bytecode

Using JRuby/Jython for Ruby/Python interoperability?

由 房东的猫 提交于 2019-12-06 20:59:54
问题 Quite-probably a silly question, as I don't know much about Java/Jython/JRuby/bytecode, but.. I stumbled across _why's unholy again today.. It allows you to output Python bytecode from Ruby code.. Basically allowing them to produce the same bytecode.. Jython outputs Java bytecode, as does JRuby.. Since these both compile to the same bytecode, does this mean you could potentially use any Python library from Ruby, and Ruby libraries from Python? 回答1: No, that won't work. At least not the way

Is it possible to track down which expression caused an NPE?

由 泄露秘密 提交于 2019-12-06 18:29:57
问题 When I get an NPE, I'll get a stack trace with line number. That's helpful, but if the line is very dense and/or contains nested expression, it's still impossible to figure out which reference was null. Surely, this information must've been available somewhere. Is there a way to figure this out? (If not java expression, then at least the bytecode instruction that caused NPE would be helpful as well) Edit #1: I've seen a few comments suggesting breaking up the line, etc, which, no offence, is

Custom Class Loader In Java [closed]

由 半世苍凉 提交于 2019-12-06 16:29:18
问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . Is it possible to make my own Custom Class Loader In java. If Yes Then Please Guide me. Instead of class obfuscation I want to change in class file so that it cant be reversed by any tool 回答1: You can use some obfuscation tools, like ProGuard. A self written ClassLoader, must be placed in a standard .class file,

Is there a tool that we could use to compare two Jars at Binary/Byte code level? [closed]

由 ▼魔方 西西 提交于 2019-12-06 16:05:33
Closed. This question is off-topic . It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 5 years ago . The idea is to compare two jars and see if they were generated from same source and compare if they're identical at Binary/Byte code level. Also if they're both compiled with the same compiler i.e. Eclipse JDT or JIT etc compiler. I've looked at Apache Common BCEL, but it only does comparison after decomposing the original byte-code into source code and then it compares it like diff tool; that compares text line

How can I create a 48-bit uint for bit mask

由 戏子无情 提交于 2019-12-06 15:16:05
问题 I am trying to create a 48-bit integer value. I understand it may be possible to use a char array or struct, but I want to be able to do bit masking/manipulation and I'm not sure how that can be done. Currently the program uses a 16-bit uint and I need to change it to 48. It is a bytecode interpreter and I want to expand the memory addressing to 4GB. I could just use 64-bit, but that would waste a lot of space. Here is a sample of the code: unsigned int program[] = { 0x1064, 0x11C8, 0x2201,

Encrypted class files with decryption handled by a native library

由 与世无争的帅哥 提交于 2019-12-06 14:58:43
问题 The article "Cracking Java byte-code encryption" (javaworld.com/javaworld/javaqa/2003-05/01-qa-0509-jcrypt.html) explains why class file encryption using a custom class loader is pointless, because at some point you always need to call defineClass(), which passes the class file to the JVM as an unencrypted byte array. However I've seen solutions where a slightly different approach is used; the class is decrypted by a native library and handed over to the JVM as a java.lang.Class instance

Which one to use cglib or javaassist

由 我的梦境 提交于 2019-12-06 13:57:27
what is the difference between working of cglib and javaassist Does cglib creates proxies runtime? How does javaassist creates proxies? What is bytecode instrumentation? How hibernate uses these libraries? The best bytecode manipulation library is ASM ( http://asm.ow2.org/ ). It's really fast and simple to understand. Ravindra babu Byte Buddy is a code generation library for creating Java classes during the runtime of a Java application and without the help of a compiler. Other than the code generation utilities, it allows the creation of arbitrary classes and is not limited to implementing

write java object into class file

由 情到浓时终转凉″ 提交于 2019-12-06 11:15:42
Is there any way to write a loaded Java object into a .class file or is there any other type of file that can easily be read to represent an instance's properties. For example, CGLIB will create an proxy bean which extends another, i really want to export this enhanced bean out to a file to see how it was enhanced. For cglib, instances can only be serialized and only if the instance's method interceptors support serialization. There is no other way. In order to get hold of a cglib-generated class file, you can call the void generateClass(ClassVisitor v) method. This method can take an ASM

Getting name and type of local variables from a Java program

由 走远了吗. 提交于 2019-12-06 10:23:19
This is the code which I am trying out: JavaCompiler compilerA = ToolProvider.getSystemJavaCompiler(); int resultA = compilerA.run(null,null,null,"/Users/a/Documents/Java/a.java"); System.out.println("Compile result code = " + resultA); File fileA = new File("/Users/a/Documents/Java/a.class"); JavaCompiler compilerB = ToolProvider.getSystemJavaCompiler(); int resultB = compilerB.run(null,null,null,"/Users/a/Documents/Java/b.java"); System.out.println("Compile result code = " + resultB); File fileB = new File("/Users/a/Documents/Java/b.class"); Here I am compiling a Java class and then using

Caching generated classes in Byte Buddy?

由 随声附和 提交于 2019-12-06 09:01:21
问题 I have been using CGLIB's Enhancer for a while, but considering to switch over to Byte Buddy. It's pretty basic stuff, proxy for up to a few hundred data access interfaces, created on demand. Enhancer enhancer = new Enhancer(); enhancer.setClassLoader(...); enhancer.setSuperclass(...); enhancer.setInterfaces(...); enhancer.setCallback(...); enhancer.create(); CGLIB is caching the generated type to improve performance. What is the recommended approach with Byte Buddy? I want to avoid any
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