From 0cc5ad2d4fe9354507427cd078a5a3dceb7dde79 Mon Sep 17 00:00:00 2001
From: CuCu <503598058@qq.com>
Date: Wed, 23 Jun 2021 16:03:14 +0800
Subject: [PATCH] add Chinese version of Example_Batch

---
 docs/cn/Example_Batch.md | 82 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 docs/cn/Example_Batch.md

diff --git a/docs/cn/Example_Batch.md b/docs/cn/Example_Batch.md
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+# 批量消息发送
+批量消息发送能够提高发送效率，提升系统吞吐量。同一批批量消息的topic、waitStoreMsgOK属性必须保持一致，批量消息不支持延迟消息。批量消息发送一次最多可以发送 4MiB 的消息，但是如果需要发送更大的消息，建议将较大的消息分成多个不超过 1MiB 的小消息。
+
+### 1 发送批量消息
+如果你一次只发送不超过 4MiB 的消息，使用批处理很容易：
+```java
+String topic = "BatchTest";
+List<Message> messages = new ArrayList<>();
+messages.add(new Message(topic, "TagA", "OrderID001", "Hello world 0".getBytes()));
+messages.add(new Message(topic, "TagA", "OrderID002", "Hello world 1".getBytes()));
+messages.add(new Message(topic, "TagA", "OrderID003", "Hello world 2".getBytes()));
+try {
+    producer.send(messages);
+} catch (Exception e) {
+    e.printStackTrace();
+    //handle the error
+}
+```
+### 2 拆分
+当您发送较大的消息时，复杂性会增加，如果您不确定它是否超过 4MiB的限制。 这时候，您最好将较大的消息分成多个不超过 1MiB 的小消息：
+
+```java
+public class ListSplitter implements Iterator<List<Message>> { 
+    private final int SIZE_LIMIT = 1024 * 1024 * 4;
+    private final List<Message> messages;
+    private int currIndex;
+    public ListSplitter(List<Message> messages) { 
+        this.messages = messages;
+    }
+    @Override public boolean hasNext() {
+        return currIndex < messages.size(); 
+    }
+    @Override public List<Message> next() { 
+        int startIndex = getStartIndex();
+        int nextIndex = startIndex;
+        int totalSize = 0;
+        for (; nextIndex < messages.size(); nextIndex++) {
+            Message message = messages.get(nextIndex); 
+            int tmpSize = calcMessageSize(message);
+            if (tmpSize + totalSize > SIZE_LIMIT) {
+                break; 
+            } else {
+                totalSize += tmpSize; 
+            }
+        }
+        List<Message> subList = messages.subList(startIndex, nextIndex); 
+        currIndex = nextIndex;
+        return subList;
+    }
+    private int getStartIndex() {
+        Message currMessage = messages.get(currIndex); 
+        int tmpSize = calcMessageSize(currMessage); 
+        while(tmpSize > SIZE_LIMIT) {
+            currIndex += 1;
+            Message message = messages.get(curIndex); 
+            tmpSize = calcMessageSize(message);
+        }
+        return currIndex; 
+    }
+    private int calcMessageSize(Message message) {
+        int tmpSize = message.getTopic().length() + message.getBody().length(); 
+        Map<String, String> properties = message.getProperties();
+        for (Map.Entry<String, String> entry : properties.entrySet()) {
+            tmpSize += entry.getKey().length() + entry.getValue().length(); 
+        }
+        tmpSize = tmpSize + 20; // Increase the log overhead by 20 bytes
+        return tmpSize; 
+    }
+}
+
+// then you could split the large list into small ones:
+ListSplitter splitter = new ListSplitter(messages);
+while (splitter.hasNext()) {
+   try {
+       List<Message>  listItem = splitter.next();
+       producer.send(listItem);
+   } catch (Exception e) {
+       e.printStackTrace();
+       // handle the error
+   }
+}
+```
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