Gson Framework Instances

 PackageCom.json;Importjava.util.ArrayList;Importjava.util.Date;ImportJava.util.HashMap;ImportJava.util.LinkedHashMap;Importjava.util.List;ImportJava.util.Map;ImportCom.google.gson.FieldNamingPolicy;ImportCom.google.gson.Gson;ImportCom.google.gson.GsonBuilder;ImportCom.google.gson.reflect.TypeToken;/*** This article refers to:http://blog.csdn.net/lk_blog/article/details/7685190 * */ Public classJsondemo {PrivateList<person>personlist; PrivatePerson Persondemo; PrivateGson Gson;  Public voidInitpersondata () {Persondemo=NewPerson ("I am Demo", 40, "China",NewDate ()); Person P1=NewPerson ("Zhang San", 20, "Beijing",NewDate ()); Person P2=NewPerson ("John Doe", 22, "Shanghai",NewDate ()); Person P3=NewPerson ("Harry", 30, "Guangzhou",NewDate ()); Personlist=NewArraylist<person>();        Personlist.add (Persondemo);        Personlist.add (p1);        Personlist.add (p2);    Personlist.add (p3); }     Public Static voidMain (string[] args) {Jsondemo demo=NewJsondemo (); intTesttype = 5; Switch(testtype) { Case1://Simple Object conversions and list conversions with genericsDemo.initpersondata (); Demo.gson=NewGson ();            Demo.printpersonresult ();  Break;  Case2://Gson Annotations and GsonbuilderDemo.initpersondata (); //Note that the Gson is constructed in Gsonbuilder, which differs from the Gson Gson = new Gson () in test1;Demo.gson =NewGsonbuilder (). Excludefieldswithoutexposeannotation ()//do not export attributes with @expose annotations in the entity. Enablecomplexmapkeyserialization ()//Map-enabled key is the form of a complex object. Serializenulls (). Setdateformat ("Yyyy-mm-dd HH:mm:ss:SSS")//time into a specific format. Setfieldnamingpolicy (Fieldnamingpolicy.upper_camel_case)//The first letter of the field is capitalized, note: The @serializedname annotation used on the entity will not take effect.. Setprettyprinting ()//formats the JSON result.. Setversion (1.0)//Some fields are not initially available and will be added as the version is upgraded, so the serialization and serialization are selected for serialization based on the version number. //the @Since (version number) is perfect for this function. Also the fields may be deleted as the version is upgraded, then//@Until (version number) can also implement this function, the gsonbuilder.setversion (double) method needs to be called.. Create ();            Demo.printpersonresult ();  Break;  Case3://example of Gson-map processingDemo.testmap1 ();  Break;  Case4://Map Processingdemo.testmap2 ();  Break;  Case5://Map Processingdemo.testmap3 ();  Break; }    }     Public voidTestMap1 () {Map<point, string> map1 =NewLinkedhashmap<point, string> ();//use Linkedhashmap to arrange results in FIFO orderMap1.put (NewPoint (3, 6), "P1"); Map1.put (NewPoint (4, 8), "P2"); Gson=NewGsonbuilder (). Enablecomplexmapkeyserialization (). Create (); String Str=Gson.tojson (MAP1); System.out.println (str);//results: [[{"X": 3, "Y": 6}, "P1"],[{"x": 4, "Y": 8}, "P2"]]Map<point, string> retmap = Gson.fromjson (str,NewTypetoken<map<point, string>>() {}.gettype ());  for(Point P:retmap.keyset ()) {System.out.println ("Key:" + P + ", Values:" +Retmap.get (p));    } System.out.println (Retmap); }     Public voidtestMap2 () {Map<string, point> map1 =NewLinkedhashmap<string, point> ();//use Linkedhashmap to arrange results in FIFO orderMap1.put ("a",NewPoint (3, 6)); Map1.put ("B",NewPoint (4, 8)); Gson=NewGsonbuilder (). Enablecomplexmapkeyserialization (). Create (); String Str=Gson.tojson (MAP1); System.out.println (str);//results: [[{"X": 3, "Y": 6}, "P1"],[{"x": 4, "Y": 8}, "P2"]]Map<string, point> retmap = Gson.fromjson (str,NewTypetoken<map<string, point>>() {}.gettype ());  for(String p:retmap.keyset ()) {System.out.println ("Key:" + P + ", Values:" +Retmap.get (p));    } System.out.println (Retmap); }     Public voidtestMap3 () {initpersondata (); Map<string, object> map =NewHashmap<string, object>(); Map.put ("Persons", personlist); List<Point> pointlist =NewArraylist<point>(); Pointlist.add (NewPoint (3, 6)); Pointlist.add (NewPoint (4, 6)); Pointlist.add (NewPoint (4, 7)); Map.put ("Points", pointlist); Gson=NewGson (); String Str=Gson.tojson (map); System.out.println (str);//Result: {"persons": [{"Name": "I am Demo", "Age": +, "address": "China", "Bir": " the"//1, 1:59:39//PM "},{" name ":" Zhang San "," Age ":" Address ":" Beijing "," Bir ":"//1, 1:59:39//PM "},{" name ":" John Doe "," Age ":" Address ":" Shanghai "," Bir ":"//1, 1:59:39//PM "},{" name ":" Harry "," age ": +," Address ":" Guangzhou "," Bir ":" The "//1, 1:59:39//PM "}]," points ": [{" X ": 3," Y ": 6},{" x ": 4," Y ": 6},{" x ": 4," Y ": 7}]}Map<string, object> retmap =Gson.fromjson (str,NewTypetoken<map<string, list<object>>>() {}.gettype ());  for(String key:retMap.keySet ()) {if("Persons". Equals (Key) {List<Person> pList = (list<person>) Retmap.get (key);            System.out.println (pList); }Else if("Points". Equals (Key) {List<Point> pList = (list<point>) Retmap.get (key);            System.out.println (pList); }        }        }    Private voidPrintpersonresult () {System.out.println ("============ Transformation of Simple Objects =============="); String P1json=Gson.tojson (Persondemo);        System.out.println (P1json); Person Refperson= Gson.fromjson (P1json, person.class);        System.out.println (Refperson); System.out.println (""); System.out.println ("============ with generic list conversion =============="); String Jsonstr=Gson.tojson (personlist); System.out.println ("Jsonstr:" +jsonstr); List<Person> reflist = Gson.fromjson (Jsonstr,NewTypetoken<list<person>>() {}.gettype ());  for(person per:reflist) {System.out.println (per); }    }}

Gson Framework Instances