Complex nested data type JSON format conversion (Geojsonpolygon) using Fastjson in network transport

If an object is too complex, the JSON-formatted data conversion in the network transfer key is prone to problems.

For example, the following class of Area.java

Import Lombok. Allargsconstructor; Import Lombok. Data; Import Lombok. Noargsconstructor; Import Org.springframework.data.mongodb.core.geo.GeoJsonPolygon, @Data @noargsconstructor@allargsconstructor  Public class Area {    private  String name;     Private Geojsonpolygon Geojsonpolygon;}

In this area class, there is a property geojsonploygon a bit complex, the source of this class I do not post, just to show you the area object contains its JSON format data representation:

 { "name": "AAAA"  "geojsonpolygon " : {  "            Span style= "COLOR: #ff0000" > "points": [{"X": 3.4, "Y": 3.9}, {"X": 6.2,        "Y": 8.1}, {"X": 9.8, "Y": 3.1}, {"X": 3.4, "Y": 3.9                }], "coordinates": [{"Type": "LineString", "coordinates": [{"X": 3.4,  "Y": 3.9}, {"X": 6.2, "Y": 8.1}, {"X":        9.8, "Y": 3.1}, {"X": 3.4, "Y": 3.9}]}], "Type": "Polygon"  } }  

The red logo above is the Geojsonpolygon JSON format.

It doesn't matter if you can't read points and coordinates here.

The following simulates a service A to another service B, the transport generic is a list of area, service b resolves the data, and returns the data.

The Controller for service A is to make a list of the generic type area, passing data to the B service through Resttemplate.

Importorg.springframework.beans.factory.annotation.Autowired;ImportOrg.springframework.context.annotation.Bean;ImportOrg.springframework.data.geo.Point;ImportOrg.springframework.data.mongodb.core.geo.GeoJsonPolygon;Importorg.springframework.http.ResponseEntity;Importorg.springframework.web.bind.annotation.GetMapping;ImportOrg.springframework.web.bind.annotation.ResponseBody;ImportOrg.springframework.web.bind.annotation.RestController;Importorg.springframework.web.client.RestTemplate;Importjava.util.ArrayList;Importjava.util.List; @RestController Public classSendcontroller {@AutowiredPrivateresttemplate resttemplate; @GetMapping (Value= "/send") @ResponseBody PublicList Sendarea () {Point point1=NewPoint (3.4, 3.9); Point Point2=NewPoint (6.2, 8.1); Point Point3=NewPoint (9.8, 3.1); Point Point4=NewPoint (3.4, 3.9); List<Point> points =NewArraylist<>();        Points.Add (POINT1);        Points.Add (Point2);        Points.Add (POINT3);        Points.Add (POINT4); List<Area> arealist =NewArraylist<>(); Arealist.add (NewArea ("AAAA",NewGeojsonpolygon (points)); Arealist.add (NewArea ("BBBB",NewGeojsonpolygon (points)); Arealist.add (NewArea ("CCCC",NewGeojsonpolygon (points)); String URL= receivecontroller.base_url+receivecontroller.post_mapping; Responseentity Entity= resttemplate.postforentity (URL,arealist, List.class); List Body=(List) entity.getbody (); returnbody; } @Bean Publicresttemplate resttemplate () {return  Newresttemplate (); }}

Controller for service B

ImportCom.alibaba.fastjson.JSON;ImportCom.alibaba.fastjson.JSONObject;Importcom.alibaba.fastjson.TypeReference;ImportOrg.springframework.data.geo.Point;ImportOrg.springframework.data.mongodb.core.geo.GeoJsonPolygon;Importorg.springframework.web.bind.annotation.PostMapping;ImportOrg.springframework.web.bind.annotation.RequestBody;ImportOrg.springframework.web.bind.annotation.ResponseBody;ImportOrg.springframework.web.bind.annotation.RestController;Importjava.util.ArrayList;Importjava.util.List; @RestController Public classReceivecontroller { Public Static FinalString base_url = "http://localhost:8080";  Public Static FinalString post_mapping = "/receive"; @PostMapping (Value=post_mapping) @ResponseBody Publiclist arealist (@RequestBody String arealist) {list<Area> list =NewArraylist<>(); if(Arealist = =NULL ){            returnlist; }        /*** list<area> liststring = Json.parseobject (arealist, New typereference<list<area>> () {}); * Note that this is wrong, the area contains the attribute Geojsonpolygon, cannot parse * have to be a list of generics written as String*/List<String> liststring = Json.parseobject (Arealist,NewTypereference<list<string>>(){}); Jsonobject Jsonobject=NULL; Jsonobject Polygonjsonobject=NULL; Geojsonpolygon Geojsonpolygon=NULL;  for(inti=0; I < liststring.size (); i++) {String s=Liststring.get (i); Jsonobject=Jsonobject.parseobject (s); //gets the value of key corresponding to the Jsonobject objectString name = jsonobject.getstring ("name"); //parsing complex Geojsonpolygon PropertiesString geojsonpolygonstring = jsonobject.getstring ("Geojsonpolygon"); Polygonjsonobject=Jsonobject.parseobject (geojsonpolygonstring); String pointsstring= Polygonjsonobject.getstring ("Points"); List<Point> points = Json.parseobject (pointsstring,NewTypereference<list<point>>() {}); Geojsonpolygon=NewGeojsonpolygon (points); Area Area=NewArea ();            Area.setname (name);            Area.setgeojsonpolygon (Geojsonpolygon);        List.add (area); }        returnlist; }}

Note: using the Fastjson version is 1.2.47, if the version 1.2.7 is executed in this statement list<point> points = Json.parseobject ( Pointsstring, New Typereference<list<point>> () {}) will error, Because 1.2.7 requires that the generic class point here must have a parameterless constructor, the 1.2.47 version does not have a parameterless constructor.

A. Service b first uses the @requestbody annotation and then parses the nested data type;

B. If the List is using list<String> liststring = Json.parseobject (arealist, new typereference <List<String>> () {}) First resolves to a List of generic String . Because the Geojsonpolygon is too complex, can not be resolved directly, if it is simple as point list<point> points = Json.parseobject (pointsstring, new Typereference<list<point>> () {});

C. If it is not a list, and the string object is nested JSON data format, the string object is parsed into a jsonobject object;

D. Use the getString method of the Jsonobject object to obtain a string of the corresponding property key, if the string is still a complex JSON data, perform a B or C step until you get the data you want or the resolution is complete.

Online json:http://www.bejson.com/

Complex nested data type JSON format conversion (Geojsonpolygon) using Fastjson in network transport