求java画图的小问题

Question

应用程序画图和applet里面画图都是一样的啊，比如JPanel上画图，你只要重载paint方法就可以画你自己的图形了

Answer 1

在http://javagarden.yeah.net/有一些关于画图的文章。

Answer 2

这是一个用箭头键控制绿色方块移动的程序
import java.awt.*;
import java.awt.event.*;public class GraphicTest extends Frame implements KeyListener
{
   int x=50,y=50;
    public void keyPressed(KeyEvent e)
    {
      int n=10;
      switch(e.getKeyCode())
      {
      case 37: {x-=n;break;}
        case 38: {y-=n;break;}
          case 39: {x+=n;break;}
            case 40: {y+=n;break;}
      }
      this.repaint();
      }
    public void keyTyped(KeyEvent e)
    {}
    public void keyReleased(KeyEvent e)
    {}  public GraphicTest() {
    super("graphictest");
    setSize(400,400);
  this.addKeyListener(this);
   this.setVisible(true);
 }
 public void paint(Graphics g)
 {
   g.setColor(Color.GREEN);
   g.fill3DRect(x,y,30,30,true);
 }
  public static void main(String[] args) {
   new GraphicTest();
  }}

Answer 3

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class GraphicsTest extends Frame
{
   int x=50,y=50;int n=10;
   public void processKeyEvent(KeyEvent e)
    {
   if(KeyEvent.KEY_PRESSED==e.getID())
   {
  switch(e.getKeyCode())
       {
      case 37: {x-=n;break;}
        case 38: {y-=n;break;}
          case 39: {x+=n;break;}
            case 40: {y+=n;break;}
      }
      this.repaint();
   }
   }
   public GraphicsTest() {
    super("graphictest");
     setSize(400,400);
 enableEvents(AWTEvent.KEY_EVENT_MASK);
    this.setVisible(true);
 }
 public void paint(Graphics g)
 {

   g.setColor(Color.green);
   g.fill3DRect(x,y,30,30,true);
 }
  public static void main(String[] args) {
  GraphicTest Gra= new GraphicTest();
  Gra.addWindowListener(new WindowAdapter()
  {
   public void windowClosing(WindowEvent e)
  {
System.exit(0);
      }
  });
     Gra.setSize(400,400);
     Gra.setVisible(true);
  }
}
此程序是借鉴上面程序来面的

Answer 4

package java2dwdztest;/**
 * <p>Title: test java 2d use</p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2003</p>
 * <p>Company: </p>
 * @author wdz
 * @version 1.0
 */import java.awt.*;
import java.awt.event.*;
import java.applet.*;public class GraphicsTest
    extends Frame {
  int x = 50, y = 50;
  int n = 100;
  public void processKeyEvent(KeyEvent e) {
    if (KeyEvent.KEY_PRESSED == e.getID()) {
      switch (e.getKeyChar()) {
        case 'a': {
          x -= n;
          break;
        }
        case 'b': {
          y -= n;
          break;
        }
        case 'c': {
          x += n;
          break;
        }
        case 'd': {
          y += n;
          break;
        }
        default:{
          y += n;
           x += n;
        }
      }
      this.repaint();
    }
  }  public GraphicsTest() {
    super("graphictest");
    setSize(400, 400);
    enableEvents(AWTEvent.KEY_EVENT_MASK);
    this.setVisible(true);
  }  public void paint(Graphics g) {    g.setColor(Color.green);
    g.fill3DRect(x, y, 30, 30, true);
    System.out.println("x="+x+",y="+y);
  }  public static void main(String[] args) {
    GraphicsTest Gra = new GraphicsTest();  }
}

