使用GSON解析JSON
问题描述：
这是我以前的问题的延续。获取JSON请求并将其转换为JSON后，我试图将结果解析为Java对象。使用GSON解析JSON
public class NetClientGet {
@SuppressWarnings("unchecked")
public static void main(String[] args) {
String urlYesterday = "http://fids.changiairport.com/webfids/fidsp/get_flightinfo_cache.php?d=-1&type=pa&lang=en";
String yesterdayJSON = getDataFromWeb(urlYesterday);
//System.out.println("yesterdayJSON : " + yesterdayJSON);
//jsonArray.add(yesterdayJSON);
Gson gson = new Gson();
List<FlightInfo> flightArray = (List<FlightInfo>) gson.fromJson(yesterdayJSON, FlightInfo.class);
System.out.println("flightArray : " + flightArray);
}
private static String getDataFromWeb(String targetURL) {
try {
URL url = new URL(targetURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());
}
BufferedReader br;
if ("gzip".equalsIgnoreCase(conn.getContentEncoding())) {
br = new BufferedReader(new InputStreamReader(
(new GZIPInputStream(conn.getInputStream()))));
} else {
br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
}
// Retrieve data from server
String output = null;
final StringBuffer buffer = new StringBuffer(16384);
while ((output = br.readLine()) != null) {
buffer.append(output);
}
conn.disconnect();
// Extract JSON from the JSONP envelope
String jsonp = buffer.toString();
String json = jsonp.substring(jsonp.indexOf("(") + 1, //this is the index of the callback envelope
jsonp.lastIndexOf(")"));
//System.out.println("Output from server");
//System.out.println(json);
return json;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
我想：
Gson gson = new Gson();
FlightInfo flightArray = gson.fromJson(yesterdayJSON, FlightInfo.class);
，但它让我空，我相信我需要因为我的数据有很多条目的解析它变成一个列表。在JSON
"flights": [
{
"date": "2013-05-12",
"scheduled_time": "23:30",
"estimated_time": "23:09*",
"airline": "TR",
"flight_no": "TR2109",
"airport": "BKK",
"origin": "Bangkok (Suvarnabhumi)",
"via": "",
"terminal": "2",
"belt": "35",
"status": "Landed",
"airline_name": "TIGER AIRWAYS",
"airline_alias": "",
"unixtime": "1368372600",
"master_flight_no": "TR2109",
"slave_flight_no": []
}
]
的
样品和我FlightInfo.class
import java.sql.Time;
import java.util.Date;
public class FlightInfo {
private Date date;
private Time scheduled_time;
private Time estimated_time;
private String airline;
private String flight_no;
private String airport;
private String origin;
private String via;
private String terminal;
private String belt;
private String status;
private String airline_name;
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
public Time getScheduled_time() {
return scheduled_time;
}
public void setScheduled_time(Time scheduled_time) {
this.scheduled_time = scheduled_time;
}
public Time getEstimated_time() {
return estimated_time;
}
public void setEstimated_time(Time estimated_time) {
this.estimated_time = estimated_time;
}
public String getAirline() {
return airline;
}
public void setAirline(String airline) {
this.airline = airline;
}
public String getFlight_no() {
return flight_no;
}
public void setFlight_no(String flight_no) {
this.flight_no = flight_no;
}
public String getAirport() {
return airport;
}
public void setAirport(String airport) {
this.airport = airport;
}
public String getOrigin() {
return origin;
}
public void setOrigin(String origin) {
this.origin = origin;
}
public String getVia() {
return via;
}
public void setVia(String via) {
this.via = via;
}
public String getTerminal() {
return terminal;
}
public void setTerminal(String terminal) {
this.terminal = terminal;
}
public String getBelt() {
return belt;
}
public void setBelt(String belt) {
this.belt = belt;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getAirline_name() {
return airline_name;
}
public void setAirline_name(String airline_name) {
this.airline_name = airline_name;
}
@Override
public String toString() {
return "FlightInfo [date=" + date + ", scheduled_time=" + scheduled_time +
", estimated_time=" + estimated_time +
", airline=" + airline +
", flight_no=" + flight_no +
", airport=" + airport +
", origin=" + origin +
", via=" + via +
", terminal=" + terminal +
", belt=" + belt +
", status=" + status +
", airline_name=" + airline_name +
"]";
}
}
答
我假设你的JSON响应由{ }包围，否则就不是有效的JSON ...
也就是说，您需要另一个类来解析您的JSON响应，例如：
public class Response {
private List<FlightInfo> flights;
//getters & setters
}
现在你可以分析你的回应：
Gson gson = new Gson();
Response response = gson.fromJson(yesterdayJSON, Response .class);
List<FlightInfo> flightArray = response.getFlights();
注：看你的FlightInfo类和你的JSON响应，我想你会遇到麻烦解析您Date和Time领域，所以我建议您将它们解析为字符串，然后进行正确的转换......否则您必须创建一个custom deserializer。
答
上述代码无法将值解释为类型FlightInfo，因为Gson调用list.getClass（）以获取其类信息，但此方法返回一个原始类List.class。这意味着Gson无法知道这是类型为列表< FlightInfo>的对象，而不仅仅是普通列表。
您可以通过为您的泛型指定正确的参数化类型来解决此问题。您可以通过使用TypeToken类来完成此操作。
Type listType = new TypeToken<List<Bar>>() {}.getType();
gson.toJson(list, listType);
gson.fromJson(json, listType);
的更多信息，请gson-user-guide
嗨啊，我刚打的错误，当我试图解析..谢谢。 – jonleech 2013-05-14 01:05:47