projecthandler.java

PIY(Program It Yourself)是一个基于Java的应用程序开发环境

package piy;

import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.util.*;
import java.lang.reflect.*;

/**
* Handles project loading/saving. Only one of these can exist at once - its instance can be
* retrieved through the getInstance() static method.
* @author David Vivash
* @version 1.0.3, 29/04/01
*/
public class ProjectHandler {

	private Project project = null;
	private static ProjectHandler instance = null;
	private FileDialog fileDialog = null;

	//set to true as soon as a change is made to the project
	private boolean changed = false;

	/**
	* Get the only instance of ProjectHandler.
	*/
	public static ProjectHandler getInstance() {
		if (instance == null) instance = new ProjectHandler();
		
		return instance;
	}

	/**
	* Instantiate the ProjectHandler.  No setup code required.
	*/
	private ProjectHandler() {
	}

	/**
	* Compile the current project into an application.
	* @return the compiled project as an application
	*/
	public Application compileProject() {
	
		//Create a clone of the project via serialization
		File oldName = project.getFileName();
		project.setFileName(new File("temp.out"));
		Project oldProject = project;
		saveProject();
		loadProject(new File("temp.out"));

		//Get rid of the piy glass panes
		java.util.List win = project.getGuiNamer().getValues();
		for (int i=0; i<win.size(); i++)
			if (win.get(i) instanceof UserWindow)
				((UserWindow)win.get(i)).setGlassPane(new MiniGlassPane());

			
		//Create our new application
		Application toReturn = new Application();
		toReturn.setMainWindow(project.getMainWindow());

		//Add all windows to the app
		java.util.List windows = project.getGuiNamer().getValues();
		for (int i=0; i<windows.size(); i++)
			if (windows.get(i) instanceof UserWindow)
				toReturn.addWindow((UserWindow)windows.get(i));

		PIYNamer guiNamer = project.getGuiNamer();
		String[] components = guiNamer.getNames();

		//set up the event listeners for each component.  
		for (int i=0; i<components.length; i++) {
			Object component = guiNamer.getValue(components[i]);
			if (component instanceof Component) {
				HashMap listeners = project.getEventListeners(component);			
				toReturn.addComponentMapping((Component)component, listeners);
			}
		}

		//restore the project to its old state
		project = oldProject;
		project.setFileName(oldName);
		
		//return the compiled application
		return toReturn;
	}

		
	/**
	* Construct a new project for editting in PIY.
	* @return a new project object
	*/
	public void newProject() {
		
		if (makeSaveEnquiry()) { //ask if user want to save
			
			closeProject(false);		
			project = new Project();
			project.setMainWindow(newWindow());	
	
			changed = false;
		}
	}

	/**
	* Retrieves the Project currently being editted.  If no project is currently being editted
	* this method first calls newProject(), which ensures that this method never returns null.
	* @return the project currently being editted
	*/
	public Project getProject() { 
		if (project == null) newProject();
		return project; 
	}

	/**
	* Save the Project currently being editted.  If the project does not yet have a filename
	* this method will ask the user to supply one.
	*/
	public void saveProject() {
		if (project.getFileName() == null) saveProjectAs();
			
		if (project.getFileName() != null) {
			UserWindowListener.getInstance().setCurrentWindow(null);
			UserWindowListener.getInstance().selectComponent(null);
	
			//Get rid of glass panes
			java.util.List win = project.getGuiNamer().getValues();
			for (int i=0; i<win.size(); i++)
				if (win.get(i) instanceof UserWindow)
					((UserWindow)win.get(i)).setGlassPane(new MiniGlassPane());
	
			boolean error = false;
			String message = "";
			
			try{
				ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(project.getFileName()));
				oos.writeObject(project);
				oos.flush();
				oos.close();
	
			} catch (InvalidClassException e) {
				System.err.println("Error saving project = invalid class exception");
				error = true;
			} catch (NotSerializableException e) {
				System.err.println("Error saving project! = class not serializable " + e.getMessage());
				error = true;
				message = e.getMessage() + "could not be added";
			} catch (Exception e) {
				System.err.println("Error saving project");
				e.printStackTrace();
				error = true;
			}		
	
			//inform the user of any error
			if (error) {
				JOptionPane pane = new JOptionPane(
					new String[] {"There was an error saving the project", message},
					JOptionPane.ERROR_MESSAGE);
					
