HashMap<String, Object> headers = new HashMap<String, Object>();
headers.put("User-Agent", "Android");
headers.put("Content-Type", "application/json");

Map map = new HashMap();
map.put("success", "true");
map.put("photoList", "ssss");
map.put("currentUser", "zhang");

JSONObject json =new JSONObject(map);
JSONObject json2 =new JSONObject(headers);
LgqLogutil.e("llll----"+json+"....."+json2);

E/lgq: httpheader----llll----{"photoList":"ssss","currentUser":"zhang","success":"true"}.....{"User-Agent":"Android","Content-Type":"application\/json"}

2、建值

Map map = new HashMap();
map.put("success", "true");
map.put("photoList", "ssss");
map.put("currentUser", "zhang");

JSONObject jsonObject = new JSONObject();
jsonObject.put("name",map);

 E/lgq: httpheader----..222....{"name":"{photoList=ssss, currentUser=zhang, success=true}"}

2、

/**
 * 将JavaBean序列化为JSON文本
 *
 * @param object
 * @return
 */
public static String toJSONString(Object object) {
    return JSON.toJSONString(object);
}

 对象转json

gson依赖；implementation 'com.google.code.gson:gson:2.8.5'

private Gson mGSon;
public String parseObjToJsonStr(Object srcObj) {
    String result = "";
    if (mGSon == null) {
        mGSon = new GsonBuilder().disableHtmlEscaping().create();
    }
    try {
        result = mGSon.toJson(srcObj);
    } catch (Exception e) {
        Log.getStackTraceString(e);
    }
    return result;
}

json转对象

Gson gson = new Gson();
String jsons = ShareUtil.getSharedString("logins");
if (TextUtils.isEmpty(jsons)){
    return;
}
LoginBean loginBean = gson.fromJson(ShareUtil.getSharedString("logins"), LoginBean.class);//第二种写法
Log.i("lgq", "wwbb==" + loginBean.getMsg());

 json转list

private List<MqttMsgBean> mqttMsgList = new ArrayList<>();

Gson gson = new Gson();

mqttMsgList =gson.fromJson(bs,  new TypeToken<List<MqttMsgBean>>() {}.getType());

生成任意格式的json数据

  private  JSONObject createJSONObject() {  
            JSONObject result = new JSONObject();  
            result.put("success", true);  
            result.put("totalCount", "30");  
            result.put("okstatus",okreString );
            
            JSONObject user1 = new JSONObject();  
            user1.put("id", "12");  
            user1.put("name", "张三");  
            user1.put("createTime", "2017-11-16 12:12:12");  
       
            JSONObject user2 = new JSONObject();  
            user2.put("id", "13");  
            user2.put("name", "李四");  
            user2.put("createTime", "2017-11-16 12:12:15"); 
            
            JSONObject department = new JSONObject();
            department.put("id", 1);
            department.put("name","技术部");
            
            user1.put("department", department);
            user2.put("department", department);
              
            // 返回一个JSONArray对象  
            JSONArray jsonArray = new JSONArray();  
              
            jsonArray.add(0, user1);  
            jsonArray.add(1, user2);  
            result.element("data", jsonArray);  
              
            return result;  
        } 

结果是：
{"success":true,"totalCount":"30","okstatus":"登录失败了","data":[{"id":"12","name":"张三","createTime":"2017-11-16 12:12:12","department":{"id":1,"name":"技术部"}},{"id":"13","name":"李四","createTime":"2017-11-16 12:12:15","department":{"id":1,"name":"技术部"}}]}