从 JSON 文件中读取并映射对象

Question

所以我得到了这个巨大的 JSON 文件，我需要从中提取数据。 JSON 格式如下所示：

{
  "enabled":true,
  "contentMetadataPartial":
  {
     "customTags":
     {
        "tag1":"value1"
     }
  },
  "simulatedChanges":
  [
     3000,
     2500,
     400
  ],
  "simulatedUpdateMetadata":
  [
     {
        "customTags":
        {
           "tag1":"value1",
        },
        "assetName":"asset1234",
     },
     {
        "duration":1111,
        "encodedRate":3333,
     }
  ]
}

为了阅读它，我试图创建一个类来映射键和对象。像这样的东西，类似于this问题：

public class ConfigData
{
    private Boolean enabled;
    private class ContentMetadataPartial
    {
        private class CustomTags
        {
            String tag1;
        }
    }
    int[] simulatedChanges = new int[3];

    //problem here
}

但我被困在数组中，它包含更多对象，而不仅仅是简单的基本数据类型。

JSON 文件很大，并且到处都有类似类型的项目。我对此很陌生，可能会犯一些错误。感谢您对正确方向的任何帮助。谢谢！

Answer 1

你需要一个类结构，而不是一体：

配置数据：

package com.example.gson;

import java.util.List;

public class ConfigData {

    private Boolean enabled;
    private ContentMetadataPartial contentMetadataPartial;
    private List<Integer> simulatedChanges = null;
    private List<SimulatedUpdateMetadatum> simulatedUpdateMetadata = null;

    public Boolean getEnabled() {
        return enabled;
    }

    public void setEnabled(Boolean enabled) {
        this.enabled = enabled;
    }

    public ContentMetadataPartial getContentMetadataPartial() {
        return contentMetadataPartial;
    }

    public void setContentMetadataPartial(ContentMetadataPartial contentMetadataPartial) {
        this.contentMetadataPartial = contentMetadataPartial;
    }

    public List<Integer> getSimulatedChanges() {
        return simulatedChanges;
    }

    public void setSimulatedChanges(List<Integer> simulatedChanges) {
        this.simulatedChanges = simulatedChanges;
    }

    public List<SimulatedUpdateMetadatum> getSimulatedUpdateMetadata() {
        return simulatedUpdateMetadata;
    }

    public void setSimulatedUpdateMetadata(List<SimulatedUpdateMetadatum> simulatedUpdateMetadata) {
        this.simulatedUpdateMetadata = simulatedUpdateMetadata;
    }

    @Override
    public String toString() {
        return "ConfigData [enabled=" + enabled + ", contentMetadataPartial=" + contentMetadataPartial
                + ", simulatedChanges=" + simulatedChanges + ", simulatedUpdateMetadata=" + simulatedUpdateMetadata
                + "]";
    }

}

内容元数据部分：

package com.example.gson;

public class ContentMetadataPartial {

    private CustomTags customTags;

    public CustomTags getCustomTags() {
        return customTags;
    }

    public void setCustomTags(CustomTags customTags) {
        this.customTags = customTags;
    }

}

自定义标签：

package com.example.gson;

public class CustomTags {

    private String tag1;

    public String getTag1() {
        return tag1;
    }

    public void setTag1(String tag1) {
        this.tag1 = tag1;
    }

}

模拟更新元数据：

package com.example.gson;

public class SimulatedUpdateMetadatum {

    private CustomTags customTags;
    private String assetName;
    private Integer duration;
    private Integer encodedRate;

    public CustomTags getCustomTags() {
        return customTags;
    }

    public void setCustomTags(CustomTags customTags) {
        this.customTags = customTags;
    }

    public String getAssetName() {
        return assetName;
    }

    public void setAssetName(String assetName) {
        this.assetName = assetName;
    }

    public Integer getDuration() {
        return duration;
    }

    public void setDuration(Integer duration) {
        this.duration = duration;
    }

    public Integer getEncodedRate() {
        return encodedRate;
    }

    public void setEncodedRate(Integer encodedRate) {
        this.encodedRate = encodedRate;
    }

}

GsonMain：

package com.example.gson;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

import com.example.gson.ConfigData;
import com.google.gson.Gson;

public class GsonMain {

    private static final String jsonFile = "files/input.json";

    public static void main(String[] args) {
        String content = readFile(jsonFile);

        ConfigData conf = new Gson().fromJson(content, ConfigData.class);
        System.out.println(conf);
    }

    private static String readFile(String filename) {
        BufferedReader br = null;
        FileReader fr = null;
        StringBuilder content = new StringBuilder();

        try {
            fr = new FileReader(filename);
            br = new BufferedReader(fr);

            String sCurrentLine;
            while ((sCurrentLine = br.readLine()) != null) {
                content.append(sCurrentLine);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (br != null)
                    br.close();
                if (fr != null)
                    fr.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return content.toString();
    }
}

而且你的 Json 格式正确：

{
  "enabled":true,
  "contentMetadataPartial":
  {
     "customTags":
     {
        "tag1":"value1"
     }
  },
  "simulatedChanges":
  [
     3000,
     2500,
     400
  ],
  "simulatedUpdateMetadata":
  [
     {
        "customTags":
        {
           "tag1":"value1"
        },
        "assetName":"asset1234"
     },
     {
        "duration":1111,
        "encodedRate":3333
     }
  ]
}

我已经使用这个web 来生成类。

Answer 2

  package com.webom.practice;

  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import org.json.JSONArray;
   import org.json.JSONException; 
   import org.json.JSONObject;

public class Sample {

    public static Map<String, Object> jsonToMap(JSONObject json) throws JSONException {
        Map<String, Object> retMap = new HashMap<String, Object>();

        if(json != JSONObject.NULL) {
            retMap = toMap(json);
        }
        return retMap;
    }

    public static Map<String, Object> toMap(JSONObject object) throws JSONException {
        Map<String, Object> map = new HashMap<String, Object>();

        Iterator<String> keysItr = object.keys();
        while(keysItr.hasNext()) {
            String key = keysItr.next();
            Object value = object.get(key);

            if(value instanceof JSONArray) {
                value = toList((JSONArray) value);
            }

            else if(value instanceof JSONObject) {
                value = toMap((JSONObject) value);
            }
            map.put(key, value);
        }
        return map;
    }
    public static List<Object> toList(JSONArray array) throws JSONException {
        List<Object> list = new ArrayList<Object>();
        for(int i = 0; i < array.length(); i++) {
            Object value = array.get(i);
            if(value instanceof JSONArray) {
                value = toList((JSONArray) value);
            }

            else if(value instanceof JSONObject) {
                value = toMap((JSONObject) value);
            }
            list.add(value);
        }
        return list;
    }
public static void main(String[]args) {
    String Jsondata="{\r\n" + 
            "  \"enabled\":true,\r\n" + 
            "  \"contentMetadataPartial\":\r\n" + 
            "  {\r\n" + 
            "     \"customTags\":\r\n" + 
            "     {\r\n" + 
            "        \"tag1\":\"value1\"\r\n" + 
            "     }\r\n" + 
            "  },\r\n" + 
            "  \"simulatedChanges\":\r\n" + 
            "  [\r\n" + 
            "     3000,\r\n" + 
            "     2500,\r\n" + 
            "     400\r\n" + 
            "  ],\r\n" + 
            "  \"simulatedUpdateMetadata\":\r\n" + 
            "  [\r\n" + 
            "     {\r\n" + 
            "        \"customTags\":\r\n" + 
            "        {\r\n" + 
            "           \"tag1\":\"value1\",\r\n" + 
            "        },\r\n" + 
            "        \"assetName\":\"asset1234\",\r\n" + 
            "     },\r\n" + 
            "     {\r\n" + 
            "        \"duration\":1111,\r\n" + 
            "        \"encodedRate\":3333,\r\n" + 
            "     }\r\n" + 
            "  ]\r\n" + 
            "}\r\n" ;
     JSONObject json = new JSONObject(Jsondata);
     System.out.println(json);
Map<String,Object> dataConversion=Sample.jsonToMap(json);
System.out.println(dataConversion);
}
}