stronger checks when creating Java UNO components

check the visibility of construction method at load time for Java UNO
components. This means that we get more informative errors at startup,
instead of failures much later on when we actually create the component.

Change-Id: I08cd16875cf53cfeeef7e8954ecd0d3177d70eb5
Reviewed-on: https://gerrit.libreoffice.org/13446Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>

javaunohelper/com/sun/star/lib/uno/helper/Factory.java

@@ -119,48 +119,80 @@ public class Factory
     private final String m_impl_name;
     private final String [] m_supported_services;
     private final Class<?> m_impl_class;
-    private java.lang.reflect.Method m_method;
-    private java.lang.reflect.Constructor m_ctor;
+    private final java.lang.reflect.Method m_method;
+    private final java.lang.reflect.Constructor m_ctor;
 
     private Factory(
         Class impl_class, String impl_name, String supported_services [] )
+                throws com.sun.star.uno.DeploymentException
     {
         m_impl_name = impl_name;
         m_supported_services = supported_services;
         m_impl_class = impl_class;
-        m_method = null;
-        m_ctor = null;
 
         Class params [] = new Class [] { XComponentContext.class };
 
+        if (!java.lang.reflect.Modifier.isPublic( impl_class.getModifiers() ))
+        {
+            throw new com.sun.star.uno.DeploymentException("class " + impl_class + " is not public");
+        }
+
+        java.lang.reflect.Method tmpMethod = null;
         try
         {
             // seeking for "public static Object __create( XComponentContext )"
-            m_method = m_impl_class.getMethod( "__create", params );
-            int mod = m_method.getModifiers();
-            if (!m_method.getReturnType().equals( Object.class ) ||
+            tmpMethod = m_impl_class.getMethod( "__create", params );
+            int mod = tmpMethod.getModifiers();
+            if (!tmpMethod.getReturnType().equals( Object.class ) ||
                 !java.lang.reflect.Modifier.isStatic( mod ) ||
                 !java.lang.reflect.Modifier.isPublic( mod ))
             {
-                m_method = null;
+                tmpMethod = null;
             }
         }
         catch (Exception exc)
         {
         }
+        m_method = tmpMethod;
 
+
+        java.lang.reflect.Constructor tmpCtor = null;
         if (null == m_method)
         {
             try
             {
                 // ctor with context
-                m_ctor = m_impl_class.getConstructor( params );
+                tmpCtor = m_impl_class.getConstructor( params );
             }
             catch (Exception exc)
+            {
+            }
+            if (tmpCtor != null)
+            {
+                if (!java.lang.reflect.Modifier.isPublic( tmpCtor.getModifiers() ))
+                {
+                    throw new com.sun.star.uno.DeploymentException("constructor with XComponentContext param for class  " + impl_class + " is not public");
+                }
+            }
+            else
             {
                 // else take default ctor
+                java.lang.reflect.Constructor defaultCtor;
+                try
+                {
+                    defaultCtor = m_impl_class.getConstructor(new Class[0]);
+                }
+                catch (Exception exc2)
+                {
+                    throw new com.sun.star.uno.DeploymentException(exc2, "class " + impl_class + " has no means of creating it, cannot find a __create method or a useful constructor.");
+                }
+                if (!java.lang.reflect.Modifier.isPublic( defaultCtor.getModifiers() ))
+                {
+                    throw new com.sun.star.uno.DeploymentException("default constructor for class  " + impl_class + " is not public");
+                }
             }
         }
+        m_ctor = tmpCtor;
     }