Question

我目前正在尝试在运行时编译一个类，但出于某种原因，它只在一个系统上工作。两个系统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得到异常，因为某些类是或应该是，在类路径中找不到。

我用来编译它的代码是：

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classpath（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。当我在我的本地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的一个问题，因为它不在第二个CentOS系统上工作。

Answer 1

Stacktrace帮助极大，以及周围的环境。

这里的问题是linux。所以你想要点击的目录：

/usr/local/gpx/users/user/127.0.0.1:25702/plugins/debug/DebugClass.java

正在寻找名为127.0.0.1:25702的目录（尽管:必须进行转义，因为大多数shell使用:作为语法字符。

您的网络地址将映射到特定目录。您将不得不创建网络共享（不熟悉CentOS，但通常非常简单），以消除对物理存在的位置的网络引用。如果您可以从命令行cd，那么您的Java运行时应该能够实际引用它。

Here is a reference用于在CentOS上安装远程文件系统。是的，我知道127.0.0.1:25702在技术上是＆＃34; localhost＆＃34;但是命令shell和java运行时都不知道如何以你想要的方式解析网络地址。它适用于Windows，因为Windows API更宽容。

Answer 2

我猜你在本地使用Windows而unix用于远程服务器？ unix机器上java的classpath分隔符是“：”，你有一个名称中带有“：”的目录，unix编译器可能会用“：”分割目录名。您是否尝试在文件/目录名称中不包含“：”的非工作计算机上使用类路径？

使用classpath在运行时编译类

2 个答案: