使用Java中的GSON解析复杂的Json对象 [英] Parsing a complex Json Object using GSON in Java

问题描述

  {我有一个非常长的JSON来解析Gson，但为简洁起见，我已将它修剪成这个示例： 
volumes：[
 {
status：available，
managed：true，
name：va_85621143-1133-412f -83b4-57a01a552638_，
support：{
status：supported
}，
storage_pool：pfm9253_pfm9254_new，
id ：afb8e294-6188-4907-9f6f-963c7623cecb，
size：9 
}，
 {
status：正在使用中，
managed：false，
name：bt_newd20，
支持：{
status：not_supported，
原因：[ 
此卷不适用于管理，因为它已连接到虚拟机。要使用PowerVC管理此卷，请选择要连接的卷管理的虚拟机，所连接的卷将自动包含管理。 
] 
}，
storage_pool：KVM，
mapped_wwpns：[
2101001B32BD4280，
2100001B329D4280，
2101001B32BD637E，
2100001B329D637E
]，
id：c7838c79-17ca-3cbc-98e5-3567fde902d8，
size：0 
 
 $ status $ b $ managed 
 $ name $ vdisk138 
support
managed：true，
status ：{
status：supported
}，
storage_pool：Chassis2_IBMi，
id：b6d00783-9f8c-40b8-ad78-956b0299478c ，
size：100 
 
 
} 
] 
} 
  

从我和其他很少的地方，我发现我需要定义一个像下面这样的顶级容器，但我不知道如何完成它的定义

 静态类VolumeContainer {
 //我不知道这里有什么。这是第一个问题
} 
  

然后为每个 Volume

  static class Volume {
 private String status; 
私有布尔管理; 
私人字符串名称; 
 
 //这是第二个问题。支持变量不应该是一个字符串。 
 //它在{}中。仅供参考，我不会使用它。 
 //私人字符串支持; 
 
 private String storagePool; 
私人列表< String> mapped_wwpns; 
私人字符串ID; 
私人字符串大小; 
 
 
 
 
 $ b我想解析它，到目前为止：
  JsonParser parser = new JsonParser（）; 
 JsonObject obj = parser.parse（response）.getAsJsonObject（）; 
 
 Gson gson = new Gson（）; 
  
 JSON字符串存储在名为response的变量中
 
 
  VolumeContainer vc = gson.fromJson（response，VolumeContainer.class）; 
  
我最后的要求是 HashTable  of  id 和相关的 name 。第一个问题：您的 VolumeContainer       需要： 
 
 
  public class VolumeContainer {
 public List< Volume>卷; 
} 
  
它不需要是静态的。
 
 
 
 第二个问题：你的 Volume 类应该是这样的： 
 
 
  public class Volume {
 private String status; 
私有布尔管理; 
私人字符串名称; 
私人支持支持; 
 private String storage_pool; 
私人字符串ID; 
 private int size; 
私人列表< String> mapped_wwpns; 
 
 public String getId（）{return id;} 
 public String getName（）{return name;} 
} 
  
我定义了一个名为 Support 的类，如下所示： 
 
 
  public class Support {
 private String status; 
私人列表< String>原因; 
 
  
 第三个问题：解析，如果 response  string包含您的示例数据，只需解析如下： 
 
 
  Gson g = new GSON（）; 
 VolumeContainer vc = g.fromJson（response，VolumeContainer.class）; 
  
 第四个问题：获取地图。最后得到 HashMap ，就这样做： 
 
 
  HashMap<字符串，字符串> hm = new HashMap< String，String>（）; （卷v：vc.volumes）
 {
 hm.put（v.getId（），v.getName（））; 
} 
  
 
I have a very long JSON to parse with Gson, but for brevity I have trimmed it to this example:
{
 "volumes": [
  {
   "status": "available", 
   "managed": true, 
   "name": "va_85621143-1133-412f-83b4-57a01a552638_", 
   "support": {
    "status": "supported"
   }, 
   "storage_pool": "pfm9253_pfm9254_new", 
   "id": "afb8e294-6188-4907-9f6f-963c7623cecb", 
   "size": 9
  }, 
  {
   "status": "in-use", 
   "managed": false, 
   "name": "bt_newd20", 
   "support": {
    "status": "not_supported", 
    "reasons": [
     "This volume is not a candidate for management because it is already attached to a virtual machine.  To manage this volume with PowerVC, select the virtual machine to which the volume is attached for management. The attached volume will be automatically included for management."
    ]
   }, 
   "storage_pool": "KVM", 
   "mapped_wwpns": [
    "2101001B32BD4280", 
    "2100001B329D4280", 
    "2101001B32BD637E", 
    "2100001B329D637E"
   ], 
   "id": "c7838c79-17ca-3cbc-98e5-3567fde902d8", 
   "size": 0
  }, 
  {
   "status": "available", 
   "managed": true, 
   "name": "vdisk138", 
   "support": {
    "status": "supported"
   }, 
   "storage_pool": "Chassis2_IBMi", 
   "id": "b6d00783-9f8c-40b8-ad78-956b0299478c", 
   "size": 100


  }
 ]
}
From SO and few other places, I have found that I need to define a top level container like one below but I do not know how to complete its definition
static class VolumeContainer {        
 //I don't know what do in here. This is the first problem 
}
and then a class for each Volume
static class Volume {
   private String status;
   private boolean managed;
   private String name;

   //This is the second problem.The "support" variable should not be a string.
   //It is in {}. Just for information, I won't use it.
   //private String support;

   private String storagePool;
   private List<String> mapped_wwpns;
   private String id;
   private String size;

}
I am trying to parse it and this is what I coded so far:
JsonParser parser = new JsonParser();
JsonObject obj = parser.parse(response).getAsJsonObject();

Gson gson = new Gson();
The JSON string is stored in a variable named response
VolumeContainer vc = gson.fromJson(response,VolumeContainer.class);
My final requirement is a HashTable of id and associated name. 
解决方案
First problem: your VolumeContainer needs to be:
public class VolumeContainer {
   public List<Volume> volumes;
}
it does not need to be static.


Second problem: your Volume class should be like this:
public class Volume {
  private String status; 
  private Boolean managed; 
  private String name; 
  private Support support; 
  private String storage_pool; 
  private String id; 
  private int size;
  private List<String> mapped_wwpns;

  public String getId(){return id;}
  public String getName(){return name;}
}
I defined a class named Support like this:
public class Support {
   private String status;
   private List<String> reasons;
}
Third problem: parsing, If response string contains your example data, simply parse like this:
Gson g = new Gson();
VolumeContainer vc = g.fromJson(response, VolumeContainer.class);
Fourth problem: get the map. Finally to get your HashMap, just do like this:
HashMap<String, String> hm = new HashMap<String,String>();
for(Volume v: vc.volumes){
  hm.put(v.getId(), v.getName());  
}


                        
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