如何通过gson解析具有多个对象的json数组？

How can I parse json using gson? I have a json array with multiple object types, and I don't know, what kind of object I need to create to save this structure. I cannot change the json data format (I don't control the server). Can I use gson or other library parse this json array, how should I do?

如何使用gson解析json？我有一个带有多个对象类型的json数组，我不知道，我需要创建哪种对象来保存这个结构。我无法更改json数据格式（我不控制服务器）。我可以使用gson或其他库解析这个json数组，我该怎么办？

This is the json code block:

这是json代码块：

[
  {
    "type": 1,
    "object": {
      "title1": "title1",
      "title2": "title2"
    }
  },
  {
    "type": 2,
    "object": [
      "string",
      "string",
      "string"
    ]
  },
  {
    "type": 3,
    "object": [
      {
        "url": "url",
        "text": "text",
        "width": 600,
        "height": 600
      },
      {
        "url": "url",
        "text": "text",
        "width": 600,
        "height": 600
      }
    ]
  },
  {
    "type": 4,
    "object": {
      "id": 337203,
      "type": 1,
      "city": "1"
    }
  }
]

4 个解决方案

#1

This json structure is inherently gson-unfriendly. i.e You cannot model this cleanly in java because the "object" key refers to a dynamic type. The best you can do with this structure is model it like so:

这种json结构固有地对gson不友好。即你不能在java中干净地建模，因为“对象”键指的是动态类型。你可以用这个结构做的最好的模型是这样的：

    public class Models extends ArrayList<Models.Container> {

    public class Container {
        public int type;
        public Object object;
    }

    public class Type1Object {
        public String title1;
        public String title2;
    }

    public class Type3Object {
        public String url;
        public String text;
        public int width;
        public int height;
    }

    public class Type4Object {
        public int id;
        public int type;
        public int city;
    }

}

Then do some awkward switch on type and the object field:

然后做一些尴尬的开关类型和对象字段：

String json = "{ ... json string ... }";
Gson gson = new Gson();
Models model = gson.fromJson(json, Models.class);


for (Models.Container container : model) {

    String innerJson = gson.toJson(container.object);

    switch(container.type){
        case 1:
            Models.Type1Object type1Object = gson.fromJson(innerJson, Models.Type1Object.class);
            // do something with type 1 object...                                
            break;
        case 2:
            String[] type2Object = gson.fromJson(innerJson, String[].class);
            // do something with type 2 object...
            break;
        case 3:
            Models.Type3Object[] type3Object = gson.fromJson(innerJson, Models.Type3Object[].class);
            // do something with type 3 object...
            break;
        case 4:
            Models.Type4Object type4Object = gson.fromJson(innerJson, Models.Type4Object.class);
            // do something with type 4 object...
            break;

    }
}

Ultimately the best solution is to get the json structure changed to something more compatible with java.

最终，最好的解决方案是将json结构更改为与java更兼容的东西。

E.g:

例如：

[
  {
    "type": 1,
    "type1Object": {
      "title1": "title1",
      "title2": "title2"
    }
  },
  {
    "type": 2,
    "type2Object": [
      "string",
      "string",
      "string"
    ]
  },
  {
    "type": 3,
    "type3Object": [
      {
        "url": "url",
        "text": "text",
        "width": 600,
        "height": 600
      },
      {
        "url": "url",
        "text": "text",
        "width": 600,
        "height": 600
      }
    ]
  },
  {
    "type": 4,
    "type4Object": {
      "id": 337203,
      "type": 1,
      "city": "1"
    }
  }
]

#2

This may be a bit late for the original poster, but hopefully it will help someone else.

对于原始海报来说，这可能有点晚了，但希望它会帮助其他人。

I am using Gson in Android. I have seen everyone use custom classes and long way round solutions. Mine is basic.

我在Android中使用Gson。我看到每个人都使用自定义类和长途解决方案。我的基本。

I have an ArrayList of many different Object types (Models for my database) - Profile is one of them. I get the item using mContactList.get(i) which returns:

我有一个包含许多不同对象类型的ArrayList（我的数据库的模型） - Profile就是其中之一。我使用mContactList.get（i）获取项目，返回：

{"profile": 
    {"name":"Josh",
     "position":"Programmer",
     "profile_id":1,
     "profile_image_id":10,
     "user_id":1472934469
    },
 "user":
    {"email":"[e-mail]",
     "phone_numbers":[],
     "user_id":1,
     "user_type_id":1
    },
 "follower":
    {"follower_id":3,
     "following_date":1.4729345E9,
     "referred_by_id":2,
     "user_from_id":1,
     "user_to_id":2
    },
 "media":
    {"link":"uploads/profiles/profile-photos/originals/1-G9FSkRCzikP4QFY.png",
     "media_description":"",
     "media_id":10,
     "media_name":"",
     "media_slug":"",
     "medium_link":"uploads/profiles/profile-photos/thumbs-medium/1-G9FSkRCzikP4QFY.png",
     "thumbnail_link":"uploads/profiles/profile-photos/thumbs-small/1-G9FSkRCzikP4QFY.png",
     "uploader_id":1
    }
}

Now I create the Gson object:

