[jboss-user] [Javassist user questions] - Can I instrument CodeConverter at runtime?
Hi everybody,
I'm trying to modify a method of my custom CodeConverter at runtime, as the
instrumentation is based on the content of a configuration file. I'm stuck at the
error You can see below.
Actually I wrote this:
| public class Main {
|
| public static void main(String[] args) throws Throwable {
|
| ClassPool cp = ClassPool.getDefault();
| Loader loader = new Loader(Main.class.getClassLoader(),cp);
|
| // Get the class and instrument
| CtClass conv = cp.get("pkg.CustomConverter");
| CtMethod m = conv.getDeclaredMethod("init");
| StringBuffer sb = new StringBuffer();
| sb.append("{\n");
| sb.append("CtMethod m1 =
thePool.get(\"pkg.Hello\").getDeclaredMethod(\"say\");\n");
| sb.append("CtMethod m2 =
thePool.get(\"pkg.Hello\").getDeclaredMethod(\"first\");\n");
| sb.append("insertBeforeMethod(m1, m2);\n");
| sb.append("}\n");
| m.setBody(sb.toString()); // (*) Here I got the error shown below
|
| CustomConverter conv = (CustomConverter) conv.toClass().newInstance();
| CustXlator xlat = new CustXlator(conv);
|
| loader.addTranslator(cp, xlat);
| loader.run(args); // Loads and runs the class pkg.Hello
| }
|
| }
|
CustXlator's onLoad method does simply:
| if (className.equals("pkg.Hello")) {
| CtClass c = pool.get(className);
| c.instrument(converter);
| // converter is an instance of CustomConverter passed as
| // the only parameter to CustXlat constructor
| }
|
while CustomConverter has only the init method that I'm trying to instrument.
I'm stuck at an exception occourring during setBody execution. The stacktrace is:
| javassist.CannotCompileException: [source error] no such class: CtMethod
| at javassist.CtBehavior.setBody(CtBehavior.java:346)
| at javassist.CtBehavior.setBody(CtBehavior.java:315)
| at pkg.Main.main(Main.java:29)
| Caused by: compile error: no such class: CtMethod
| at javassist.compiler.MemberResolver.searchImports(MemberResolver.java:416)
| at javassist.compiler.MemberResolver.lookupClass(MemberResolver.java:392)
| at javassist.compiler.MemberResolver.lookupClassByJvmName(MemberResolver.java:310)
| at javassist.compiler.MemberResolver.resolveJvmClassName(MemberResolver.java:460)
| at javassist.compiler.MemberCodeGen.resolveClassName(MemberCodeGen.java:1064)
| at javassist.compiler.CodeGen.atDeclarator(CodeGen.java:698)
| at javassist.compiler.ast.Declarator.accept(Declarator.java:99)
| at javassist.compiler.CodeGen.atStmnt(CodeGen.java:344)
| at javassist.compiler.ast.Stmnt.accept(Stmnt.java:49)
| at javassist.compiler.CodeGen.atStmnt(CodeGen.java:344)
| at javassist.compiler.ast.Stmnt.accept(Stmnt.java:49)
| at javassist.compiler.CodeGen.atMethodBody(CodeGen.java:285)
| at javassist.compiler.Javac.compileBody(Javac.java:212)
| at javassist.CtBehavior.setBody(CtBehavior.java:340)
| ... 2 more
|
It seems that CustomConverter was unable to resolve CtMethod class!!!
But if I statically modify the init method all is ok.
I really don't know how to solve the problem.
Can someone help me? I'll appreciate it very much!
Thanks in advance, Mauro.
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