import java.util.ArrayList;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 import com.google.gson.Gson;

 public class GsonTest {

     public static void main(String[] args) {

         Gson g = new Gson();

         Map<String,Object> map = new HashMap<String,Object>();

         //添加两个普通节点

         map.put("a","1");

         map.put("b",2);

         //添加一个list1 => "list1":[{"c":"3","d":4}]

         Map<String,Object> m5 = new HashMap<String,Object>();

         List<Object> l = new ArrayList<Object>();

         m5.put("c","3");

         m5.put("d",4);

         l.add(m5);

         map.put("list1",l);

         //添加一个map1 =>"map1":{"e":"5","f":"6"}

         Map<String,Object> m2 = new HashMap<String,Object>();

         m2.put("e","5");

         m2.put("f","6");

         map.put("map1",m2);

         //添加一个list2 => "list2":[{"g":"7","h":8},{"g":"9","h":10}]

         List<Object> l2 = new ArrayList<Object>();

         Map<String,Object> m3 = new HashMap<String,Object>();

         Map<String,Object> m4 = new HashMap<String,Object>();

         m3.put("g","7");

         m3.put("h",8);

         m4.put("g","9");

         m4.put("h",10);

         l2.add(m3);

         l2.add(m4);

         map.put("list2",l2);

         //添加一个map2 => "map2":{"i":"5","j":[{"j":"5","k":"5"}],"l":{"j":"5","k":"5"}}

         Map<String,Object> m6 = new HashMap<String,Object>();

         List<Object> l3 = new ArrayList<Object>();

         Map<String,Object> m7 = new HashMap<String,Object>();

         m6.put("i","5");

         m7.put("j","5");

         m7.put("k","5");

         m6.put("l",m7);

         l3.add(m7);

         m6.put("j",l3);

         map.put("map2",m6);

         //转换成JSON格式内容

         String s = g.toJson(map);

         System.out.println(s);

     }

 }

 {

     "list1":[

         {

             "c":"3",

             "d":4

         }

     ],

     "a":"1",

     "b":2,

     "map2":{

         "i":"5",

         "j":[

             {

                 "j":"5",

                 "k":"5"

             }

         ],

         "l":{

             "j":"5",

             "k":"5"

         }

     },

     "map1":{

         "e":"5",

         "f":"6"

     },

     "list2":[

         {

             "g":"7",

             "h":8

         },

         {

             "g":"9",

             "h":10

         }

     ]

 }