Re: Lookup BCEL Method for a particular java.lang.reflect.Method

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/
>
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