Java：如何将存储为byte []的类加载到JVM中？

问题描述

如果有人将整个.class文件序列化为byte []，并假设该类的名称已知（与byte []一起传递），那么如何转换byte [] - > Class - >然后加载它到JVM以便我以后可以通过调用Class.forName（）来使用它？

If one has serialized the entire .class file into byte[], and assuming the name of the class is known (passed along with the byte[]), how do you convert byte[] -> Class -> then load it to the JVM so that I could later use it by calling the Class.forName()?

注意：
我'这样做是因为我将.class发送到另一台主机，并且主机的JVM不知道这个.class。

NOTE:I'm doing this because I sent the .class over to another host, and the host's JVM doesn't know about this .class.

推荐答案

I'm actually using something like this right now in a test to give a set of Class definitions as byte[] to a ClassLoader:

  public static class ByteClassLoader extends URLClassLoader {
    private final Map<String, byte[]> extraClassDefs;

    public ByteClassLoader(URL[] urls, ClassLoader parent, Map<String, byte[]> extraClassDefs) {
      super(urls, parent);
      this.extraClassDefs = new HashMap<String, byte[]>(extraClassDefs);
    }

    @Override
    protected Class<?> findClass(final String name) throws ClassNotFoundException {
      byte[] classBytes = this.extraClassDefs.remove(name);
      if (classBytes != null) {
        return defineClass(name, classBytes, 0, classBytes.length);
      }
      return super.findClass(name);
    }

  }

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