AppendChunk- und GetChunk-Methode (Beispiel) (VJ++)

Gilt für: Access 2013, Office 2013

In diesem Beispiel werden die Methoden AppendChunk und GetChunk verwendet, um ein Bildfeld mit Daten aus einem anderen Datensatz zu füllen.

 
// BeginAppendChunkJ 
import com.ms.wfc.data.*; 
import java.io.*; 
import com.ms.com.*; 
import java.util.*; 
 
public class AppendChunkX 
{ 
 
 // The main entry point for the application. 
 
 public static void main (String[] args) 
 { 
 AppendChunkX(); 
 System.exit(0); 
 } 
 
 // AppendChunkX function 
 
 static void AppendChunkX() 
 { 
 // Define ADO Objects. 
 Connection cnConn1 = null; 
 Recordset rstPubInfo = null; 
 
 //Declarations. 
 String strCnn; 
 String strPubID; 
 String strPRInfo; 
 String strMessage = ""; 
 long lngOffset = 0; 
 long lngLogoSize; 
 final int conChunkSize = 100; 
 byte[] varChunk = new byte[conChunkSize]; 
 int intCommand = 0 ; 
 int intMulChunkSize,intLastChunkSize; 
 Vector varLogo = new Vector(); 
 BufferedReader in = 
 new BufferedReader(new InputStreamReader(System.in)); 
 String line = null; 
 int noOfRecords; 
 int noOfRecordesDisplayed = 5; 
 int recordCount = 0; 
 String info; 
 int indexOfComma ; 
 
 try 
 { 
 // Open a connection. 
 strCnn = "Provider='sqloledb';Data Source='MySqlServer';" 
 + "Initial Catalog='Pubs';Integrated Security='SSPI';"; 
 cnConn1 = new Connection(); 
 cnConn1.open(strCnn,"","",AdoEnums.CommandType.UNSPECIFIED); 
 
 // Open the pub_info Table. 
 rstPubInfo = new Recordset(); 
 rstPubInfo.setCursorType(AdoEnums.CursorType.KEYSET ); 
 rstPubInfo.setLockType(AdoEnums.LockType.OPTIMISTIC ); 
 
 rstPubInfo.open("pub_info", cnConn1,AdoEnums.CursorType.KEYSET , 
 AdoEnums.LockType.OPTIMISTIC, AdoEnums.CommandType.TABLE ); 
 System.out.println ("Available logos are : \n"); 
 
 noOfRecords = rstPubInfo.getRecordCount(); 
 
 // Prompt for the Logo to copy. 
 for ( int i = 0; i < noOfRecords; i++) 
 { 
 recordCount++; 
 strMessage = strMessage + 
 rstPubInfo.getField("pub_id").getString() + "\n"; 
 indexOfComma = 
 rstPubInfo.getField("pr_info").getString().indexOf(","); 
 info = 
 rstPubInfo.getField("pr_info").getString().substring(0, 
 indexOfComma ); 
 strMessage = strMessage + info + "\n\n"; 
 // Display five records at a time. 
 if ( recordCount == noOfRecordesDisplayed) 
 { 
 System.out.println(strMessage); 
 System.out.println("\n\nPress <Enter> to continue.."); 
 line = in.readLine(); 
 strMessage = ""; 
 recordCount = 0; 
 } 
 rstPubInfo.moveNext(); 
 // Display last records and exit if last record. 
 if(rstPubInfo.getEOF()) 
 { 
 System.out.println(strMessage); 
 break; 
 } 
 } 
 System.out.println ("\nEnter the ID of a logo to copy :\n" ); 
 strPubID = in.readLine(); 
 
 // Copy the logo to a variable in chunks. 
 rstPubInfo.setFilter("pub_id = '" + strPubID + "'"); 
 lngLogoSize = rstPubInfo.getField("logo").getActualSize(); 
 while (lngOffset < lngLogoSize) 
 { 
 varChunk = rstPubInfo.getField("logo") 
 .getByteChunk(conChunkSize); 
 int i = 0; 
 while (i < conChunkSize && varLogo.size() < (int)lngLogoSize) 
 { 
 varLogo.addElement(new Byte(varChunk[i])); 
 i++; 
 } 
 lngOffset = lngOffset + conChunkSize ; 
 } 
 //Get the data for New ID from the user. 
 System.out.println 
 ("\nEnter a new pub ID [must be > 9899 & < 9999]:"); 
 strPubID = in.readLine().trim(); 
 
