1.这里我们会运用到封装的思想：

例如我们想重复调用一个代码，就要进行封装：

想要重复调用的代码：

JButton btn = new JButton("直线")；

jf.add(btn);

btn.addActionListener(null);

我们现在可以这样：

for(int i = 0;i< str.length;i++){
        addMyButton(str[i],jf,drawListener);

}

public void addMyButton (String text,JFrame jf,ActionListener al){

        JButton btn = new JButton(text);

        jf.add(btn);

        btn.addActionListener(al);

}

同理，我们可以加上颜色：

addColorButton(colors[i],jf,drawListener);

//封装好可以重复调用的代码

oublic void addColorButton(Color color,JFrame jf,ActionListener al){

        JButton btn = new JButton("");

        btn.setBackgrounf(color);

        jf.add(btn);

        btn.addActionListener(al);

}

来看代码：

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionListener;public class Partssave {   //首先定义一个类PartssaveString[] strs = {"直线", "圆", "矩形", "三角形", "多边形", "山", "树", "Empty", "Withdraw"};   //定义数组，赋初值Color[] color = {Color.BLACK, Color.WHITE, Color.RED, Color.green, Color.blue, Color.CYAN, Color.ORANGE, Color.YELLOW, Color.MAGENTA, Color.PINK};  //添加颜色Partssavelistener ptl = new Partssavelistener(); //连接监听器public void Partsrr() {JFrame jf = new JFrame();jf.setTitle("图形绘制");jf.setSize(900, 900);jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//加入监听器FlowLayout fl = new FlowLayout();jf.setLayout(fl);//封装好可重复调用的直线/** JButton jb = new JButton("直线");jf.add(jb);jb.addActionListener(null); **/for (int i = 0; i < strs.length; i++) {addMyButton(strs[i], jf, ptl);}for (int i = 0; i < color.length; i++) {addColorButton(color[i], jf, ptl);}jf.setVisible(true);jf.addMouseListener(ptl);ptl.g = jf.getGraphics();}//封装好 可以重复调用的代码public void addMyButton(String text, JFrame jf, ActionListener al) {JButton jb = new JButton(text);jf.add(jb);jb.addActionListener(al);}//封装好 可以重复调用的代码public void addColorButton(Color color, JFrame jf, ActionListener al) {JButton jb = new JButton("");jb.setBackground(color);jf.add(jb);jb.addActionListener(al);}public static void main(String[] args) {new Partssave().Partsrr();}
}

2.我们来看监听器这部分：

 

import javax.accessibility.Accessible;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;public class Partssavelistener implements ActionListener, MouseListener {Graphics g;//判断图形 字符串String typeStr ="Rect";int x1,x2,y1,y2;Color color = Color.black;public void actionPerformed(ActionEvent e){System.out.println("按钮被点击了");String str = e.getActionCommand();if (str.equals("")){System.out.println("这是一个颜色按钮");//获取点击的对象 按钮JButton jb = (JButton) e.getSource();//获取按钮背景颜色color = jb.getBackground();//设置给画笔对象g.setColor(color);}else{//如果不是空格 那就把字符存入typeStrtypeStr = str;}}public void mouseClicked(MouseEvent e){}public void mousePressed(MouseEvent e){x1=e.getX();y1=e.getY();}Shape[] shapeList = new Shape[100];int index = 0; //下标索引public void mouseReleased(MouseEvent e){x2=e.getX();y2=e.getY();//创建一个图形对象Shape shape = new Shape();shape.setShapeData(typeStr,x1,x2,y1,y2,color);shape.drawShape(g);shapeList[index] = shape;index++;}public void mouseEntered(MouseEvent e){//鼠标触发进入窗体时 绘制所有图形for(int i = 0;i<shapeList.length;i++){//只调用有的图形if (shapeList[i]!=null){shapeList[i].drawShape(g);}}}public void mouseExited(MouseEvent e){//鼠标触发离开窗体 绘制所有的图形for(int i = 0;i<shapeList.length;i++){//只调用有的图形if (shapeList[i]!=null){shapeList[i].drawShape(g);}}}
}

3.创建一个shape类 ，完成图形绘制

import java.awt.*;/**根据图形的属性特性* 创建一个图形类 类可以创建对象 对象的属性可以 以对象为单位保存*/public class Shape {String type;int x1, x2, y1, y2;Color color;//设置图形数据public void setShapeData(String type, int x1, int x2, int y1, int y2, Color color) {this.type = type;this.x1 = x1;this.x2 = x2;this.y1 = y1;this.y2 = y2;this.color = color;}public void drawShape(Graphics g) {g.setColor(color);if (type.equals("直线")) {g.drawLine(x1, y1, x2, y2);} else if (type.equals("矩形")) {g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1 - x2), Math.abs(y1 - y2));} else if (type.equals("圆")) {g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x1 - x2), Math.abs(y1 - y2));}}
}