Update- und CancelUpdate-Methode (Beispiel) (VJ++)

Gilt für: Access 2013, Office 2013

Dieses Beispiel veranschaulicht die Update-Methode in Verbindung mit der CancelUpdate-Methode.

 
// BeginUpdateJ 
import java.io.*; 
import com.ms.wfc.data.*; 
 
public class UpdateX 
{ 
 // The main entry point of the application. 
 
 public static void main (String[] args) 
 { 
 UpdateX(); 
 UpdateX2(); 
 System.exit(0); 
 } 
 // UpdateX Function 
 
 static void UpdateX() 
 { 
 // Define ADO objects. 
 Recordset rstEmployees = null; 
 
 // Declarations. 
 String strCnn = "Provider='sqloledb';Data Source='MySqlServer';"+ 
 "Initial Catalog='Pubs';Integrated Security='SSPI';"; 
 String strOldFirst; 
 String strOldLast; 
 String strMessage; 
 BufferedReader in = 
 new BufferedReader(new InputStreamReader(System.in)); 
 
 try 
 { 
 // Open Recordset with names from Employees table. 
 rstEmployees = new Recordset(); 
 rstEmployees.setCursorType(AdoEnums.CursorType.KEYSET); 
 rstEmployees.setLockType(AdoEnums.LockType.OPTIMISTIC); 
 rstEmployees.open("SELECT fname,lname FROM Employees " + 
 "ORDER BY lname", strCnn, AdoEnums.CursorType.KEYSET, 
 AdoEnums.LockType.OPTIMISTIC, AdoEnums.CommandType.TEXT); 
 
 // Store Original data. 
 strOldFirst = rstEmployees.getField("fname").getString(); 
 strOldLast = rstEmployees.getField("lname").getString(); 
 
 // Change data in edit buffer. 
 rstEmployees.getField("fname").setString("Linda"); 
 rstEmployees.getField("lname").setString("Kobara"); 
 
 // Show contents of buffer and get user input. 
 strMessage = "Edit in Progress :\n" + 
 "\tOriginal Data = " + strOldFirst + " " + strOldLast + 
 "\n\tData in Buffer = " + 
 rstEmployees.getField("fname").getString() + " " + 
 rstEmployees.getField("lname").getString() + "\n\n" + 
 "Use Update to replace the original data with " + 
 "the buffered data in the Recordset?Enter (Y/N)"; 
 
 System.out.println(strMessage); 
 if(in.readLine().trim().equalsIgnoreCase("Y")) 
 rstEmployees.update(); 
 else 
 rstEmployees.cancelUpdate(); 
 
 // Show the resulting data. 
 System.out.println("Data in Recordset = " + 
 rstEmployees.getField("fname").getString() + 
 " " + rstEmployees.getField("lname").getString()+ "\n"); 
 
 // Restore original data because this is a demonstration. 
 if(!(strOldFirst.equals( 
 rstEmployees.getField("fname").getString()) && 
 strOldLast.equals( 
 rstEmployees.getField("lname").getString()))) 
 { 
 rstEmployees.getField("fname").setString(strOldFirst); 
 rstEmployees.getField("lname").setString(strOldLast); 
 rstEmployees.update(); 
 } 
 // Cleanup Objects before exit. 
 rstEmployees.close(); 
 
 System.out.println("Press <Enter> to continue.."); 
 in.readLine(); 
 
 } 
 catch(AdoException ae) 
 { 
 // Notify the user of any errors that result from ADO. 
 
 // As passing a recordset, check for null pointer first. 
 if(rstEmployees != null) 
 { 
 PrintProviderError(rstEmployees.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 (rstEmployees != null) 
 if (rstEmployees.getState() == 1) 
 rstEmployees.close(); 
 } 
 } 
 // UpdateX2 Function 
 
 static void UpdateX2() 
 { 
 // This example demonstrates the Update method in conjunction 
 // with the AddNew method. 
 
 // Define ADO Objects. 
 Connection cnn1 = null; 
 Recordset rstEmployees = null; 
 
 // Declarations. 
 String strCnn = "Provider='sqloledb';Data Source='MySqlServer';"+ 
 "Initial Catalog='Pubs';Integrated Security='SSPI';"; 
 String strEmpID; 
 String strOldFirst; 
 String strOldLast; 
 String strMessage; 
 BufferedReader in = 
 new BufferedReader(new InputStreamReader(System.in)); 
 
 try 
 { 
 // Open a connection. 
 cnn1 = new Connection(); 
 cnn1.open(strCnn); 
 
 // Open Recordset with data from Employees table. 
 rstEmployees = new Recordset(); 
 rstEmployees.setCursorType(AdoEnums.CursorType.KEYSET); 
 rstEmployees.setLockType(AdoEnums.LockType.OPTIMISTIC); 
 rstEmployees.open("employee", cnn1, AdoEnums.CursorType.KEYSET, 
 AdoEnums.LockType.OPTIMISTIC, AdoEnums.CommandType.TABLE); 
 
 rstEmployees.addNew(); 
 strEmpID="B-S55555M"; 
 rstEmployees.getField("emp_id").setString(strEmpID); 
 rstEmployees.getField("fname").setString("Bill"); 
 rstEmployees.getField("lname").setString("Sornsin"); 
 
 // Show contents of buffer and get user input. 
 strMessage = "AddNew in progress : " + "\n" + 
 "\tData in Buffer = " + 
 rstEmployees.getField("emp_id").getString() + 
 " " + rstEmployees.getField("fname").getString() + " " + 
 rstEmployees.getField("lname").getString()+ "\n\n" + 
 "Use Update to save buffer to recordset?Enter (Y/N)"; 
 System.out.println(strMessage); 
 if(in.readLine().trim().equalsIgnoreCase("Y")) 
 { 
 rstEmployees.update(); 
 // Go to the new record and show the resulting data. 
 System.out.println("Data in recordset = " + 
 rstEmployees.getField("emp_id").getString()+ 
 " " + rstEmployees.getField("fname").getString() + 
 " " + rstEmployees.getField("lname").getString() + "\n"); 
 } 
 else 
 { 
 rstEmployees.cancelUpdate(); 
 System.out.println("No new Record added.\n"); 
 } 
 // Delete new data because this is a demonstration. 
 cnn1.execute( 
 "DELETE FROM employee WHERE emp_id='" + strEmpID +"'"); 
 
 // Cleanup Objects before exit 
 rstEmployees.close(); 
 
 System.out.println("Press <Enter> to continue.."); 
 in.readLine(); 
 } 
 catch(AdoException ae) 
 { 
 // Notify the user of any errors that result from ADO. 
 
 // As passing a recordset, check for null pointer first. 
 if(rstEmployees != null) 
 { 
 PrintProviderError(rstEmployees.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 (rstEmployees != null) 
 if (rstEmployees.getState() == 1) 
 rstEmployees.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("\t Source: " + je.getClass() + "\n"); 
 System.out.println("\t Description: "+ je.getMessage() + "\n"); 
 } 
} 
// EndUpdateJ