access.java

java 与COM组件的连接桥

/*
 * Copyright (c) 1999-2004 Sourceforge JACOB Project.
 * All rights reserved. Originator: Dan Adler (http://danadler.com).
 * Get more information about JACOB at http://sourceforge.net/projects/jacob-project
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
package com.jacob.samples.access;

import com.jacob.com.*;
import com.jacob.activeX.*;

/**
 * May need to run with some command line options (including from inside Eclipse).  
 * Look in the docs area at the Jacob usage document for command line options.
 *
 */
class Access 
{
    /**
     * the main loop for the test
     * @param args
     * @throws Exception
     */
  public static void main(String[] args) throws Exception
  {
    ComThread.InitSTA();
    // original test used this
    // ActiveXComponent ax = new ActiveXComponent("DAO.PrivateDBEngine");
    // my xp box with a later release of access needed this
    ActiveXComponent ax = new ActiveXComponent("DAO.PrivateDBEngine.35");
	// this only works for access files pre-access-2000
    // this line doesn't work on my xp box in Eclipse
    //Dispatch db = open(ax, ".\\sample2.mdb");
    // this works when running in eclipse because the test cases run pwd project root
    Dispatch db = open(ax, "samples/com/jacob/samples/access/sample2.mdb");
    String sql = "select * from MainTable";
    // make a temporary querydef
    Dispatch qd = Dispatch.call(db, "CreateQueryDef","").toDispatch();
    // set the SQL string on it
    Dispatch.put(qd, "SQL", sql);
    Variant result = getByQueryDef(qd);
		// the 2-d safearray is transposed from what you might expect
    System.out.println("resulting array is "+result.toSafeArray());
    close(db);
    System.out.println("about to call ComThread.Release()");
	ComThread.Release();
  }

  /**
   * Open a database 
   * @param ax
   * @param fileName
   * @return dispatch object that was opened
   */
  public static Dispatch open(ActiveXComponent ax, String fileName)
  {
    Variant f = new Variant(false);
    // open the file in read-only mode
    Variant[] args = new Variant[] {new Variant(fileName), f, f};
    Dispatch openDB = ax.invoke("OpenDatabase", args).toDispatch();
    return openDB;
  }

  /**
   * Close a database
   * @param openDB db to be closed
   */
  public static void close(Dispatch openDB)
  {
    Dispatch.call(openDB, "Close");
  }

  /**
   * Extract the values from the recordset
   * @param recset
   * @return Variant that is the returned values
   */
  public static Variant getValues(Dispatch recset)
  {
    Dispatch.callSub(recset,"moveFirst");
    Variant vi = new Variant(4096);
    Variant v = Dispatch.call(recset,"GetRows", vi);
    return v;
  }

  /**
   * should return ?? for the passed in ??
   * @param qd
   * @return Variant results of query?
   */
  public static Variant getByQueryDef(Dispatch qd)
  {
    // get a reference to the recordset
    Dispatch recset = Dispatch.call(qd, "OpenRecordset").toDispatch();
    // get the values as a safe array
    String[] cols = getColumns(recset);
    for(int i=0;i<cols.length;i++)
    {
      System.out.print(cols[i]+" ");
    }
    System.out.println("");
    Variant vals = getValues(recset);
    return vals;
  }

  /**
   * gets the columns form the rec set
   * @param recset
   * @return list of column names
   */
  public static String[] getColumns(Dispatch recset)
  {
    Dispatch flds = Dispatch.get(recset, "Fields").toDispatch();
    int n_flds = Dispatch.get(flds, "Count").getInt();
    String[] s = new String[n_flds];
    Variant vi = new Variant();
    for (int i=0;i<n_flds;i++) {
      vi.putInt(i);
      // must use the invoke method because this is a method call
      // that wants to have a Dispatch.Get flag...
      Dispatch fld = Dispatch.invoke(recset, "Fields",
                       Dispatch.Get, new Object[] {vi}, new int[1]).toDispatch();
      Variant name = Dispatch.get(fld, "Name");
      s[i] = name.toString();
    }
    return s;
  }
}