概述本文旨在记录Java代码初学者的学习历程并表达本人对代码的理解。本文的内容包括边框布局的使用方法功能面板的设置方法窗口内容面板颜色的控制方法Graphics类数据颜色及宽度的控制窗口多个JPanel线条偏移问题的解决方法。1.边框布局边框布局的具体形式如上且NORTH和SOUTH无法控制宽度WEST和EAST无法控制长度CENTER无法控制大小并且每一块区域仅能放置一个组件放置多个组件仅显示最后一个。JFrame的默认布局即是边框布局。设置边框布局的方法和将组件添加到要求位置的方法如下jframe.setLayout(new BorderLayout()); jframe.add(jpanel,BorderLayout.NORTH);//这里的NORTH也可换为其它位置2.功能面板我们需要让线条不遮挡按钮因此需要用JPanel将窗口分为两个区域同时JPanel也相当于容器可以将多个组件放在边框布局的一个位置。这两个区域都可以叫功能面板。JPanel jpanelnew JPanel(); jpanel.setBackground(Color.BLUE);//设置面板的颜色 jpanel.setPreferredSize(new Dimension(0,40));//设置面板的大小 jframe.add(jpanel,BorderLayout.NORTH);//将这个面板添加到窗口的NORTH部分。 JButton jbuttonnew JButton(直线); JButton jbutton2new JButton(矩形); JButton jbutton3new JButton(等腰三角形); JButton jbutton4new JButton(任意三角形); JButton jbutton5new JButton(多边形); JButton jbutton6new JButton(曲线); JButton jbutton7new JButton(橡皮擦); JButton Red new JButton(红色); jpanel.add(jbutton); jpanel.add(jbutton2); jpanel.add(jbutton3); jpanel.add(jbutton4); jpanel.add(jbutton5); jpanel.add(jbutton6); jpanel.add(jbutton7); jpanel.add(Red);//将多个按钮添加到这个面板 JPanel jpanel2new JPanel(); jpanel2.setBackground(Color.WHITE); jframe.add(jpanel2,BorderLayout.CENTER); jpanel2.setPreferredSize(new Dimension(600,560));//第二个面板用于画线条 jframe.setVisible(true);因为我们要在第二个组件上画线所以我们的画笔需要改为从第二个面板取得。3.窗口内容面板的颜色设置代码如下jframe.getContentPane().setBackground(new Color(255,255,255));//若写成setBackground则仅会改变边框颜色4.线条颜色及宽度的控制代码如下gr.setColor(Color.BLACK);//设置线条颜色 Graphics2D gr2(Graphics2D) gr;//将Graphics类的gr强制转变为Graphics2D gr2.setStroke(new BasicStroke(2));//对于Graphics2D的gr2可设置线条宽度5.窗口多个JPanel线条偏移问题的解决方法本质上是因为坐标不对导致的我们仅需要将鼠标监听器和鼠标运动监听器都绑定在第二个面板即可让e.getX()所得到的坐标正确。jpanel2.addMouseListener(drawListener); jpanel2.addMouseMotionListener(drawListener);6.鼠标运动监听器的使用其接口名为MouseMotionListener其中有两个方法体public void mouseDragged(MouseEvent e){} public void mouseMoved(MouseEvent e){}第一个是鼠标按住并移动时生效第二个是鼠标移动时触发。7.代码展示import javax.swing.*; import java.awt.*; public class DrawSoftWare { public void drawer(){ JFrame jframenew JFrame(); jframe.setSize(700,600);//窗口大了按钮会消失 jframe.setTitle(Draw SoftWare); jframe.setDefaultCloseOperation(3); jframe.setLocationRelativeTo(null); jframe.getContentPane().setBackground(new Color(255,255,255)); JPanel jpanelnew JPanel(); jframe.setLayout(new BorderLayout()); jpanel.setBackground(Color.BLUE); jpanel.setPreferredSize(new Dimension(0,40)); jframe.add(jpanel,BorderLayout.NORTH); JButton jbuttonnew JButton(直线); JButton jbutton2new JButton(矩形); JButton jbutton3new JButton(等腰三角形); JButton jbutton4new JButton(任意三角形); JButton jbutton5new JButton(多边形); JButton jbutton6new JButton(曲线); JButton jbutton7new JButton(橡皮擦); JButton Red new JButton(红色); jpanel.add(jbutton); jpanel.add(jbutton2); jpanel.add(jbutton3); jpanel.add(jbutton4); jpanel.add(jbutton5); jpanel.add(jbutton6); jpanel.add(jbutton7); jpanel.add(Red); jframe.setVisible(true); JPanel jpanel2new