syncresolver.java

Mobile 应用程序使用 Java Micro Edition (Java ME) 平台

 *     try {
 *
 *         crs.acceptChanges(con);
 *
 *     } catch (SyncProviderException spe) {
 *
 *         SyncResolver resolver = spe.getSyncResolver();
 *
 *         Object crsValue;  // value in the <code>RowSet</code> object 
 *         Object resolverValue:  // value in the <code>SyncResolver</code> object
 *         Object resolvedValue:  // value to be persisted
 *
 *         while(resolver.nextConflict())  {
 *             if(resolver.getStatus() == SyncResolver.UPDATE_ROW_CONFLICT)  {
 *                 int row = resolver.getRow();
 *                 crs.absolute(row);
 *
 *                 int colCount = crs.getMetaData().getColumnCount();
 *                 for(int j = 1; j <= colCount; j++) {
 *                     if (resolver.getConflictValue(j) != null)  {
 *                         crsValue = crs.getObject(j);
 *                         resolverValue = resolver.getConflictValue(j);
 *                         . . . 
 *                         // compare crsValue and resolverValue to determine
 *                         // which should be the resolved value (the value to persist)
 *                         resolvedValue = crsValue;
 *
 *                         resolver.setResolvedValue(j, resolvedValue);
 *                      } 
 *                  } 
 *              }
 *          }
 *      }
 * </PRE>
 * @author  Jonathan Bruce
 */

public interface SyncResolver extends RowSet {
    /**
     * Indicates that a conflict occurred while the <code>RowSet</code> object was
     * attempting to update a row in the data source. 
     * The values in the data source row to be updated differ from the
     * <code>RowSet</code> object's original values for that row, which means that
     * the row in the data source has been updated or deleted since the last 
     * synchronization. 
     */
     public static int UPDATE_ROW_CONFLICT = 0; 

    /** 
     * Indicates that a conflict occurred while the <code>RowSet</code> object was
     * attempting to delete a row in the data source.
     * The values in the data source row to be updated differ from the
     * <code>RowSet</code> object's original values for that row, which means that 
     * the row in the data source has been updated or deleted since the last 
     * synchronization. 
     */
    public static int DELETE_ROW_CONFLICT = 1;
    
   /**
    * Indicates that a conflict occurred while the <code>RowSet</code> object was
    * attempting to insert a row into the data source.  This means that a
    * row with the same primary key as the row to be inserted has been inserted
    * into the data source since the last synchronization.
    */
    public static int INSERT_ROW_CONFLICT = 2;           
    
    /**
     * Indicates that <b>no</b> conflict occured while the <code>RowSet</code> object
     * was attempting to update, delete or insert a row in the data source. The values in
     * the <code>SyncResolver</code> will contain <code>null</code> values only as an indication
     * that no information in pertitent to the conflict resolution in this row.
     */
    public static int NO_ROW_CONFLICT = 3;
          
    /**
     * Retrieves the conflict status of the current row of this <code>SyncResolver</code>,
     * which indicates the operation
     * the <code>RowSet</code> object was attempting when the conflict occurred.
     *
     * @return one of the following constants:
     *         <code>SyncResolver.UPDATE_ROW_CONFLICT</code>,
     *         <code>SyncResolver.DELETE_ROW_CONFLICT</code>, 
     *         <code>SyncResolver.INSERT_ROW_CONFLICT</code>, or
     *         <code>SyncResolver.NO_ROW_CONFLICT</code>
     */
    public int getStatus();
    
    /**
     * Retrieves the value in the designated column in the current row of this
     * <code>SyncResolver</code> object, which is the value in the data source
     * that caused a conflict.
     *
     * @param index an <code>int</code> designating the column in this row of this
     *        <code>SyncResolver</code> object from which to retrieve the value 
     *        causing a conflict
     * @return the value of the designated column in the current row of this
     *         <code>SyncResolver</code> object 
     * @throws SQLException if a database access error occurs     
     */
    public Object getConflictValue(int index) throws SQLException;
    
    /**
     * Retrieves the value in the designated column in the current row of this
     * <code>SyncResolver</code> object, which is the value in the data source
     * that caused a conflict.
     *
     * @param columnName a <code>String</code> object designating the column in this row of this
     *        <code>SyncResolver</code> object from which to retrieve the value 
     *        causing a conflict
     * @return the value of the designated column in the current row of this
     *         <code>SyncResolver</code> object 
     * @throws SQLException if a database access error occurs     
     */
    public Object getConflictValue(String columnName) throws SQLException;
    
    /**
     * Sets <i>obj</i> as the value in column <i>index</i> in the current row of the
     * <code>RowSet</code> object that is being synchronized. <i>obj</i>
     * is set as the value in the data source internally.
     *
     * @param index an <code>int</code> giving the number of the column into which to
     *        set the value to be persisted
     * @param obj an <code>Object</code> that is the value to be set in the 
     *        <code>RowSet</code> object and persisted in the data source
     * @throws SQLException if a database access error occurs
     */
    public void setResolvedValue(int index, Object obj) throws SQLException; 
    
    /**
     * Sets <i>obj</i> as the value in column <i>columnName</i> in the current row of the
     * <code>RowSet</code> object that is being synchronized. <i>obj</i>
     * is set as the value in the data source internally.
     *
     * @param columnName a <code>String</code> object giving the name of the column 
     *        into which to set the value to be persisted
     * @param obj an <code>Object</code> that is the value to be set in the 
     *        <code>RowSet</code> object and persisted in the data source
     * @throws SQLException if a database access error occurs
     */
    public void setResolvedValue(String columnName, Object obj) throws SQLException; 
    
    /**
     * Moves the cursor down from its current position to the next row that contains
     * a conflict value. A <code>SyncResolver</code> object's
     * cursor is initially positioned before the first conflict row; the first call to the 
     * method <code>nextConflict</code> makes the first conflict row the current row; 
     * the second call makes the second conflict row the current row, and so on.
     * <p>
     * A call to the method <code>nextConflict</code> will implicitly close 
     * an input stream if one is open and will clear the <code>SyncResolver</code> 
     * object's warning chain.
     *
     * @return <code>true</code> if the new current row is valid; <code>false</code>
     *         if there are no more rows
     * @throws SQLException if a database access error occurs or the result set type
     *     is <code>TYPE_FORWARD_ONLY</code>
     *
     */
    public boolean nextConflict() throws SQLException;
    
    /**
     * Moves the cursor up from its current position to the previous conflict 
     * row in this <code>SyncResolver</code> object.
     * <p>
     * A call to the method <code>previousConflict</code> will implicitly close 
     * an input stream if one is open and will clear the <code>SyncResolver</code> 
     * object's warning chain.
     *
     * @return <code>true</code> if the cursor is on a valid row; <code>false</code>
     *     if it is off the result set 
     * @throws SQLException if a database access error occurs or the result set type
     *     is <code>TYPE_FORWARD_ONLY</code>
     */
    public boolean previousConflict() throws SQLException;
                    
}