1、精選文檔 JAVA期末畫板實驗報告課程題目：運用JAVA語言編寫一個畫板程序，這個畫板要有畫圖，特殊圖形繪制，顏色改變，畫筆大小改變等功能。設計思想：1. 進行界面設計2. 進行算法實現(xiàn)3. 運行調(diào)試4. 總結問題設計過程：A. 界面設計新建一個Jframe容器，然后定義一個panel（ Panel convas2），convas2是工具欄。用borderlayout布置容器的邊框布局，將工具欄放在NORTH部分。完成界面設計。add(canvas2,BorderLayout.NORTH);Panel canvas2 = new Panel();添加工具按鍵Panel canvas2 = ne

2、w Panel();Button btn1 = new Button(直線);Button btn2 = new Button(橢圓);Button btn3 = new Button(矩形);Button btn4 = new Button(清除);Button btn5 = new Button(畫筆);Button btn6 = new Button(橡皮);Choice choice = new Choice(); Choice choice1 = new Choice();canvas2.add(choice);canvas2.add(choice1);canvas2.add(btn

3、1);canvas2.add(btn2);canvas2.add(btn3);canvas2.add(btn4);canvas2.add(btn5);canvas2.add(btn6);在工具表中，有兩個下拉菜單，分別收錄畫筆的大小和顏色。1. 畫筆的大小：choice1.add(1);choice1.add(3);choice1.add(5);choice1.add(7);choice1.add(9);2. 畫筆顏色choice.add(黑色);choice.add(藍色);choice.add(紅色);choice.add(黃色); choice.add(綠色);3展示畫板B. 算法實現(xiàn)運

4、用畫板，首先要對工具欄按鍵和鼠標進行監(jiān)聽，然后對監(jiān)聽進行響應。運行相應程序進行畫圖1. 監(jiān)聽程序展示：choice.addItemListener(this);choice1.addItemListener(this);btn1.addActionListener(this);btn2.addActionListener(this);btn3.addActionListener(this);btn4.addActionListener(this);btn5.addActionListener(this);btn6.addActionListener(this);addMouseListener

5、(this);addMouseMotionListener(this);2. 按鍵監(jiān)聽響應監(jiān)聽到按鍵后，判斷當前會話工具public void actionPerformed(ActionEvent e) if(e.getSource().equals(btn1)a=1;if(e.getSource().equals(btn2)a=2;if(e.getSource().equals(btn3)a=3;if(e.getSource().equals(btn4) Graphics g = this.getGraphics();g.clearRect(0, 0, this.getWidth(), t

6、his.getHeight();if(e.getSource().equals(btn5)a=4;if(e.getSource().equals(btn6)a=5;定義一個變量a，對按鍵監(jiān)聽進行響應，例如當監(jiān)聽到btn1時賦值a=1（a為char型），即當前工具為直線。但是當監(jiān)聽到btn4時不進行對a賦值而是直接進行清除操作，由于清除操作是對畫布進行清除，不參與鼠標事件，因此可以直接執(zhí)行。3. 鼠標監(jiān)聽響應a. 鼠標按鈕按下事件，獲取畫圖起始坐標x0，y0.public void mousePressed(MouseEvent e)x0=e.getX();y0=e.getY();b. 鼠標移動

7、事件public void mouseMoved(MouseEvent e) c. 鼠標按鈕松開事件，此次響應完成對直線，橢圓，矩形進行繪制。public void mouseReleased(MouseEvent e)Graphics2D g = (Graphics2D)this.getGraphics();size=new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);g.setColor(b);g.setStroke(size);switch(a)case 1:g.drawLine(x0, y0, e.getX(

8、), e.getY();break;case 2:g.drawOval(x0, y0, e.getX() - x0, e.getY() - y0);break;case 3:g.drawRect(x0, y0, e.getX() - x0, e.getY() - y0);break;d. 鼠標進入事件：public void mouseEntered(MouseEvent e)e. 鼠標離開事件：public void mouseExited(MouseEvent e) f.鼠標單擊事件：public void mouseClicked(MouseEvent e)g.鼠標拖動事件：此次響應實現(xiàn)

9、畫筆（隨筆畫），橡皮的繪制。public void mouseDragged(MouseEvent e) Graphics2D g = (Graphics2D)this.getGraphics();size=new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);g.setColor(b);g.setStroke(size);switch(a)case 4:g.drawLine(x0, y0, e.getX(), e.getY();x0 = e.getX();y0 = e.getY();break;case 5:g.cl

10、earRect(x0 - 10, y0 - 10, 20, 20);x0 = e.getX();y0 = e.getY();break;4. 下拉列表響應a. 顏色下拉列表響應：if(e.getSource()=choice)if(choice.getSelectedIndex()=0)b=Color.black;if(choice.getSelectedIndex()=1)b=Color.BLUE;if(choice.getSelectedIndex()=2)b=Color.red;if(choice.getSelectedIndex()=3)b=Color.yellow;if(choice

11、.getSelectedIndex()=4)b=Color.green;調(diào)用choice.getSelectedIndex()返回被選中的選項的序號（下拉列表中第一個選項序號為0，依次遞加。）即進行選擇顏色的操作b. 畫筆大小下拉列表響應：if(e.getSource()=choice1)if(choice1.getSelectedItem()=1)con=1;else if(choice1.getSelectedItem()=3)con=3;else if(choice1.getSelectedItem()=5)con=5;else if(choice1.getSelectedItem()=

