String userStr=readJSONString(request);
System.out.println(userStr);//能输出
JSONObject jsonObj = JSONObject.fromObject(userStr);//我感觉这有问题
System.out.println(jsonObj.getInt("userid"));//后台没输出
System.out.println(jsonObj.getString("username"));
输出结果如下
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
should be
JSONObjectimport错了，或者是版本不对吧，我本地用的是 json-lib-2.4net.sf.json.JSONObject, which is OK.If the frontend transmits json type data, then the backend receives json type data, and there is no need to transfer it anymore
1. First confirm whether your userStr is a json string:
For example: String jstr="{'json':'jsonvalue','bool':true,'int':1,'double':'20.5'} ";
2. Then check whether the JOSNObject you are using is the json.jar package.
3. Confirm whether your json package is imported correctly.
First take a look at the package introduction of the net.sf.json.JSONObject version mentioned by taomaokun, and then check whether your json string is written correctly. This is generally available