Windows鼠标框选效果

常见情况下，一个JTable是放到一个JScrollPane，这样数据量很大的时候，可以通过滚动条来控制。因此要实现框选效果，需要考虑到这两个主要组件的paint问题。

框选操作，可以分解为 鼠标左键点击，拖拽，释放三个动作，因此需要实现MouseInputListener。考虑到此框选操作为特定look&feel拥有，故以BasicTableUI为基类实现

public class MyTableUI extends BasicTableUI {
	
	protected MouseInputListener createMouseInputListener() {

        return new MyMouseInputHandler();

    }
	class MyMouseInputHandler extends MouseInputHandler {

        private boolean ignoreDrag = false;
    	
        public void mousePressed(MouseEvent e) {
            if (e.getClickCount() == 2) {
                table.clearSelection();
            }
            Point origin = e.getPoint();
            int row = table.rowAtPoint(origin);
            int column = table.columnAtPoint(origin);
            if (row != -1 && column != -1) {
            	if(table instanceof AbstractTable){
            		((AbstractTable)table).mousePressed(e.getPoint());
            	}
                if (table.isCellSelected(row, column)) {
                    ignoreDrag = true;
                } else {
                    super.mousePressed(e);
                }
            }
        }
        
        public void mouseClicked(MouseEvent e) {
            super.mouseClicked(e);
        }

        public void mouseDragged(MouseEvent e) {
            if (!ignoreDrag) {
                super.mouseDragged(e);
                if(table instanceof AbstractTable){
	            	((AbstractTable)table).mouseDragged((Point)e.getPoint().clone());
            	}
            } 
        }
        
        public void mouseExited(MouseEvent e) {
        	if(table instanceof AbstractTable){
            	((AbstractTable)table).mouseExit();
        	}
        }
        
        public void mouseReleased(MouseEvent e) {
            if (ignoreDrag) {
                super.mousePressed(e);
                ignoreDrag = false;
               
            }  
            if(table instanceof AbstractTable){
            	((AbstractTable)table).mouseReleased();
        	}
            super.mouseReleased(e);
        }
        
    }

然后在其中的AbstractTable类中实现相应的鼠标事件处理。

public class AbstractTable extends JTable {

	private static final long serialVersionUID = 1L;
	
	private volatile boolean canSelected = true;
	
	private AbstractScollPane srcollPane;

	AbstractTable() {
		super();
		setUI(new MyTableUI());
	}

	/* 
	 * (non-Javadoc)
	 * @see javax.swing.JTable#changeSelection(int, int, boolean, boolean)
	 */
	public void changeSelection(int rowIndex,int columnIndex,boolean toggle, boolean extend) {
		if(columnIndex != 1){
			return;
		}else{
			super.changeSelection(rowIndex, columnIndex, toggle, extend);
		}
	}
	
	/**
	 * @param p
	 */
	public void mousePressed(Point p) {
		if(srcollPane == null){
			srcollPane = (AbstractScollPane)SwingUtilities.getAncestorOfClass(AbstractScollPane.class, this);
		}
		Point pp = SwingUtilities.convertPoint(this, p, srcollPane);
		srcollPane.setStartPoint(pp);
		//clearSelection();
	}

	public void mouseReleased() {
		canSelected = true;
		try {
			srcollPane.makeRectSelected();
			srcollPane.setStartPoint(null);
			srcollPane.setEndPoint(null);
			srcollPane.repaint();
		} catch (Exception e1) {
			e1.printStackTrace();
		} finally {
			canSelected = true;
		}
	}
	
	/**
	 * @param p
	 */
	public void mouseDragged(Point p) {
		Point pp = SwingUtilities.convertPoint(this, p, srcollPane);
		canSelected = false;
		srcollPane.setEndPoint(pp);
		srcollPane.repaint();
	}
	
	/**
	 * 
	 */
	public void mouseExit() {
		//startPoint = null;
		//endPoint = null;
		//canSelected = true;
	}
	
