我试图将一个字符串（每个JSON对象都用逗号分隔，但第一个JSON对象是该集合的描述）与JSON对象转换为JsonArray，然后尝试对每个对象的某个子元素进行迭代JsonElement，但是每次尝试都以一个错误。
字符串示例：
{"type":"FeatureCollection","metadata":{"generated":1554314439000,"url":"https://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&eventtype=earthquake","title":"USGS Earthquakes","status":200,"api":"1.7.0","count":8970},"features":[{"type":"Feature","properties":{"mag":2.2,"place":"84km SSE of Old Iliamna, Alaska","time":1554313967537,"updated":1554314345998,"tz":-540,"url":"https://earthquake.usgs.gov/earthquakes/eventpage/ak0194a3ew0w","detail":"https://earthquake.usgs.gov/fdsnws/event/1/query?eventid=ak0194a3ew0w&format=geojson","felt":null,"cdi":null,"mmi":null,"alert":null,"status":"automatic","tsunami":0,"sig":74,"net":"ak","code":"0194a3ew0w","ids":",ak0194a3ew0w,","sources":",ak,","types":",geoserve,origin,","nst":null,"dmin":null,"rms":0.74,"gap":null,"magType":"ml","type":"earthquake","title":"M 2.2 - 84km SSE of Old Iliamna, Alaska"},"geometry":{"type":"Point","coordinates":[-154.542,59.0119,127.6]},"id":"ak0194a3ew0w"},
{"type":"Feature","properties":{"mag":1.1,"place":"107km W of Cantwell, Alaska","time":1554313769466,"updated":1554313953376,"tz":-540,"url":"https://earthquake.usgs.gov/earthquakes/eventpage/ak0194a3e7ki","detail":"https://earthquake.usgs.gov/fdsnws/event/1/query?eventid=ak0194a3e7ki&format=geojson","felt":null,"cdi":null,"mmi":null,"alert":null,"status":"automatic","tsunami":0,"sig":19,"net":"ak","code":"0194a3e7ki","ids":",ak0194a3e7ki,","sources":",ak,","types":",geoserve,origin,","nst":null,"dmin":null,"rms":0.63,"gap":null,"magType":"ml","type":"earthquake","title":"M 1.1 - 107km W of Cantwell, Alaska"},"geometry":{"type":"Point","coordinates":[-151.0662,63.2378,7.8]},"id":"ak0194a3e7ki"},
我试过了：
JsonArray jsonObject = new JsonParser()
.parse(result)
.getAsJsonArray();
List<String> names = new ArrayList<>();
for (JsonElement jsonElement : jsonObject) {
names.add(jsonElement.getAsJsonObject().get("properties").getAsString());
insect.usgs.gov API以GeoJSON格式返回有效载荷。有geogson一个实现所有必需适配器的库。您只需要添加依赖项：
<dependency>
<groupId>com.github.filosganga</groupId>
<artifactId>geogson-core</artifactId>
<version>1.2.21</version>
</dependency>
在下面，您可以找到如何使用它的简单示例：
import com.github.filosganga.geogson.gson.GeometryAdapterFactory;
import com.github.filosganga.geogson.model.FeatureCollection;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
public class GsonApp {
public static void main(String[] args) throws Exception {
URL url = new URL("https://earthquake.usgs.gov/fdsnws/event/1/query?format=geojson&eventtype=earthquake");
URLConnection yc = url.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(yc.getInputStream()));
Gson gson = new GsonBuilder()
.registerTypeAdapterFactory(new GeometryAdapterFactory())
.create();
FeatureCollection collection = gson.fromJson(in, FeatureCollection.class);
collection.features().forEach(f -> {
System.out.println(f.properties());
});
}
}
应用上方的照片：
null, cdi=null, url="https://earthquake.usgs.gov/earthquakes/eventpage/us1000jimv", ids=",us1000jimv,", time=1552230050190, detail="https://earthquake.usgs.gov/fdsnws/event/1/query?eventid=us1000jimv&format=geojson", updated=1553025676040, status="reviewed"}
{dmin=0.01354, code="73150236", sources=",nc,", tz=-480, mmi=null, type="earthquake", title="M 0.3 - 8km WNW of Cobb, CA", magType="md", nst=10, sig=2, tsunami=0, mag=0.32, alert=null, gap=159, rms=0.02, place="8km WNW of Cobb, CA", net="nc", types=",geoserve,nearby-cities,origin,phase-data,scitech-link,", felt=null, cdi=null, url="https://earthquake.usgs.gov/earthquakes/eventpage/nc73150236", ids=",nc73150236,", time=1552229803430, detail="https://earthquake.usgs.gov/fdsnws/event/1/query?eventid=nc73150236&format=geojson", updated=1552436044263, status="reviewed"}
{dmin=0.0134, code="73150231", sources=",nc,", tz=-480, mmi=null, type="earthquake", title="M 0.6 - 8km WNW of Cobb, CA", magType="md", nst=9, sig=5, tsunami=0, mag=0.57, alert=null, gap=152, rms=0.01, place="8km WNW of Cobb, CA", net="nc", types=",geoserve,nearby-cities,origin,phase-data,scitech-link,", felt=null, cdi=null, url="https://earthquake.usgs.gov/earthquakes/eventpage/nc73150231", ids=",nc73150231,", time=1552229731210, detail="https://earthquake.usgs.gov/fdsnws/event/1/query?eventid=nc73150231&format=geojson", updated=1552235523281, status="automatic"}
....
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