bytecode

问题 I have a .JAR file and it has tons of classes. One, that I need is set as final, so I cannot extend it. There is one method, that I basically have to extend and fix, otherwise everything breaks. How can I do that? I know Reflection and Javassist can be used for this, but I have no idea how. Any other tool is also acceptable, as long as it works. 回答1: You can't use reflection to modify existing class definitions. If the licence of that JAR allows you to, I would suggest a different solution:

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . Lately I've been thinking about the difference about native and bytecode. I did some research and all information I've read was about

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 4 years ago . There are a few questions regarding this (like Java: Prefix/postfix of increment/decrement operators?) but I'm not asking about the general difference between postfix and prefix ++ operators (I know that part), but about the fundamental difference between them at the Java

问题 I want to add instructions to the code of methods. These instructions should be executed after reaching and before leaving the method. In order to make sure that the latter instructions are always executed before leaving I want to put these in a finally block. (I know the class AdviceAdapter but it does not ensure the execution of exit-code when an invoked method throws an exception.) My problem is that the instructions in the result are in the wrong order. Method to be processed: @Test

问题 At this moment I participate in big legacy project with many huge classes and generated code. I wish to find all methods that have bytecode length bigger than 8000 bytes (because OOTB java will not optimize it). I found manual way like this: How many bytes of bytecode has a particular method in Java? , however my goal is to scan many files automatically. I tried to use jboss-javassist, but AFAIK getting bytecode length is available only on class level. 回答1: Huge methods might indeed never get

问题 I have the following Java code: public int sign(int a) { if(a<0) return -1; else if (a>0) return 1; else return 0; } which when compiled generated the following bytecode: public int sign(int); Code: 0: iload_1 1: ifge 6 4: iconst_m1 5: ireturn 6: iload_1 7: ifle 12 10: iconst_1 11: ireturn 12: iconst_0 13: ireturn I want to know how the byte offset count (the first column) is calculated, in particular, why is the byte count for the ifge and ifle instructions 3 bytes when all the other

问题 I found the following construction in legacy java bytecode while trying to troubleshoot server application startup. My IDE decompiled some third party libraries and I'm curious how this can be valid - never saw before keywords can be used as field names in bytecode. Bytecode version is 48.0 (Java 1.4). public final class f implements UserContext{ private final String try; private final UserInfo do; // a lot of code here public UserInfo getUserInfo(){ return this.do; } public String

问题 I am using byte-buddy to build an ORM on top of Ignite, we need to add a field to a class and then access it in a method interceptor.. So here's an example where I add a field to a class final ByteBuddy buddy = new ByteBuddy(); final Class<? extends TestDataEnh> clz = buddy.subclass(TestDataEnh.class) .defineField("stringVal",String.class) .method(named("setFieldVal")).intercept( MethodDelegation.to(new SetterInterceptor()) ) .make() .load(getClass().getClassLoader(), ClassLoadingStrategy

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: while (1) Vs. for while(True) — Why is there a difference? I see sometimes in other people code "while 1" instead of "while True". I think using True is more pythonic, but I wanted to check if there is any difference in practice. So I tried to do the following, and the result is surprising. For what I can see it looks like the interpreter can optimize away the 1 boolean conversion while it doesn't with the True,

问题 I'm trying to intercept constructor calls with Byte Buddy, this is my sample code: package t; import static net.bytebuddy.dynamic.loading.ClassLoadingStrategy.Default.INJECTION; import static net.bytebuddy.implementation.MethodDelegation.to; import static net.bytebuddy.matcher.ElementMatchers.any; import java.util.concurrent.Callable; import net.bytebuddy.ByteBuddy; import net.bytebuddy.implementation.bind.annotation.RuntimeType; import net.bytebuddy.implementation.bind.annotation.SuperCall;