为什么我得到一个JsonSyntaxException：预期BEGIN_ARRAY但STRING在这里？ [英] Why am I getting a JsonSyntaxException: Expected BEGIN_ARRAY but was STRING here?

问题描述

我有一个JSON文件：

I have one JSON file:

{
"settings": {
    "header": {
        "id": "240A64CDC43F",
        "filename": "network",
        "sequence": "0",
        "last_modified": "2015-04-21T16:33",
        "JSON_file_version": "2.1"
    },
    "data": {
        "engine_config": {
            "bed_name": "IdealTempCDC43F",
            "provisioned": "false",
            "connected": "false",
            "IP_address": "192.168.10.1",
            "connection_error": "None"
        },
        "networks": {
            "available": "7",
            "SSIDs": {
                "wireless_1": {
                    "SSID": "$$ASI_WIFI$$",
                    "mac_address": "A0:EC:F9:11:35:04",
                    "channel": "11",
                    "RSSI": "-64dBm",
                    "security": "true",
                    "security_type": "WPA"
                },
                "wireless_2": {
                    "SSID": "$$ASI_GUEST$$",
                    "mac_address": "A0:EC:F9:11:35:02",
                    "channel": "11",
                    "RSSI": "-65dBm",
                    "security": "true",
                    "security_type": "WPA"
                }
            }
        }
    }
}
}

有关解析此JSON我使用这样的：

For parsing this json I am using this:

HttpResponse response = client.execute(request); 
String strResponse = response.toString();
parseJSON(strResponse);

和

public void parseJSON(String jsonString) {
  Gson gsonParser = new Gson();
  ProveQuerySetting gsonResponse = new ProveQuerySetting();
  Type collectionType = new TypeToken<Collection<ProveQuerySetting>>() {
  }.getType();
  gsonResponse = gsonParser.fromJson(jsonString, collectionType);
  String str = gsonParser.toJson(gsonResponse);
  System.out.println(" final json " + str);
}

但我得到这个异​​常：

But I am getting this exception:

04-21 07:08:13.864: W/System.err(4187): com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $
04-21 07:08:13.864: W/System.err(4187): com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $
04-21 07:08:13.865: W/System.err(4187):     at com.google.gson.Gson.fromJson(Gson.java:822)
04-21 07:08:13.865: W/System.err(4187):     at com.google.gson.Gson.fromJson(Gson.java:775)
04-21 07:08:13.865: W/System.err(4187):     at com.google.gson.Gson.fromJson(Gson.java:724)
04-21 07:08:13.865: W/System.err(4187):     at com.easi.main.network.NetworkCom.parseJSON(NetworkCom.java:127)
04-21 07:08:13.865: W/System.err(4187):     at com.easi.main.network.NetworkCom.sendFirst(NetworkCom.java:50)
04-21 07:08:13.865: W/System.err(4187):     at com.easi.main.setting.ConnectToBox$MyAsyncTask.doInBackground(ConnectToBox.java:89)
04-21 07:08:13.865: W/System.err(4187):     at com.easi.main.setting.ConnectToBox$MyAsyncTask.doInBackground(ConnectToBox.java:1)
04-21 07:08:13.865: W/System.err(4187):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
04-21 07:08:13.865: W/System.err(4187):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
04-21 07:08:13.865: W/System.err(4187):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
04-21 07:08:13.865: W/System.err(4187):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
04-21 07:08:13.865: W/System.err(4187):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
04-21 07:08:13.865: W/System.err(4187):     at java.lang.Thread.run(Thread.java:818)
04-21 07:08:13.865: W/System.err(4187): Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1 path $
04-21 07:08:13.865: W/System.err(4187):     at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350)
04-21 07:08:13.866: W/System.err(4187):     at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:79)
04-21 07:08:13.866: W/System.err(4187):     at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
04-21 07:08:13.866: W/System.err(4187):     at com.google.gson.Gson.fromJson(Gson.java:810)
04-21 07:08:13.866: W/System.err(4187):     ... 12 more

下面是我的POJO类：

Here is my POJO class:

public class ProveQuerySetting {
  ProvQueryData provEngnData;
  ProvQueryHeader provEngnhHeader;

  public ProvQueryData getProvEngnData() {
    return provEngnData;
  }

  public void setProvEngnData(ProvQueryData provEngnData) {
    this.provEngnData = provEngnData;
  }

  public ProvQueryHeader getProvEngnhHeader() {
    return provEngnhHeader;
  }

  public void setProvEngnhHeader(ProvQueryHeader provEngnhHeader) {
    this.provEngnhHeader = provEngnhHeader;
  }
}

为什么我得到这个例外？

Why I am getting this exception?

