如何将JSON映射到java模型类

Question

我需要将JSONobj 映射到一个类及其数组ArrayList,Android并且它应该包含所有子数据.(也有嵌套的arraylists),我需要再次将更新的数据列表转换为jsonobject

我的json字符串是

  {
    "type": "already_planted",
    "crops": [
      {
        "crop_id": 1,
        "crop_name": "apple",
        "crop_details": [
          {
            "created_id": "2017-01-17",
            "questions": [
              {
                "plants": "10"
              },
              {
                "planted_by": "A person"
              }
            ]
          },
          {
            "created_id": "2017-01-30",
            "questions": [
              {
                "plants": "15"
              },
              {
                "planted_by": "B person"
              }
            ]
          }
        ]
      },
      {
        "crop_id": 2,
        "crop_name": "Cashew",
        "crop_details": [
          {
            "created_id": "2017-01-17",
            "questions": [
              {
                "plants": "11"
              },
              {
                "planted_by": "c person"
              }
            ]
          }
        ]
      }
    ]
  }

Answer 1

首先,您需要创建要在其中映射JSON的类.

幸运的是,有一个网站,可以为你做它在这里

其次,您可以使用谷歌Gson库轻松映射

1.添加依赖项.

        dependencies {
          compile 'com.google.code.gson:gson:2.8.2'
         }  

2.从您的对象到JSON.

        MyData data =new MyData() ; //initialize the constructor 
        Gson gson = new Gson();  
        String Json = gson.toJson(data );  //see firstly above above
        //now you have the json string do whatever.

3.从JSON到对象.

        String  jsonString =doSthToGetJson(); //http request 
        MyData data =new MyData() ; 
        Gson gson = new Gson();  
        data= gson.fromJson(jsonString,MyData.class); 
        //now you have Pojo do whatever

有关gson的更多信息,请参阅本教程.