cardfileabstract.java

jdbc 的实例源码

/*
 * Copyright 1996 John Wiley & Sons, Inc. All Rights Reserved. Reproduction
 * or translation of this work beyond that permitted in Section 117 of the 1976
 * United States Copyright Act without the express written permission of the
 * copyright owner is unlawful. Requests for further information should be 
 * addressed to Permissions Department, John Wiley & Sons, Inc. The 
 * purchaser may make back-up copies for his/her own use only and not for 
 * distribution or resale. The Publisher assumes no responsibility for errors, 
 * omissions, or damages, caused by the use of this  software or from the use
 * of the information contained herein.
 *
 */
import java.awt.*;
import java.lang.*;
import java.util.*;

public abstract class CardFileAbstract extends Frame {

  // the myTextField objects for each column

  myTextField txt_name, txt_address, txt_city, txt_state, 
            txt_zip, txt_country, txt_phone, txt_id;

  String formstate; // indicates whether we are adding or editing

  //  String    name, address, city, state, zip, country, phone;

  // a layout manager for the Frame

  GridBagLayout layoutmangler = new GridBagLayout();

  // each of the buttons and a Panel to hold them

  Button next, previous, quit, save, newrow, edit, cancel, delete;
  Panel actionbuttons;

  // this hash is used to map column names to the 
  // corresponding objects (the myTextFields)

  Hashtable columnmap = new Hashtable();

  // the default constructor

  public CardFileAbstract(String[] argv) {
    login(argv);
    CreateForm();
  }

  public void CreateForm() {

    // set the layout for the frame
    this.setLayout(layoutmangler);

    // this is the offset within the GridBagLayout. If
    // I want the next object on a different line, I 
    // postincrement. If not, I don't.
    int i = 0;

    // the name field
    //
    // first, I add an anonymous text label to the Frame using
    // the AddToFrame method. Note that it uses column 0, and
    // row i (currently zero). I don't want the textfield
    // to appear on a different row, so I don't postincrement i.

    AddToFrame(new Label("Name:"), 0, i);

    // now, I instantiate txt_name. This is a textfield with 20
    // spaces. Then, I add it to the frame, and insert a reference
    // to it in the columnmap, keyed by 'name', which is the name 
    // of the column in the CardFile table
    
    txt_name = new myTextField(20);
    txt_name.setEditable(false);
    AddToFrame(txt_name, 1, i++);
    columnmap.put("name", txt_name);

    // the rest of the fields. Everything is pretty much the same as above.
    //
    // the address field

    AddToFrame(new Label("Address:"), 0, i);
    txt_address = new myTextField(35);
    txt_address.setEditable(false);
    AddToFrame(txt_address, 1, i++);
    columnmap.put("address", txt_address);

    // the city field
    // don't postincrement i, so state will show up
    // on the same row.
    
    AddToFrame(new Label("City:"), 0, i);
    txt_city = new myTextField(20);
    txt_city.setEditable(false);
    AddToFrame(txt_city, 1, i);
    columnmap.put("city", txt_city);

    // the state field

    AddToFrame(new Label("State:"), 2, i);
    txt_state = new myTextField(2);
    txt_state.setEditable(false);
    AddToFrame(txt_state, 3, i++);
    columnmap.put("state", txt_state);

    // the zip field

    AddToFrame(new Label("Zip:"), 0, i);
    txt_zip = new myTextField(11);
    txt_zip.setEditable(false);
    AddToFrame(txt_zip, 1, i++);
    columnmap.put("zip", txt_zip);

    // the country field

    AddToFrame(new Label("Country:"), 0, i);
    txt_country = new myTextField(25);
    txt_country.setEditable(false);
    AddToFrame(txt_country, 1, i++);
    columnmap.put("country", txt_country);

    // the phone field

    AddToFrame(new Label("Phone:"), 0, i);
    txt_phone = new myTextField(20);
    txt_phone.setEditable(false);
    AddToFrame(txt_phone, 1, i++);
    columnmap.put("phone", txt_phone);

    // the id field. 

    AddToFrame(new Label("Id:"), 0, i);
    txt_id = new myTextField(4);
    txt_id.setEditable(false);
    AddToFrame(txt_id, 1, i++);
    columnmap.put("id", txt_id);

    // create the button panel and give it a new FlowLayout

    actionbuttons = new Panel();
    actionbuttons.setLayout(new FlowLayout(FlowLayout.CENTER, 5, 5));
    
    // The constraints for the button panel are a little
    // more complex than the constraints for the labels
    // and textfields, so we'll set it up here, and add
    // the actionbuttons panel
    
    GridBagConstraints c = new GridBagConstraints();
    c.gridwidth = 3; c.gridheight = 1;
    c.fill = GridBagConstraints.NONE;
    c.anchor = GridBagConstraints.CENTER;
    c.weightx = 0.0; c.weighty = 0.0;   
    c.gridx = 0; c.gridy = i;
    ((GridBagLayout)this.getLayout()).setConstraints(actionbuttons, c);   
    this.add(actionbuttons);

    // instantiate and add each of the buttons

    previous = new Button("Previous");
    actionbuttons.add(previous);

    next = new Button("Next");
    actionbuttons.add(next);

    quit = new Button("Quit");
    actionbuttons.add(quit);

    newrow = new Button("New");
    actionbuttons.add(newrow);

    edit = new Button("Edit");
    actionbuttons.add(edit);

    delete = new Button("Delete");
    actionbuttons.add(delete);

    // save and cancel are disabled until the user
    // is adding or editing.

    save = new Button("Save");
    actionbuttons.add(save);
    save.setEnabled(false);

    cancel = new Button("Cancel");
    actionbuttons.add(cancel);
    cancel.setEnabled(false);

    // call getRow() to display the first row in the table.
 