12、7)con=7;else if(choice1.getSelectedItem()=9)con=9;調(diào)用choice1.getSelectedItem()返回被選中選項的標簽文本字符串，即確定畫筆的大小（con）。5. 工具欄工具實現(xiàn)程序詳解（1）Graphics2D g = (Graphics2D)this.getGraphics(); size=newBasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);g.setColor(b);g.setStroke(size);繪制圖形用到類Graphics2D，其中包括很多繪制圖形

13、的方法，定義一個Graphics2D類g，用getGraphics()來得到一個Graphics2D對象，它相當于組建的繪圖環(huán)境，可以進行各種繪圖操作。size=new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);定義一個BasicStroke類 size來確定畫筆的大小，其中BasicStroke類定義針對圖形圖元輪廓呈現(xiàn)屬性的一個基本集合，這些圖元使用 Graphics2D 對象呈現(xiàn)，而該對象的 Stroke 屬性設置為此 BasicStroke。其中con為畫筆寬度，CAP_BUTT指無裝飾地結束未封閉的子路徑

14、和虛線線段，JOIN_BEVEL通過直線連接寬體輪廓的外角，將路徑線段連接在一起。（以上內(nèi)容為網(wǎng)上查找資料所得。） （2） 實現(xiàn)直線，橢圓，矩形繪制： switch(a)case 1:g.drawLine(x0, y0, e.getX(), e.getY();break;case 2:g.drawOval(x0, y0, e.getX() - x0, e.getY() - y0);break;case 3:g.drawRect(x0, y0, e.getX() - x0, e.getY() - y0);break;（3）隨筆畫和橡皮switch(a)case 4:g.drawLine(x0,

15、y0, e.getX(), e.getY();x0 = e.getX();y0 = e.getY();break;case 5:g.clearRect(x0 - 10, y0 - 10, 20, 20);x0 = e.getX();y0 = e.getY();break;6. 主類程序得以運行的入口，進入主類后即運行l(wèi)itao（）類。C. 調(diào)試運行調(diào)試運行后得到了畫板和預期的所有功能，實現(xiàn)結果展示：D. 遇到問題1.繪制完成后，將窗口最大化或者最小化后再打開，原本繪制的圖形消失。尚未解決。2.確定畫筆大小時不得要領，后來通過查找資料解決。附表1：源程序：import java.awt.*;im

16、port java.awt.event.*;import javax.swing.JFrame;public class litao extends JFrame implements MouseMotionListener,MouseListener,ActionListener, ItemListener Panel canvas2 = new Panel();Button btn1 = new Button(直線);Button btn2 = new Button(橢圓);Button btn3 = new Button(矩形);Button btn4 = new Button(清除);

17、Button btn5 = new Button(畫筆);Button btn6 = new Button(橡皮);Choice choice = new Choice(); Choice choice1 = new Choice();Color b;int x0,y0;char a=4;int con=1;BasicStroke size;private static Color colors = Color.black, Color.blue, Color.red,Color.yellow, Color.green ;public litao()choice1.add(1);choice1

18、.add(3);choice1.add(5);choice1.add(7);choice1.add(9);choice.add(黑色);choice.add(藍色);choice.add(紅色);choice.add(黃色); choice.add(綠色);canvas2.add(choice);canvas2.add(choice1);canvas2.add(btn1);canvas2.add(btn2);canvas2.add(btn3);canvas2.add(btn4);canvas2.add(btn5);canvas2.add(btn6);choice.addItemListener

19、(this);choice1.addItemListener(this);btn1.addActionListener(this);btn2.addActionListener(this);btn3.addActionListener(this);btn4.addActionListener(this);btn5.addActionListener(this);btn6.addActionListener(this);addMouseListener(this);addMouseMotionListener(this);add(canvas2,BorderLayout.NORTH);setBa

20、ckground(Color.white);canvas2.setBackground(Color.blue);this.setBackground(Color.white);setSize(800, 600);setVisible(true);public void paint(Graphics g)public void actionPerformed(ActionEvent e) if(e.getSource().equals(btn1)a=1;if(e.getSource().equals(btn2)a=2;if(e.getSource().equals(btn3)a=3;if(e.g

21、etSource().equals(btn4) Graphics g = this.getGraphics();g.clearRect(0, 0, this.getWidth(), this.getHeight();if(e.getSource().equals(btn5)a=4;if(e.getSource().equals(btn6)a=5;public void mousePressed(MouseEvent e)x0=e.getX();y0=e.getY();public void mouseMoved(MouseEvent e) public void mouseReleased(M

22、ouseEvent e)Graphics2D g = (Graphics2D)this.getGraphics();size=new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);g.setColor(b);g.setStroke(size);switch(a)case 1:g.drawLine(x0, y0, e.getX(), e.getY();break;case 2:g.drawOval(x0, y0, e.getX() - x0, e.getY() - y0);break;case 3:g.drawRect(

23、x0, y0, e.getX() - x0, e.getY() - y0);break;public void mouseEntered(MouseEvent e)public void mouseExited(MouseEvent e)public void mouseClicked(MouseEvent e)public void mouseDragged(MouseEvent e) Graphics2D g = (Graphics2D)this.getGraphics();size=new BasicStroke(con,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);g