Ich schreibe eine einfache Java-Anwendung, die es einem Benutzer ermöglicht, Details über Personen in eine SQLite-Datenbank einzugeben. Ich verwende Eclipse SWT für die GUI.
Eclipse SWT definiert einen Typ Image ( org.eclipse.swt.graphics.Image ) für die Anzeige von Bildern in einer grafischen Benutzeroberfläche.
Ich versuche, einem Benutzer zu ermöglichen, das Dateisystem zu durchsuchen, ein Bild auszuwählen und dieses Bild dann in eine Datenbank einzufügen. Ich möchte auch in der Lage sein, dieses Bild aus der Datenbank abzurufen und es in der grafischen Benutzeroberfläche anzuzeigen.
Alles ganz einfach, aber ich kann es einfach nicht zum Laufen bringen! Ich habe auch viel herumgesucht und kann keine Lösung dafür finden.
Ich verwende die Eclipse IDE für Java-Entwickler (3.6), sqlite-jdbc-3.7.2.jar und JDK 1.6.0_22.
import org.eclipse.swt.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.graphics.*;
import java.sql.*;
/***********************************************************************/
/*** Tests reading and writing SWT Images from an SQLite Database ***/
/***********************************************************************/
public class ImageTest {
Shell shell;
//Variables to store the current values when editing
private Canvas personPhoto;
private Image personImage;
private int personID = 1;
private double photoWidth = 100;
private double photoHeight = 100;
//Database connection and statement variables
private static Connection connection = null;
private static Statement statement = null;
private static PreparedStatement ps = null;
private static ResultSet rs = null;
public ImageTest(Shell parent, Connection passedConnection) {
shell = new Shell(parent, SWT.DIALOG_TRIM | SWT.PRIMARY_MODAL);
shell.setLayout(new GridLayout());
connection = passedConnection;
}
private void createControlButtons() {
Composite composite = new Composite(shell, SWT.NONE);
composite.setLayoutData(new GridData(GridData.HORIZONTAL_ALIGN_END));
GridLayout layout = new GridLayout();
layout.numColumns = 2;
composite.setLayout(layout);
Button okButton = new Button(composite, SWT.PUSH);
okButton.setText("OK");
okButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
if(personID > 0){
try {
PreparedStatement ps = connection.prepareStatement("UPDATE person SET photo = ? " +
"WHERE person_id = ?");
ps.setBytes(1, personImage.getImageData().data);
ps.setInt(2, personID);
ps.executeUpdate();
ps.close();
} catch (SQLException err) {
err.printStackTrace();
}
} else {
try {
PreparedStatement ps = connection.prepareStatement("INSERT INTO person (photo) VALUES (?)");
ps.setBytes(1, personImage.getImageData().data);
ps.executeUpdate();
ps.close();
} catch (SQLException err) {
err.printStackTrace();
}
}
shell.close();
}
});
Button cancelButton = new Button(composite, SWT.PUSH);
cancelButton.setText("Cancel");
cancelButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
shell.close();
}
});
shell.setDefaultButton(okButton);
}
private void createTextWidgets(final Display display) {
GridLayout gridLayout = new GridLayout();
gridLayout.numColumns = 2;
shell.setLayout(gridLayout);
new Label(shell, SWT.NONE).setText("Photo:");
personPhoto = new Canvas(shell, SWT.BORDER);
GridData gridData = new GridData(GridData.FILL, GridData.FILL, true, true);
gridData.widthHint = (int)photoWidth;
gridData.heightHint = (int)photoHeight;
gridData.verticalSpan = 5;
gridData.horizontalSpan = 2;
personPhoto.setLayoutData(gridData);
personPhoto.redraw();
personPhoto.addPaintListener(new PaintListener() {
public void paintControl(final PaintEvent event) {
if (personImage != null) {
event.gc.drawImage(personImage, 0, 0);
}
}
});
//Skip a Column
new Label(shell, SWT.NONE);
Button browse = new Button(shell, SWT.PUSH);
browse.setText("Browse...");
gridData = new GridData(GridData.FILL, GridData.CENTER, true, false);
gridData.horizontalIndent = 5;
browse.setLayoutData(gridData);
browse.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent event) {
String fileName = new FileDialog(shell).open();
if (fileName != null) {
personImage = new Image(display, fileName);
personPhoto.redraw();
}
}
});
Button delete = new Button(shell, SWT.PUSH);
delete.setText("Delete");
gridData = new GridData(GridData.FILL, GridData.BEGINNING, true, false);
gridData.horizontalIndent = 5;
delete.setLayoutData(gridData);
delete.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent event) {
if (personImage != null) {
personImage.dispose();
personImage = null;
personPhoto.redraw();
}
}
});
//Skip a Column
new Label(shell, SWT.NONE);
//Skip two Rows
new Label(shell, SWT.NONE);
new Label(shell, SWT.NONE);
new Label(shell, SWT.NONE);
new Label(shell, SWT.NONE);
}
public void open() {
Display display = shell.getDisplay();
//To avoid null pointer exceptions
personImage = new Image(display,"user.png");
try{
PreparedStatement ps = connection.prepareStatement("SELECT photo FROM person WHERE person_id = ?");
ps.setInt(1, personID);
rs = ps.executeQuery();
while (rs.next()) {
//dispose of the current image
personImage.dispose();
personImage = new Image(display, (int) photoWidth, (int) photoHeight);
//Retrieve the photo for this person
personImage.getImageData().data = rs.getBytes("photo");
}
ps.close();
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
createTextWidgets(display);
createControlButtons();
shell.pack();
shell.open();
while(!shell.isDisposed()){
if(!display.readAndDispatch())
display.sleep();
}
}
}Ich habe den Code jetzt vereinfacht, aber ich kann es immer noch nicht richtig ziehen das Byte-Array aus der Datenbank und zeigen es als SWT-Bild. Hat irgendjemand eine Idee? Für jede Hilfe wäre ich sehr dankbar!