    getRow();
    System.out.println("CardFileAbstract was started successfully.");

  }

  public abstract void login(String[] argv);
  public abstract void getRow();
  public abstract void delRow();
  public abstract void nextRow();
  public abstract void prevRow();
  public abstract void save();
  public abstract void update();

  /**
   * clearForm()
   *
   * Clear all of the input fields
   *
   */
  protected void clearForm () {

    // blank the name field
    txt_name.setText("");

    // blank the address field
    txt_address.setText("");

    // blank the city field
    txt_city.setText("");

    // blank the state field
    txt_state.setText("");

    // blank the zip field
    txt_zip.setText("");

    // blank the country field
    txt_country.setText("");

    // blank the phone field
    txt_phone.setText("");

    // blank the id field
    txt_id.setText("");

  }

  /**
   * AddToFrame()
   *
   * A convenience method to wrap the living hell
   * that is GridBagConstraints()
   *
   */
  protected void AddToFrame (Component item, int x, int y) {

    // some sane layout defaults.

    GridBagConstraints c = new GridBagConstraints();
    c.gridwidth = 1; c.gridheight = 1;
    c.fill = GridBagConstraints.NONE;
    c.anchor = GridBagConstraints.NORTHWEST;
    c.weightx = 0.0; c.weighty = 0.0;        

    // set the grid coordinates

    c.gridx = x; c.gridy = y;

    // set the constraints, and add the item to the layout

    ((GridBagLayout)this.getLayout()).setConstraints(item, c);    
    this.add(item);

  }


  /**
   * handleEvent
   *
   * Deal with things the user did...
   */
  public boolean handleEvent(Event event) {

    switch(event.id) {

    // deal with action buttons

    case Event.ACTION_EVENT:

      if (event.target == next) {
        nextRow();
      }

      if (event.target == previous) {
        prevRow();
      }

      if (event.target == delete) {
        delRow();
      }
      
      // if the user pressed quit, then let's get out of here!

      if (event.target == quit) {
        System.exit(0);
      }

      // if the user wants to edit the current row,
      // then set the formstate as appropriate, and 
      // call the setEdit() method.

      if (event.target == edit) {
        formstate = "edit";
        setEdit();
      }

      // in case the user presses the new button, I
      // want to 1) clear the form, 2) set the formstate
      // to "new", 3) let them modify the id field, and
      // 4) call setEdit()

      if (event.target == newrow) {
        clearForm();
        formstate = "new";
        txt_id.setEditable(true);        

        setEdit();
      }

      // in case the user hits the save button, I need
      // to distinguish between "new" and "edit" mode,
      // so I know whether to call save() or update().
      // Also, I need 
      if (event.target == save) {
        if (formstate.equals("new")) {
          save();
          txt_id.setEditable(false); // make the id field uneditable
        }
        if (formstate.equals("edit")) {
          update();
        }

        // set the formstate to "browse", and call setBrowse()
        formstate = "browse";
        setBrowse();
      }

      // if the user pressed cancel, return the formstate to browse

      if (event.target == cancel) {
        
        // if it was new, make sure that they can't edit the
        // id field...

        if (formstate.equals("new")) {
          txt_id.setEditable(false);
        } 

        // return the formstate to browse, call getRow()
        // to retrieve the row they were looking at
        // before editing or adding, and call setBrowse()

        formstate = "browse";
        getRow();
        setBrowse();
      }

      break;

    // in case they closed the window, then take
    // it as a sign that they want to quit
    case Event.WINDOW_DESTROY:
        System.exit(0);
        break;            // hmmm...

    // just pass these on
    case Event.MOUSE_DOWN:
    case Event.MOUSE_UP:
    case Event.MOUSE_DRAG:
    case Event.KEY_PRESS:
    case Event.KEY_ACTION:
    case Event.KEY_RELEASE:
    case Event.KEY_ACTION_RELEASE:
    case Event.GOT_FOCUS:
    case Event.LOST_FOCUS:
    case Event.MOUSE_ENTER:
    case Event.MOUSE_EXIT:
    case Event.MOUSE_MOVE:
      return false;
    }

    return true;
  }

  /**
   * setEdit()
   *
   * prepare the form for editing/adding
   *
   */
  protected void setEdit () {
    
    // disable all these buttons

    next.setEnabled(false);
    previous.setEnabled(false);
    newrow.setEnabled(false);
    edit.setEnabled(false);
    delete.setEnabled(false);

    // set everything except the id to be editable
    txt_name.setEditable(true);
    txt_address.setEditable(true);
    txt_city.setEditable(true);
    txt_state.setEditable(true);
    txt_zip.setEditable(true);
    txt_country.setEditable(true);
    txt_phone.setEditable(true);

    // enable these two buttons

    save.setEnabled(true);
    cancel.setEnabled(true);
  }

  /**
   * setBrowse()
   *
   * prepare the form for viewing
   *
   */
  protected void setBrowse() {

    // enable all these buttons
    
    next.setEnabled(true);
    previous.setEnabled(true);
    newrow.setEnabled(true);
    edit.setEnabled(true);
    delete.setEnabled(true);

    // disable the fields
    
    txt_name.setEditable(false);
    txt_address.setEditable(false);
    txt_city.setEditable(false);
    txt_state.setEditable(false);
    txt_zip.setEditable(false);
    txt_country.setEditable(false);
    txt_phone.setEditable(false);
    txt_id.setEditable(false);
   
    // disable these two buttons

    save.setEnabled(false);
    cancel.setEnabled(false);
  }


}


class myTextField extends TextField {

  public myTextField(int size) {
    super( size );
  }

  public String getText() {

    String retval = super.getText();
    if (retval.equals("")) {
      return " ";
    } else {
      return retval;
    }
  }
}