[GitHub] [pulsar] BewareMyPower commented on a change in pull request #12088: [PIP 96] Add payload converter for Pulsar client

[GitBox <gi...@apache.org>]

BewareMyPower commented on a change in pull request #12088:
URL: https://github.com/apache/pulsar/pull/12088#discussion_r711588876



##########
File path: pulsar-client/src/main/java/org/apache/pulsar/client/converter/PayloadConverterProxy.java
##########
@@ -0,0 +1,85 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.client.converter;
+
+import io.netty.buffer.ByteBuf;
+import java.util.Iterator;
+import java.util.Set;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.pulsar.common.api.proto.BrokerEntryMetadata;
+import org.apache.pulsar.common.api.proto.MessageMetadata;
+import org.apache.pulsar.common.api.raw.PayloadConverter;
+import org.reflections.Reflections;
+import org.reflections.scanners.SubTypesScanner;
+
+/**
+ * The proxy class for {@link PayloadConverter}.
+ */
+@Slf4j
+public class PayloadConverterProxy {
+
+    private final PayloadConverter payloadConverter;
+
+    public PayloadConverterProxy(final boolean enabled, final String packageName) {
+        this.payloadConverter = createConverter(enabled, packageName);
+    }
+
+    public ByteBuf convert(final BrokerEntryMetadata brokerEntryMetadata,
+                           final MessageMetadata metadata,
+                           final ByteBuf payload) {
+        return payloadConverter.convert(brokerEntryMetadata, metadata, payload);
+    }
+
+    private static PayloadConverter createConverter(final boolean enabled, final String packageName) {
+        if (!enabled) {
+            return (brokerEntryMetadata, metadata, payload) -> payload;
+        }
+
+        final Reflections reflections = new Reflections(packageName, new SubTypesScanner(false));
+        final Set<Class<? extends PayloadConverter>> converters = reflections.getSubTypesOf(PayloadConverter.class);
+        final Iterator<Class<? extends PayloadConverter>> iterator = converters.iterator();
+
+        PayloadConverter payloadConverter = null;
+        while (iterator.hasNext()) {
+            try {
+                final Class<? extends PayloadConverter> clazz = iterator.next();
+                if (!clazz.getPackage().getName().equals(packageName)) {
+                    // Ignore the sub packages
+                    continue;
+                }
+                payloadConverter = clazz.newInstance();

Review comment:
       I used `clazz.getConstructor().getInstance()` instead, because it only allows public constructor. PTAL again.




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