Wednesday November 19, 2008
Wednesday November 19, 2008
Getting Started with the Database Explorer API
Now that the Database Explorer API is official, I need to write a tutorial covering some typical things that you might want to do with it. David Van Couvering, who leads this area of NetBeans, provided me with the following notes. Thanks a lot David. The use case is that of a developer wanting to inspect metadata for a connection in the Database Explorer.
- Get a connection. Normally the first step for this is to find out what connection the user wants to use. We provide a helper utility that provides you with a combo box containing all current connections in the Database Explorer, as well as the ability to create a new connection. Here's how you might use this API:
- In your UI, create a combo box.
- Associate the combo box with the utility:
DatabaseExplorerUIs.connect(dbconnComboBox, ConnectionManager.getDefault());
- In your action listener for your combo box:
Object selected = dbconnComboBox.getSelectedItem(); if (selected instanceof DatabaseConnection) { dbconn = (DatabaseConnection) selected; }
- Make sure you're connected. It's possible your database connection is not connected. Here's what you do:
Connection conn = dbconn.getJDBCConnection(true); if (conn == null) { ConnectionManager.getDefault().showConnectionDialog(dbconn); } conn = dbconn.getJDBCConnection(true); if (conn == null) { // user chose not to connect, handle this } - Get metadata. Let's say you want to get all the tables for the connection. We are going to be adding a new Metadata API, but for now you just use the native JDBC DatabaseMetadata. So, for example:
Connection conn = dbconn.getJDBCConnection(true); try { ResultSet rs = conn.getMetaData().getTables(null, null, "*", new String[]{"TABLE"}); while (rs.next()) { System.out.println("Table name is " + rs.getString("TABLE_SCHEMA") + "." + rs.getString("TABLE")); } } catch (SQLException sqle) { // handle me }
For example, here's a TopComponent showing the result of the code above:
Finally, here's some code, also from David, for dragging and dropping in a snippet. It comes from J2EEComponentDropProvider.java in org.netbeans.modules.form.j2ee:
/**
* Processes given transferable and returns the corresponding
* NewComponentDrop.
*
* @param formModel corresponding form model.
* @param transferable description of transferred data.
* @return NewComponentDrop that corresponds to given
* transferable or null if this provider
* don't understand to or don't want to process this data transfer.
*/
public NewComponentDrop processTransferable(FormModel formModel, Transferable transferable) {
try {
if (transferable.isDataFlavorSupported(DatabaseMetaDataTransfer.CONNECTION_FLAVOR)) {
DatabaseMetaDataTransfer.Connection connection = (DatabaseMetaDataTransfer.Connection)transferable.getTransferData(DatabaseMetaDataTransfer.CONNECTION_FLAVOR);
return new DBConnectionDrop(formModel, connection);
} else if (transferable.isDataFlavorSupported(DatabaseMetaDataTransfer.COLUMN_FLAVOR)) {
DatabaseMetaDataTransfer.Column column = (DatabaseMetaDataTransfer.Column)transferable.getTransferData(DatabaseMetaDataTransfer.COLUMN_FLAVOR);
return new DBColumnDrop(formModel, column);
} else if (transferable.isDataFlavorSupported(DatabaseMetaDataTransfer.TABLE_FLAVOR)) {
DatabaseMetaDataTransfer.Table table = (DatabaseMetaDataTransfer.Table)transferable.getTransferData(DatabaseMetaDataTransfer.TABLE_FLAVOR);
return new DBTableDrop(formModel, table);
}
} catch (Exception ex) {
// should not happen
Logger.getLogger(getClass().getName()).log(Level.INFO, ex.getMessage(), ex);
}
return null;
}
All the above code will be part of a new tutorial soon.
Nov 19 2008, 01:14:28 AM PST Permalink
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