您的JSON不正确。而不是

Your JSON is not correct. Instead of

JSONObject cred = new JSONObject();
JSONObject auth=new JSONObject();
JSONObject parent=new JSONObject();
cred.put("username","adm");
cred.put("password", "pwd");
auth.put("tenantName", "adm");
auth.put("passwordCredentials", cred.toString()); // <-- toString()
parent.put("auth", auth.toString());              // <-- toString()

OutputStreamWriter wr= new OutputStreamWriter(con.getOutputStream());
wr.write(parent.toString());

写

JSONObject cred = new JSONObject();
JSONObject auth=new JSONObject();
JSONObject parent=new JSONObject();
cred.put("username","adm");
cred.put("password", "pwd");
auth.put("tenantName", "adm");
auth.put("passwordCredentials", cred);
parent.put("auth", auth);

OutputStreamWriter wr= new OutputStreamWriter(con.getOutputStream());
wr.write(parent.toString());

因此，对于外部对象，JSONObject.toString（）只能调用一次。

So, the JSONObject.toString() should be called only once for the outer object.

另一件事（很可能不是你的问题，但我想提一提）：

Another thing (most probably not your problem, but I'd like to mention it):

要运行编码问题，应该指定编码，如果不是 UTF-8 ：

To be sure not to run into encoding problems, you should specify the encoding, if it is not UTF-8:

con.setRequestProperty("Content-Type", "application/json; charset=UTF-8");

// ...

OutputStream os = con.getOutputStream();
os.write(parent.toString().getBytes("UTF-8"));
os.close();