java中的DynamoDb分页查询

Question

我是dynamodb的新手。我必须实现分页。我必须在我的html页面显示十个记录。我对dynamodb完全陌生。任何人都可以共享dynamodb中分页的任何示例查询吗?我研究了亚马逊发电机数据库教程，但我没有得到任何想法。我可以使用高级和低级api实现分页吗?有人能建议从哪里开始吗?

Answer 1

作为yegor256建议，您可以使用查询(QueryRequest)或扫描(ScanRequest)与setExclusiveStartKey代替。下面是如何做到这一点的代码片段

HashMap<String, Condition> scanFilter = new HashMap<String, Condition>();
Condition condition = new Condition()
            .withComparisonOperator(ComparisonOperator.LT.toString())
            .withAttributeValueList(new AttributeValue().withN("100"));
scanFilter.put("column1", condition);
Boolean lastEval = true;
int count = 0;
ScanRequest scanRequest = new ScanRequest(tableName).withScanFilter(scanFilter);
while(lastEval) {
    ScanResult scanResult = dynamoDB.scan(scanRequest);
    count += scanResult.getCount();
    System.out.println("Page Size: " + scanResult.getCount());
    System.out.println("Total count = " + count);
    if (scanResult.getLastEvaluatedKey() != null)
        lastEval = scanResult.getLastEvaluatedKey().isEmpty() == false;
    else
        lastEval = false;
    if (lastEval) {
        scanRequest.setExclusiveStartKey(scanResult.getLastEvaluatedKey());
    }
}

Answer 2

您应该使用query(QueryRequest)或scan(ScanRequest)与addExclusiveStartKeyEntry()

同时，检查这个库:jcabi-dynamo