Gson 的基本使用

 

  1 import java.util.ArrayList;
  2 import java.util.HashMap;
  3 import java.util.Iterator;
  4 import java.util.List;
  5 
  6 import com.google.gson.Gson;
  7 import com.google.gson.GsonBuilder;
  8 import com.google.gson.reflect.TypeToken;
  9 
 10 class User {
 11     private String username;
 12     private String password;
 13 
 14     public String getUsername() {
 15         return username;
 16     }
 17 
 18     public void setUsername(String username) {
 19         this.username = username;
 20     }
 21 
 22     public String getPassword() {
 23         return password;
 24     }
 25 
 26     public void setPassword(String password) {
 27         this.password = password;
 28     }
 29 
 30     @Override
 31     public String toString() {
 32         return username + "'s password is:" + password;
 33     }
 34 }
 35 
 36 class UserGroup {
 37     private String id;
 38     private HashMap<String, User> usermap;
 39     private List<User> userlist;
 40 
 41     public String getId() {
 42         return id;
 43     }
 44 
 45     public void setId(String id) {
 46         this.id = id;
 47     }
 48 
 49     public HashMap<String, User> getUsermap() {
 50         return usermap;
 51     }
 52 
 53     public void setUsermap(HashMap<String, User> usermap) {
 54         this.usermap = usermap;
 55     }
 56 
 57     public List<User> getUserlist() {
 58         return userlist;
 59     }
 60 
 61     public void setUserlist(List<User> userlist) {
 62         this.userlist = userlist;
 63     }
 64 
 65     public String toString() {
 66         String str = "";
 67         Iterator it = usermap.keySet().iterator();
 68         while (it.hasNext()) {
 69             Object key = it.next();
 70             str+="key:" + key+" , value:" + usermap.get(key)+"\n";
 71         }
 72 
 73         return "id:" + id + "\n"+str;
 74     }
 75 }
 76 
 77 public class testJson {
 78 
 79     /**
 80      * @param args
 81      */
 82     public static void main(String[] args) {
 83         BeanGroupDemo();
 84 
 85     }
 86 
 87     static void BeanDemo() {
 88         User user = new User();
 89         user.setUsername("zhoubiwen");
 90         user.setPassword("123456");
 91 
 92         GsonBuilder builder = new GsonBuilder();
 93         // builder.excludeFieldsWithoutExposeAnnotation();
 94         Gson gson = builder.create();
 95         String jsonUser = gson.toJson(user);
 96         System.out.println(jsonUser);
 97 
 98         User user2 = new User();
 99         user2 = gson.fromJson(jsonUser, User.class);
100         System.out.println(user2);
101     }
102 
103     static void BeanGroupDemo() {
104         UserGroup users = new UserGroup();
105         users.setId("001");
106         HashMap<String, User> usermap = new HashMap<String, User>();
107         User user1 = new User();
108         user1.setUsername("001");
109         user1.setPassword("001pwd");
110         User user2 = new User();
111         user2.setUsername("002");
112         user2.setPassword("002pwd");
113         usermap.put("user1", user1);
114         usermap.put("user2", user2);
115 
116         users.setUsermap(usermap);
117 
118         GsonBuilder builder = new GsonBuilder();
119         Gson gson = builder.create();
120         String jsonUser = gson.toJson(users);
121         System.out.println(jsonUser);
122 
123         UserGroup users2 = new UserGroup();
124         users2 = gson.fromJson(jsonUser, UserGroup.class);
125         System.out.println(users2);
126     }
127 
128     static void ListDemo() {
129         Gson gson = new Gson();
130         List<String> list = new ArrayList<String>();
131         list.add("one");
132         list.add("two");
133         list.add("three");
134         String gsonstr = gson.toJson(list);
135         System.out.println(gsonstr);
136         list.clear();
137         list = gson.fromJson(gsonstr, new TypeToken<ArrayList<String>>() {
138         }.getType());
139         System.out.println(list);
140     }
141 
142     static void HashMapDemo() {
143         Gson gson = new Gson();
144         HashMap map = new HashMap();
145         map.put("k1", "v1");
146         map.put("k2", "v2");
147         map.put("k3", "v3");
148         String gsonstr = gson.toJson(map);
149         System.out.println(gsonstr);
150         map.clear();
151         map = gson.fromJson(gsonstr, new TypeToken<HashMap<String, String>>() {
152         }.getType());
153         System.out.println(map);
154 
155     }
156 
157 }
158