Json,Gson,FastJson解析笔记-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_2903/article/details/82636091

本文介绍了如何使用Java中的Json、Gson及FastJson库实现JavaBean与JSON之间的相互转换，包括单个对象及集合的处理，并提供了详细的代码示例。

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Json
1.将JavaBean转换成Json对象：


public static String CreatJsonFromObject(Object key,Object value)
	{
		JSONObject JObj =new JSONObject();
		JObj.put(key, value);
		return JObj.toString();
	}

2.解析Json：


  public static  Person parseJsonPerson(String key,String jsonStr)
    {
        System.out.print(key+"-->"+jsonStr);
        Person person =new Person();
        JSONObject jobj;
        try
        {
            jobj = new JSONObject(jsonStr);
            JSONObject personObj =jobj.getJSONObject(key);
            person.setAge(personObj.getInt("age"));
            person.setName(personObj.getString("name"));
            person.setSex(personObj.getString("sex"));
        }
        catch (JSONException e)
        {
            e.printStackTrace();
        }
        return person;

    }

    public static List<Person> parseJsonListPerson(String key,String jsonStr)
    {
        System.out.print(key+"-->"+jsonStr);
        List<Person> list=new ArrayList<Person>();
        try
        {
            JSONObject jobj;
            jobj = new JSONObject(jsonStr);
            JSONArray personArr =jobj.getJSONArray(key);
            for(int i=0;i<personArr.length();i++)
            {
                JSONObject personObj = personArr.getJSONObject(i);
                Person person =new Person();
                person.setAge(personObj.getInt("age"));
                person.setName(personObj.getString("name"));
                person.setSex(personObj.getString("sex"));
                list.add(person);
            }
        }
        catch (JSONException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return list;
    }

    public static List<String> parseJsonListString(String key,String jsonStr)
    {
        System.out.print(key+"-->"+jsonStr);
        List<String> list =new ArrayList<String>();
        try
        {
            JSONObject jobj;
            jobj = new JSONObject(jsonStr);
            JSONArray personArr =jobj.getJSONArray(key);
            for(int i=0;i<personArr.length();i++)
            {
                String personObj = personArr.getString(i);
                list.add(personObj);
            }
        }
        catch (JSONException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return list;
    }

    public static List<Map<String, Object>> parseJsonListMap(String key,String jsonStr)
    {
        System.out.print(key+"-->"+jsonStr);
        List<Map<String, Object>> list =new ArrayList<Map<String,Object>>();
        try
        {
            JSONObject jobj;
            jobj = new JSONObject(jsonStr);
            JSONArray personArr =jobj.getJSONArray(key);
            for(int i=0;i<personArr.length();i++)
            {
                JSONObject personObj = personArr.getJSONObject(i);
                Iterator<String> set =personObj.keys();
                while(set.hasNext())
                {
                    String tempKey =set.next();
                    Object tempValue =personObj.get(tempKey);
                    HashMap<String,Object> map =new HashMap<String,Object>();
                    //注意tempValue可能为空
                    if(tempValue == null)
                    {
                        tempValue="";
                    }
                    map.put(tempKey, tempValue);
                    list.add(map);
                }
            }

        }
        catch (JSONException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        return list;
    }

Gson:
1.将JavaBean转换成Gson String


	public static String CreatJsonFromObject(Object value)
	{
		Gson gson =new Gson();
		return gson.toJson(value);

	}

2.解析Gson String


 public static <T> T getPerson(String Json, Class<T> cls)
    {
        Gson gson = new Gson();
        T t = gson.fromJson(Json, cls);
        return t;
    }

   public static <T> List<T> getPersons(String Json, Class<T> Type)
    {
        List<T> list = new Gson().fromJson(Json, new TypeToken<List<T>>()
        {
        }.getType());
        return list;
    }

   public  static List<String> getString(String Json)
    {
        List<String> retStr = new Gson().fromJson(Json, new TypeToken<List<String>>()
        {
        }.getType());
        return retStr;
    }

   public   static List<Map<String, Object>> getListMap(String Json)
    {
        List<Map<String, Object>> retStr = new Gson().fromJson(Json, new TypeToken<List<Map<String, Object>>>()
        {
        }.getType());
        return retStr;
    }

FastJson:
1.将JavaBean转换成FastJson String
服务端利用上述方式实现
2.解析FastJson String


 public static <T> T getPerson(String jsonStr, Class<T> cls)
    {
        T t = JSON.parseObject(jsonStr, cls);
        return t;
    }

    public static <T> List<T> getPersons(String jsonStr, Class<T> cls)
    {
        List<T> list = JSON.parseArray(jsonStr, cls);
        return list;
    }

    /**
     * @param jsonStr
     * @return
     */
    public static List<Map<String, Object>> getListMap(String jsonStr)
    {
        List<Map<String, Object>> list = JSON.parseObject(jsonStr, new TypeReference<List<Map<String, Object>>>()
        {
        });
        return list;
    }