JSONObject参数顺序问题

签名需要规定参数顺序不能错。

一开始是这么写的

JSONObject param = new JSONObject();
param.put("idcard", user.getIdCard());
param.put("mobile", user.getPhone());
param.put("uid", user.getId());
param.put("username", user.getName());

期望得到的顺序应该是：

{"idcard":"370781199901230125","mobile":"156****2845","uid":1,"username":"张三"}

但是实际得到的顺序却是：

{"uid":1,"idcard":"370781199901230125","mobile":"156****2845","username":"张三"}

解决方法1：

JSONObject param = new JSONObject(true);
param.put("idcard", user.getIdCard());
param.put("mobile", user.getPhone());
param.put("username", user.getName());
param.put("uid", user.getId());

得到：{"idcard":"370781199901230125","mobile":"156****2845","username":"张三","uid":1}

解决方法2：

JSONObject param = new JSONObject(new LinkedHashMap<>());
param.put("idcard", user.getIdCard());
param.put("mobile", user.getPhone());
param.put("username", user.getName());
param.put("uid", user.getId());

同样得到：{"idcard":"370781199901230125","mobile":"156****2845","username":"张三","uid":1}