Answer 5

下面是一个类，太长点，分开2帖，拼起来就能运行！
========================== 第一部分 ================================
/**
 *  [DrawDemo.java]   2D图形绘制类
 *
 * 2D图形绘制演示
 * 创建日期：(2003-11-27)
 * @author：XWTs
 */
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.lang.Math;
import javax.swing.border.*;
public class DrawDemo extends JFrame { private Container contentPane = this.getContentPane();
private Canvas canvas = new Canvas();
private Graphics GPH; //画布Graphics引用
private boolean isFill = false;
private JButton bDraw = new JButton("自由手绘");
private JButton bLine = new JButton("画直线");
private JButton bOval = new JButton("画椭圆");
private JButton bRect = new JButton("画矩形");
private JButton bRound = new JButton("画圆角矩形");
private JButton clear = new JButton("清空画面");

private JToolBar edit = new JToolBar();
private JButton lineColor = new JButton("前景色");
private JButton backColor = new JButton("背景色");
//private JButton catchPIC = new JButton("保存图片");
private JCheckBox noFill = new JCheckBox("不填充",true);

private Point start, end, tmpPoint;

private boolean draw = true;
private boolean line = false;
private boolean oval = false;
private boolean rect = false;
private boolean round = false;

/**
* 构造方法：创建面板
*/
    public DrawDemo() {
     super("\"二维图形绘制演示\"        By 徐文滔");
     JPanel btPanel = new JPanel();
     btPanel.setBorder(new TitledBorder(new EtchedBorder()));
     btPanel.add(bDraw);
     btPanel.add(bLine);
     btPanel.add(bOval);
     btPanel.add(bRect);
     btPanel.add(bRound);
     btPanel.add(clear);
    
     JPanel cvPanel = new JPanel();
     cvPanel.setLayout(new BorderLayout());
     cvPanel.setBorder(new CompoundBorder(
                   BorderFactory.createLineBorder(Color.BLACK,1),
                   BorderFactory.createLineBorder(Color.BLACK,1)));
     canvas.setSize(500,300);
     canvas.setBackground(Color.WHITE);
     cvPanel.add(canvas); 
    
     edit.add(lineColor);
     edit.add(backColor);
     edit.add(noFill);
     //edit.add(catchPIC);
    
    contentPane.add(btPanel,BorderLayout.NORTH);
    contentPane.add(cvPanel,BorderLayout.CENTER);
    contentPane.add(edit,BorderLayout.SOUTH);
    
    addDrawListener();
    addEditListener();
    showFace();
    GPH = canvas.getGraphics();
    }
    
/**
* 方法：添加绘图按钮事件
*/
    public void addDrawListener() {
     canvas.addMouseListener(new MouseAdapter() { //鼠标按下
            public void mousePressed(MouseEvent e) {
             start = new Point(e.getX(),e.getY()); //提取开始点
             tmpPoint = new Point(e.getX(),e.getY());
            }
            
            public void mouseReleased(MouseEvent e) { //鼠标放开
             end = new Point(e.getX(),e.getY());  //提取结束点
             int width = end.x - start.x;
             int hight = end.y - start.y;
             if(line) { //画线
                     GPH.drawLine(start.x, start.y, end.x, end.y);
             }
             else {
             end = new Point(Math.max(e.getX(),start.x),
                             Math.max(e.getY(),start.y));
             start = new Point(Math.min(e.getX(),start.x),
                             Math.min(e.getY(),start.y));
             if(oval) { //画椭圆
                 if(isFill)
                     GPH.fillOval(start.x, start.y, width, hight);
                 else
                     GPH.drawOval(start.x, start.y, width, hight);
             }
             if(rect) { //画矩形
             if(isFill)
                 GPH.fillRect(start.x, start.y, width, hight);
             else
                     GPH.drawRect(start.x, start.y, width, hight);
             }
             if(round) { //画圆角矩形
             if(isFill)
                 GPH.fillRoundRect(start.x, start.y, width, hight, 10, 10);
             else
                     GPH.drawRoundRect(start.x, start.y, width, hight, 10, 10);
             }
             }
            }
        });        canvas.addMouseMotionListener(new MouseMotionAdapter() { //鼠标拖动
         public void mouseDragged(MouseEvent e) {
             if(draw) { //画自由线
             GPH.drawLine(tmpPoint.x,tmpPoint.y,e.getX(),e.getY());
             tmpPoint = new Point(e.getX(),e.getY());
             }
            }
        });