现在我创建Gson对象：

Gson gson = new Gson();
// this creates the JSON string you see above with all of the objects
String str_obj = new Gson().toJson(mContactList.get(i)); 

Now instead of creating a custom class - just pass it through as a JsonObject using the following code:

现在不是创建自定义类 - 只需使用以下代码将其作为JsonObject传递：

JsonObject obj = gson.fromJson(str_obj, JsonObject.class);

And now, you can call the object like so:

现在，您可以像这样调用对象：

JsonObject profile = obj.getAsJsonObject("profile");

#3

You can set the methods in your model class very easily. Just make a StringRequest. Below is a snippet:

您可以非常轻松地在模型类中设置方法。只需创建一个StringRequest。以下是一个片段：

List<YourModelClass> inpList;
StringRequest greq = new StringRequest(Request.Method.POST, yourURL, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                try {
                        Log.d("response array===>  ", response.toString());

                        Type type = new TypeToken<List<YourModelClass>>(){}.getType();
                        inpList = new Gson().fromJson(response, type);

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                error.printStackTrace();

            }
        }){
            @Override
            protected Map<String, String> getParams() throws AuthFailureError {
                Map<String, String> params = new HashMap<String, String>();
                //return params back to server, if any
            }
        };

        yourVolley.getRequestQueue().add(greq);

I have used this to generate your model class from you json. Your model class will look something like this:

我用它来从你的json生成你的模型类。您的模型类看起来像这样：

 package com.example;

import javax.annotation.Generated;
import com.google.gson.annotations.Expose;

@Generated("org.jsonschema2pojo")
public class YourModelClass {

@Expose
private Integer type;
@Expose
private Object object;

/**
* 
* @return
* The type
*/
public Integer getType() {
return type;
}

/**
* 
* @param type
* The type
*/
public void setType(Integer type) {
this.type = type;
}

/**
* 
* @return
* The object
*/
public Object getObject() {
return object;
}

/**
* 
* @param object
* The object
*/
public void setObject(Object object) {
this.object = object;
}

}
-----------------------------------com.example.Object.java-----------------------------------

package com.example;

import javax.annotation.Generated;
import com.google.gson.annotations.Expose;

@Generated("org.jsonschema2pojo")
public class Object {

@Expose
private Integer id;
@Expose
private Integer type;
@Expose
private String city;

/**
* 
* @return
* The id
*/
public Integer getId() {
return id;
}

/**
* 
* @param id
* The id
*/
public void setId(Integer id) {
this.id = id;
}

/**
* 
* @return
* The type
*/
public Integer getType() {
return type;
}

/**
* 
* @param type
* The type
*/
public void setType(Integer type) {
this.type = type;
}

/**
* 
* @return
* The city
*/
public String getCity() {
return city;
}

/**
* 
* @param city
* The city
*/
public void setCity(String city) {
this.city = city;
}

}

#4

For you issue, I suggest the following solution:

对于你的问题，我建议以下解决方案：

Because your inner object can be a json object or a json array, so I will use a generic JsonElement of gson (you can find more information about this class by pressing Ctrl-B at it in your project or refering here)

因为您的内部对象可以是json对象或json数组，所以我将使用gson的通用JsonElement（您可以通过在项目中按Ctrl-B或在此处引用来查找有关此类的更多信息）

public class CustomJson {
     private int type;
     private JsonElement object;
}

Then in your Activity, using Gson to parse:

然后在你的Activity中，使用Gson解析：

Gson gson = new Gson();
CustomJson[] customJson = gson.fromJson(jsonString, CustomJson[].class);

Because com.google.gson.JsonElement can be a JsonObject (not JSONObject) or a JsonArray (not JSONArray), if you want to convert to JSONObject and JSONArray, use the following code:

因为com.google.gson.JsonElement可以是JsonObject（不是JSONObject）或JsonArray（不是JSONArray），所以如果要转换为JSONObject和JSONArray，请使用以下代码：

        if (customJson!= null && customJson.length > 0) {
            for (CustomJson aCustomJson : customJson) {
                JsonElement jsonElement = aCustomJson.object;
                if (jsonElement instanceof JsonObject) {
                    try {
                        JSONObject jsonObject = new JSONObject(jsonElement.toString());
                        Log.i(LOG_TAG, jsonObject.toString());
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                } else if (jsonElement instanceof JsonArray) {
                    try {
                        JSONArray jsonArray = new JSONArray(jsonElement.toString());
                        Log.i(LOG_TAG, jsonArray.toString());
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }
        }

Here are the logcat results in my project I have tested:

以下是我测试的项目中的logcat结果：

09-08 15:41:48.024    6202-6202/com.example.jsonparse I/JSONParse﹕ {"title1":"title1","title2":"title2"}
09-08 15:41:51.458    6202-6202/com.example.jsonparse I/JSONParse﹕ ["string","string","string"]
09-08 15:41:51.458    6202-6202/com.example.jsonparse I/JSONParse﹕ [{"text":"text","url":"url","height":600,"width":600},{"text":"text","url":"url","height":600,"width":600}]
09-08 15:41:51.458    6202-6202/com.example.jsonparse I/JSONParse﹕ {"type":1,"id":337203,"city":"1"}

Hope this helps!

希望这可以帮助！