java.library.path 中没有字体管理器

Question

以下代码在我的桌面上运行良好：

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();
        g.setFont(new Font("SansSerif", Font.BOLD, 18));

        Graphics2D graphics = (Graphics2D) g;
        graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
        graphics.drawString(s, 5, 20);

但是，当我在我的服务器上运行此代码（在 Docker 容器内的 linux alpine 上运行的 openjdk）时，它失败并显示以下错误：

java.lang.UnsatisfiedLinkError: no fontmanager in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1867)
at java.lang.Runtime.loadLibrary0(Runtime.java:870)
at java.lang.System.loadLibrary(System.java:1122)
at sun.font.FontManagerNativeLibrary$1.run(FontManagerNativeLibrary.java:61)
at java.security.AccessController.doPrivileged(Native Method)
at sun.font.FontManagerNativeLibrary.<clinit>(FontManagerNativeLibrary.java:32)
at sun.font.SunFontManager$1.run(SunFontManager.java:339)
at java.security.AccessController.doPrivileged(Native Method)
at sun.font.SunFontManager.<clinit>(SunFontManager.java:335)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at sun.font.FontManagerFactory$1.run(FontManagerFactory.java:82)
at java.security.AccessController.doPrivileged(Native Method)
at sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:74)
at java.awt.Font.getFont2D(Font.java:491)
at java.awt.Font.access$000(Font.java:224)
at java.awt.Font$FontAccessImpl.getFont2D(Font.java:228)
at sun.font.FontUtilities.getFont2D(FontUtilities.java:180)
at sun.java2d.SunGraphics2D.checkFontInfo(SunGraphics2D.java:669)
at sun.java2d.SunGraphics2D.getFontInfo(SunGraphics2D.java:830)
at sun.java2d.pipe.GlyphListPipe.drawString(GlyphListPipe.java:50)
at sun.java2d.pipe.ValidatePipe.drawString(ValidatePipe.java:165)
at sun.java2d.SunGraphics2D.drawString(SunGraphics2D.java:2928)

java -version（在我的服务器上）给出：

openjdk version "1.8.0_77-internal"
OpenJDK Runtime Environment (build 1.8.0_77-internal-alpine-r0-b03)
OpenJDK 64-Bit Server VM (build 25.77-b03, mixed mode)

我搜索了 awt 库，它们可以在这里找到：

/usr/lib/jvm/java-1.8-openjdk/jre/lib/amd64/libawt_headless.so
/usr/lib/jvm/java-1.8-openjdk/jre/lib/amd64/libawt.so

Answer 1

我在运行 Alpine Linux 3.4 时遇到了完全相同的问题。我按照这个 github 问题中的说明解决了这个问题：

1. 安装具有 GUI 支持的 JRE，即openjdk8-jre代替openjdk8-jre-head
2. 安装fontconfig和ttf-dejavu包

我的 Dockerfile 中的 RUN 行如下所示：

RUN apk add openjdk8-jre fontconfig ttf-dejavu

此后，JDK 能够自动加载默认字体，异常消失了。