JPanel(); jpanel2.setBackground(Color.WHITE); jframe.add(jpanel2,BorderLayout.CENTER); jpanel2.setPreferredSize(new Dimension(600,560)); jframe.setVisible(true); Graphics gjpanel2.getGraphics(); DrawListener drawListenernew DrawListener(); jpanel2.addMouseListener(drawListener); jpanel2.addMouseMotionListener(drawListener); drawListener.grg; jbutton.addActionListener(drawListener); jbutton2.addActionListener(drawListener); jbutton3.addActionListener(drawListener); jbutton4.addActionListener(drawListener); jbutton5.addActionListener(drawListener); jbutton6.addActionListener(drawListener); jbutton7.addActionListener(drawListener); Red.addActionListener(drawListener); } public static void main(String[] args){ DrawSoftWare dnew DrawSoftWare(); d.drawer(); } }import java.awt.*; import java.awt.event.*; public class DrawListener implements MouseListener, ActionListener, MouseMotionListener{ public int x1,y1,x2,y2,x3,y3,x4,y4; public static Graphics gr ; public String Command; public String color; public boolean flag; public void actionPerformed(ActionEvent e) { colore.getActionCommand(); if(!color.equals(红色)!color.equals(橡皮擦)){ Command e.getActionCommand(); } if(color.equals(红色)){ gr.setColor(Color.RED); } if(color.equals(橡皮擦)){ gr.setColor(Color.WHITE); Graphics2D gr2(Graphics2D) gr; gr2.setStroke(new BasicStroke(8)); } flag true; System.out.println(Command); System.out.println(color); } public void mousePressed(MouseEvent e){ if(flagtrue){ x1e.getX(); y1e.getY(); } if(!color.equals(红色)!color.equals(橡皮擦)){ gr.setColor(Color.BLACK); Graphics2D gr2(Graphics2D) gr; gr2.setStroke(new BasicStroke(2)); } } public void mouseReleased(MouseEvent e) { if (flag true) { x2 e.getX(); y2 e.getY(); } if (Command.equals(直线)) { gr.drawLine(x1, y1, x2, y2);//直线 System.out.println(x1x1y1y1x2x2y2y2); } if (Command.equals(矩形)) { int wid Math.abs(x2 - x1); int hei Math.abs(y2 - y1); int xMin Math.min(x1, x2); int yMin Math.min(y1, y2); gr.drawRect(xMin, yMin, wid, hei);//矩形 } if (Command.equals(等腰三角形)) { gr.drawLine(x1, y1, x2, y1); int xMid Math.abs((x2 x1) / 2); gr.drawLine(x1, y1, xMid, y2); gr.drawLine(x2, y1, xMid, y2); } if (Command.equals(任意三角形)) { gr.drawLine(x1, y1, x2, y2); flag false; } if (Command.equals(多边形)flag) { gr.drawLine(x1, y1, x2, y2); flag false; } } public void mouseClicked(MouseEvent e){ x3e.getX(); y3e.getY(); if(Command.equals(任意三角形)){ gr.drawLine(x1, y1, x3, y3); gr.drawLine(x2, y2, x3, y3); flagtrue; } if(Command.equals(多边形)){ gr.drawLine(x2, y2, x3, y3); x2x3; y2y3; int timese.getClickCount(); if (times2){ gr.drawLine(x1, y1, x3, y3); flagtrue; } } } public void mouseDragged(MouseEvent e){ if(Command.equals(曲线)){ x4e.getX(); y4e.getY(); gr.drawLine(x1, y1, x4, y4); x1x4; y1y4; } if(color.equals(橡皮擦)){ x4e.getX(); y4e.getY(); gr.drawLine(x1, y1, x4, y4); x1x4; y1y4; } } public void mouseMoved(MouseEvent e){ } public void mouseEntered(MouseEvent e){ } public void mouseExited(MouseEvent e){ } }除前面提到的需求我们还额外增加了橡皮擦和曲线功能。