推荐答案

好了，你要使用默认的GSON。大！默认GSON是聪明的，但不那么聪明。你有你的类设计为精确匹配的你取回的JSON格式，或使用 @SerializedName 注释，如果你不希望设计一个自定义解串器。当我说的精确匹配后，我的意思是，字段名必须为完全相同作为系列化GSON，无论是在字段名称或注释。

Okay, so you are trying to use the default Gson. Great! The default Gson is smart, but not that smart. You have to design your classes to exactly match the format of the json you're getting back, or use the @SerializedName annotation, if you don't want to design a custom deserializer. When I say exactly match, I mean, the field names must be exactly the same as the serialized Gson, either in the field name or the annotation.

我创建了下面的POJO（包括你，与修正字段名）。我没有包括getter / setter方法​​为简洁：

I created the following POJOs (including yours, with modified field names). I have not included the getters/setters for brevity:

public class ProvEngineConfig {
  private String bed_name;
  private String provisioned;
  private String connected;
  private String IP_Address;
  private String connection_error;
}

public class ProvNetworks {
  private String available;
  private Map<String, ProvSSID> SSIDs;  // Notice this is a map
}

public class ProveQuerySetting {
  ProvQueryData data;
  ProvQueryHeader header;
}

public class ProvQueryData {
  ProvEngineConfig engine_config;
  ProvNetworks networks;
}

public class ProvQueryHeader {
  String id;
  String filename;
  String sequence;
  String last_modified;
  String JSON_file_version;
}

public class ProvSSID {
  String SSID;
  String mac_address;
  String channel;
  String RSSI;
  String security;
  String security_type;
}

同样，你看到的字段名称是如何的究竟一样在你的JSON的人？请注意，在 ProvNetworks ，我使用的地图，因为您提供的JSON是无线的名字地图，以精确匹配SSID的对象。

Again, do you see how the field names are exactly the same as the ones in your JSON? Notice that in ProvNetworks, I'm using a map, because the JSON you provided is a map of wireless names to exactly matching SSID objects.

在我的POJO分别设立了类似下面，还请注意，您所提供的JSON是不是查询设置的收藏，它实际上是一个地图＆LT ;弦乐，ProvQuerySetting＆GT; ，你从字设置来的引擎配置对象映射。所以我分析它是这样的：

Once my POJOs were set up like the following, notice also that your provided JSON is not a Collection of Query settings, it's actually a Map<String, ProvQuerySetting>, you map from the word "settings" to the Engine config object. So I parsed it like this:

public static void parseJSON(String jsonString) {
  Gson gsonParser = new Gson();
  Map<String, ProveQuerySetting> gsonResponse; // You don't need to do new here
  Type collectionType = new TypeToken<Map<String, ProveQuerySetting>>() {}.getType();
  gsonResponse = gsonParser.fromJson(jsonString, collectionType);

  String str = gsonParser.toJson(gsonResponse);
  System.out.println(" final json " + str);
}

输出：

final json {"settings":{"data":{"engine_config":{"bed_name":"IdealTempCDC43F","provisioned":"false","connected":"false","connection_error":"None"},"networks":{"available":"7","SSIDs":{"wireless_1":{"SSID":"$$ASI_WIFI$$","mac_address":"A0:EC:F9:11:35:04","channel":"11","RSSI":"-64dBm","security":"true","security_type":"WPA"},"wireless_2":{"SSID":"$$ASI_GUEST$$","mac_address":"A0:EC:F9:11:35:02","channel":"11","RSSI":"-65dBm","security":"true","security_type":"WPA"}}}},"header":{"id":"240A64CDC43F","filename":"network","sequence":"0","last_modified":"2015-04-21T16:33","JSON_file_version":"2.1"}}}

---

总结：

您要么需要：

1. 完全符合您的POJO和字段名/注释字段名相匹配的JSON


2. 写自己的自定义解串器，如<一个描述href=\"https://google-gson.google$c$c.com/svn-history/r1298/trunk/gson/docs/javadocs/com/google/gson/stream/JsonReader.html\"相对=nofollow> JsonReader

1. Exactly match your POJOs and field names/annotated field names to match the JSON
2. Write your own custom deserializer, as described in JsonReader

这篇关于为什么我得到一个JsonSyntaxException：预期BEGIN_ARRAY但STRING在这里？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！