引入fastJson的依赖

  <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.58</version>
        </dependency>

HashMap<String,String>map = new HashMap<>();
map.put("a","1");
map.put("b","2");
map.put("c","3");
 
String json = JSON.toJSONString(map);//map转String
JSONObject jsonObject = JSON.parseObject(json);//String转json
 
//json转map
 Map<String, String> jsonMap = JSONObject.toJavaObject(jsonObject, Map.class);
 //String转map
 Map<String, String> jsonMap1 = JSONObject.parseObject(json, Map.class);