[英]How to parse JSON Response with GSON (Java / Android)
I just need a quick advice, as i am a total beginner with JSON. 我只是一个快速建议,因为我是JSON的初学者。
I get the following response from a webserver, which i store in a String: 我从存储在String中的Web服务器收到以下响应:
{
"station62":[
{
"departureTime":1982,
"delay":"-1.0",
"line":"6",
"stationName":"randomname",
"direction":2
}
],
"station63":[
{
"departureTime":1234,
"delay":"-1.0",
"line":"87",
"stationName":"anotherrandomname",
"direction":2
}
],
"station64":[
{
"departureTime":4542,
"delay":"-1.0",
"line":"4",
"stationName":"yetanotherrandomname",
"direction":2
}
],
"station65":[
{
"departureTime":1232,
"delay":"-1.0",
"line":"23",
"stationName":"onemorerandomname",
"direction":2
}
]
}
(Sorry, i dont know how the indent works on here.) (对不起,我不知道缩进在这里如何工作。)
The response is longer, but for this example it is shortened. 响应时间更长,但在此示例中,响应时间缩短了。 So what i need is to parse the information of each of these "station"-objects. 因此,我需要解析每个“站”对象的信息。 I dont need the "station62"-String, i only need "departureTime", "delay", "line", "stationName" and "direction" in a java-object. 我不需要“ station62” -String,我只需要Java对象中的“ departureTime”,“ delay”,“ line”,“ stationName”和“ direction”。
I have read this, but i couldnt make it work: https://stackoverflow.com/a/16378782 我已经读过了,但是我无法使它起作用: https : //stackoverflow.com/a/16378782
I am a total beginner, so any help would be really appreciated. 我是一个初学者,所以我们将不胜感激。
Edit: Here is my code: 编辑:这是我的代码:
I made a wrapper class just like in the example link above. 就像上面的示例链接一样,我制作了一个包装器类。 I played with the map types a bit, but no luck so far. 我玩了一些地图类型,但到目前为止还没有运气。
public class ServerResponse
{
private Map<String, ArrayList<Station>> stationsInResponse = new HashMap<String, ArrayList<Station>>();
public Map<String, ArrayList<Station>> getStationsInResponse()
{
return stationsInResponse;
}
public void setStationsInResponse(Map<String, ArrayList<Station>> stationsInResponse)
{
this.stationsInResponse = stationsInResponse;
}
}
The problem is, that this map does not get filled by the gson.fromJSON(...)-call i am showing below. 问题是,我在下面显示的gson.fromJSON(...)调用无法填充此地图。 The map size is always zero. 地图大小始终为零。
Station class looks like this: 站类如下:
public class Station
{
String line;
String stationName;
String departureTime;
String direction;
String delay;
// getters and setters are there aswell
}
And what i am trying to do is 我想做的是
Gson gson = new Gson();
ServerResponse response = gson.fromJson(jsonString, ServerResponse.class);
where "jsonString" contains the JSON response as a string. 其中“ jsonString”包含JSON响应作为字符串。
I hope that code shows what i need to do, it should be pretty simple but i am just not good enough in JSON. 我希望代码能够显示我需要做的事情,它应该非常简单,但是我对JSON的了解还不够。
EDIT 2 编辑2
Would i need my JSON to be like this? 我需要我的JSON这样吗?