 System.out.println ("\nEnter descriptive text :"); 
 strPRInfo = in.readLine().trim(); 
 
 //Temporarily add new publisher to publishers table to 
 //avoid getting error foreign key constraint. 
 cnConn1.execute("INSERT publishers(pub_id) VALUES('" + 
 strPubID + "')"); 
 
 //Add a new record. 
 rstPubInfo.addNew(); 
 rstPubInfo.getField("pub_id").setString(strPubID); 
 rstPubInfo.getField("pr_info").setString(strPRInfo); 
 
 //Copy the selected logo to the new logo in chunks. 
 lngOffset = 0; 
 
 //Divide logosize in multiples of constant chunk size. 
 intMulChunkSize = 
 (varLogo.size()/conChunkSize) * conChunkSize; 
 intLastChunkSize = varLogo.size()- intMulChunkSize ; 
 byte[] arrChunk = new byte[conChunkSize]; 
 byte[] lastChunk = new byte[intLastChunkSize]; 
 
 while ( lngOffset < varLogo.size () ) 
 { 
 int ii = 0 ; 
 // Copy the logo in constant chunk size. 
 if ( (int)lngOffset < intMulChunkSize) 
 { 
 while (ii < conChunkSize && 
 (int)lngOffset < varLogo.size () ) 
 { 
 arrChunk[ii] = 
 ((Byte)varLogo.elementAt 
 ((int)lngOffset)).byteValue(); 
 ii++; 
 lngOffset++; 
 } 
 rstPubInfo.getField("logo").appendChunk(arrChunk); 
 } 
 // Copy the last remaining chunk. 
 else 
 { 
 while (ii < intLastChunkSize && 
 (int)lngOffset < varLogo.size () ) 
 { 
 lastChunk[ii] = 
 ((Byte)varLogo.elementAt 
 ((int)lngOffset)).byteValue(); 
 ii++; 
 lngOffset++; 
 
 } 
 rstPubInfo.getField("logo").appendChunk(lastChunk); 
 } 
 
 } 
 
 // Update the new recordset with new logo. 
 
 rstPubInfo.update(); 
 
 //Show the newly added data. 
 System.out.println ("\nNew Record : " + 
 rstPubInfo.getField("pub_id").getString() + "\n"); 
 System.out.println ("Description : " + 
 rstPubInfo.getField("pr_info").getString() + "\n"); 
 System.out.println ("Logo Size : " + 
 rstPubInfo.getField("logo").getActualSize() ); 
 
 System.out.println ("\n\nPress <Enter> key to continue."); 
 in.readLine(); 
 
 //Delete new records because this is a demonstration. 
 rstPubInfo.requery(); 
 cnConn1.execute("DELETE FROM pub_info WHERE pub_id = '" + 
 strPubID + "'"); 
 cnConn1.execute("DELETE FROM publishers WHERE pub_id = '" + 
 strPubID + "'"); 
 } 
 catch( AdoException ae ) 
 { 
 // Notify user of any errors that result from ADO. 
 
 // Check for null pointer for connection object. 
 if(rstPubInfo.getActiveConnection()==null) 
 System.out.println("Exception: " + ae.getMessage()); 
 // As passing a Recordset, check for null pointer first. 
 if (rstPubInfo != null) 
 { 
 PrintProviderError(rstPubInfo.getActiveConnection()); 
 PrintADOError(ae); 
 } 
 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 (rstPubInfo != null) 
 if (rstPubInfo.getState() == 1) 
 rstPubInfo.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"); 
 } 
 
 // PrintADOError Function 
 
 static void PrintADOError(AdoException ae) 
 { 
 System.out.println("\t Error Source = " + ae.getSource() + "\n"); 
 System.out.println("\t Description = " + ae.getMessage() + "\n"); 
 } 
} 
// EndAppendChunkJ