怎么样通过SWT实现安全保存对话框？

SWT & JFace 没有直接的安全保存对话框,本文对安全对话框进行了实现,并且可以设置保存类型.

package org.gridhome.ui.window;

import java.io.File;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.FileDialog;
import org.eclipse.swt.widgets.MessageBox;
import org.eclipse.swt.widgets.Shell;

public class SafeSaveDialog {
public SafeSaveDialog(){
}
FileDialog dlg;

public SafeSaveDialog(Shell shell) {
dlg = new FileDialog(shell, SWT.SAVE);// 设置为保存对话框
// 设置保存类型
dlg.setFilterNames(new String[] {
"Text Files(*.txt)",
"Sql Files (*.sql)",
"All Files (*.*)"
});
dlg.setFilterExtensions(new String[] {
"*.txt", "*.sql", "*.*"
});
}

public String open() {
// Store the selected file name in fileName
String fileName = null;

// The user has finished when one of the
// following happens:
// 1) The user dismisses the dialog by pressing Cancel
// 2) The selected file name does not exist
// 3) The user agrees to overwrite existing file
boolean done = false;

while (!done) {
// Open the File Dialog
fileName = dlg.open();
if (fileName == null) {
// User has cancelled, so quit and return
done = true;
} else {
// User has selected a file; see if it already exists
File file = new File(fileName);
if (file.exists()) {
// The file already exists; asks for confirmation
MessageBox mb = new MessageBox(dlg.getParent(),
SWT.ICON_WARNING | SWT.YES | SWT.NO);
mb.setText("Tips");
mb.setMessage(fileName
+ " already exists. Do you want to replace it?");

// If they click Yes, drop out. If they click No,
// redisplay the File Dialog
done = mb.open() == SWT.YES;
} else {
// File does not exist, so drop out
done = true;
}
}
}
return fileName;
}
public String getFileName() {
return dlg.getFileName();
}

public String[] getFileNames() {
return dlg.getFileNames();
}

public String[] getFilterExtensions() {
return dlg.getFilterExtensions();
}

public String[] getFilterNames() {
return dlg.getFilterNames();
}

public String getFilterPath() {
return dlg.getFilterPath();
}

public void setFileName(String string) {
dlg.setFileName(string);
}

public void setFilterExtensions(String[] extensions) {
dlg.setFilterExtensions(extensions);
}

public void setFilterNames(String[] names) {
dlg.setFilterNames(names);
}

public void setFilterPath(String string) {
dlg.setFilterPath(string);
}

public Shell getParent() {
return dlg.getParent();
}

public int getStyle() {
return dlg.getStyle();
}

public String getText() {
return dlg.getText();
}

public void setText(String string) {
dlg.setText(string);
}
/**
* Runs the application
*/
public void run() {
Display display = new Display();
Shell shell = new Shell(display);
shell.setText("Safe Save");
createContents(shell);
shell.pack();
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}


display.dispose();
}
/**
* Creates the window contents
*
* @param shell the parent shell
*/
private void createContents(final Shell shell) {
shell.setLayout(new GridLayout(2, false));
Button button = new Button(shell, SWT.PUSH);
button.setText("Save as ...");
button.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent event) {
// Create the color-change dialog
SafeSaveDialog dlg = new SafeSaveDialog(shell);

dlg.open();
// Call pack() to resize the window to fit the new font
shell.pack();
}
});
}


public static void main(String[] args) {
new SafeSaveDialog().run();
}
}

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