1  2 
 3 import java.util.ArrayList;
 4 import java.util.HashMap;
 5 import java.util.List;
 6 import java.util.Map;
 7 import com.google.gson.Gson;
 8 
 9 public class GsonTest {
10 
11     public static void main(String[] args) {
12                 
13         Gson g = new Gson();
14         Map<String,Object> map = new HashMap<String,Object>();
15         //添加两个普通节点
16         map.put("a","1");
17         map.put("b",2);
18         
19         //添加一个list1 => "list1":[{"c":"3","d":4}]
20         Map<String,Object> m5 = new HashMap<String,Object>();
21         List<Object> l = new ArrayList<Object>();                
22         m5.put("c","3");
23         m5.put("d",4);
24         l.add(m5);    
25         map.put("list1",l);
26 
27         //添加一个map1 =>"map1":{"e":"5","f":"6"}
28         Map<String,Object> m2 = new HashMap<String,Object>();
29         m2.put("e","5");
30         m2.put("f","6");
31         map.put("map1",m2);
32         
33         //添加一个list2 => "list2":[{"g":"7","h":8},{"g":"9","h":10}]
34         List<Object> l2 = new ArrayList<Object>();
35         Map<String,Object> m3 = new HashMap<String,Object>();
36         Map<String,Object> m4 = new HashMap<String,Object>();
37         m3.put("g","7");
38         m3.put("h",8);
39         m4.put("g","9");
40         m4.put("h",10);
41         l2.add(m3);
42         l2.add(m4);
43         map.put("list2",l2);
44         
45     
46         //添加一个map2 => "map2":{"i":"5","j":[{"j":"5","k":"5"}],"l":{"j":"5","k":"5"}}
47         Map<String,Object> m6 = new HashMap<String,Object>();        
48         List<Object> l3 = new ArrayList<Object>();
49         Map<String,Object> m7 = new HashMap<String,Object>();
50         m6.put("i","5");
51         
52         m7.put("j","5");
53         m7.put("k","5");
54         m6.put("l",m7);
55         
56         l3.add(m7);
57         m6.put("j",l3);
58         map.put("map2",m6);
59         
60         
61         //转换成JSON格式内容
62         String s = g.toJson(map);
63         System.out.println(s);
64         
65     }
66 
67 }

 1 {
 2     "list1":[
 3         {
 4             "c":"3",
 5             "d":4
 6         }
 7     ],
 8     "a":"1",
 9     "b":2,
10     "map2":{
11         "i":"5",
12         "j":[
13             {
14                 "j":"5",
15                 "k":"5"
16             }
17         ],
18         "l":{
19             "j":"5",
20             "k":"5"
21         }
22     },
23     "map1":{
24         "e":"5",
25         "f":"6"
26     },
27     "list2":[
28         {
29             "g":"7",
30             "h":8
31         },
32         {
33             "g":"9",
34             "h":10
35         }
36     ]
37 }