Answer 6

========================== 第二部分 ================================       
//按钮事件   
     bDraw.addActionListener(new ActionListener(){     //"自由手绘"
            public void actionPerformed(ActionEvent e){
             setButtonFalse();
             draw = true;
            }
        });
        
        bLine.addActionListener(new ActionListener(){     //"画线"
            public void actionPerformed(ActionEvent e){
             setButtonFalse();
             line = true;
            }
        });
        
        bOval.addActionListener(new ActionListener(){     //"画椭圆"
            public void actionPerformed(ActionEvent e){
             setButtonFalse();
             oval = true;
            }
        });
        
        bRect.addActionListener(new ActionListener(){     //"画矩形"
            public void actionPerformed(ActionEvent e){
             setButtonFalse();
             rect = true;
            }
        });
        
        bRound.addActionListener(new ActionListener(){     //"画园角矩形"
            public void actionPerformed(ActionEvent e){
             setButtonFalse();
             round = true;
            }
        });
    
     clear.addActionListener(new ActionListener(){     //"清除"
            public void actionPerformed(ActionEvent e){
             canvas.repaint();
            }
        });
    }
    
    
/**
* 方法：添加编辑按钮事件
*/
    private void addEditListener() {
    
     lineColor.addActionListener(new ActionListener(){     //"线条色"
            public void actionPerformed(ActionEvent e){
             Color tmpColor = JColorChooser.showDialog(null,"线条颜色选择",Color.BLACK);
             if(tmpColor != null)
                    GPH.setColor(tmpColor);
            }
        });
        
        backColor.addActionListener(new ActionListener(){     //"背景色"
            public void actionPerformed(ActionEvent e){
             Color tmpColor = JColorChooser.showDialog(null,"背景颜色选择",Color.WHITE);
                if(tmpColor != null)
                    canvas.setBackground(tmpColor);
            }
        });
        
        noFill.addActionListener(new ActionListener(){   //"填充选项"
            public void actionPerformed(ActionEvent e){
                if(noFill.isSelected())
                    isFill = false;
                else
                    isFill = true;
            }
        });
    }
    
/**
* 方法：按钮重设
*/
    private void setButtonFalse() {
     draw = false;
    line = false;
    oval = false;
    rect = false;
    round = false;
    } 
    
/**
* 方法：显示面板
*/
    private void showFace() {
        pack();
        Toolkit tmpTK = Toolkit.getDefaultToolkit();  //新建工具包
    Dimension dime = tmpTK.getScreenSize();  //取得屏幕大小
        Dimension frameSize = this.getPreferredSize(); //取得面板大小
        setLocation(dime.width/2 - (frameSize.width/2), //面板居中显示
                    dime.height/2 - (frameSize.height/2));
        setResizable(false);
        setVisible(true); //设置面板可视
        
        //窗口关闭事件
        this.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
         System.exit(0);
            }
         });
    }
    
    
/**
* 方法：程序入口
*/   
    public static void main(String args[]) {
     //获取设置系统风格：
        try {
         String laf = UIManager.getSystemLookAndFeelClassName();
        UIManager.setLookAndFeel(laf);
        } catch (Exception e) {}
        
        //全局字体设置
        UIManager.put("Button.font",new Font("宋体",Font.PLAIN,12));
        
     new DrawDemo();
    }
    
}

Answer 7

一画图就调用paint()
我就不想这样干
没其他的方法了吗??

Answer 8

onefox(一品狐):pack()很重要，没它就不能画图，这个语句什么意思？

Answer 9

要是没有paint()的话，你最小化后就看不到所绘的图了，这个比较重要！它是重画

Answer 10

CSDN好像不让上传文件，有些遗憾啊，这样好多例子，包括自己作的一些东西就不能分享了