如何使用 Retrofit 和 GSON 解析 JSON 数组？

Question

我已经学会了如何通过 Retrofit Gson 解析 JSON 对象，但我需要通过 Retrofit Gson 解析完整的 JSON 数组。

我需要解析以下内容：

"{\n" +
        "  \"snappedPoints\": [\n" +
        "    {\n" +
        "      \"location\": {\n" +
        "        \"latitude\": -35.2784167,\n" +
        "        \"longitude\": 149.1294692\n" +
        "      },\n" +
        "      \"originalIndex\": 0,\n" +
        "      \"placeId\": \"ChIJoR7CemhNFmsRQB9QbW7qABM\"\n" +
        "    },\n" +
        "    {\n" +
        "      \"location\": {\n" +
        "        \"latitude\": -35.280321693840129,\n" +
        "        \"longitude\": 149.12908274880189\n" +
        "      },\n" +
        "      \"originalIndex\": 1,\n" +
        "      \"placeId\": \"ChIJiy6YT2hNFmsRkHZAbW7qABM\"\n" +
        "    },\n" +
        "    {\n" +
        "      \"location\": {\n" +
        "        \"latitude\": -35.280960897210818,\n" +
        "        \"longitude\": 149.1293250692261\n" +
        "      },\n" +
        "      \"originalIndex\": 2,\n" +
        "      \"placeId\": \"ChIJW9R7smlNFmsRMH1AbW7qABM\"\n" +
        "    },\n" +
        "    {\n" +
        "      \"location\": {\n" +
        "        \"latitude\": -35.28142839817933,\n" +
        "        \"longitude\": 149.1298619971291\n" +
        "      },\n" +
        "      \"originalIndex\": 3,\n" +
        "      \"placeId\": \"ChIJy8c0r2lNFmsRQEZUbW7qABM\"\n" +
        "    },\n" +
        "    {\n" +
        "      \"location\": {\n" +
        "        \"latitude\": -35.28193988170618,\n" +
        "        \"longitude\": 149.13001013387623\n" +
        "      },\n" +
        "      \"originalIndex\": 4,\n" +
        "      \"placeId\": \"ChIJ58xCoGlNFmsRUEZUbW7qABM\"\n" +
        "    },\n" +
        "    {\n" +
        "      \"location\": {\n" +
        "        \"latitude\": -35.282819705480151,\n" +
        "        \"longitude\": 149.1295597114644\n" +
        "      },\n" +
        "      \"originalIndex\": 5,\n" +
        "      \"placeId\": \"ChIJabjuhGlNFmsREIxAbW7qABM\"\n" +
        "    },\n" +
        "    {\n" +
        "      \"location\": {\n" +
        "        \"latitude\": -35.283139388422363,\n" +
        "        \"longitude\": 149.12895618087012\n" +
        "      },\n" +
        "      \"originalIndex\": 6,\n" +
        "      \"placeId\": \"ChIJ1Wi6I2pNFmsRQL9GbW7qABM\"\n" +
        "    },\n" +
        "    {\n" +
        "      \"location\": {\n" +
        "        \"latitude\": -35.284728724835304,\n" +
        "        \"longitude\": 149.12835061713685\n" +
        "      },\n" +
        "      \"originalIndex\": 7,\n" +
        "      \"placeId\": \"ChIJW5JAZmpNFmsRegG0-Jc80sM\"\n" +
        "    }\n" +
        "  ]\n" +
        "}"

我只需要纬度和经度。

这是我知道的通过 Retrofit GSON

解析 JSON 对象的方法

package com.example.akshay.retrofitgson;

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

/**
 * Created by Akshay on 9/6/2015.
 */
public class gitmodel {
    @SerializedName("latitude")
    @Expose
    public String latitude;
    @SerializedName("longitude")
    @Expose
    public String longitude;

    public void setLatitude(String latitude)
    {
        this.latitude = latitude;
    }
    public String getLatitude()
    {
        return latitude;
    }
    public void setLongitude(String longitude)
    {
        this.longitude = longitude;
    }

    public String getlatitude()
    {
        return  latitude;
    }
}

Answer 1

Retrofit 使用 Gson library 序列化 Json 响应。只要您正确设置了模型 class，就可以告诉 Gson 尝试将 json 序列化为该模型 class 的实例。您的代码应如下所示：

String json; // retrieved from file/server
MyObject myObject = new Gson().fromJson(json, MyObject.class)

Answer 2

您可能只需要 lat/longs，但最简单的方法是设置您的 POJO 以获取所有内容，然后从 POJO 中提取经纬度。如果需要，您甚至可以将反序列化对象设计为隐藏内部对象。对于您的 JSON，这很简单，只需这样做：

public static class SnappedPoints {
  private List<Point> snappedPoints;

  public String toString() {
    return snappedPoints.toString();
  }
}

public static class Point {
  private Location location;

  public double getLatitude() {
    return location.getLatitude();
  }

  public double getLongitude() {
    return location.getLongitude();
  }

  public String toString() {
    return "{" + location.getLatitude() + "," + location.getLongitude() + "}";
  }
}

public static class Location {
  double latitude;
  double longitude;

  public double getLatitude() {
    return latitude;
  }
  public double getLongitude() {
    return longitude;
  }
}

您只需执行以下操作即可看到实际效果：

public static void main(String[] args) {
  System.out.println(new Gson().fromJson(json, SnappedPoints.class));
}

或者，在 Retrofit 的情况下，是这样的：

public interface MyRetrofitAPI {
  @GET("/path/to/json")
  void getSnappedPoints(/* arguments */, Callback<SnappedPoints> callback);
}

如何使用 Retrofit 和 GSON 解析 JSON 数组？

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retrofit