Overview
- We have seen in prev post how to use GSON to convert a JSON to Java Object and other way around
- In this post, we will see how to convert JSON which has Dynamic Keys.
Sample JSON
{
"Sample_01": {
"class": "Tenant",
"A1": {
"class": "Application",
"template": "http",
"serviceMain": {
"class": "Service_HTTP",
"virtualAddresses": [
"10.0.1.10"
],
"pool": "web_poolddd"
},
"web_poolddd": {
"class": "Pool",
"monitors": [
"http"
],
"members": [
{
"servicePort": 80,
"serverAddresses": [
"192.0.13.10",
"192.0.14.11"
]
}
]
}
}
},
"Sample_20": {
"class": "Tenant",
"A1": {
"class": "Application",
"template": "http",
"serviceMain": {
"class": "Service_HTTP",
"virtualAddresses": [
"10.2.2.2"
],
"pool": "web_pool_data"
},
"web_pool_data": {
"class": "Pool",
"monitors": [
"http"
],
"members": [
{
"servicePort": 80,
"serverAddresses": [
"192.0.10.10",
"192.0.10.11"
]
}
]
}
}
}
}- If you notice in above JSON Sample_01 and Sample_20 are dynamic.
- In this case, we can’t simply define a Java POJO and map it to this JSON.
So how do we read this kind of JSON?
We will use a combination of TypeToken and JsonParser to read this JSON.
public static void main(String[] args) {
String json = "{\"Sample_01\":{\"class\":\"Tenant\",\"A1\":{\"class\":\"Application\",\"template\":\"http\",\"serviceMain\":{\"class\":\"Service_HTTP\",\"virtualAddresses\":[\"10.0.1.10\"],\"pool\":\"web_poolddd\"},\"web_poolddd\":{\"class\":\"Pool\",\"monitors\":[\"http\"],\"members\":[{\"servicePort\":80,\"serverAddresses\":[\"192.0.13.10\",\"192.0.14.11\"]}]}}},\"Sample_20\":{\"class\":\"Tenant\",\"A1\":{\"class\":\"Application\",\"template\":\"http\",\"serviceMain\":{\"class\":\"Service_HTTP\",\"virtualAddresses\":[\"10.2.2.2\"],\"pool\":\"web_pool_data\"},\"web_pool_data\":{\"class\":\"Pool\",\"monitors\":[\"http\"],\"members\":[{\"servicePort\":80,\"serverAddresses\":[\"192.0.10.10\",\"192.0.10.11\"]}]}}}}";
Type listType = new TypeToken<Map<String, Object>>(){}.getType();
Gson gson = new Gson();
Map<String,Object> myList = gson.fromJson(json, listType);
JsonParser parser = new JsonParser();
for (Map.Entry<String,Object> m : myList.entrySet())
{
System.out.println("==============");
if(m.getValue() instanceof String){
// get String value
}else{ // if value is an Object
System.out.println("VIP Sec: Name: "+m.getKey());
Map<String,Object> myList1 = gson.fromJson(m.getValue().toString(), listType);
for (Map.Entry<String,Object> m1 : myList1.entrySet())
{
if(!( m1.getValue() instanceof String)){
Map<String,Object> myList2 = gson.fromJson(m1.getValue().toString(), listType);
for (Map.Entry<String,Object> m2 : myList2.entrySet())
{
if(!( m2.getValue() instanceof String)){
Map<String,Object> myList3 = gson.fromJson(m2.getValue().toString(), listType);
for (Map.Entry<String,Object> m3 : myList3.entrySet())
{
if(m3.getKey().equals("virtualAddresses")){
System.out.println("VIP Sec: IP Address: "+m3.getValue());
}
else if(m3.getKey().equals("pool")){
System.out.println("Pool Sec: Name: "+m3.getValue());
}else if(m3.getKey().equals("monitors")){
JsonArray monitors = parser.parse(m3.getValue().toString()).getAsJsonArray();
int count = 0;
while(count < monitors.size()){
String monitor = monitors.get(count).getAsString();
System.out.println("Monitor: "+monitor);
count++;
}
}else if(m3.getKey().equals("members")){
JsonArray members = parser.parse(m3.getValue().toString()).getAsJsonArray();
int count = 0;
while(count < members.size()){
// Parsing as Object to key values by key directly
JsonObject mem = members.get(count).getAsJsonObject();
String port = mem.get("servicePort").getAsString();
System.out.println("Port: "+port);
JsonElement ipAddrs = mem.get("serverAddresses");
if(ipAddrs.isJsonArray()){
JsonArray ips = ipAddrs.getAsJsonArray();
int c = 0;
while(c < ips.size()){
String ip = ips.get(c).getAsString();
System.out.println("IP: "+ip);
c++;
}
}
count++;
}
}
}
}
}
}
}
}
}
}
OUTPUT:
==============
VIP Sec: Name: Sample_01
VIP Sec: IP Address: [10.0.1.10]
Pool Sec: Name: web_poolddd
Monitor: http
Port: 80.0
IP: 192.0.13.10
IP: 192.0.14.11
==============
VIP Sec: Name: Sample_20
VIP Sec: IP Address: [10.2.2.2]
Pool Sec: Name: web_pool_data
Monitor: http
Port: 80.0
IP: 192.0.10.10
IP: 192.0.10.11Steps:
- First, we are converting JSON to Map using TypeToken so that we can iterate over our dynamic key.
- Value can be String, Object. We are further converting Object to Map to iterate in child loop.
- Finally, we are using JsonObject, JsonArray to parse value so that we can get desired value by key.
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