将JSON数组解析为java.util。列表与Gson-ParsingJSONarrayintojava.util.ListwithGson

213  

Definitely the easiest way to do that is using Gson's default parsing function fromJson().

最简单的方法就是使用Gson的默认解析函数fromJson()。

There is an implementation of this function suitable for when you need to deserialize into any ParameterizedType (e.g., any List), which is fromJson(JsonElement json, Type typeOfT).

这个函数的实现适用于当您需要反序列化为任何参数类型(例如，任何列表)时，它是fromJson(JsonElement json，类型typeOfT)。

In your case, you just need to get the Type of a List and then parse the JSON array into that Type, like this:

在您的示例中，只需获取列表 的类型，然后将JSON数组解析为该类型，如下所示:

import java.lang.reflect.Type;
import com.google.gson.reflect.TypeToken;

JsonElement yourJson = mapping.get("servers");
Type listType = new TypeToken>() {}.getType();

List yourList = new Gson().fromJson(yourJson, listType);

In your case yourJson is a JsonElement, but it could also be a String, any Reader or a JsonReader.

在您的例子中，您的json是一个JsonElement，但它也可以是一个字符串、任何读取器或JsonReader。

You may want to take a look at Gson API documentation.

您可能想看看Gson API文档。

16  

Below code is using com.google.gson.JsonArray. I have printed the number of element in list as well as the elements in List

下面的代码使用com.google.gson.JsonArray。我已经打印了列表中的元素数量以及列表中的元素

import java.util.ArrayList;

import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;


public class Test {

    static String str = "{ "+ 
            "\"client\":\"127.0.0.1\"," + 
            "\"servers\":[" + 
            "    \"8.8.8.8\"," + 
            "    \"8.8.4.4\"," + 
            "    \"156.154.70.1\"," + 
            "    \"156.154.71.1\" " + 
            "    ]" + 
            "}";

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        try {

            JsonParser jsOnParser= new JsonParser();
            JsonObject jo = (JsonObject)jsonParser.parse(str);
            JsonArray jsOnArr= jo.getAsJsonArray("servers");
            //jsonArr.
            Gson googleJson = new Gson();
            ArrayList jsOnObjList= googleJson.fromJson(jsonArr, ArrayList.class);
            System.out.println("List size is : "+jsonObjList.size());
                    System.out.println("List Elements are  : "+jsonObjList.toString());


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

}

OUTPUT

输出

List size is : 4

List Elements are  : [8.8.8.8, 8.8.4.4, 156.154.70.1, 156.154.71.1]

1  

I read solution from official website of Gson at here

我在这里阅读了Gson官方网站的解决方案

And this code for you:

这是你的密码:

    String json = "{"client":"127.0.0.1","servers":["8.8.8.8","8.8.4.4","156.154.70.1","156.154.71.1"]}";

    JsonObject jsOnObject= new Gson().fromJson(json, JsonObject.class);
    JsonArray jsOnArray= jsonObject.getAsJsonArray("servers");

    String[] arrName = new Gson().fromJson(jsonArray, String[].class);

    List lstName = new ArrayList<>();
    lstName = Arrays.asList(arrName);

    for (String str : lstName) {
        System.out.println(str);
    }    

Result show on monitor:

监测结果表明:

8.8.8.8
8.8.4.4
156.154.70.1
156.154.71.1

0  

I was able to get the list mapping to work with just using @SerializedName for all fields.. no logic around Type was necessary.

我可以使用@SerializedName为所有字段进行列表映射。没有逻辑围绕类型。

Running the code - in step #4 below - through the debugger, I am able to observe that the List mGalleryImages object populated with the JSON data

通过调试器运行代码—在第4步—通过调试器，我可以看到列表 mGalleryImages对象填充了JSON数据。

Here's an example:

这里有一个例子:

1. The JSON

1。JSON

   {
    "name": "Some House",
    "gallery": [
      {
        "description": "Nice 300sqft. den.jpg",
        "photo_url": "image/den.jpg"
      },
      {
        "description": "Floor Plan",
        "photo_url": "image/floor_plan.jpg"
      }
    ]
  }

2. Java class with the List

2。带有列表的Java类

public class FocusArea {

    @SerializedName("name")
    private String mName;

    @SerializedName("gallery")
    private List mGalleryImages;
}

3. Java class for the List items

3所示。列表项的Java类。

public class ContentImage {

    @SerializedName("description")
    private String mDescription;

    @SerializedName("photo_url")
    private String mPhotoUrl;

    // getters/setters ..
}

4. The Java code that processes the JSON

4所示。处理JSON的Java代码

    for (String key : focusAreaKeys) {

        JsonElement sectiOnElement= sectionsJsonObject.get(key);
        FocusArea focusArea = gson.fromJson(sectionElement, FocusArea.class);
    }

-2  

Check this out, I believe this is what you need.

看看这个，我相信这就是你需要的。

public class Test {
public static void main(String[] args) {
    //  this part is just to create the JSON object in question, so I am sure you are already having it.
    JsonObject mappings = new JsonObject();
    JsonElement e = new JsonPrimitive("127.0.0.1");
    mappings.add("client", e);

    JsonArray servers = new JsonArray();
    JsonElement s1 = new JsonPrimitive("8.8.8.8");
    JsonElement s2 = new JsonPrimitive("8.8.4.4");
    JsonElement s3 = new JsonPrimitive("156.154.70.1");
    JsonElement s4 = new JsonPrimitive( "156.154.71.1");
    servers.add(s1);
    servers.add(s2);
    servers.add(s3);
    servers.add(s4);

    mappings.add("servers", servers);

    // json creation ends.

    // split the resultant string based on comma and then convert the resultant array into a list.  
    String[] split = mappings.get("servers").getAsJsonArray().toString().split(",");
    List myList = new ArrayList();
    Collections.addAll(myList, split);

    // again the following part is to demonstrate that the strings were populated in the list.
    for(String l : myList){
        System.out.println(l);
    }
}
}