我目前正在尝试在运行时编译一个类，但由于某种原因它只能在一个系统上运行。两个系统都使用完全相同的代码并安装了相同的 java 版本，但是在一个系统上，我的 .java 文件编译为 .class，而在另一个系统上，我遇到了异常，因为某些类在或应该在找不到类路径。
我用来编译它的代码是这样的：
private static File compile(File file) {
try {
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
List<String> optionList = new ArrayList<>();
File jar = getJar(RuntimeCompiler.class);
File pluginDirectory = new File(jar.getAbsolutePath().substring(0, jar.getAbsolutePath().length() - jar.getName().length()));
String classes = buildClassPath(getJar(Bukkit.class).getAbsolutePath(), pluginDirectory.getAbsolutePath() + "/*");
optionList.addAll(Arrays.asList("-classpath",classes));
boolean success;
try (StandardJavaFileManager fileManager = compiler.getStandardFileManager( null, null, null )) {
Iterable<? extends JavaFileObject> units;
units = fileManager.getJavaFileObjectsFromFiles(Arrays.asList(file));
JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, null, optionList, null, units);
success = task.call();
}
if(success) {
return new File(file.getAbsolutePath().substring(0, file.getAbsolutePath().length() - 5) + ".class");
}
else {
return null;
}
} catch (IOException ex) {
Logger.getLogger(RuntimeCompiler.class.getName()).log(Level.SEVERE, null, ex);
return null;
}
}
private static String buildClassPath(String... paths) {
StringBuilder sb = new StringBuilder();
for (String path : paths) {
if (path.endsWith("*")) {
path = path.substring(0, path.length() - 1);
File pathFile = new File(path);
for (File file : pathFile.listFiles()) {
if (file.isFile() && file.getName().endsWith(".jar")) {
sb.append(path);
sb.append(file.getName());
sb.append(System.getProperty("path.separator"));
}
}
} else {
sb.append(path);
sb.append(System.getProperty("path.separator"));
}
}
String s = sb.toString();
s = s.substring(0,s.length() - 1);
return s;
}
包含必要文件的 Core-1.0-SNAPSHOT.jar 的类路径 (optionList.toString())。
[-classpath, /usr/local/gpx/users/user/127.0.0.1:25702/spigot.jar:25702/plugins/Core-1.0-SNAPSHOT.jar]
堆栈跟踪
/usr/local/gpx/users/user/127.0.0.1:25702/plugins/debug/DebugClass.java:1: error: package net.nowcraft.core does not exist
[14:04:10] [Server thread/WARN]: import net.nowcraft.core.core;
[14:04:10] [Server thread/WARN]: ^
[14:04:10] [Server thread/WARN]: /usr/local/gpx/users/user/127.0.0.1:25702/plugins/debug/DebugClass.java:2: error: package net.nowcraft.core.RuntimeCompiler does not exist
[14:04:10] [Server thread/WARN]: import net.nowcraft.core.RuntimeCompiler.Debugger
[14:04:10] [Server thread/WARN]:
[14:04:10] [Server thread/WARN]: /usr/local/gpx/users/user/127.0.0.1:25702/plugins/debug/DebugClass.java:7: error: method does not override or implement a method from a supertype
[14:04:10] [Server thread/WARN]: @Override
[14:04:10] [Server thread/WARN]: ^
[14:04:10] [Server thread/WARN]: 3 errors
[14:04:10] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'rd' in plugin NowCraftCore v1.0
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[spigot.jar:git-Spigot-330d66b-fe41b01]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) ~[spigot.jar:git-Spigot-330d66b-fe41b01]
at org.bukkit.craftbukkit.v1_8_R1.CraftServer.dispatchCommand(CraftServer.java:642) ~[spigot.jar:git-Spigot-330d66b-fe41b01]
at net.minecraft.server.v1_8_R1.PlayerConnection.handleCommand(PlayerConnection.java:1115) [spigot.jar:git-Spigot-330d66b-fe41b01]
at net.minecraft.server.v1_8_R1.PlayerConnection.a(PlayerConnection.java:950) [spigot.jar:git-Spigot-330d66b-fe41b01]
at net.minecraft.server.v1_8_R1.PacketPlayInChat.a(PacketPlayInChat.java:26) [spigot.jar:git-Spigot-330d66b-fe41b01]
at net.minecraft.server.v1_8_R1.PacketPlayInChat.a(PacketPlayInChat.java:53) [spigot.jar:git-Spigot-330d66b-fe41b01]
at net.minecraft.server.v1_8_R1.PacketHandleTask.run(SourceFile:13) [spigot.jar:git-Spigot-330d66b-fe41b01]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_25]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_25]
at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:683) [spigot.jar:git-Spigot-330d66b-fe41b01]
at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316) [spigot.jar:git-Spigot-330d66b-fe41b01]
at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:623) [spigot.jar:git-Spigot-330d66b-fe41b01]
at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:526) [spigot.jar:git-Spigot-330d66b-fe41b01]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25]
Caused by: java.lang.NullPointerException
at net.nowcraft.core.RuntimeCompiler.RuntimeCompiler.load(RuntimeCompiler.java:127) ~[?:?]
at net.nowcraft.core.RuntimeCompiler.RuntimeCompiler.loadHastebin(RuntimeCompiler.java:88) ~[?:?]
at net.nowcraft.core.RuntimeCompiler.RuntimeCompiler.debugFromHastebin(RuntimeCompiler.java:170) ~[?:?]
at net.nowcraft.core.commands.RuntimeDebug.onCommand(RuntimeDebug.java:35) ~[?:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[spigot.jar:git-Spigot-330d66b-fe41b01]
... 14 more
编辑：我还在不同的目录中对其进行了测试，但没有奏效。当我在本地 Windows 笔记本电脑上使用代码时，它确实可以工作。
编辑 2：这似乎是 CentOS 的一个问题，因为它也不能在第二个 CentOS 系统上运行。