Create arbitrary Java class at runtime

Does anyone know of a开发者_如何学JAVAny Java libraries that would allow me to define a new Java class at runtime and also instantiate an instance of that class?

---

ASM is an all purpose Java bytecode manipulation and analysis framework. It can be used to modify existing classes or dynamically generate classes, directly in binary form.

---

I'm not sure whether this is what you're looking for but consider Javassist or cglib library.

Javassist (Java Programming Assistant) makes Java bytecode manipulation simple. It is a class library for editing bytecodes in Java; it enables Java programs to define a new class at runtime and to modify a class file when the JVM loads it. [...]

cglib is a powerful, high performance and quality Code Generation Library, It is used to extend JAVA classes and implements interfaces at runtime. [...]

---

If you don't want to work at bytecode level, a possible solution is to use the Compiler API of Java SE 6. See here for an example.

---

Java's Proxy class can be used to create dynamic classes that implement specific interfaces at runtime. Such classes use an InvocationHandler to handle method calls.