Java使用Graphics2D画图，画圆，矩形，透明度等实现

背景

如上图，需要使用Java生成一个图片，并以base64编码的形式返回给前端展示。

使用Graphics2D类，来进行画图，其中需要画方框、原型、插入图标、写入文字等，同时需要设置透明度等细节点

环境：Jdk17，springboot2.7.13

代码如下

有详细的注释

package com.demo;import cn.hutool.core.codec.Base64;
import cn.hutool.core.io.FileUtil;
import com.google.common.collect.Lists;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.ThreadLocalRandom;/*** <p>* 功能描述:* </p>** @author MILLA* @version 1.0* @since 2024/06/24 9:14*/
@Slf4j
public class ImageDemo {/*** 每个div的高度*/private static final int LINE_HEIGHT = 80;private static final double COLOR_WIDTH = 0.7;/*** 处方笺图片宽*/private static final int PIC_WIDTH = 1200;/*** 顶部与底部留白*/private static final int MARGIN_Y = 52;/*** 左右留白*/private static final int MARGIN_X = 50;/*** 生成图片后缀*/private static final String FILE_SUFFIX = ".jpg";public static void main(String[] args) throws Exception {List<Object> objects = Lists.newArrayList(1, 2, 3, 4, 5, 6);String base64 = new ImageDemo().getImage(objects);System.out.println(base64);}/*** 初始化** @param image    画布* @param graphics 画笔*/private void initiation(BufferedImage image, Graphics2D graphics) {int width = image.getWidth();int height = image.getHeight();graphics.setClip(0, 0, width, height);// 设置画笔颜色graphics.setColor(Color.white);// 绘制背景graphics.fillRect(0, 0, width, height);// 设置抗锯齿graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);}private String getImage(List<Object> objects) throws IOException {//读取图标流InputStream stream = this.getClass().getClassLoader().getResourceAsStream("static/icon.png");BufferedImage avatar = ImageIO.read(stream);// 新建图片BufferedImage image = new BufferedImage(PIC_WIDTH, objects.size() * LINE_HEIGHT + MARGIN_Y * 2, BufferedImage.TYPE_INT_BGR);// 创建画笔Graphics2D graphics = image.createGraphics();// 初始化背景色initiation(image, graphics);// 定义marginMargin margin = new Margin(MARGIN_Y, MARGIN_Y, MARGIN_X, MARGIN_X);// 初始化坐标Point point = new Point(margin.getLeft(), margin.getTop());ThreadLocalRandom random = ThreadLocalRandom.current();for (int i = 0; i < objects.size(); i++) {Color color = new Color(random.nextInt(0, 255), random.nextInt(0, 255), random.nextInt(0, 255));drawDiv(point, image, graphics, color, avatar, "颜色名称: " + (i + 1), "P", "颜色编码：" + (i + 1));}// 销毁画笔，结束绘制graphics.dispose();byte[] bytes = toByteArray(image);//文件生成log.info("文件路径", FileUtil.writeBytes(bytes, "test" + FILE_SUFFIX));String prefix = "data:image/jpg;base64,";return prefix + Base64.encode(bytes);}private void drawDiv(Point point, BufferedImage image, Graphics2D graphics, Color color, BufferedImage avatar, String name, String type, String code) {Font font = new Font("宋体", Font.BOLD, 28);int width = image.getWidth() - 2 * point.getX();// 设置div的绘制区域graphics.setClip(point.getX(), point.getY(), width, LINE_HEIGHT);
//         设置画笔颜色graphics.setColor(color);int firstWidth = (int) (COLOR_WIDTH * width);
//         绘制背景 一行的前半部分graphics.fillRect(point.getX(), point.getY() + 1, firstWidth, LINE_HEIGHT - 2);// 设置画笔int nameX = point.getX() + 18;drawContent(name, graphics, nameX, point.getY(), Color.WHITE, image.getWidth(), point, font);int circleX = firstWidth - 15;drawCircle(point, graphics, circleX);font = new Font("宋体", Font.BOLD, 23);drawContent(type.toUpperCase(Locale.ROOT), graphics, circleX + 5, point.getY(), Color.WHITE, image.getWidth(), point, font);// 绘制背景 一行的后半部分--外部矩形框Color outerColor = new Color(Integer.parseInt("DDDDDD", 16));graphics.setColor(outerColor);int secondWidth = (int) ((1 - COLOR_WIDTH) * width);graphics.fillRect(point.getX() + firstWidth, point.getY(), secondWidth, LINE_HEIGHT);// 绘制背景 一行的后半部分---内部矩形框Color innerColor = new Color(Integer.parseInt("F4F4F4", 16));graphics.setColor(innerColor);graphics.fillRect(point.getX() + firstWidth + 1, point.getY() + 1, secondWidth - 2, LINE_HEIGHT - 2);//图标int avatarHeight = avatar.getHeight() / 2;int avatarX = point.getX() + firstWidth + 31;graphics.drawImage(avatar, avatarX, point.getY() + 1 + (LINE_HEIGHT - avatarHeight) / 2, avatar.getWidth() / 2, avatarHeight, innerColor, null);//图标 --文字int codTextX = avatarX + avatar.getWidth() / 3 + 33;font = new Font("宋体", Font.PLAIN, 20);drawContent(code, graphics, codTextX, point.getY(), Color.BLACK, image.getWidth(), point, font);point.setY(point.y + LINE_HEIGHT - 1);}private void drawCircle(Point point, Graphics2D graphics, int circleX) {Composite composite = graphics.getComposite();//透明度设置AlphaComposite instance = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f);graphics.setComposite(instance);graphics.setColor(Color.BLACK);graphics.fillOval(circleX, point.getY() + (LINE_HEIGHT - 32) / 2, 32, 32);//恢复原来的透明度graphics.setComposite(composite);}private void drawContent(String text, Graphics2D cs, int x, int y, Color color, int width, Point point, Font font) {//临时将需要裁剪区域置空cs.setClip(null);//设置文本颜色cs.setColor(color);//设置文本字体cs.setFont(font);//文本抗锯齿cs.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);cs.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);//为画布添加文字，并居中FontMetrics fm = cs.getFontMetrics(font);int ascent = fm.getAscent();int descent = fm.getDescent();cs.drawString(text, x + 5, y + (LINE_HEIGHT - (ascent + descent)) / 2 + ascent);//恢复之前的裁剪区域cs.setClip(point.getX(), point.getY(), width - 2 * point.getX(), LINE_HEIGHT);}private byte[] toByteArray(BufferedImage image) throws IOException {// 输出png图片ByteArrayOutputStream os = new ByteArrayOutputStream();image.flush();ImageIO.write(image, "png", os);return os.toByteArray();}@Data@AllArgsConstructorpublic static class Margin {/*** 上*/private int top;/*** 底*/private int bottom;/*** 左*/private int left;/*** 右*/private int right;}@Data@AllArgsConstructorpublic static class Point {private int x;private int y;}}

