java画图板之新手入门

初到蓝杰，才真正开始了我的代码生涯，以前也只是随便写过两句，没有一个大的项目或者目标，也不知道要去写什么，怎么去写。
首先，通过画图板项目，来学习java的基础知识。

各模块功能

drawUI类

1、 设计窗体（名称、大小、位置、背景、关闭时结束程序等）

        JFrame ui = new JFrame();
        //设置窗体属性
        ui.setTitle("画图板--倪颢");
        ui.setSize(1000, 800);
        //ui.setLocation(300, 300);
        ui.setLocationRelativeTo(null);//居中
        //关闭时结束程序
        ui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        ui.setBackground(Color.yellow);

2、设置布局（具体内容会在之后的博客中）

        FlowLayout flow = new FlowLayout();
        ui.setLayout(flow);

3、添加鼠标监听器

        mouselistener mousel = new mouselistener();
        ui.addMouseListener(mousel);

4、添加组件（这里以添加按钮为例）

        String textArr[] = {"直线", "点", "迭代"};
        for (String text : textArr) {
            JButton btn = new JButton(text);
            Dimension botton = new Dimension(100, 50);
            btn.setPreferredSize(botton);
            ui.add(btn);
            btn.addActionListener(mousel);
        }

5、在窗体全都完成后，设置可见，并获取画布对象

        ui.setVisible(true);
        //创建画布对象,必须在设置可见后
        Graphics g = ui.getGraphics();
        mousel.setgraphic(g);

6、主函数

    public static void main(String args[]) {
        drawUI drawui = new drawUI();
        drawui.showUI();
    }

监听器类

1、鼠标点击

    public void mouseClicked(MouseEvent e) {

  a、选择“点”按钮

    g.fillOval((int)startx - r, (int)starty-r, r,r);

 b、选择“迭代”按钮

            point[clicknum%4][0]=e.getX();
            point[clicknum%4][1]=e.getY();
            //g.drawLine(ax, ay, ax, ay);        
            g.fillOval(point[clicknum%4][0] - r, point[clicknum%4][1] - r, r, r);         
            clicknum++;

            if (clicknum % 4 == 0) {
                System.out.println("(" + point[0][0] + "," + point[0][1] + ")" + "(" + point[1][0] + "," + point[1][1] + ")" + "(" + point[2][0] + "," + point[2][1] + ")" + "(" + point[3][0] + "," + point[3][1] + ")");
                for (int i = 0; i <= 10000; i++) {
                    int temp = 0;
                    temp = (int) (Math.random() * 3);
                    if (temp == 0) {
                        point[4][0] = (point[0][0] + point[3][0]) / 2;
                        point[4][1] = (point[0][1] + point[3][1]) / 2;
                    } else if (temp == 1) {
                        point[4][0] = (point[1][0] + point[3][0]) / 2;
                        point[4][1] = (point[1][1] + point[3][1]) / 2;
                    } else if (temp == 2) {
                        point[4][0] = (point[2][0] + point[3][0]) / 2;
                        point[4][1] = (point[2][1] + point[3][1]) / 2;
                    }
                    g.fillOval(point[3][0] - r, point[3][1] - r, r, r);
                    point[3][0] = point[4][0];
                    point[3][1] = point[4][1];
                }
            }

  第二种迭代（还有很多有趣的图案，大家可以去试试）

            startx = e.getX();
            starty = e.getY();
            for (int i = 0; i < 10000; i++) {
                System.out.println("(" + startx + "," + starty + ")" );
                g.drawLine((int)(startx*100)+300 - r, (int)(starty*100)+300-r,(int)(startx*100)+300 - r, (int)(starty*100)+300-r);
                tempx = Math.sin(a * starty) + c * Math.cos(a * startx);
                tempy = Math.sin(b * startx) + d * Math.cos(b * starty);
                startx = tempx;
                starty = tempy;                         
            }

2、鼠标松开触发器

    public void mouseReleased(MouseEvent e) {
        if (bottonText.equals("直线")) {
            endx = e.getX();
            endy = e.getY();

            for (int i = 0; i <= 256; i++) {
                Color c = new Color(200, 200, i);
                g.setColor(c);
                g.drawLine((int)startx, (int)starty, (int)endx, (int)endy);
            }
        }
    }

3、屏幕点击触发器

    public void actionPerformed(ActionEvent e) {
        if ("直线".equals(e.getActionCommand())) {
            bottonText = "直线";
        } else if ("点".equals(e.getActionCommand())) {
            bottonText = "点";
        } else if ("迭代".equals(e.getActionCommand())) {
            bottonText = "迭代";
        }
    }

