你好，我是猿java。

最近在折腾AWS(亚马逊)的一些产品，开发中用到了DynamoDB这款NoSql数据库，需求是需要对user表做user_id in查询，中间查阅了dynamoDB的很多API doc，最后终于写出了一个可以使用的test demo，代码如下：

|---------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper; public class TestClass { @Autowired DynamoDBMapper dynamoDBMapper; @Test public void scanWithInSelectTest() { initData(); List<String> userList = new ArrayList<>(); userList.add("iamtest"); userList.add("iamtest2"); DynamoDBScanExpression queryExpression = new DynamoDBScanExpression(); queryExpression.setConsistentRead(false); String condFilter = ""; HashMap<String, AttributeValue> attrs = new HashMap<>(); // 拼装in 的sql语句 if (!userList.isEmpty()) { condFilter += " #UserId in (" + IntStream.range(0, userList.size()).mapToObj(i -> ":userId" + i).collect(Collectors.joining(",")) + ")"; for (int i = 0; i < userList.size(); i++) { attrs.put(":userId" + i, new AttributeValue().withS(userList.get(i))); } queryExpression.setExpressionAttributeNames(Map.of("#UserId", "UserId")); } queryExpression.setFilterExpression(condFilter); queryExpression.withExpressionAttributeValues(attrs); PaginatedScanList<UserModel> jobs = dynamoDBMapper.scan(UserModel.class, queryExpression); assertTrue(!jobs.isEmpty()); } } |

我使用的是gradle编译的，aws-java-sdk依赖如下，使用maven可以查看下对应的依赖，最后大家有相关的绣球可以根据实际开发修改对应的代码。

|---------------|-------------------------------------------------------------------------------------------------| | 1 2 3 | dependencies { implementation platform("com.amazonaws:aws-java-sdk-bom:$aws_sdk_ver") } |

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