Isolate classId x methodId -> Method algorithm in AMQImpl: getMethodClass(int, int);

use reflection to invoke constructor in readMethodFrom().

Author: Steve Powell

codegen.py

@@ -416,6 +416,7 @@ def printHeader():
         print
         print "import java.io.IOException;"
         print "import java.io.DataInputStream;"
+        print "import java.lang.reflect.Constructor;"
         print "import java.util.Collections;"
         print "import java.util.HashMap;"
         print "import java.util.Map;"
@@ -428,7 +429,6 @@ def printHeader():
     def printClassMethods(spec, c):
         print
         print "    public static class %s {" % (java_class_name(c.name))
-        print "        public static final int INDEX = %s;" % (c.index)
         for m in c.allMethods():
 
             def getters():
@@ -464,9 +464,9 @@ def constructors():
 
             def others():
                 print
-                print "            public int protocolClassId() { return %s; }" % (c.index)
-                print "            public int protocolMethodId() { return %s; }" % (m.index)
-                print "            public String protocolMethodName() { return \"%s.%s\";}" % (c.name, m.name)
+                print "            public int protocolClassId() { return PROTOCOL_CLASS_ID; }"
+                print "            public int protocolMethodId() { return PROTOCOL_METHOD_ID; }"
+                print "            public String protocolMethodName() { return PROTOCOL_METHOD_NAME; }"
                 print
                 print "            public boolean hasContent() { return %s; }" % (trueOrFalse(m.hasContent))
                 print
@@ -503,8 +503,9 @@ def write_arguments():
             print "            extends Method"
             print "            implements com.rabbitmq.client.AMQP.%s.%s" % (java_class_name(c.name), java_class_name(m.name))
             print "        {"
-            print "            public static final int INDEX = %s;" % (m.index)
-            print
+            print "            private static final int PROTOCOL_CLASS_ID = %s;" % (c.index)
+            print "            private static final int PROTOCOL_METHOD_ID = %s;" % (m.index)
+            print "            public static final String PROTOCOL_METHOD_NAME = \"%s.%s\";" % (c.name, m.name)
             for a in m.arguments:
                 print "            private final %s %s;" % (java_field_type(spec, a.domain), java_field_name(a.name))
 
@@ -534,24 +535,37 @@ def printMethodVisitor():
                print "        public Object visit(%s.%s x) throws IOException { throw new UnexpectedMethodError(x); }" % (java_class_name(c.name), java_class_name(m.name))
         print "    }"
 
-    def printMethodArgumentReader():
+    def printGetMethodClassMethod():
         print
-        print "    public static Method readMethodFrom(DataInputStream in) throws IOException {"
-        print "        int classId = in.readShort();"
-        print "        int methodId = in.readShort();"
+        print "    public static Class<? extends Method> getMethodClass(int classId, int methodId) {"
         print "        switch (classId) {"
         for c in spec.allClasses():
             print "            case %s:" % (c.index)
             print "                switch (methodId) {"
             for m in c.allMethods():
                 fq_name = java_class_name(c.name) + '.' + java_class_name(m.name)
                 print "                    case %s: {" % (m.index)
-                print "                        return new %s(new MethodArgumentReader(in));" % (fq_name)
+                print "                        return %s.class;" % (fq_name)
                 print "                    }"
             print "                    default: break;"
             print "                } break;"
         print "        }"
         print
+        print "        return null;"
+        print "    }"
+
+    def printMethodArgumentReader():
+        print
+        print "    public static Method readMethodFrom(DataInputStream in) throws IOException {"
+        print "        int classId = in.readShort();"
+        print "        int methodId = in.readShort();"
+        print "        Class<? extends Method> clazz = getMethodClass(classId, methodId);"
+        print "        if (clazz != null) {"
+        print "            try {"
+        print "                Constructor<? extends Method> cons = clazz.getConstructor(MethodArgumentReader.class);"
+        print "                return cons.newInstance(new MethodArgumentReader(in));"
+        print "            } catch (Exception e) { /*ignore*/ }"
+        print "        }"
         print "        throw new UnknownClassOrMethodId(classId, methodId);"
         print "    }"
 
@@ -576,6 +590,7 @@ def printContentHeaderReader():
     for c in spec.allClasses(): printClassMethods(spec,c)
 
     printMethodVisitor()
+    printGetMethodClassMethod()
     printMethodArgumentReader()
     printContentHeaderReader()