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margin
Margin 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
@AllArgsConstructor
public static class Margin {
/**
* 上
*/
private int top;
/**
* 底
*/
private int bottom;
/**
* 左
*/
private int left;
/**
* 右
*/
private int right;
}
@Data
@AllArgsConstructor
public 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！
