Gson入门教程

点击右边图片下载jar包 ,gson不像Json-lib.jar依赖其它jar包, gson就一个jar包行天下.

package ccc.json;public class Person {    Integer id;    String name;    String place;    public Person(Integer id, String name, String place) {        super();        this.id = id;        this.name = name;        this.place = place;    }    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPlace() {        return place;    }    public void setPlace(String place) {        this.place = place;    }    @Override    public String toString() {        return "Person [id=" + id + ", name=" + name + ", place=" + place + "]";    }    }

用于生成各种形式的对象如Object,List,List<Map<String,Object>> :

package ccc.json;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class JsonService {          public Person getPerson(){          Person person=new Person(123,"bobo","HangZhou");          return person;      }            public List<Person> getPersonList(){          List<Person> list=new ArrayList<Person>();          Person person1 = new Person(123,"sisi","BeiJing");          Person person2 = new Person(2002, "bobo", "HangZhou");        list.add(person1);          list.add(person2);                    return list;                }      public List<String> getList(){          List<String> list=new ArrayList<String>();          list.add("BeiJing");          list.add("HangZhou");          return list;      }            public Map<String,Object> getMap(){          Map<String,Object> map=new HashMap<String, Object>();          map.put("id", 123);          map.put("name","sisi");          map.put("place", "BeiJing");         return map;     }        public List<Map<String,Object>> getlistMap(){          List<Map<String,Object>> list=new ArrayList<Map<String,Object>>();          Map<String,Object> map1=new HashMap<String, Object>();          map1.put("id", 123);          map1.put("name","sisi");          map1.put("place", "BeiJing");          Map<String,Object> map2=new HashMap<String, Object>();          map2.put("id", 456);          map2.put("name","bobo");          map2.put("place", "HangZhou");          list.add(map1);          list.add(map2);          return list;      }    } 

package ccc.json;import java.util.List;import java.util.Map;import com.google.gson.Gson;import com.google.gson.reflect.TypeToken;public class Json_demo {    public static void main(String[] args) {        Gson gson = new Gson();        JsonService service = new JsonService();                String str1 = gson.toJson(service.getPerson());        System.out.PRintln("1: "+str1);//        1: {"id":123,"name":"bobo","place":"HangZhou"}                String str4 = gson.toJson(service.getMap());        System.out.println("2: "+str4);//        2: {"id":123,"name":"sisi","place":"BeiJing"}                String str2 = gson.toJson(service.getPersonList());        System.out.println("3: "+str2);//        3: [{"id":123,"name":"sisi","place":"BeiJing"},{"id":2002,"name":"bobo","place":"HangZhou"}]                String str3 = gson.toJson(service.getList());        System.out.println("4: "+str3);//        4: ["BeiJing","HangZhou"]                String str5 = gson.toJson(service.getlistMap());        System.out.println("5: "+str5);//        5: [{"id":123,"name":"sisi","place":"BeiJing"},{"id":456,"name":"bobo","place":"HangZhou"}]                        Person  personA = gson.fromJson(str4, Person.class);        System.out.println(personA);//        Person [id=123, name=sisi, place=BeiJing]                Map<String,Object> mapA = gson.fromJson(str4, Map.class);        System.out.println(mapA);//        {id=123.0, name=sisi, place=BeiJing}                //在已经知道要转成List的情况下可以直接带List.class参数        List<Map> list = gson.fromJson(str5 /*str2*/, List.class);        for(Map map : list){            String s = gson.toJson(map);            Person p =gson.fromJson(s, Person.class);            System.out.println(p);        }//        Person [id=123, name=sisi, place=BeiJing]//        Person [id=456, name=bobo, place=HangZhou]                //转泛型的时候会把int转成double        List<Map<String,Object>> list_map = gson.fromJson(str5, new TypeToken<List<Map<String,Object>>>(){}.getType());        for(Map m: list_map){            System.out.println(m);        }//        {id=123.0, name=sisi, place=BeiJing}//        {id=456.0, name=bobo, place=HangZhou}                //转Person可以把double的小数舍去        List<Person> personList = gson.fromJson(str2 /*str5*/, new TypeToken<List<Person>>(){}.getType());        for(Person p: personList){            System.out.println(p);        }//        Person [id=123, name=sisi, place=BeiJing]//        Person [id=2002, name=bobo, place=HangZhou]    }}

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