从课程中获取完整的课程路径 [英] getting full classpath from a class

问题描述

我正在寻找一种实用程序方法，以便给定一个类将返回在外部运行该类所需的完整类路径。这意味着该类所在的jar以及它使用的所有类的jar（或文件夹）。

I'm looking a utility method so that given a class will return the full classpath required to run this class externally. This means the jar the class is in as well as all jars (or folders) of classes that it uses.

更新：有些工具可以分析.class文件来查找依赖关系。这不是我想要的。我正在寻找在已加载的类上使用Java的反射API的东西。我将解决一些分析字节码的问题，如果它可以通过类加载器递归地进入它所找到的类中

UPDATE: there are tools that analyze .class files to find dependencies. This is not what I'm looking for. I'm looking for something that uses Java's reflection API on an already loaded class. I'll settle for something that analyzes byte code, if it goes recursively into classes it finds through the class loader

推荐答案

反射将对此没有太大帮助。您将需要分析字节码以找到依赖关系。

Reflection will not help you a lot for this one. You will need to analyse the byte code to find dependencies.

更新：

然后。我正在使用几年前制作的库，您可以在此处下载。

Alright then. I am using a library that I made years ago, that you can download here.

以下代码：

package classdep;

import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import org.jedo.classfile.ClassFile;
import org.jedo.classfile.ConstantPool;

public class Main {

    public static void main(String[] args) {
        try {
            ClassLoader cl = Thread.currentThread().getContextClassLoader();
            List<String> classes = new ArrayList<String>();
            classes.add(args[0].replace('.', '/'));
            for (int i = 0; i < classes.size(); ++i) {
                String className = classes.get(i);
                URL url = cl.getResource(className + ".class");
                if (url == null) {
                    System.out.println("--- class not found " + className);
                } else {
                    System.out.println(url);
                    ClassFile classFile = new ClassFile();
                    InputStream in = url.openStream();
                    try {
                        classFile.load(in);
                    } finally {
                        in.close();
                    }
                    ConstantPool cp = classFile.getConstantPool();
                    for (String name: cp.getClassNames()) {
                        if (!classes.contains(name)) {
                            classes.add(name);
                        }
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

将为您提供所有依赖项一堂课应用于org.jedo.classfile.ClassFile时，它将产生以下输出：

Will give you all the dependencies of a class. When applied to org.jedo.classfile.ClassFile, it produces the following output:

file:/D:/projects/casagrande/jedo/build/classes/org/jedo/classfile/ClassFile.class
file:/D:/projects/casagrande/jedo/build/classes/org/jedo/classfile/ConstantPool.class
file:/D:/projects/casagrande/jedo/build/classes/org/jedo/classfile/FieldInfo.class
file:/D:/projects/casagrande/jedo/build/classes/org/jedo/classfile/MethodInfo.class
file:/D:/projects/casagrande/jedo/build/classes/org/jedo/classfile/AttributeInfo.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/io/File.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/io/FileInputStream.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/io/DataInputStream.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/io/StreamCorruptedException.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/io/FileOutputStream.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/io/DataOutputStream.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/lang/StringBuilder.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/lang/StringBuffer.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/lang/Object.class
jar:file:/C:/Program%20Files/Java/jdk1.6.0_18/jre/lib/rt.jar!/java/io/IOException.class
...

后面有很多系统类。您需要过滤掉系统类，并解析其他URL以提取.jar文件（如果是jar：url）或目录（如果是文件：url）。

Followed by a lot of system classes. You need to filter out system classes, and parse the other urls to extract either the .jar file if it is a jar: url, or the directory if it is a file: url.

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