总结

也没什么好总结的，找到规律，写好代码其实不难，我今后会将写的项目和遇到的问题写成博客，欢迎各位大佬前来交流指导。

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附录（源代码）

1、drawUI类

package drawline;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JFrame;
import java.awt.Graphics;
import javax.swing.JButton;

public class drawUI {

    public void showUI() {
        JFrame ui = new JFrame();
        //设置窗体属性
        ui.setTitle("画图板--倪颢");
        ui.setSize(1000, 800);
        //ui.setLocation(300, 300);
        ui.setLocationRelativeTo(null);//居中

        ui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        ui.setBackground(Color.yellow);
        //设置布局
        FlowLayout flow = new FlowLayout();
        ui.setLayout(flow);
        //添加鼠标监听器
        mouselistener mousel = new mouselistener();
        ui.addMouseListener(mousel);

        //添加组件(按钮）
        String textArr[] = {"直线", "点", "迭代"};
        for (String text : textArr) {
            JButton btn = new JButton(text);
            Dimension botton = new Dimension(100, 50);
            btn.setPreferredSize(botton);
            ui.add(btn);
            btn.addActionListener(mousel);
        }
        //设置可见
        ui.setVisible(true);
        //创建画布对象,必须在设置可见后
        Graphics g = ui.getGraphics();
        mousel.setgraphic(g);
    }

    public static void main(String args[]) {
        drawUI drawui = new drawUI();
        drawui.showUI();
    }
}

2、mouselistener类（刚开始名称书写还是不规范）

package drawline;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JOptionPane;

public class mouselistener implements MouseListener, ActionListener {

    double startx, starty, endx, endy, tempx, tempy;
    double a=-1.8,b=-2.0,c=-0.5,d=-0.9;
    int[][] point = new int[5][2];
    int r = 6;//设置点的半径
    int clicknum = 0;
    String bottonText = "";
    Graphics g;

    public void setgraphic(Graphics g) {
        this.g = g;
    }

    public void mouseClicked(MouseEvent e) {
        if (bottonText.equals("迭代")) {
            
            point[clicknum%4][0]=e.getX();
            point[clicknum%4][1]=e.getY();
            //g.drawLine(ax, ay, ax, ay);        
            g.fillOval(point[clicknum%4][0] - r, point[clicknum%4][1] - r, r, r);         
            clicknum++;

            if (clicknum % 4 == 0) {
                System.out.println("(" + point[0][0] + "," + point[0][1] + ")" + "(" + point[1][0] + "," + point[1][1] + ")" + "(" + point[2][0] + "," + point[2][1] + ")" + "(" + point[3][0] + "," + point[3][1] + ")");
                for (int i = 0; i <= 10000; i++) {
                    int temp = 0;
                    temp = (int) (Math.random() * 3);
                    if (temp == 0) {
                        point[4][0] = (point[0][0] + point[3][0]) / 2;
                        point[4][1] = (point[0][1] + point[3][1]) / 2;
                    } else if (temp == 1) {
                        point[4][0] = (point[1][0] + point[3][0]) / 2;
                        point[4][1] = (point[1][1] + point[3][1]) / 2;
                    } else if (temp == 2) {
                        point[4][0] = (point[2][0] + point[3][0]) / 2;
                        point[4][1] = (point[2][1] + point[3][1]) / 2;
                    }
                    g.fillOval(point[3][0] - r, point[3][1] - r, r, r);
                    point[3][0] = point[4][0];
                    point[3][1] = point[4][1];
                }
            }
            /*
            startx = e.getX();
            starty = e.getY();
            for (int i = 0; i < 10000; i++) {
                System.out.println("(" + startx + "," + starty + ")" );
                g.drawLine((int)(startx*100)+300 - r, (int)(starty*100)+300-r,(int)(startx*100)+300 - r, (int)(starty*100)+300-r);
                tempx = Math.sin(a * starty) + c * Math.cos(a * startx);
                tempy = Math.sin(b * startx) + d * Math.cos(b * starty);
                startx = tempx;
                starty = tempy;                         
            }*/
        } else if (bottonText.equals("点")) {
            g.fillOval((int)startx - r, (int)starty-r, r,r);
        }
    }

    public void mousePressed(MouseEvent e) {
        if (bottonText.equals("")) {
            JOptionPane.showMessageDialog(null, "请选择一个按钮", "错误", JOptionPane.ERROR_MESSAGE);
        }
        startx = e.getX();
        starty = e.getY();
    }

    public void mouseReleased(MouseEvent e) {
        if (bottonText.equals("直线")) {
            endx = e.getX();
            endy = e.getY();

            for (int i = 0; i <= 256; i++) {
                Color c = new Color(200, 200, i);
                g.setColor(c);
                g.drawLine((int)startx, (int)starty, (int)endx, (int)endy);
            }
        }
    }

    public void mouseEntered(MouseEvent e) {
    }

    public void mouseExited(MouseEvent e) {
    }

    public void actionPerformed(ActionEvent e) {
        if ("直线".equals(e.getActionCommand())) {
            bottonText = "直线";
        } else if ("点".equals(e.getActionCommand())) {
            bottonText = "点";
        } else if ("迭代".equals(e.getActionCommand())) {
            bottonText = "迭代";
        }
    }

}