Graphics2D画图案例

谁践踏了优雅 2022-09-10 06:14 128阅读 0赞

### 文章目录 ###

*   *  绘制线
     *  绘制矩形 圆形矩形 利用矩形的圆角魔改成圆形
     *  写字:
     *  小案例
     *  海报案例关键代码
     *  效果
     *  git代码地址:

> `背景`：  
> 项目中需要用到一个小程序海报，然后分享给别人，因为前端绘制太慢，所以思路就是: 在后端绘制，绘制完毕后，提前存起来该海报的url地址，前端进入分享页面直接显示即可，增强体验性。为此，作为Java后端的我，花了2天时间学习了下Java的Graphics2D的基本的绘制技巧，基本能实现既定的目标。后面的绘制后面再说，这里先把网上搜到的好的案例记录下:

## 绘制线 ##

2个点连起来:

import java.awt.Color;
    import java.awt.Graphics;
    import javax.swing.JFrame;
    
    public class DrawLineDemo extends JFrame { 
        public DrawLineDemo() { 
            setSize(500, 300);
            setDefaultCloseOperation(EXIT_ON_CLOSE);
            setLocationRelativeTo(null);
        }
    
        public void paint(Graphics g) { 
            g.setColor(Color.blue);
            g.drawLine(50, 30, 450, 260);
        }
    
        public static void main(String[] args) { 
            new DrawLineDemo().setVisible(true);
        }
    }

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## 绘制矩形 圆形矩形 利用矩形的圆角魔改成圆形 ##

import java.awt.Color;
    import java.awt.Graphics;
    import javax.swing.JFrame;
    
    public class DrawRectDemo extends JFrame { 
        public DrawRectDemo() { 
            setSize(500, 300);
            setDefaultCloseOperation(EXIT_ON_CLOSE);
            setLocationRelativeTo(null);
        }
    
        public void paint(Graphics g) { 
            g.setColor(Color.blue); //设置颜色
    // g.drawRect(100, 100, 300, 100); //画出长为300，宽为100的矩形框。
    		//圆角矩形
    // g.drawRoundRect(100,100,300,100, 40, 40);
    		//当矩形的宽和高相等，圆角弧的横向直径和圆角弧的纵向直径也相等，并等于矩形的宽和高时，画的就是圆形。
    		g.fillRoundRect(200,110,100,100, 100, 100);
    	}
    
        public static void main(String[] args) { 
            new DrawRectDemo().setVisible(true);
        }
    }

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5oCS5pS-ZGXnlJ_lkb0yMDEw_size_11_color_FFFFFF_t_70_g_se_x_16 1]

## 写字: ##

import javax.swing.*;
    import java.awt.*;
    
    public class DrawStringDemo extends JFrame { 
        public DrawStringDemo() { 
            setSize(500, 300);
            setDefaultCloseOperation(EXIT_ON_CLOSE);
            setLocationRelativeTo(null);
        }
    
        public void paint(Graphics g) { 
            g.setColor(Color.GREEN);
            g.setFont(new Font("楷体", Font.HANGING_BASELINE, 20));
            //用此图形上下文的当前字体和颜色绘制由指定 string 给定的文本。
            //最左侧字符的基线位于此图形上下文坐标系的 (x, y) 位置处。
            g.drawString("使用画笔绘制的字符串内容", 80, 150);
    
        }
    
        public static void main(String[] args) { 
            new DrawStringDemo().setVisible(true);
        }
    }

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5oCS5pS-ZGXnlJ_lkb0yMDEw_size_11_color_FFFFFF_t_70_g_se_x_16 2]

## 小案例 ##

import java.awt.Color;
    import java.awt.Graphics2D;
    import java.awt.RenderingHints;
    import java.awt.image.BufferedImage;
    import java.io.FileNotFoundException;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.Random;
     
    import javax.imageio.ImageIO;
     
    public class Graphic2DTest { 
     
    	public static void draw() throws IOException{ 
    		//绘制宽=480，长=640的图板
    		int width=480,hight=720;
    		BufferedImage image = new BufferedImage(width,hight,BufferedImage.TYPE_INT_RGB);
    		//获取图形上下文,graphics想象成一个画笔
    		Graphics2D graphics = (Graphics2D)image.getGraphics();
    		
    		//消除线条锯齿
    		graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    		
    		//对指定的矩形区域填充颜色
    		graphics.setColor(Color.ORANGE);	//GREEN:绿色； 红色：RED; 灰色：GRAY
    		graphics.fillRect(0, 0, 240, 720);
    		//对指定的矩形区域填充颜色
    		graphics.setColor(Color.PINK);	
    		graphics.fillRect(240, 0, 240, 720);
    		
    		//生成随机数
    		Random random = new Random();
    		/* * 画线 x,y是坐标，定义线段的两个坐标点 */
    		graphics.setColor(Color.BLACK);
    		int x=100,y=100,x1=100,y1=y;
    		graphics.drawLine(x,y,x+x1,y1);
    		/* *画出一个折线 */
    		int[] xPoints = { 100,100,250,250};
    		int[] yPoints = { 180,150,150,180};
    		graphics.drawPolyline(xPoints, yPoints, 4);
    		/* * 画出一个闭合多边形(三角形) */
    		int[] xPoints1 = { 100,100,200};
    		int[] yPoints1 = { 240,320,280};
    		graphics.drawPolygon(xPoints1, yPoints1, 3);
    		/* * 画出一个闭合多边形(菱形) */
    		int[] xPoints2 = { 240,300,360,300};
    		int[] yPoints2 = { 280,240,280,320};
    		graphics.drawPolygon(xPoints2, yPoints2, 4);
    		graphics.setColor(Color.ORANGE);
    		graphics.fillPolygon(xPoints2, yPoints2, 4);
    		/* *绘制一个椭圆形 */
    		graphics.setColor(Color.GREEN);
    		int xOval=100,yOval=360;
    		graphics.drawOval(xOval, yOval, 100, 100);
     
