1. alibaba
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.41</version>
</dependency>
JSONUtils.toJSONString(requestMap);
2. json-lib
<dependency>
<groupId>net.sf.json-lib</groupId>
<artifactId>json-lib</artifactId>
<version>2.5</version>
</dependency>
JSONObject jsonObject = JSONObject.fromObject(map);
String result = jsonObject.toString();
3. google
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.3.1</version>
</dependency>
new Gson().toJson(param);
原文：https://www.cnblogs.com/cgy-home/p/11757657.html