import gnu.bytecode.Method; //导入依赖的package包/类
static byte[] gnuByteCodeHelloWorld() {
    ClassType c = new ClassType("HelloWorld");
    c.setSuper("java.lang.Object");
    c.setModifiers(Access.PUBLIC);
    c.setSourceFile("HelloWorld.java");

    Method m = c.addMethod("<init>", "()V", Access.PUBLIC);
    CodeAttr code = m.startCode();
    code.pushScope();
    code.emitPushThis();
    code.emitInvokeSpecial(objectCtor);
    code.emitReturn();
    code.popScope();

    m = c.addMethod("main", "([Ljava/lang/String;)V", Access.PUBLIC
            | Access.STATIC);
    code = m.startCode();
    code.pushScope();
    code.emitGetStatic(outField);
    code.emitPushString("Hello world!");
    code.emitInvokeVirtual(printlnMethod);
    code.emitReturn();
    code.popScope();

    return c.writeToArray();
}