				JDialog dialog = pane.createDialog(null, "Cannot Save");
				dialog.setResizable(false);
				dialog.show();
			}
			
						
			//Add glass panes back to all windows
			for (int i=0; i<win.size(); i++)
				if (win.get(i) instanceof UserWindow)
					UserWindowListener.getInstance().listenOnFrame((UserWindow)win.get(i));

			changed = false;
		}
	}

	/**
	* Saves the project currently being editted under a different filename, which the user will
	* be asked for.
	*/
	public void saveProjectAs() {
		//get a valid filename, then call saveProject
		fileDialog = getFileDialog(new Frame());
		fileDialog.setMode(FileDialog.SAVE);

		try{	
			fileDialog.show();

			if (fileDialog.getFile() != null)
				project.setFileName(new File(fileDialog.getDirectory(), fileDialog.getFile()));
	
			if (project.getFileName() != null) saveProject();

		} catch (Exception e) {
			//inform the user of the error
			JOptionPane pane = new JOptionPane("There was an error saving the project", JOptionPane.ERROR_MESSAGE);
				
			JDialog dialog = pane.createDialog(null, "Cannot Save");
			dialog.setResizable(false);
			dialog.show();
		}		
	}

	/**
	* Loads a project.  Implicitly closes the project currently being editted, via a call to
	* closeProject().
	* @param fileName the filename of the project to be loaded.
	*/
	private void loadProject(File fileName) {

		if ((fileName == null) || !fileName.exists()) {
			JOptionPane pane = new JOptionPane("The specified project filename doesn't exist", JOptionPane.ERROR_MESSAGE);
				
			JDialog dialog = pane.createDialog(null, "Cannot Load");
			dialog.setResizable(false);
			dialog.show();

			return;
		}

		//don't need save enquiry - this method is called privately
		closeProject(false);
	
		try{
			ObjectInputStream ois = new ObjectInputStream(new FileInputStream(fileName));
			project = (Project)ois.readObject();
			ois.close();

		} catch (Exception e) {
			JOptionPane pane = new JOptionPane("There was an error loading the project", JOptionPane.ERROR_MESSAGE);
				
			JDialog dialog = pane.createDialog(null, "Cannot Load");
			dialog.setResizable(false);
			dialog.show();

			e.printStackTrace();			

			changed = false;
			newProject();
		}		
	}

	/**
	* Asks the user which project to load, and then loads it.  If the user does not
	* specify a file, this method will not cause the project currently being editted to
	* close, and will return back to its previous state.
	*/
	public void loadProject() {
		if (makeSaveEnquiry()) { //ask the user to save the current project if it has changed
			//get a valid filename, then call loadProject
			fileDialog = getFileDialog(new Frame());
			fileDialog.setMode(FileDialog.LOAD);
	
			try {
				fileDialog.show();
				if (fileDialog.getFile() == null) return; //the user selected "Cancel"
									
				File loadFileName = new File(fileDialog.getDirectory(), fileDialog.getFile());
				if (loadFileName != null) loadProject(loadFileName);

			} catch (Exception e) {
				JOptionPane.showMessageDialog(null, "There was an error loading the project", "Cannot Load", JOptionPane.ERROR_MESSAGE);
				
				e.printStackTrace();
				
				changed = false;
				newProject();
			}		
	
			//Add glass panes to all windows
			java.util.List win = project.getGuiNamer().getValues();
			for (int i=0; i<win.size(); i++)
				if (win.get(i) instanceof UserWindow)
					UserWindowListener.getInstance().listenOnFrame((UserWindow)win.get(i));
		
			changed = false;
		}
	}

	/**
	* Close the current project. 
	* @param enquiry set this to true if the call to this method should first make
	* a call to makeSaveEnquiry.  For most purposes this is true.
	* @return true if the project was closed, false if the user decided to cancel the
	* close operation.  Calling methods should cancel their course of action if this
	* method returns false.
	*/
	public boolean closeProject(boolean enquiry) {
		if (project != null) {
			if (enquiry ? makeSaveEnquiry() : true) {
				
				//Dispose of all windows
				java.util.List win = project.getGuiNamer().getValues();
				for (int i=0; i<win.size(); i++)
					if (win.get(i) instanceof UserWindow)
						((UserWindow)win.get(i)).dispose();
		
				project = null;
				
				return true;
			} else return false;