	/* 
	 * (non-Javadoc)
	 * @see javax.swing.JTable#isCellSelected(int, int)
	 */
	public boolean isCellSelected(int row, int column) {
		if (column != 1) {
			return false;
		} else {
			if(canSelected){
				return super.isCellSelected(row, column);
			}else{
				return false;
			}
		}
	}

	public void paintComponent(Graphics g) {
		super.paintComponent(g);
	}
}

最后由AbstractScollPane 来实现真正的框选效果。

public class AbstractScollPane extends JScrollPane {
	
	private static final long serialVersionUID = 1L;
	public String type;
	
	private transient Point startPoint;
	private transient Point endPoint;
	
	public AbstractScollPane(Component comp){
		super(comp);
		this.addMouseListener(new   MouseAdapter(){
            public   void   mousePressed(MouseEvent   e){
            	startPoint   =e.getPoint();
            	if(getViewport().getView() instanceof AbstractTable) {
            		AbstractTable table = (AbstractTable)getViewport().getView();
            		table.clearSelection();
            	}
            }
            public   void   mouseReleased(MouseEvent   e){
            	makeRectSelected();
            	startPoint = null;
            	endPoint = null;
            	repaint();
            }
		});
		this.addMouseMotionListener(new   MouseMotionAdapter(){
            public   void   mouseDragged(MouseEvent   e){
            	endPoint   =e.getPoint();                
                repaint();
            }
		}); 
	}
	public String getType(){
		return type;
	}
	/**
	 * @param type the type to set
	 */
	public void setType(String type) {
		this.type = type;
	}
	
	public void paint(Graphics g) {
		super.paint(g);
		Graphics2D g2 = (Graphics2D) g;
		if (startPoint != null && endPoint != null) {
			g2.setColor(Color.red);
			int x = Math.min(startPoint.x, endPoint.x);
			int y = Math.min(startPoint.y, endPoint.y);
			int width = Math.abs(startPoint.x - endPoint.x);
			int height = Math.abs(startPoint.y - endPoint.y);
			g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.2f));
			g2.drawRect(x, y, width, height);
			g2.setColor(Color.yellow);
			g2.fillRect(x, y, width, height);
		}	
	}
	
	public void paintComponent(Graphics g) {
		super.paintComponent(g);			
	}
	
	public void makeRectSelected() {
		if(startPoint != null && endPoint != null) {
			 if(getViewport().getView() instanceof AbstractTable) {
				 AbstractTable table = (AbstractTable)getViewport().getView();
				 Point tableLocation = table.getLocation();
				 Point tablePointInScroll = SwingUtilities.convertPoint(table, tableLocation, this);				 
				 Rectangle mousedRect = new Rectangle(Math.min(startPoint.x, endPoint.x),Math.min(startPoint.y, endPoint.y),Math.abs(startPoint.x - endPoint.x),Math.abs(startPoint.y - endPoint.y));
				 Rectangle interSection = SwingUtilities.computeIntersection(tablePointInScroll.x, tablePointInScroll.y, getSize().width, table.getHeight(), mousedRect);
				 if(interSection.equals(new Rectangle(0,0,0,0))){
					 return;
				 }else {					 
					 Point start = SwingUtilities.convertPoint(this, new Point(interSection.x,interSection.y), table);
					 Point end = SwingUtilities.convertPoint(this, new Point(interSection.x + interSection.width,interSection.y+interSection.height), table);					 
					 int srow = table.rowAtPoint(start);
						int scolumn = table.columnAtPoint(start);
						int erow = table.rowAtPoint(end);
						if (erow == -1)
							erow = table.getRowCount() - 1;
						if (srow == -1)
							srow = 0;
						if ((scolumn == 0 || scolumn == 1) && Math.abs(erow - srow) >= 0) {
							table.setRowSelectionInterval(srow, erow);
							table.setColumnSelectionInterval(0, 1);
						}else {
							table.clearSelection();
						}
				 }				
			 }
		}
	}
	
	/**
	 * @param endPoint the endPoint to set
	 */
	public void setEndPoint(Point endPoint) {
		this.endPoint = endPoint;
	}
	
	/**
	 * @param startPoint the startPoint to set
	 */
	public void setStartPoint(Point startPoint) {
		this.startPoint = startPoint;
	}
}

总的来说，如果框选初始事件由最里层的AbstractTable捕获，则外传到包装它的AbstractScollPane由它来做具体的paint操作；如果是在AbstractScollPane上直接发生框选事件，就直接paint.