PS:生成的图片如文头，base64编码如下图

但是在移植到docker容器中部署的时候，报以下错误

2024-06-25 16:26:31.019 [http-nio-10008-exec-7] ERROR com.a.mybatis.common.exception.RestfulExceptionHandler - 异常堆栈:
jakarta.servlet.ServletException: Handler dispatch failed: java.lang.UnsatisfiedLinkError: /opt/java/openjdk/lib/libfontmanager.so: Error loading shared library libfreetype.so.6: No such file or directory (needed by /opt/java/openjdk/lib/libfontmanager.so)at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1096)at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:974)at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1011)at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:903)at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:705)at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885)at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:814)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:223)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)at com.github.xiaoymin.knife4j.extend.filter.basic.JakartaServletSecurityBasicAuthFilter.doFilter(JakartaServletSecurityBasicAuthFilter.java:55)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)at com.huanyu.common.config.filter.TokenFilter.doFilter(TokenFilter.java:58)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:177)at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:119)at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:400)at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:859)at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1734)at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.lang.UnsatisfiedLinkError: /opt/java/openjdk/lib/libfontmanager.so: Error loading shared library libfreetype.so.6: No such file or directory (needed by /opt/java/openjdk/lib/libfontmanager.so)at java.base/jdk.internal.loader.NativeLibraries.load(Native Method)at java.base/jdk.internal.loader.NativeLibraries$NativeLibraryImpl.open(Unknown Source)at java.base/jdk.internal.loader.NativeLibraries.loadLibrary(Unknown Source)at java.base/jdk.internal.loader.NativeLibraries.loadLibrary(Unknown Source)at java.base/jdk.internal.loader.NativeLibraries.findFromPaths(Unknown Source)at java.base/jdk.internal.loader.NativeLibraries.loadLibrary(Unknown Source)at java.base/java.lang.ClassLoader.loadLibrary(Unknown Source)at java.base/java.lang.Runtime.loadLibrary0(Unknown Source)at java.base/java.lang.System.loadLibrary(Unknown Source)at java.desktop/sun.font.FontManagerNativeLibrary$1.run(Unknown Source)at java.base/java.security.AccessController.doPrivileged(Unknown Source)at java.desktop/sun.font.FontManagerNativeLibrary.<clinit>(Unknown Source)at java.desktop/sun.font.SunFontManager$1.run(Unknown Source)at java.desktop/sun.font.SunFontManager$1.run(Unknown Source)at java.base/java.security.AccessController.doPrivileged(Unknown Source)at java.desktop/sun.font.SunFontManager.initStatic(Unknown Source)at java.desktop/sun.font.SunFontManager.<clinit>(Unknown Source)at java.base/java.lang.Class.forName0(Native Method)at java.base/java.lang.Class.forName(Unknown Source)at java.desktop/sun.font.FontManagerFactory$1.run(Unknown Source)at java.base/java.security.AccessController.doPrivileged(Unknown Source)at java.desktop/sun.font.FontManagerFactory.getInstance(Unknown Source)at java.desktop/java.awt.Font.getFont2D(Unknown Source)at java.desktop/java.awt.Font$FontAccessImpl.getFont2D(Unknown Source)at java.desktop/sun.font.FontUtilities.getFont2D(Unknown Source)at java.desktop/sun.java2d.SunGraphics2D.checkFontInfo(Unknown Source)at java.desktop/sun.java2d.SunGraphics2D.getFontInfo(Unknown Source)at java.desktop/sun.java2d.pipe.GlyphListPipe.drawString(Unknown Source)at java.desktop/sun.java2d.pipe.ValidatePipe.drawString(Unknown Source)at java.desktop/sun.java2d.SunGraphics2D.drawString(Unknown Source)

原因分析：

Graphics2D类在执行文本写入的时候，需要使用字体插件，因为当前的运行环境中没有对应的 Error loading shared library libfreetype.so.6插件，因此就会报上述的错误。

经排查，博主使用的docker镜像是精简版本的，将一些不常用的功能代码都去除了，因此会出现这样那样的问题，最终使用完全的jre17，解决了该问题，备查！