YngwieWang commented on a change in pull request #9299: [FLINK-13405][docs-zh]
Translate "Basic API Concepts" page into Chinese
URL: https://github.com/apache/flink/pull/9299#discussion_r317586108
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File path: docs/dev/api_concepts.zh.md
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@@ -315,55 +239,54 @@ val grouped = input.groupBy(0,1)
</div>
</div>
-Here, we group the tuples on a composite key consisting of the first and the
-second field.
+这里我们用第一个字段和第二个字段组成的组合键对 Tuple 分组
-A note on nested Tuples: If you have a DataStream with a nested tuple, such as:
+对于嵌套 Tuple 请注意： 如果你的 DataStream 是嵌套 Tuple，例如：
{% highlight java %}
DataStream<Tuple3<Tuple2<Integer, Float>,String,Long>> ds;
{% endhighlight %}
-Specifying `keyBy(0)` will cause the system to use the full `Tuple2` as a key
(with the Integer and Float being the key). If you want to "navigate" into the
nested `Tuple2`, you have to use field expression keys which are explained
below.
+指定 `keyBy(0)` 将导致系统使用整个 `Tuple2` 作为键（一个整数和一个浮点数）。 如果你想“进入”到 `Tuple2`
的内部，你必须使用如下所述的字段表达式键。
-### Define keys using Field Expressions
+### 使用字段表达式定义键
{:.no_toc}
-You can use String-based field expressions to reference nested fields and
define keys for grouping, sorting, joining, or coGrouping.
+可以使用基于字符串的字段表达式来引用嵌套字段，并定义用于分组、排序、join 或 coGrouping 的键。
-Field expressions make it very easy to select fields in (nested) composite
types such as [Tuple](#tuples-and-case-classes) and [POJO](#pojos) types.
+字段表达式可以很容易地选取复合（嵌套）类型中的字段，例如 [Tuple](#tuples-and-case-classes) 和
[POJO](#pojos) 类型。
<div class="codetabs" markdown="1">
<div data-lang="java" markdown="1">
-In the example below, we have a `WC` POJO with two fields "word" and "count".
To group by the field `word`, we just pass its name to the `keyBy()` function.
+下例中，我们有一个包含“word”和“count”两个字段的 POJO：`WC`。要用 `word` 字段分组，我们只需要把它的名字传给 `keyBy()`
函数即可。
{% highlight java %}
-// some ordinary POJO (Plain old Java Object)
+// 普通的 POJO（简单的 Java 对象）
public class WC {
public String word;
public int count;
}
DataStream<WC> words = // [...]
-DataStream<WC> wordCounts = words.keyBy("word").window(/*window
specification*/);
+DataStream<WC> wordCounts = words.keyBy("word").window(/*指定窗口*/);
{% endhighlight %}
-**Field Expression Syntax**:
+**字段表达式语法**：
-- Select POJO fields by their field name. For example `"user"` refers to the
"user" field of a POJO type.
+- 根据字段名称选择 POJO 的字段。例如 `“user”` 就是指 POJO 类型的“user”字段。
-- Select Tuple fields by their field name or 0-offset field index. For example
`"f0"` and `"5"` refer to the first and sixth field of a Java Tuple type,
respectively.
+- 根据字段名称或 0 开始的字段索引选择 Tuple 的字段。例如 `“f0”` 和 `“5”` 分别指 Java Tuple 类型的第一个和第五个字段。
Review comment:
👍
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