Maven Shade跳过MCCoroutine类文件致Spigot插件启动失败求助

问题概述 #

用Kotlin和Maven构建的Spigot插件运行时抛出类缺失错误，打包生成的jar文件中找不到com.github.shynixn.mccoroutine.bukkit.impl.MCCoroutineImpl，执行ls -R命令已确认该问题。不过impl目录下存在一个命名特殊的文件：./com/github/shynixn/mccoroutine/bukkit/impl: 'CoroutineSessionImpl$init$inlined$Runnable$1.class'。

环境细节 #

• Kotlin v1.9.0
• Kotlin插件 232-1.9.20-release-507-IJ10072.27
• Maven Shade插件 v3.5.1（v3.5.0版本也存在相同问题）
• Maven编译器插件 v3.11.0
• 已启用minimizeJar配置

构建日志 #

[INFO] Including com.github.shynixn.mccoroutine:mccoroutine-bukkit-api:jar:2.13.0 in the shaded jar.
[INFO] Including com.github.shynixn.mccoroutine:mccoroutine-bukkit-core:jar:2.13.0 in the shaded jar.

运行时错误日志 #

java.lang.RuntimeException: Failed to load MCCoroutine implementation. Shade mccoroutine-bukkit-core into your plugin.
        at com.github.shynixn.mccoroutine.bukkit.MCCoroutineKt$mcCoroutine$2.invoke(MCCoroutine.kt:20) ~[?:?]
        at com.github.shynixn.mccoroutine.bukkit.MCCoroutineKt$mcCoroutine$2.invoke(MCCoroutine.kt:15) ~[?:?]
        at me.sd_master92.kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74) ~[?:?]
        at com.github.shynixn.mccoroutine.bukkit.MCCoroutineKt.getMcCoroutine(MCCoroutine.kt:15) ~[?:?]
        at com.github.shynixn.mccoroutine.bukkit.MCCoroutineKt.getMinecraftDispatcher(MCCoroutine.kt:40) ~[?:?]
        at com.github.shynixn.mccoroutine.bukkit.MCCoroutineKt.launch$default(MCCoroutine.kt:85) ~[?:?]
        at me.sd_master92.customvoting.CV.enable(CV.kt:53) ~[?:?]
        at me.sd_master92.core.plugin.CustomPlugin.onEnable(CustomPlugin.kt:42) ~[?:?]
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:266) ~[spigot-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:342) ~[spigot-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:480) ~[spigot-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.craftbukkit.v1_20_R2.CraftServer.enablePlugin(CraftServer.java:548) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at org.bukkit.craftbukkit.v1_20_R2.CraftServer.enablePlugins(CraftServer.java:462) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at org.bukkit.craftbukkit.v1_20_R2.CraftServer.reload(CraftServer.java:970) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at org.bukkit.Bukkit.reload(Bukkit.java:834) ~[spigot-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.command.defaults.ReloadCommand.execute(ReloadCommand.java:27) ~[spigot-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:149) ~[spigot-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.craftbukkit.v1_20_R2.CraftServer.dispatchCommand(CraftServer.java:879) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at org.bukkit.craftbukkit.v1_20_R2.CraftServer.dispatchServerCommand(CraftServer.java:864) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at net.minecraft.server.dedicated.DedicatedServer.bf(DedicatedServer.java:412) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at net.minecraft.server.dedicated.DedicatedServer.b(DedicatedServer.java:388) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:1179) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:996) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at net.minecraft.server.MinecraftServer.lambda$0(MinecraftServer.java:298) ~[spigot-1.20.2-R0.1-SNAPSHOT.jar:3943-Spigot-7de1049-8e162d0]
        at java.lang.Thread.run(Thread.java:1583) ~[?:?]
Caused by: java.lang.ClassNotFoundException: com.github.shynixn.mccoroutine.bukkit.impl.MCCoroutineImpl
        at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:160) ~[spigot-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:112) ~[spigot-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
        at java.lang.Class.forName0(Native Method) ~[?:?]
        at java.lang.Class.forName(Class.java:421) ~[?:?]
        at java.lang.Class.forName(Class.java:412) ~[?:?]
        at com.github.shynixn.mccoroutine.bukkit.MCCoroutineKt$mcCoroutine$2.invoke(MCCoroutine.kt:17) ~[?:?]
        ... 24 more

解决方法 #

问题根源是Maven Shade插件的minimizeJar配置会移除它认为未被直接引用的类，而MCCoroutineImpl是通过反射加载的，Shade插件无法识别这种间接引用关系，导致被误删。

方案1：禁用minimizeJar #

在Maven Shade插件配置中删除minimizeJar参数，或者将其设置为false。此方法会保留所有依赖类，虽然jar体积会增大，但能彻底避免类被误删。

方案2：强制保留特定类 #

如果需要保留minimizeJar的优化功能，可以在Shade插件配置中添加过滤规则，强制保留mccoroutine-bukkit-core中impl包下的所有类：

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>3.5.1</version>
    <executions>
        <execution>
            <phase>package</phase>
            <goals>
                <goal>shade</goal>
            </goals>
            <configuration>
                <minimizeJar>true</minimizeJar>
                <filters>
                    <filter>
                        <artifact>com.github.shynixn.mccoroutine:mccoroutine-bukkit-core</artifact>
                        <includes>
                            <include>com/github/shynixn/mccoroutine/bukkit/impl/**</include>
                        </includes>
                    </filter>
                </filters>
            </configuration>
        </execution>
    </executions>
</plugin>

该配置会确保反射加载的实现类不会被Shade插件的最小化功能移除。

内容的提问来源于stack exchange，提问作者sd_master92