zcalculator.java

用Java写的报表.功能如下: 0.内建网络打印,网络预览功能！ 1.文件操作。包括url 指定的文件。 2.全功能打印支持。包括打印预览。 3.Undo 和 redo。 4.合并单元格。 5.Cel

/*
 * Copyright 2002 EZCell , Inc. All rights reserved.
 * Version  1.0.
 * Author   W.John
 */
package ezcell;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;


/**
 * DOCUMENT ME!
 *
 * @version 1.00
 * @author W.John
 */
public class ZCalculator extends Thread {
    static int NOT_CHECKED_EXPRESSION = -1;
    private ZDefaultSheet sheet;
    private Hashtable items;
    private boolean itemChanged;
    private int cookie;
    private Vector parsingCells;

    ZCalculator(ZDefaultSheet sheet) {
        this.sheet = sheet;

        items = new Hashtable();
        parsingCells = new Vector();
        start();
    }

    /**
     *
     * @param cell
     *
     * @return
     */
    public String getText(ZCell cell) throws Exception {
        _Value value = (_Value) items.get(cell);

        if (value.cookie == NOT_CHECKED_EXPRESSION) {
            throw new Exception("invalid expression!");
        } else {
            return String.valueOf(value.value);
        }
    }

    /**
     *
     * @param r
     * @param c
     *
     * @return
     */
    public double getValue(int r, int c) {
        ZCell cell = sheet.getCell(r, c);

        return getValue(cell);
    }

    /**
     *
     * @param cell
     *
     * @return
     */
    public double getValue(ZCell cell) {
        // is recurse?
        if (parsingCells.contains(cell)) {
            return 0.0f;
        }

        if(cell.isChild() )
          return 0.0f;

        parsingCells.add(cell);

        double value = 0.0f;

        if (items.containsKey(cell)) {
            _Value vo = (_Value) items.get(cell);

            // if the value just be refreshed ,needn't calculate again
            if (vo.cookie == cookie) {
                parsingCells.remove(cell);

                return vo.value;
            }

            try {
                if (cell.getText().charAt(0) == '?') {
                    // launches a parser
                    ZFormulaParser parser = new ZFormulaParser(this);
                    value = parser.eval(cell.getText().substring(1));

                  //  System.out.println("cell:" + cell.getRow() + "" + cell.getCol() + ":" + value);


                    // signs it ,avoid repeatedly parsing
                    vo.cookie = cookie;

                    if (vo.value != value) {
                        vo.value = value;


                        // gives a change to its canvas for refreshing
                        sheet.firePropertyChanged(new ZRect(cell.getCol(), cell.getRow(), cell.getCol(), cell.getRow()), true);
                       //                        System.out.println(new ZRect(cell.getCol(), cell.getRow(), cell.getCol(), cell.getRow()));
                    }
                } else {
                    // invalid expression, no longer need to be computed!
                    items.remove(cell);
                }
            } catch (Exception ex) {
                // invalid expression, no longer need to be computed!
                items.remove(cell);
            }
        } else {
            try {
                value = Double.valueOf(cell.getText()).doubleValue();
            } catch (NumberFormatException ex) {
                // if get here , cell's text must not be composed with digits
            }
        }

        parsingCells.remove(cell);

        return value;
    }

    /**
     * Checks if cell items has been changed since last calculation. If true,
     * have the thread wait.
     *
     * This wait thread will be activated by set,remove method.
     */

    synchronized public void checkItemChanged() {
        try {
            // i would like have a rest, if everything has been done
            if (!itemChanged) {
                wait();
            }

            itemChanged = false;
        } catch (InterruptedException ex) {
        }
    }

    /**
     * Removes the cell from items which being computed. The method does nothing
     * if the cell is not in the items.
     * @param cell  the cell that need to be removed.
     */

    synchronized public void remove(ZCell cell) {
        if (!items.containsKey(cell)) {
            items.remove(cell);
        }
        itemChanged = true;
        this.notifyAll();
    }

    /**
     */
    public void run() {
        while (!interrupted()) {
            checkItemChanged();

            cookie++;

            // avoid the same value of cookie as not checked expression
            if (cookie == NOT_CHECKED_EXPRESSION) {
                cookie++;
            }

            parsingCells.clear();

            Enumeration cells = items.keys();

            while (cells.hasMoreElements()) {
                if (itemChanged) {
                    break;
                }

                ZCell cell = (ZCell) cells.nextElement();

                getValue(cell);
            }

           //                        System.out.println(cookie);
        }
    }

    /**
     *
     * @param cell
     */

    synchronized public void set(ZCell cell) {
        try {
            if (cell.getText().charAt(0) == '?') {
                if (!items.containsKey(cell)) {
                    items.put(cell, new _Value());
                }
            } else if (items.containsKey(cell)) {
                items.remove(cell);
            }
        } catch (Exception ex) {
            if (items.containsKey(cell)) {
                items.remove(cell);
            }
        }

        itemChanged = true;
        this.notifyAll();
    }

    /**
     * DOCUMENT ME!
     *
     * @version 1.00
     * @author W.John
     */
    class _Value {
        double value;
        int cookie;

        _Value(double value, int cookie) {
            this.value = value;
            this.cookie = cookie;
        }

        _Value() {
            this.cookie = NOT_CHECKED_EXPRESSION;
        }
    }
}