获取JAR文件的位置

Question

我正在尝试获取运行Runnable JAR文件的位置

try {
    String path = new java.io.File(".").getCanonicalPath();
} catch (IOException e) {
    e.printStackTrace();
}

但结果是：

C:\Users\Kevin\Desktop/server/Server

而JAR文件位于

C:\Users\Kevin\Desktop

我也试过

return new file(Server.class.getProtectionDomain().getCodeSource().getLocation().getPath());

但结果是：

C:\Users\Kevin\Desktop\server.jar/server/Server

所以基本上我想要的是JAR文件的路径，而不是类路径，而不是文件名。

有办法吗？

Answer 1

在我最终找到一个有效的解决方案之前，我不得不胡思乱想了很多
可能jarLocation带有前缀，如file:\或jar:file\，可以使用String#substring（）删除。

URL jarLocationUrl = MyClass.class.getProtectionDomain().getCodeSource().getLocation();
String jarLocation = new File(jarLocationUrl.toString()).getParent();

Answer 2

下面是我计算jar目录的版本

/**
 * Compute the absolute file path to the jar file.
 * The framework is based on http://stackoverflow.com/a/12733172/1614775
 * But that gets it right for only one of the four cases.
 * 
 * @param aclass A class residing in the required jar.
 * 
 * @return A File object for the directory in which the jar file resides.
 * During testing with NetBeans, the result is ./build/classes/,
 * which is the directory containing what will be in the jar.
 */
public static File getJarDir(Class aclass) {
    URL url;
    String extURL;      //  url.toExternalForm();

    // get an url
    try {
        url = aclass.getProtectionDomain().getCodeSource().getLocation();
          // url is in one of two forms
          //        ./build/classes/   NetBeans test
          //        jardir/JarName.jar  froma jar
    } catch (SecurityException ex) {
        url = aclass.getResource(aclass.getSimpleName() + ".class");
        // url is in one of two forms, both ending "/com/physpics/tools/ui/PropNode.class"
        //          file:/U:/Fred/java/Tools/UI/build/classes
        //          jar:file:/U:/Fred/java/Tools/UI/dist/UI.jar!
    }

    // convert to external form
    extURL = url.toExternalForm();

    // prune for various cases
    if (extURL.endsWith(".jar"))   // from getCodeSource
        extURL = extURL.substring(0, extURL.lastIndexOf("/"));
    else {  // from getResource
        String suffix = "/"+(aclass.getName()).replace(".", "/")+".class";
        extURL = extURL.replace(suffix, "");
        if (extURL.startsWith("jar:") && extURL.endsWith(".jar!"))
            extURL = extURL.substring(4, extURL.lastIndexOf("/"));
    }

    // convert back to url
    try {
        url = new URL(extURL);
    } catch (MalformedURLException mux) {
        // leave url unchanged; probably does not happen
    }

    // convert url to File
    try {
        return new File(url.toURI());
    } catch(URISyntaxException ex) {
        return new File(url.getPath());
    }
}

Answer 3

使现代化

由于它在某些测试用例中不起作用，我将更新答案。

正确的方法应该是使用ClassLoader：

File jarDir = new File(ClassLoader.getSystemClassLoader().getResource(".").getPath());
System.out.println(jarDir.getAbsolutePath());

在不同的类路径上测试，结果是正确的。

老生常谈

这应该管用

File f = new File(System.getProperty("java.class.path"));
File dir = f.getAbsoluteFile().getParentFile();
String path = dir.toString();

它为我工作，我的程序在：

C:\Users\User01\Documents\app1\dist\JavaApplication1.jar

然后它返回

C:\Users\User01\Documents\app1\dist