add different send examples

example/src/main/java/org/apache/rocketmq/example/quickstart/Producer.java

@@ -18,6 +18,7 @@ package org.apache.rocketmq.example.quickstart;
 
 import org.apache.rocketmq.client.exception.MQClientException;
 import org.apache.rocketmq.client.producer.DefaultMQProducer;
+import org.apache.rocketmq.client.producer.SendCallback;
 import org.apache.rocketmq.client.producer.SendResult;
 import org.apache.rocketmq.common.message.Message;
 import org.apache.rocketmq.remoting.common.RemotingHelper;
@@ -65,6 +66,39 @@ public class Producer {
                  * Call send message to deliver message to one of brokers.
                  */
                 SendResult sendResult = producer.send(msg);
+                /*
+                 * There are different ways to send message, if you don't care about the send result,you can use this way
+                 * {@code
+                 * producer.sendOneway(msg);
+                 * }
+                 */
+
+                /*
+                 * if you want to get the send result in a synchronize way, you can use this send method
+                 * {@code
+                 * SendResult sendResult = producer.send(msg);
+                 * System.out.println(sendResult.toString());
+                 * }
+                 */
+
+                /*
+                 * if you want to get the send result in a asynchronize way, you can use this send method
+                 * {@code
+                 *
+                 *  producer.send(msg, new SendCallback() {
+                 *  @Override
+                 *  public void onSuccess(SendResult sendResult) {
+                 *      // do something
+                 *  }
+                 *
+                 *  @Override
+                 *  public void onException(Throwable e) {
+                 *      // do something
+                 *  }
+                 *});
+                 *
+                 *}
+                 */
 
                 System.out.printf("%s%n", sendResult);
             } catch (Exception e) {