "Provider='sqloledb';Data Source='MySqlServer';" + 
 "Initial Catalog='Pubs';Integrated Security='SSPI';"; 
 BufferedReader in = 
 new BufferedReader(new InputStreamReader(System.in)); 
 File file; 
 
 try 
 { 
 rstAuthors = new Recordset(); 
 rstAuthors.setCursorLocation(AdoEnums.CursorLocation.CLIENT); 
 rstAuthors.open("SELECT * FROM Authors", 
 strCnn, 
 AdoEnums.CursorType.DYNAMIC, 
 AdoEnums.LockType.OPTIMISTIC, 
 AdoEnums.CommandType.TEXT); 
 
 // For the sake of illustration, save the recordset to a 
 //diskette in XML format. 
 file = new File("c:\\Pubs.xml"); 
 if(!file.exists()) 
 rstAuthors.save("c:\\Pubs.xml",AdoEnums.PersistFormat.XML); 
 else 
 { 
 System.out.println("\nFile already exists."); 
 System.out.println("\nPress <Enter> to continue.."); 
 in.readLine(); 
 System.exit(0); 
 } 
 } 
 catch( AdoException ae ) 
 { 
 // Notify user of any errors that result from ADO. 
 
 // As passing a Recordset, check for null pointer first. 
 if (rstAuthors != null) 
 { 
 PrintProviderError(rstAuthors.getActiveConnection()); 
 } 
 else 
 { 
 System.out.println("Exception: " + ae.getMessage()); 
 } 
 } 
 // System read requires this catch. 
 catch( java.io.IOException je) 
 { 
 PrintIOError(je); 
 } 
 
 finally 
 { 
 // Cleanup objects before exit. 
 if (rstAuthors != null) 
 if (rstAuthors.getState() == 1) 
 rstAuthors.close(); 
 } 
 } 
 
 // At this point, you have arrived at your destination. You will 
 // access the Authors table as a local, disconnected Recordset. 
 // Don't forget you must have the MSPersist provider on the machine 
 // you are using in order to access the saved file, a:\Pubs.xml. 
 
 // SaveX2 function 
 
 static void SaveX2() 
 { 
 // Define ADO Objects. 
 Recordset rstAuthors = null; 
 
 // Declarations. 
 BufferedReader in = 
 new BufferedReader(new InputStreamReader(System.in)); 
 
 try 
 { 
 rstAuthors = new Recordset(); 
 
 // For sake of illustration, we specify all parameters. 
 rstAuthors.open("c:\\Pubs.xml", 
 "Provider=MSPersist;", 
 AdoEnums.CursorType.FORWARDONLY, 
 AdoEnums.LockType.BATCHOPTIMISTIC, 
 AdoEnums.CommandType.FILE); 
 
 // Now you have a local, disconnected recordset. 
 // Edit it as you desire. 
 // (In this example, the change makes no difference). 
 rstAuthors.find("au_lname = 'Carson'"); 
 if(rstAuthors.getEOF()) 
 { 
 System.out.println("Name not found."); 
 System.out.println("\nPress <Enter> to continue.."); 
 in.readLine(); 
 return; 
 } 
 rstAuthors.getField("city").setString("Berkeley"); 
 rstAuthors.update(); 
 
 // Save changes in ADTG format this time, for illustration. 
 // Note that previous version on the diskette, as a:\Pubs.xml. 
 rstAuthors.save("c:\\Pubs.adtg",AdoEnums.PersistFormat.ADTG); 
 
 } 
 catch( AdoException ae ) 
 { 
 // Notify user of any errors that result from ADO. 
 
 // As passing a Recordset, check for null pointer first. 
 if (rstAuthors != null) 
 { 
 PrintProviderError(rstAuthors.getActiveConnection()); 
 } 
 else 
 { 
 System.out.println("Exception: " + ae.getMessage()); 
 } 
 } 
 
 // System read requires this catch. 
 catch( java.io.IOException je) 
 { 
 PrintIOError(je); 
 } 
 
 finally 
 { 
 // Cleanup objects before exit. 
 if (rstAuthors != null) 
 if (rstAuthors.getState() == 1) 
 rstAuthors.close(); 
 } 
 } 
 
 // Finally, update the database with your changes. 
 
 // SaveX3 function 
 
 static void SaveX3() 
 { 
 // Define ADO Objects. 
 Connection cnConn1 = null; 
 Recordset rstAuthors = null; 
 
 // Declarations. 
 String strCnn = "Provider='sqloledb';Data Source='MySqlServer';" + 
 "Initial Catalog='Pubs';Integrated Security='SSPI';"; 
 
 try 
 { 
 // If there is no ActiveConnection, you can open with defaults. 
 rstAuthors = new Recordset(); 
 rstAuthors.open("c:\\Pubs.adtg"); 
 
 // Connect to the database, associate the Recordset with 
 // connection, then update the database table with the changed 
 // Recordset. 
 cnConn1 = new Connection(); 
 cnConn1.open(strCnn); 
 rstAuthors.setActiveConnection(cnConn1); 
 rstAuthors.updateBatch(); 
 } 
 catch( AdoException ae ) 
 { 
 // Notify user of any errors that result from ADO. 
 
 // As passing a Recordset, check for null pointer first. 
 if (rstAuthors != null) 
 { 
 PrintProviderError(rstAuthors.getActiveConnection()); 
 } 
 else 
 { 
 System.out.println("Exception: " + ae.getMessage()); 
 } 
 } 
 
 finally 
 { 
 // Cleanup objects before exit. 
 if (rstAuthors != null) 
 if (rstAuthors.getState() == 1) 
 rstAuthors.close(); 
 if (cnConn1 != null) 
 if (cnConn1.getState() == 1) 
 cnConn1.close(); 
 } 
 } 
 
 // PrintProviderError Function 
 
 static void PrintProviderError( Connection Cnn1 ) 
 { 
 // Print Provider errors from Connection object. 
 // ErrItem is an item object in the Connections Errors collection. 
 com.ms.wfc.data.Error ErrItem = null; 
 long nCount = 0; 
 int i = 0; 
 
 nCount = Cnn1.getErrors().getCount(); 
 
 // If there are any errors in the collection, print them. 
 if( nCount > 0); 
 { 
 // Collection ranges from 0 to nCount - 1 
 for (i = 0; i< nCount; i++) 
 { 
 ErrItem = Cnn1.getErrors().getItem(i); 
 System.out.println("\t Error number: " + ErrItem.getNumber() 
 + "\t" + ErrItem.getDescription() ); 
 } 
 } 
 
 } 
 
 // PrintIOError Function 
 
 static void PrintIOError( java.io.IOException je) 
 { 
 System.out.println("Error \n"); 
 System.out.println("\tSource = " + je.getClass() + "\n"); 
 System.out.println("\tDescription = " + je.getMessage() + "\n"); 
 } 
} 
// EndSaveJ