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JDBCAdapter.javaAPI DocSun JDK 1.4.2 Example8741Thu May 12 00:35:28 BST 2005None

JDBCAdapter

public class JDBCAdapter extends AbstractTableModel
An adaptor, transforming the JDBC interface to the TableModel interface.
version
1.20 09/25/97
author
Philip Milne

Fields Summary
Connection
connection
Statement
statement
ResultSet
resultSet
String[]
columnNames
Vector
rows
ResultSetMetaData
metaData
Constructors Summary
public JDBCAdapter(String url, String driverName, String user, String passwd)


        
                           
        try {
            Class.forName(driverName);
            System.out.println("Opening db connection");

            connection = DriverManager.getConnection(url, user, passwd);
            statement = connection.createStatement();
        }
        catch (ClassNotFoundException ex) {
            System.err.println("Cannot find the database driver classes.");
            System.err.println(ex);
        }
        catch (SQLException ex) {
            System.err.println("Cannot connect to this database.");
            System.err.println(ex);
        }
     
Methods Summary
public voidclose()

        System.out.println("Closing db connection");
        resultSet.close();
        statement.close();
        connection.close();
    
public java.lang.StringdbRepresentation(int column, java.lang.Object value)

        int type;

        if (value == null) {
            return "null";
        }

        try {
            type = metaData.getColumnType(column+1);
        }
        catch (SQLException e) {
            return value.toString();
        }

        switch(type) {
        case Types.INTEGER:
        case Types.DOUBLE:
        case Types.FLOAT:
            return value.toString();
        case Types.BIT:
            return ((Boolean)value).booleanValue() ? "1" : "0";
        case Types.DATE:
            return value.toString(); // This will need some conversion.
        default:
            return "\""+value.toString()+"\"";
        }

    
public voidexecuteQuery(java.lang.String query)

        if (connection == null || statement == null) {
            System.err.println("There is no database to execute the query.");
            return;
        }
        try {
            resultSet = statement.executeQuery(query);
            metaData = resultSet.getMetaData();

            int numberOfColumns =  metaData.getColumnCount();
            columnNames = new String[numberOfColumns];
            // Get the column names and cache them.
            // Then we can close the connection.
            for(int column = 0; column < numberOfColumns; column++) {
                columnNames[column] = metaData.getColumnLabel(column+1);
            }

            // Get all rows.
            rows = new Vector();
            while (resultSet.next()) {
                Vector newRow = new Vector();
                for (int i = 1; i <= getColumnCount(); i++) {
	            newRow.addElement(resultSet.getObject(i));
                }
                rows.addElement(newRow);
            }
            //  close(); Need to copy the metaData, bug in jdbc:odbc driver.
            fireTableChanged(null); // Tell the listeners a new table has arrived.
        }
        catch (SQLException ex) {
            System.err.println(ex);
        }
    
protected voidfinalize()

        close();
        super.finalize();
    
public java.lang.ClassgetColumnClass(int column)

        int type;
        try {
            type = metaData.getColumnType(column+1);
        }
        catch (SQLException e) {
            return super.getColumnClass(column);
        }

        switch(type) {
        case Types.CHAR:
        case Types.VARCHAR:
        case Types.LONGVARCHAR:
            return String.class;

        case Types.BIT:
            return Boolean.class;

        case Types.TINYINT:
        case Types.SMALLINT:
        case Types.INTEGER:
            return Integer.class;

        case Types.BIGINT:
            return Long.class;

        case Types.FLOAT:
        case Types.DOUBLE:
            return Double.class;

        case Types.DATE:
            return java.sql.Date.class;

        default:
            return Object.class;
        }
    
public intgetColumnCount()

        return columnNames.length;
    
public java.lang.StringgetColumnName(int column)

        if (columnNames[column] != null) {
            return columnNames[column];
        } else {
            return "";
        }
    
public intgetRowCount()

        return rows.size();
    
public java.lang.ObjectgetValueAt(int aRow, int aColumn)

        Vector row = (Vector)rows.elementAt(aRow);
        return row.elementAt(aColumn);
    
public booleanisCellEditable(int row, int column)

        try {
            return metaData.isWritable(column+1);
        }
        catch (SQLException e) {
            return false;
        }
    
public voidsetValueAt(java.lang.Object value, int row, int column)

        try {
            String tableName = metaData.getTableName(column+1);
            // Some of the drivers seem buggy, tableName should not be null.
            if (tableName == null) {
                System.out.println("Table name returned null.");
            }
            String columnName = getColumnName(column);
            String query =
                "update "+tableName+
                " set "+columnName+" = "+dbRepresentation(column, value)+
                " where ";
            // We don't have a model of the schema so we don't know the
            // primary keys or which columns to lock on. To demonstrate
            // that editing is possible, we'll just lock on everything.
            for(int col = 0; col<getColumnCount(); col++) {
                String colName = getColumnName(col);
                if (colName.equals("")) {
                    continue;
                }
                if (col != 0) {
                    query = query + " and ";
                }
                query = query + colName +" = "+
                    dbRepresentation(col, getValueAt(row, col));
            }
            System.out.println(query);
            System.out.println("Not sending update to database");
            // statement.executeQuery(query);
        }
        catch (SQLException e) {
            //     e.printStackTrace();
            System.err.println("Update failed");
        }
        Vector dataRow = (Vector)rows.elementAt(row);
        dataRow.setElementAt(value, column);