    		/* *绘制一个矩形 */
    		//graphics.setColor(Color.GRAY);//--设置矩形边框颜色 。GREEN:绿色； 红色：RED; 灰色：GRAY
    		int xRect=240,yRect=360;
    		graphics.drawRect(xRect, yRect, 200, 100);
     
    		//设置文字颜色
    		graphics.setColor(new Color( 20+random.nextInt(100),  20+random.nextInt(100),  20+random.nextInt(100) ));
    		//设置文字内容、位置
    		graphics.drawString("直线",100+50,100-5);
    		graphics.drawString("折线", 200, 150-5);
    		graphics.drawString("空心三角形", 110, 280);
    		graphics.drawString("实心菱形", 300-20, 280);
    		graphics.drawString("椭圆形", 100+50, 360+50);
    		graphics.drawString("矩形", 240+50, 360+50);
    		//graphics.drawString("错误的背景颜色", 100, 540);
    		
    		//graphics.setPaintMode();
    		//graphics.translate(400, 600);
    		
    		graphics.dispose();//释放此图形的上下文并释放它所使用的所有系统资源
    		FileOutputStream out=new FileOutputStream("d:/1.jpeg");
    		ImageIO.write(image,"JPEG",out);
    		
    		out.flush();
    		out.close();
    		//super.doGet(request, response);
     
    	}
    	
    	
    	public static void main(String[] args) { 
    		try { 
    			draw();
    		} catch (IOException e) { 
    			
    			e.printStackTrace();
    		}
     
    	}
     
    }

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## 海报案例关键代码 ##

public InputStream videoPoster(GoodsPosterEntity goodsPosterEntity) { 
            try { 
                BufferedImage bimg = getUrlByBufferedImage(goodsPosterEntity.getBackground());
                //得到Graphics2D 对象
                Graphics2D g2d = getG2d(bimg);
    
                //用户头像
                BufferedImage userLogo = getSque(getUrlByBufferedImage(goodsPosterEntity.getUserLogo()));
    
                g2d.drawImage(setRadius(userLogo,3), 40, 40, 102, 102, null);
    
                String userName = goodsPosterEntity.getUserName();
                Font font2 = new Font(typeface, Font.BOLD, 28);
                g2d.setFont(font2);
                g2d.setColor(Color.WHITE);
                g2d.drawString(userName, 160, 71);
    
                font2 = new Font(typeface, Font.PLAIN, 28);
                g2d.setFont(font2);
                g2d.setColor(Color.WHITE);
                g2d.drawString("给您分享了精彩视频", 160, 112);
    
                BufferedImage goodsImg = getUrlByBufferedImage(goodsPosterEntity.getGoodsUrl());
                //视频图片
                g2d.drawImage(setRadius(goodsImg,2), 40, 182, 670, 660, null);
    
                BufferedImage iconPlay = getUrlByBufferedImage(goodsPosterEntity.getIconPlay());
                //播放按钮图片
                g2d.drawImage(iconPlay, 294, 436, 160, 160, null);
    
    
                //右上角背景
                BufferedImage rightImgBg = getUrlByBufferedImage(goodsPosterEntity.getImagePath());
                g2d.drawImage(setRadius(rightImgBg,1), 480, 50, 230, 82, null);
    
                BufferedImage bottomBg = getUrlByBufferedImage(goodsPosterEntity.getBgCardBottom());
                g2d.drawImage(setRadius(bottomBg,2), 40, 790, 670, 504, null);
    
                g2d.setColor(new Color(56, 56, 56));
                String goodsName = goodsPosterEntity.getGoodsName();
                Font font1 = new Font(typeface, Font.BOLD, 36);
                g2d.setFont(font1);
                g2d.drawString(goodsName, 82, 880);
    
                Image sunCodeUrl = getUrlByBufferedImage(goodsPosterEntity.getSunCodeUrl());
                g2d.drawImage(sunCodeUrl, 490, 1074, 180, 180, null);
                g2d.setColor(new Color(168, 168, 168));
    
                //太阳码中间logo
                BufferedImage goodsImgSun = getUrlByBufferedImage(goodsPosterEntity.getGoodsUrl());
                //商品图片
                g2d.drawImage(setRadius(goodsImgSun,3), 540, 1124, 80, 80, null);
    
                // 释放对象
                g2d.dispose();
    
                return upload(bimg);
            } catch (Exception c) { 
                c.printStackTrace();
                log.info("goodsCard:{}",c.getMessage());
            }
            return null;
        }

## 效果 ##

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5oCS5pS-ZGXnlJ_lkb0yMDEw_size_11_color_FFFFFF_t_70_g_se_x_16 3]

--------------------

## git代码地址: ##

[https://gitee.com/hfl-learn-note/java-jui-demo.git][https_gitee.com_hfl-learn-note_java-jui-demo.git]

--------------------

摘抄：  
原文链接：[https://blog.csdn.net/qq\_42185999/article/details/88375505][https_blog.csdn.net_qq_42185999_article_details_88375505]

[https://blog.csdn.net/iteye\_6988/article/details/82637406][https_blog.csdn.net_iteye_6988_article_details_82637406]

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[https_gitee.com_hfl-learn-note_java-jui-demo.git]: https://gitee.com/hfl-learn-note/java-jui-demo.git
[https_blog.csdn.net_qq_42185999_article_details_88375505]: https://blog.csdn.net/qq_42185999/article/details/88375505
[https_blog.csdn.net_iteye_6988_article_details_82637406]: https://blog.csdn.net/iteye_6988/article/details/82637406