【发布时间】：2014-12-22 18:30:01
【问题描述】：
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： 我也在不同的目录中测试过，没有用。当我在本地 Windows 笔记本电脑上使用该代码时，它确实可以工作。
编辑 2： 这似乎是 CentOS 的问题，因为它也不能在第二个 CentOS 系统上运行。
【问题讨论】：
-
你能发布堆栈跟踪吗？
-
您是否验证了依赖类实际上可以在发生编译失败的系统的类路径中找到？另外，您是否验证过“问题”系统与成功实例的 java 版本相同？
-
@avgvstvs 是的，它们确实具有相同的 Java 版本 (1.8)，我使用堆栈跟踪编辑了主要帖子。
-
我有一半的想法暗示 javac 可能无法解析您指定的 URL 中的网络链接。尝试为 lib 文件使用非网络位置，即，只需将它们放在相对于您正在构建的目录的
lib文件夹中。 -
这不是一个网络位置，它是一个名为 127.0.0.1:25702 的目录
标签： java compilation classpath runtime-compilation