Re: Lookup BCEL Method for a particular java.lang.reflect.Method / Create JavaClass from java.lang.Class

I went with a slightly different solution, by Constructing the signature for the
java.lang.reflect.Method and check with org.apache.bcel.classfile.Method's getSignature(). One
more use case we has was to construct a JavaClass given a java.lang.Class. See BCEL.java at
http://cvs.apache.org/viewcvs.cgi/xml-axis/java/src/org/apache/axis/utils/bytecode/ on how we got
around both problems. 

Wish #1: Wish this was a helper method in JavaClass with the following Signature
public org.apache.bcel.classfile.Method getMethod(java.lang.reflect.Method). 

Wish #2: Wish i could create a JavaClass from java.lang.Class as shown below.
Class clazz = Class.forName("XXXX");
ClassParser parser = new ClassParser(clazz);
JavaClass jclazz = parser.parse();

I can send in patches for both if anyone is interested.

Thanks,
dims

--- Juozas Baliuka <[email protected]> wrote:
> 
> if declaring class is the same, you can loop and compare method names and 
> argument type names returned from reflection and BCEL method representations.
> 
> 
> At 04:25 2002.06.12 -0700, Davanum Srinivas wrote:
> >Folks,
> >
> >Can someone help me port from serp/tt-bytecode to BCEL? We construct a 
> >JavaClass from a
> >java.lang.Class (see code below).  We have a java.lang.reflect.Method for 
> >which we need to find
> >the corresponding org.apache.bcel.classfile.Method. How do i do it? 
> >java.lang.reflect.Method's
> >toString() and org.apache.bcel.classfile.Method's toString() don't really 
> >output the same stuff.
> >
> >We need to get this information to move Apache Axis 
> >(http://xml.apache.org/axis/) from
> >Serp/tt-bytecode to BCEL.
> >
> >Thanks in Advance,
> >dims
> >
> >----------------------------------------------------------------------------------------------
> >     /**
> >      * Get Parameter Names using BCEL
> >      *
> >      * @param method the Java method we're interested in
> >      * @return list of names or null
> >      */
> >     public String[] 
> > getParameterNamesFromDebugInfo(java.lang.reflect.Method m) {
> >         Class c = m.getDeclaringClass();
> >         int numParams = m.getParameterTypes().length;
> >         Vector temp = new Vector();
> >
> >         // Don't worry about it if there are no params.
> >         if (numParams == 0)
> >             return null;
> >
> >         // Try to obtain a tt-bytecode class object
> >         JavaClass bclass = (JavaClass) clazzCache.get(c);
> >
> >         if (bclass == null) {
> >             try {
> >                 String className = c.getName();
> >                 String classFile = className.replace('.', '/');
> >                 InputStream is =
> >                         c.getClassLoader().getResourceAsStream(classFile 
> > + ".class");
> >
> >                 ClassParser parser = new ClassParser(is, className);
> >                 bclass = parser.parse();
> >
> >                 clazzCache.put(c, bclass);
> >             } catch (IOException e) {
> >                 // what now?
> >             }
> >         }
> >
> >         Method[] methods = bclass.getMethods();
> >         Method method = null;
> >         // HOW DO I GET THE BCEL METHOD CORRESPONDING TO
> >         // a java.lang.reflect.Method?
> >         for (int i = 0; i < methods.length; i++) {
> >             if (m.getName() == methods[i].getName() &&
> >                     m.toString().equals(methods[i].toString())) {
> >                 method = methods[i];
> >                 break;
> >             }
> >         }
> >
> >         // Obtain the exact method we're interested in.
> >         if (method == null)
> >             return null;
> >
> >         // Get the Code object, which contains the local variable table.
> >         Code code = method.getCode();
> >         if (code == null)
> >             return null;
> >
> >         LocalVariableTable attr = method.getLocalVariableTable();
> >         if (attr == null)
> >             return null;
> >
> >         // OK, found it.  Now scan through the local variables and record
> >         // the names in the right indices.
> >         LocalVariable[] vars = attr.getLocalVariableTable();
> >
> >         String[] argNames = new String[numParams + 1];
> >         argNames[0] = null; // don't know return name
> >
> >         // NOTE: we scan through all the variables here, because I have been
> >         // told that jikes sometimes produces unpredictable ordering of the
> >         // local variable table.
> >         for (int j = 0; j < vars.length; j++) {
> >             LocalVariable var = vars[j];
> >             if (!var.getName().equals("this")) {
> >                 if (temp.size() < var.getIndex() + 1)
> >                     temp.setSize(var.getIndex() + 1);
> >                 temp.setElementAt(var.getName(), var.getIndex());
> >             }
> >         }
> >         int k = 0;
> >         for (int j = 0; j < temp.size(); j++) {
> >             if (temp.elementAt(j) != null) {
> >                 k++;
> >                 argNames[k] = (String) temp.elementAt(j);
> >                 if (k + 1 == argNames.length)
> >                     break;
> >             }
> >         }
> >         return argNames;
> >     }
> >----------------------------------------------------------------------------------------------
> >
> >=====
> >Davanum Srinivas - http://xml.apache.org/~dims/
> >
> >__________________________________________________
> >Do You Yahoo!?
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> >
> >--
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> 
> 
> 
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> 


=====
Davanum Srinivas - http://xml.apache.org/~dims/

__________________________________________________
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Yahoo! - Official partner of 2002 FIFA World Cup
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