Shay
/* Imports */
import org.eclipse.swt.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.graphics.*;
import java.sql.*;
/***********************************************************************/
/*** Tests reading and writing SWT Images from an SQLite Database ***/
/***********************************************************************/
public class ImageTest {
Shell shell;
//Variables to store the current values when editing
private Canvas personPhoto;
private Image personImage;
private int personID = 1;
private double photoWidth = 100;
private double photoHeight = 100;
//Database connection and statement variables
private static Connection connection = null;
private static Statement statement = null;
private static PreparedStatement ps = null;
private static ResultSet rs = null;
public ImageTest(Shell parent, Connection passedConnection) {
shell = new Shell(parent, SWT.DIALOG_TRIM | SWT.PRIMARY_MODAL);
shell.setLayout(new GridLayout());
connection = passedConnection;
}
private void createControlButtons() {
Composite composite = new Composite(shell, SWT.NONE);
composite.setLayoutData(new GridData(GridData.HORIZONTAL_ALIGN_END));
GridLayout layout = new GridLayout();
layout.numColumns = 2;
composite.setLayout(layout);
Button okButton = new Button(composite, SWT.PUSH);
okButton.setText("OK");
okButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
if(personID > 0){
try {
PreparedStatement ps = connection.prepareStatement("UPDATE person SET photo = ? " +
"WHERE person_id = ?");
ps.setBytes(1, personImage.getImageData().data);
ps.setInt(2, personID);
ps.executeUpdate();
ps.close();
} catch (SQLException err) {
err.printStackTrace();
}
} else {
try {
PreparedStatement ps = connection.prepareStatement("INSERT INTO person (photo) VALUES (?)");
ps.setBytes(1, personImage.getImageData().data);
ps.executeUpdate();
ps.close();
} catch (SQLException err) {
err.printStackTrace();
}
}
shell.close();
}
});
Button cancelButton = new Button(composite, SWT.PUSH);
cancelButton.setText("Cancel");
cancelButton.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
shell.close();
}
});
shell.setDefaultButton(okButton);
}
private void createTextWidgets(final Display display) {
GridLayout gridLayout = new GridLayout();
gridLayout.numColumns = 2;
shell.setLayout(gridLayout);
new Label(shell, SWT.NONE).setText("Photo:");
personPhoto = new Canvas(shell, SWT.BORDER);
GridData gridData = new GridData(GridData.FILL, GridData.FILL, true, true);
gridData.widthHint = (int)photoWidth;
gridData.heightHint = (int)photoHeight;
gridData.verticalSpan = 5;
gridData.horizontalSpan = 2;
personPhoto.setLayoutData(gridData);
personPhoto.redraw();
personPhoto.addPaintListener(new PaintListener() {
public void paintControl(final PaintEvent event) {
if (personImage != null) {
event.gc.drawImage(personImage, 0, 0);
}
}
});
//Skip a Column
new Label(shell, SWT.NONE);
Button browse = new Button(shell, SWT.PUSH);
browse.setText("Browse...");
gridData = new GridData(GridData.FILL, GridData.CENTER, true, false);
gridData.horizontalIndent = 5;
browse.setLayoutData(gridData);
browse.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent event) {
String fileName = new FileDialog(shell).open();
if (fileName != null) {
personImage = new Image(display, fileName);
personPhoto.redraw();
}
}
});
Button delete = new Button(shell, SWT.PUSH);
delete.setText("Delete");
gridData = new GridData(GridData.FILL, GridData.BEGINNING, true, false);
gridData.horizontalIndent = 5;
delete.setLayoutData(gridData);
delete.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent event) {
if (personImage != null) {
personImage.dispose();
personImage = null;
personPhoto.redraw();
}
}
});
//Skip a Column
new Label(shell, SWT.NONE);
//Skip two Rows
new Label(shell, SWT.NONE);
new Label(shell, SWT.NONE);
new Label(shell, SWT.NONE);
new Label(shell, SWT.NONE);
}
public void open() {
Display display = shell.getDisplay();
//To avoid null pointer exceptions
personImage = new Image(display,"user.png");
try{
PreparedStatement ps = connection.prepareStatement("SELECT photo FROM person WHERE person_id = ?");
ps.setInt(1, personID);
rs = ps.executeQuery();
while (rs.next()) {
//dispose of the current image
personImage.dispose();
personImage = new Image(display, (int) photoWidth, (int) photoHeight);
//Retrieve the photo for this person
personImage.getImageData().data = rs.getBytes("photo");
}
ps.close();
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
createTextWidgets(display);
createControlButtons();
shell.pack();
shell.open();
while(!shell.isDisposed()){
if(!display.readAndDispatch())
display.sleep();
}
}
}
