次の 3 つの例では、Save メソッドと Open メソッドを一緒に使用する方法を示します。
ある社員が仕事で出張する予定があり、出張先にデータベースに含まれるテーブルを持っていく必要があるとします。出かける前に、Recordset としてデータにアクセスし、それを持ち出し可能な形式に保存します。出張先では、接続されていないローカルな Recordset としてアクセスします。Recordset に変更を加え、変更分と共に Recordset を再度保存します。最終的に会社に戻ったときに、再度データベースに接続し、出張中に行った変更に関する更新を、データベースに対して行います。
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 = "DSN=Pubs;Provider=MSDASQL;uid=sa;pwd=;";
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("a:\\Pubs.xml");
if(!file.exists())
rstAuthors.save("a:\\Pubs.xml",AdoEnums.PersistFormat.XML);
else
{
System.out.println("\nFile already exists.");
System.out.println("\nPress <Enter> to continue..");
in.readLine();
System.exit(0);
}
// Cleanup objects before exit.
rstAuthors.close();
}
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);
}
}
// 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("a:\\Pubs.xml",
"Provider=MSPersist;",
AdoEnums.CursorType.FORWARDONLY,
AdoEnums.LockType.OPTIMISTIC,
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("a:\\Pubs.adtg",AdoEnums.PersistFormat.ADTG);
// Cleanup objects before exit.
rstAuthors.close();
}
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, update the database with your changes.
// SaveX3 function
static void SaveX3()
{
// Define ADO Objects.
Connection cnConn1 = null;
Recordset rstAuthors = null;
// Declarations.
String strCnn = "DSN=Pubs;Provider=MSDASQL;uid=sa;pwd=;";
try
{
// If there is no ActiveConnection, you can open with defaults.
rstAuthors = new Recordset();
rstAuthors.open("a:\\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();
// Cleanup objects before exit.
rstAuthors.close();
cnConn1.close();
}
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());
}
}
}
// PrintProviderError Function
static void PrintProviderError( Connection Cnn1 )
{
// Print Provider errors from Connection object.
// ErrItem is an item object in the Connection’s 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");
}
}