DynamoDB列表类型

Question

我在理解如何从Android应用中为dynamoDB创建List时遇到问题。 我可以从我的应用中存储并加载{ "deviceId": "920e185a-63ed-46ca-bfca-f7a484ccb708" }。但是然后添加List并将我的JSON对象存储为列表中的Map是我的努力。

我想创建和填充的dynamoDB结构看起来像JSON格式：

{ "data": [ { "heartBeatId": 1, "status": 1, "timeStamp": 1502183502711 }, { "heartBeatId": 2, "status": 1, "timeStamp": 1502183502812 } ], "deviceId": "90563daa-63ae-40c5-905e-9e8c02f9624f" } 然后我想用心跳对象填充数据列表，该对象是Map类型。 { "heartBeatId": 2, "status": 1, "timeStamp": 1502183502812 } 因此，在定义@DynamoDBTable(tableName = "heartbeat")类以创建此结构时遇到问题。

我在这里阅读了List和DynamoDBDocument：

DynamoDBDocument

DataType List

@DynamoDBTable(tableName = "heartbeat")课程现在看起来如何。

我希望有人可以帮助我定义它，或者告诉我如何继续获得我需要的结构。

package com.example.android.awsdynamoapp;

import com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBAttribute;
import com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBDocument;
import com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBHashKey;
import com.amazonaws.mobileconnectors.dynamodbv2.dynamodbmapper.DynamoDBTable;

import java.lang.annotation.Annotation;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@DynamoDBTable(tableName = "heartbeat")
public class HeartBeat implements DynamoDBTable {

private String deviceId;
private Map<String, Integer> data;
private List dataList;

public HeartBeat(){};
public HeartBeat(String deviceId){this.deviceId = deviceId;};

public HeartBeat(String deviceId, List dataList) {
    this.deviceId = deviceId;
    this.dataList = dataList;
  //  this.timeStamp = timeStamp;
}

@DynamoDBHashKey(attributeName = "deviceId")
public String getDeviceId() {
    return deviceId;
}

public void setDeviceId(String deviceId) {
    this.deviceId = deviceId;
}
public void setTimeStamp(String timeStamp) {
    //this.timeStamp = timeStamp;
}


public void setData(String deviceId) {
    Map<String, Integer> data = new HashMap<>();

}

@DynamoDBAttribute(attributeName = "data")
public List getData() {
    return this.dataList;
}

@DynamoDBDocument
public static class JsonArray {
    private String heartBeatId;
    private String status;
    private String timeStamp;

}

/**
 * The name of the table to use for this class.
 */
@Override
public String tableName() {
    return "heartbeat";
}

@Override
public Class<? extends Annotation> annotationType() {
    return null;
}
}

Answer 1

可以按如下方式创建地图对象列表。上述结构中的好处是data中的所有属性都是数字。如果需要，您可以将其更改为String。根据您的预期输出，我将其定义为Long。

属性定义： -

private List<Map<String, Long>> data;

@DynamoDBAttribute(attributeName = "data")  
public List<Map<String, Long>> getData() {
    return data;
}

public void setData(List<Map<String, Long>> data) {
    this.data = data;
}

填充数据： -

    MoviesWithData movies = new MoviesWithData();
    movies.setYearKey(1917);
    movies.setTitle("Tilte with list of map");

    Map<String, Long> dataMap1 = new HashMap<>();
    dataMap1.put("heartBeatId", 1L);
    dataMap1.put("status", 1L);
    dataMap1.put("timeStamp", 1502183502812L);

    Map<String, Long> dataMap2 = new HashMap<>();
    dataMap2.put("heartBeatId", 2L);
    dataMap2.put("status", 2L);
    dataMap2.put("timeStamp", 1503183502812L);

    movies.setData(Arrays.asList(dataMap1, dataMap2));
    dynamoDBMapper.save(movies, consistentDynamoDBMapperConfig);

示例输出： -