用GSON解析內層數組，從API JSON

Question

所以我想解析一下我用GSON從api獲得的json。所有的例子都非常清楚，我完美地運作了它。但現在API給了我這樣的東西。在第二個大括號中爲項目製作課程不起作用，請參見下文。

所以我的問題是沒有人有一個想法如何使這項工作？

SOLUTION：

存放在這個地方，member.json

{"Peter":{"id":585897,"name":"PhPeter","profileIconId":691,"age":99,"email":"peter@adress.com "}} 

類，Member.java

package JsonPackage; 

public class Summoner { 

    int id; 
    String name; 
    int profileIconId; 
    int summonerLevel; 
    long revisionDate; 

    //getters setters 

    public String getName() { 
     return name; 
    } 

    public int getId() { 
     return id; 
    } 

    public int getProfileIconId() { 
     return profileIconId; 
    } 

    public int getSummonerLevel() { 
     return summonerLevel; 
    } 

    public long getRevisionDate() { 
     return revisionDate; 
    } 
} 

主類，MemberRead2Java.java：

package JsonPackage; 

import java.io.BufferedReader; 
import java.io.FileReader; 
import java.io.StringReader; 
import java.util.Collection; 
import java.util.Iterator; 
import java.util.Map; 

import com.google.gson.Gson; 

public class ReadSummonerObject { 

    public static void main(String[] args) { 
     Gson gson = new Gson(); 

     try { 

      BufferedReader br = new BufferedReader(new FileReader("C:\\member.json")); //path to your file 


      Object obj = gson.fromJson(br, Object.class); 
      if (obj instanceof Map) { 
       Map map = (Map) obj; 
       Collection coll = map.values(); 
       Iterator iter = coll.iterator(); 
       while (iter.hasNext()) { 
        Object str = iter.next(); 

        StringReader sr = new StringReader(str.toString()); 
        Summoner summonerObj = gson.fromJson(sr, Summoner.class); 
        System.out.println("Id: " + summonerObj.getId()); 
        System.out.println("Name: " +summonerObj.getName()); 
        System.out.println("ProfileIconID: " + summonerObj.getProfileIconId()); 
        System.out.println("SummonerLevel: " + summonerObj.getSummonerLevel()); 
        System.out.println("RevisionDate: " + summonerObj.getRevisionDate()); 
       } 

      } 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 
} 

Answer 1

這裏是你如何能做到這一點：

基本上你會得到一個地圖爲您輸入(a key-value pair, in your case key is "Peter" and value is your Member object details)，所以你必須遍歷映射值，（其中地圖的值是你的會員對象），只是轉換字符串到成員對象。

這裏我已經使用了StringReader（只是從字符串中讀取json）而不是BufferedReader（從.json文件讀取）。

public static void main(String[] args) { 

String json ="{\"Peter\":{\"id\":585897,\"name\":\"PhPeter\",\"profileIconId\":691,\"age\":99,\"email\":\"peter@adress.com \"}}"; 
Gson gson = new Gson(); 
StringReader reader = new StringReader(json); 
    //convert the json string back to object 
Object obj = gson.fromJson(reader, Object.class); 
if(obj instanceof Map){ 
    Map map =(Map)obj; 
    Collection coll = map.values(); 
    Iterator iter = coll.iterator(); 
    while(iter.hasNext()){ 
     Object str = iter.next(); 

     StringReader sr = new StringReader(str.toString()); 
     Member memberObj = gson.fromJson(sr, Member.class); 
    System.out.println("Id: " + memberObj.getId()); 
    System.out.println("Name: " + memberObj.getName()); 
    System.out.println("ProfileIconID: " + memberObj.getProfileIconId()); 
    System.out.println("Age: " + memberObj.getAge()); 
    System.out.println("Email: " + memberObj.getEmail()); 
    } 

} 

    } 

編輯： 這裏是另一個版本，從file.Just閱讀替換爲以下內容的主要方法，確保的FileReader路徑是正確的：

public static void main(String[] args) { 

     Gson gson = new Gson(); 
     try { 
      BufferedReader br = new BufferedReader(new FileReader("src/Member.json")); 

      Object obj = gson.fromJson(br, Object.class); 
      if (obj instanceof Map) { 
       @SuppressWarnings("unchecked") 
      Map<String,Object> map = (Map<String,Object>) obj; 
      Collection<Object> coll = map.values(); 
      Iterator<Object> iter = coll.iterator(); 
       while (iter.hasNext()) { 
        Object str = iter.next(); 

        StringReader sr = new StringReader(str.toString()); 
        Member memberObj = gson.fromJson(sr, Member.class); 
        System.out.println("Id: " + memberObj.getId()); 
        System.out.println("Name: " + memberObj.getName()); 
        System.out.println("ProfileIconID: " 
          + memberObj.getProfileIconId()); 
        System.out.println("Age: " + memberObj.getAge()); 
        System.out.println("Email: " + memberObj.getEmail()); 
       } 

      } 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 

打印：

Id: 585897 
Name: PhPeter 
ProfileIconID: 691 
Age: 99 
Email: peter@adress.com 

對於您在評論中提出的問題：

public static void main(String[] args) { 
     Gson gson = new Gson(); 

     try { 

      BufferedReader br = new BufferedReader(new FileReader("src/Members.json")); //path to your file 


      Object obj = gson.fromJson(br, Object.class); 
      if (obj instanceof Map) { 
       Map map = (Map) obj; 
       Collection coll = map.values();  
       Iterator iter = coll.iterator(); 
       JsonParser parser = new JsonParser(); 
       while (iter.hasNext()) { 

        Object str = iter.next(); 
        JsonArray jsonArr = parser.parse(str.toString()).getAsJsonArray(); 
        for(int i=0;i<jsonArr.size();i++){ 

        Member memberObj = gson.fromJson(jsonArr.get(i).toString(), Member.class); 
        System.out.println("Id: " + memberObj.getId()); 
        System.out.println("Name: " +memberObj.getName()); 
        System.out.println("ProfileIconID: " + memberObj.getProfileIconId()); 
        System.out.println("Email: " + memberObj.getEmail()); 
        System.out.println("Age: " + memberObj.getAge()); 
        } 
       } 

      } 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 

Answer 2

既然你有一個內部數組，GSON期望這個內部數組作爲一個內部類，因爲它沒有找到一個，它可能會拋出錯誤。創建您的成員類如下：

class Member { 

    String member_name; // To hold the member name in the outer array 
    Details details; // You need an existing instance to parse the data into. I missed this. 

    // Inner class corresponding to inner array 
    public static class Details { 
     int id; 
     String name; 
     int profileIconId; 
     int age; 
     String email; 
     // Getters and setters for inner class 
    } 
    // Getters and setters for outer class 
    public Details getDetails() { 
     return this.details; 
    } 
    // Other getters and setters 
} 

構建您的成員對象從這個類，並引用它，你會像通常會與靜態嵌套類一樣。

Member memberObj = gson.fromJson(br, Member.class); 

要從內部類的訪問方法，只要做到以下幾點： //見我怎麼現在訪問現有的實例，而不是創建一個新的實例 //我想在飛行中被遺忘這個 Member.Details details = memberObj.getDetails（）; String item = detail.getterMethodForItem（）;