我需要将AWS DYNAMODB JSON转换为标准JSON对象。所以我可以从DynamoDB JSON中删除数据类型更像是：
在DYNAMODB JSON中：
"videos": [
{
"file": {
"S": "file1.mp4"
},
"id": {
"S": "1"
},
"canvas": {
"S": "This is Canvas1"
}
},
{
"file": {
"S": "main.mp4"
},
"id": {
"S": "0"
},
"canvas": {
"S": "this is a canvas"
}
}
]
to Standard JSON
"videos": [
{
"file": "file1.mp4"
,
"id": "1"
,
"canvas": "This is Canvas1"
,
"file": "main.mp4"
,
"id": "0"
,
"canvas": "this is a canvas"
}
]
我在Javascript中找到了一个很好的工具，但是为了做到这一点，Java中是否有任何工具？
以下是从Dynamo JSON转换为标准JSON的完整代码：
import com.amazonaws.services.dynamodbv2.document.Item;
import com.amazonaws.services.dynamodbv2.document.internal.InternalUtils;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.DynamodbEvent;
import com.amazonaws.services.lambda.runtime.events.DynamodbEvent.DynamodbStreamRecord;
import com.google.gson.Gson;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* Main Lambda class to receive event stream, parse it to Survey
* and process them.
*/
public class SurveyEventProcessor implements
RequestHandler<DynamodbEvent, String> {
private static final String INSERT = "INSERT";
private static final String MODIFY = "MODIFY";
public String handleRequest(DynamodbEvent ddbEvent, Context context) {
List<Item> listOfItem = new ArrayList<>();
List<Map<String, AttributeValue>> listOfMaps = null;
for (DynamodbStreamRecord record : ddbEvent.getRecords()) {
if (INSERT.equals(record.getEventName()) || MODIFY.equals(record.getEventName())) {
listOfMaps = new ArrayList<Map<String, AttributeValue>>();
listOfMaps.add(record.getDynamodb().getNewImage());
listOfItem = InternalUtils.toItemList(listOfMaps);
}
System.out.println(listOfItem);
try {
// String json = new ObjectMapper().writeValueAsString(listOfItem.get(0));
Gson gson = new Gson();
Item item = listOfItem.get(0);
String json = gson.toJson(item.asMap());
System.out.println("JSON is ");
System.out.println(json);
}catch (Exception e){
e.printStackTrace();
}
}
return "Successfully processed " + ddbEvent.getRecords().size() + " records.";
}
}
你可以在aws sdk中使用ItemUtils类。以下是使用Kotlin的示例代码：
import com.amazonaws.services.dynamodbv2.document.ItemUtils
import com.amazonaws.services.dynamodbv2.model.AttributeValue
fun main(args: Array<String>) {
val data = HashMap<String,AttributeValue>()
data.put("hello",AttributeValue().withS("world"))
println(data.toString())
println(ItemUtils.toItem(data).toJSON())
}
输出：
{hello={S: world,}}
{"hello":"world"}
以下是一个简单的解决方案，可用于将任何DynamoDB Json转换为Simple JSON。
//passing the reponse.getItems()
public static Object getJson(List<Map<String,AttributeValue>> mapList) {
List<Object> finalJson= new ArrayList();
for(Map<String,AttributeValue> eachEntry : mapList) {
finalJson.add(mapToJson(eachEntry));
}
return finalJson;
}
//if the map is null then it add the key and value(string) in the finalKeyValueMap
public static Map<String,Object> mapToJson(Map<String,AttributeValue> keyValueMap){
Map<String,Object> finalKeyValueMap = new HashMap();
for(Map.Entry<String, AttributeValue> entry : keyValueMap.entrySet())
{
if(entry.getValue().getM() == null) {
finalKeyValueMap.put(entry.getKey(),entry.getValue().getS());
}
else {
finalKeyValueMap.put(entry.getKey(),mapToJson(entry.getValue().getM()));
}
}
return finalKeyValueMap;
}
这将以List>的形式产生您想要的Json。然后使用Gson，您可以将其转换为Json格式。
Gson gson = new Gson();
String jsonString = gson.toJson(getJson(response.getItems()));
亚马逊有一个内部实用工具，可以在一行中完成工作的核心。
Map<String, Object> jsonMapWithId = InternalUtils.toSimpleMapValue(attributeValueMap);
包含一些配置的长版本：
import com.amazonaws.services.dynamodbv2.document.internal.InternalUtils;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import java.lang.Map;
import java.lang.HashMap;
public class JsonConvert {
public static void main(String[] args) {
Map<String,Object> jsonMap = new HashMap();
jsonMap.put("string", "foo");
jsonMap.put("number", 123);
Map<String,Object> innerMap = new HashMap();
innerMap.put("key", "value");
jsonMap.put("map", innerMap);
AttributeValue attributeValue = InternalUtils.toAttributeValue(jsonMap);
Map<String, AttributeValue> attributeValueMap = new HashMap();
attributeValueMap.put("id", attributeValue);
Map<String, Object> jsonMapWithId = InternalUtils.toSimpleMapValue(attributeValueMap);
Map<String, Object> jsonMap = jsonMapWithId.get("id"); // This is a regular map, values are not Amazon AttributeValue
Gson gson = new Gson();
String json = gson.toJson(jsonMap);
System.out.println(json);
}
}
首先使用将JSON字符串转换为Map
JSONObject jsonObj = new JSONObject(logString);
HashMap<String, Object> myMap = new Gson().fromJson(jsonObj.toString(), HashMap.class);
将DynamoDB JSON转换为标准JSON的功能
public static Map<String,Object> mapToJson(Map map){
Map<String,Object> finalKeyValueMap = new HashMap();
Iterator it = map.entrySet().iterator();
while(it.hasNext()) {
Map.Entry pair = (Map.Entry)it.next();
Map obj1 = (Map) pair.getValue();
if(obj1.get("m") == null) {
if(obj1.get("n") != null)
finalKeyValueMap.put(pair.getKey().toString(),obj1.get("n"));
else if(obj1.get("s") != null)
finalKeyValueMap.put(pair.getKey().toString(),obj1.get("s"));
}
else {
Map obj2 = (Map) pair.getValue();
Map obj3 = (Map) obj2.get("m");
finalKeyValueMap.put(pair.getKey().toString(),mapToJson(obj3));
}
}
System.out.println(finalKeyValueMap.toString());
return finalKeyValueMap;
}
调用mapToJson(myMap);将返回一个标准Map，您可以将其转换回JSON