Java 使用falstjson包 技巧

1.map转json

Map<String, Object> map = new HashMap<String, Object>();
map.put("a", "a");
map.put("b", "123");
JSONObject json = new JSONObject(map);

2.map转string

Map<String, Object> map = new HashMap<>();
map.put("a", "b");
String s = JSONObject.toJSONString(map);

3.json转string

JSONObject json = new JSONObject();
json.put("c", "v");
json.put("z", "123n);
json.toJSONString();

4.json转map

JSONObject json = new JSONObject();
json.put("ccc", "321");
json.put("bbb", "123");
Map<String, Object> map = (Map<String, Object>)json;

5.string转json

String str = "{\"username\":\"dsad\",\"qwewqe\":\"123\"}";
JSONObject json = JSONObject.parseObject(str);

6.json转map

private static Object json_to_map(String json)
{
    Object array = JSONObject.parse(json);
    if(array instanceof JSONArray){
        List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
        for (int i= 0;i<((JSONArray) array).size();i++)
        {
            JSONObject myjObject = ((JSONArray)array).getJSONObject(i);
            Map<String,Object> ret1 = new HashMap<String, Object>();
            for (Map.Entry<String, Object> entry : myjObject.entrySet()) {
                if(isJson(entry.getValue().toString()))
                {
                    ret1.put(entry.getKey(), json_to_map(entry.getValue().toString()));
                }else{
                    log.info("JSONObject=>   key:" + entry.getKey().toString()+"   value:"+entry.getValue());
                    ret1.put(entry.getKey(), entry.getValue());
                }
            }
            list.add(ret1);
        }
        return list;
    }
    else if(array instanceof JSONObject){
        Map<String,Object> ret = new HashMap<String, Object>();
        for (Map.Entry<String, Object> entry : ((JSONObject)array).entrySet()) {
            if(isJson(entry.getValue().toString()))
            {
                ret.put(entry.getKey(), json_to_map(entry.getValue().toString()));
            }else{
                log.info("JSONObject=>   key:" + entry.getKey().toString()+"   value:"+entry.getValue());
                ret.put(entry.getKey(), entry.getValue());
            }
        }
        return ret;
    }
    return null;
}

判断是否为json串

/*
*字符串{},[]都是正确的json串
*/
public static boolean isJson(String str){
    if (StringUtils.isBlank(str)){
        return false;
    }
    try{
        Object parse = JSON.parse(str);
        if (parse instanceof JSONObject || parse instanceof JSONArray){
            return true;
        }
    }catch (Exception e){
        return false;
    }
    return false;
}

判断Object类型

Object ret =  json_to_map(jsonmap);
log.info(ret == null ? "null" : ret instanceof HashMap ? "HashMap" : ret instanceof ArrayList ? "ArrayList" : ret.getClass().getTypeName());