{"stationsInResponse": {
"station62": [{
"departureTime": 1922,
"delay": "-1.0",
"line": "8",
"stationName": "whateverrandomname",
"direction": 2
}],
"station67": [{
"departureTime": 1573,
"delay": "-1.0",
"line": "8",
"stationName": "rndmname",
"direction": 2
}],
"station157": [{
"departureTime": 1842,
"delay": "-2.0",
"line": "8",
"stationName": "randomname",
"direction": 2
}]
}}
Here is the working code: 这是工作代码:
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import com.google.gson.Gson;
public class GSONTest {
public static void main(String[] args){
String gsonStr = "{\"stationsInResponse\": { \"station62\":[ { \"departureTime\":1982,\"delay\":\"-1.0\",\"line\":\"6\",\"stationName\":\"randomname\",\"direction\":2} ],\"station63\":[ { \"departureTime\":1981,\"delay\":\"-1.1\",\"line\":\"7\",\"stationName\":\"randomname2\",\"direction\":3} ]}}";
Gson gson = new Gson();
Response response = gson.fromJson(gsonStr, Response.class);
System.out.println("Map size:"+response.getStationsInResponse().size());
for (Iterator iterator = response.getStationsInResponse().keySet().iterator(); iterator.hasNext();) {
String key = (String) iterator.next();
ArrayList<Station> stationList = (ArrayList<Station>) response.getStationsInResponse().get(key);
for (Iterator iterator2 = stationList.iterator(); iterator2.hasNext();) {
Station station = (Station) iterator2.next();
System.out.println("Delay: "+station.getDelay());
System.out.println("DepartureTime: "+station.getDepartureTime());
System.out.println("Line: "+station.getLine());
System.out.println("StationName: "+station.getStationName());
}
}
}
}
class Response {
private Map<String, List<Station>> stationsInResponse;
//getters and setters
public Map<String, List<Station>> getStationsInResponse() {
return stationsInResponse;
}
public void setStationsInResponse(Map<String, List<Station>> stationsInResponse) {
this.stationsInResponse = stationsInResponse;
}
}
class Station {
private String departureTime;
public String getDepartureTime() {
return departureTime;
}
public void setDepartureTime(String departureTime) {
this.departureTime = departureTime;
}
public String getDelay() {
return delay;
}
public void setDelay(String delay) {
this.delay = delay;
}
public String getLine() {
return line;
}
public void setLine(String line) {
this.line = line;
}
public String getStationName() {
return stationName;
}
public void setStationName(String stationName) {
this.stationName = stationName;
}
public String getDirection() {
return direction;
}
public void setDirection(String direction) {
this.direction = direction;
}
private String delay;
private String line;
private String stationName;
private String direction;
}
Output in console is like this(as I shortened your json string): 控制台中的输出是这样的(因为我缩短了您的json字符串):
Map size:2
Delay: -1.0
DepartureTime: 1982
Line: 6
StationName: randomname
Delay: -1.1
DepartureTime: 1981
Line: 7
StationName: randomname2
First I'll point out your mistake, then I'll give you the solution. 首先,我会指出您的错误,然后再为您提供解决方案。
The structure you're asking for in your deserialization code looks like this: 您在反序列化代码中要求的结构如下:
{
"stationsInResponse": {
"station1": [
{
"name": "Station 1"
}
],
"station2": [
{
"name": "Station 2"
}
]
}
}
The deserialization code you really need to deserialize the structure you're getting as input, is as follows: 真正反序列化输入所要获取的结构所需的反序列化代码如下:
Gson gson = new Gson();
Type rootType = new TypeToken<Map<String, List<Station>>>(){}.getType();
Map<String, List<Station>> stationsMap = gson.fromJson(json, rootType);
This is because a JSON object, whose properties are unknown at compile-time, which your root object is, maps to a Java Map<String, ?>
. 这是因为根对象是在编译时未知的JSON对象映射到Java Map<String, ?>
。 The ?
?
represent the expected Java type of the JSON object value, which in your case is either List<Station>
or Station[]
, whichever you prefer. 表示JSON对象值的预期Java类型,在您的情况下为List<Station>
或Station[]
(无论您喜欢哪种)。
If you wanted to, you could combine all the stations in the map into one List
of stations like so: 如果愿意,可以将地图中的所有站点合并为一个站点List
,如下所示:
List<Station> stations = new ArrayList<>(stationsMap.size());
for (List<Station> stationsList : stationsMap.values()) {
for (Station station : stationsList) {
stations.add(station);
}
}
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