Gson应用：利用map和list来拼装Json消息

 2 
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);
        
    }

}

输出

{"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}]}

{
    "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
        }
    ]
}