Java 生成图片时自定义字体

背景是由于 Linux 下无中文字体，导致写中文乱码，又不想引入环境依赖。

SpringBoot 项目，ttf 或 ttc 文件放置于 resource/font/cn.ttf。

POM 添加打包配置，避免 ttf 文件打包时被处理导致文件 FontFormatException 损坏。

<plugin>
    <artifactId>maven-resources-plugin</artifactId>
    <version>3.1.0</version>
    <configuration>
        <nonFilteredFileExtensions>
            <nonFilteredFileExtension>ttf</nonFilteredFileExtension>
        </nonFilteredFileExtensions>
    </configuration>
</plugin>

加载字体 Font 对象相关代码

package com.seliote.utils.font;

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.springframework.util.ResourceUtils;

import java.awt.*;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.Enumeration;
import java.util.Objects;

/**
 * 字体相关工具
 *
 * @author seliote
 * @since 2022-03-28
 */
@Slf4j
public class FontUtils {

    /**
     * 加载中文字体
     *
     * @param style 字体样式
     * @param size  字体大小
     * @return 中文字体
     */
    public static Font loadCNFont(int style, float size) throws Exception {
        final String fontFile = "/font/cn.ttf";
        final String fontFamily = "宋体";
        GraphicsEnvironment graphicsEnvironment = GraphicsEnvironment.getLocalGraphicsEnvironment();
        String[] fontFamilies = graphicsEnvironment.getAvailableFontFamilyNames();
        log.info("Total available font {}", fontFamilies.length);
        for (String eachFamily : fontFamilies) {
            if (fontFamily.equals(eachFamily)) {
                log.info("Font in env, return");
                return new Font(fontFamily, style, (int) Math.ceil(size));
            }
        }
        Font font;
        if (isInJar()) {
            log.debug("Running in JAR mode, try load resource TTC");
            font = Font.createFont(Font.TRUETYPE_FONT,
                    Objects.requireNonNull(FontUtils.class.getClassLoader().getResourceAsStream(fontFile)));
        } else {
            log.debug("Running in local mode, try load classpath TTC");
            font = Font.createFont(Font.TRUETYPE_FONT,
                    new File(ResourceUtils.getURL("classpath:").getPath(), fontFile));
        }
        font = font.deriveFont(style, size);
        log.info("Register font family {}", fontFamily);
        graphicsEnvironment.registerFont(font);
        return font;
    }

    /**
     * 判断当前是否为 JAR 方式启动
     *
     * @return 当为 true 时为 JAR 方式启动，否则为非 JAR
     */
    private static boolean isInJar() {
        try {
            Enumeration<URL> resources = Thread.currentThread().getContextClassLoader().getResources("");
            if (resources.hasMoreElements()) {
                log.debug("Application is in JAR!");
                return StringUtils.equalsIgnoreCase(resources.nextElement().getProtocol(), "jar");
            }
        } catch (IOException e) {
            log.error("Failed load resource, ", e);
            throw new RuntimeException(e);
        }
        log.debug("Application is not in JAR!");
        return false;
    }
}

使用时

FontUtils.loadCNFont(Font.PLAIN, fontSize)