/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.gears.sample.databasedemo.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyDownEvent;
import com.google.gwt.event.dom.client.KeyDownHandler;
import com.google.gwt.gears.client.Factory;
import com.google.gwt.gears.client.database.Database;
import com.google.gwt.gears.client.database.DatabaseException;
import com.google.gwt.gears.client.database.ResultSet;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;
import java.util.Date;
/**
* Sample application demonstrating how to use the {@link Database} class.
*/
public class DatabaseDemo implements EntryPoint {
private static final int NUM_SAVED_ROWS = 3;
private static final int NUM_DATA_TABLE_COLUMNS = 3;
private final Button addButton = new Button("Add");
private final Button clearButton = new Button("Clear Database");
private Database db;
private final TextBox input = new TextBox();
private final FlexTable dataTable = new FlexTable();
public void onModuleLoad() {
VerticalPanel outerPanel = new VerticalPanel();
outerPanel.setSpacing(10);
outerPanel.getElement().getStyle().setPropertyPx("margin", 15);
HorizontalPanel textAndButtonsPanel = new HorizontalPanel();
textAndButtonsPanel.add(new Label("Enter a Phrase: "));
textAndButtonsPanel.add(input);
textAndButtonsPanel.add(addButton);
textAndButtonsPanel.add(clearButton);
outerPanel.add(textAndButtonsPanel);
outerPanel.add(new Label("Last 3 Entries:"));
outerPanel.add(dataTable);
for (int i = 0; i <= NUM_SAVED_ROWS; ++i) {
dataTable.insertRow(i);
for (int j = 0; j < NUM_DATA_TABLE_COLUMNS; j++) {
dataTable.addCell(i);
}
}
dataTable.setWidget(0, 0, new HTML("<b>Id</b>"));
dataTable.setWidget(0, 1, new HTML("<b>Phrase</b>"));
dataTable.setWidget(0, 2, new HTML("<b>Timestamp</b>"));
// Create the database if it doesn't exist.
try {
db = Factory.getInstance().createDatabase();
db.open("database-demo");
db.execute("CREATE TABLE IF NOT EXISTS Phrases (Id INTEGER PRIMARY KEY AUTOINCREMENT, Phrase VARCHAR(255), Timestamp INTEGER)");
} catch (DatabaseException e) {
RootPanel.get("demo").add(
new HTML("Error opening or creating database: <font color=\"red\">"
+ e.toString() + "</font>"));
// Fatal error. Do not build the interface.
return;
}
input.addKeyDownHandler(new KeyDownHandler() {
public void onKeyDown(KeyDownEvent event) {
if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER) {
insertPhrase();
}
}
});
addButton.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
insertPhrase();
}
});
clearButton.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
clearPhrases();
displayRecentPhrases();
}
});
RootPanel.get("demo").add(outerPanel);
displayRecentPhrases();
}
/**
* Remove all phrases from the database.
*/
private void clearPhrases() {
try {
db.execute("DELETE FROM Phrases");
} catch (DatabaseException e) {
Window.alert(e.toString());
}
}
/**
* Fill the labels with the phrases from the database.
*/
private void displayRecentPhrases() {
try {
ResultSet rs = db.execute("SELECT * FROM Phrases ORDER BY Id DESC");
int i;
for (i = 1; rs.isValidRow(); ++i, rs.next()) {
if (i <= NUM_SAVED_ROWS) {
dataTable.setText(i, 0, rs.getFieldAsString(0));
dataTable.setText(i, 1, rs.getFieldAsString(1));
dataTable.setText(i, 2, new Date(rs.getFieldAsLong(2)).toString());
} else {
db.execute("DELETE FROM Phrases WHERE Id = ?",
new String[]{rs.getFieldAsString(0)});
}
}
// If a phrase has been removed, clear the label.
for (; i <= NUM_SAVED_ROWS; i++) {
for (int j = 0; j < NUM_DATA_TABLE_COLUMNS; j++) {
dataTable.clearCell(i, j);
}
}
rs.close();
} catch (DatabaseException e) {
Window.alert(e.toString());
}
}
/**
* Add a new phrase to the database.
*/
private void insertPhrase() {
try {
String phrase = input.getText();
if (phrase.length() > 0) {
db.execute("INSERT INTO Phrases (Phrase, Timestamp) VALUES (?, ?)",
new String[]{phrase, Long.toString(System.currentTimeMillis())});
displayRecentPhrases();
input.setText("");
}
} catch (DatabaseException e) {
Window.alert(e.toString());
}
}
}