fastjson与各类型的转换

参考：

https://www.cnblogs.com/ceshi2016/p/7381478.html

http://www.cnblogs.com/goody9807/p/4244862.html

 https://www.cnblogs.com/DreamDrive/p/5778959.html

https://www.cnblogs.com/janson071/p/9646678.html 多层嵌套

/**字符串转Json数组并解析**/

try {

JSONArray array =  JSONArray.parseArray(line));
         String[] fields = {"lat", "lng", "poi_id", "poi_name", "poi_type", "roadidx"};
         if (null != array) {
             Iterator<Object> iter = array.iterator();
             while (iter.hasNext()) {
                 JSONObject json = (JSONObject)iter.next();
                 for (int i = 0; i < fields.length; i++) {
                     System.out.println(json.getString(fields[i]));
                 }
             }
         }

}catch (JSONException e) {
　　System.err.println("json paese exception = " + jsonStr);
}

/**map转Json对象**/
Map<String, String> map = new HashMap<String, String>();
JSONObject jsonObject = JSONObject.parseObject(JSON.toJSONString(map));
/**Json对象转map**/
Map<String, Object> map2 = JSONObject.toJavaObject(jsonObject, Map.class);


/**将List转换成JSONArray**/
List<String> list = new ArrayList<String>();
JSONArray jsonArray = JSONArray.parseArray(JSON.toJSONString(list));
/**将JSONArray转换成List**/
http://www.cnblogs.com/goody9807/p/4244862.html


/**字符串转Json对象**/
String jsonInfo = "";
JSONObject jsonObject2 = JSONObject.parseObject(jsonInfo);
/**字符串转Json对象**/
String jsonStrng = JSON.toJSONString(jsonObject2);

/**对JSONObject中的指定字段重新赋值**/

JSONObject posJson = new JSONObject();

posJson.put("op", "in");

/**其它**/

public class JsonDemo {
    public static void main(String[] args) {

        //1.json字符串转换为对象
        String jsonString="{'name':'42313123','id':'2345','age':12}";
        JSONObject jsonObject = JSONObject.parseObject(jsonString);
        String id = jsonObject.getString("id");
        System.out.println(id);

        //2. JSONObject转化成自定义类对象
        PeoplePo peoplePo1 = JSONObject.parseObject(jsonString, PeoplePo.class);
        System.out.println(peoplePo1);

        //3. JSONObject转化成Map集合
        Map map = JSONObject.parseObject(jsonString, Map.class);
        System.out.println(map);

        //4. 自定义对象转化成json格式的字符串
        PeoplePo peoplePo = new PeoplePo();
        peoplePo.setId("1");
        peoplePo.setAge(11);
        peoplePo.setName("LH");
        String peopleJson = JSON.toJSONString(peoplePo);
        System.out.println(peopleJson);

        //5. String类型转化成JSONObject;
        String str = "{"result":"success","message":"成功！"}";
        JSONObject jsonObject1 = JSONObject.parseObject(str);
        System.out.println(jsonObject1);

        //6. JSONObject转化成JSONArray的两种方式
        String str1 = "{"result":"success","message":"成功！","data":[{"name":"Tom","age":"20"}]}";
        JSONObject jsonToArray = JSONObject.parseObject(str1);
        //方式一
        JSONArray data = jsonToArray.getJSONArray("data");
        System.out.println(data);
        //方式二
        JSONArray jsonArray = JSONArray.parseArray(jsonToArray.getString("data"));
        System.out.println(jsonArray);

        //7. jsonArray转化成JSONObject并取出其中的元素数据
        JSONObject o = (JSONObject) jsonArray.get(0);
        String name = o.getString("name");
        System.out.println(o);
        System.out.println(name);
        System.out.println(jsonArray.toString());
    }
}
//转自 https://blog.csdn.net/lh19960914/article/details/87861308