第一种alibaba falstjson：

Map转JSON

  Map map = new HashMap();        map.put("a", "a");        map.put("b", "123");        JSONObject json = new JSONObject(map);

map转string

  Map map = new HashMap<>();        map.put("a", "b");        String s = JSONObject.toJSONString(map);

JSON转String

  JSONObject json = new JSONObject();        json.put("c", "v");        json.put("z", "123n);        json.toJSONString();

JSON转Map

JSONObject json = new JSONObject();        json.put("ccc", "321");        json.put("bbb", "123");        Map map = (Map)json;

String转JSON

 String str = "{"username":"dsad","qwewqe":"123"}";JSONObject json = JSONObject.parseObject(str);

2 google

maven坐标

    com.google.code.gson    gson    2.3.1

//Map转换成JSON

Map map = new HashMap(); map.put("a","aaa"); map.put("b","bbb"); map.put("c","ccc"); String json=JSON.toJSONString(map); System.out.println(json);//输出{"a":"aaa","b":"bbb","c":"ccc"}

//JSON转换成Map

Map map1 = JSON.parseObject(json);System.out.println(map1.get("a"));for (Object mapData : map.entrySet()) {Map.Entry entry = (Map.Entry)mapData;System.out.println(entry.getKey()+"--->"+entry.getValue());}

map中含有对象Map -> JSON

//Map -> JSONMap map = new HashMap(); map.put("a",new Bar()); map.put("b",new Bar()); map.put("c",new Bar()); String json = JSON.toJSONString(map,true); System.out.println(json); 

//JSON -> Map

Map map1 = (Map)JSON.parse(json); for (String key : map1.keySet()) { System.out.println(key+":"+map1.get(key)); } 

-------------------=-------------------------附–MAP的ASCII排序-----------------------=------------------------

StringBuilder sb = new StringBuilder();    List keys = new ArrayList(map.keySet());    Collections.sort(keys);//排序。    for(String k : keys){        String v = params.get(k);        if(StringUtils.isNotEmpty(v)){            sb.append(v);        }    }    //return MD5.toMD5(sb+key, "UTF-8");这个就不用看了~~~

来源地址：https://blog.csdn.net/jcc4261/article/details/129660911