GSON应为BEGIN_ARRAY，但在第1行是字符串错误

Question

我试图使用从API返回的retfit和GSON解析字符串数组：

["Scan finished, scan information embedded in this object", "https://www.virustotal.com/url/297c349554bdc7e2f09a85be309f08cb2f16a9174068bd5bc6e298ed90a5eed9/analysis/1485313628/", 8, 64]

这是在特定情况下（情况2）响应的样子：

["Scan request successfully queued, come back later for the report", "https://www.virustotal.com/url/d06ed0b4b29aab735ee7b85c5c0af98fd4d983edcc597afe60e4c4ac2e25ea08/analysis/1485847248/", null, null]

在本例（情况2）中，我从registfit/gson得到一个错误：

W/System.err: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 2 path $
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:80)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:61)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at retrofit2.converter.gson.GsonResponseBodyConverter.convert(GsonResponseBodyConverter.java:37)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at retrofit2.converter.gson.GsonResponseBodyConverter.convert(GsonResponseBodyConverter.java:25)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at retrofit2.ServiceMethod.toResponse(ServiceMethod.java:117)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at retrofit2.OkHttpCall.parseResponse(OkHttpCall.java:211)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:106)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at okhttp3.RealCall$AsyncCall.execute(RealCall.java:133)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
01-31 13:42:41.922 15746-15746/com.ssrij.testapp W/System.err:     at java.lang.Thread.run(Thread.java:761)

我这样调用API：

Call<ArrayList<String>> scanResults = myAPI.getScanResults(id);
scanResults.enqueue(...)

Answer 1

“expected BEGIN_ARRAY but was String”意味着Gson正在解析的字符是“”，但它期望的是[（因为您试图解析列表）。由于输入与预期的输入不一致，Gson必须失败。从Gson的角度来看，Case2输入与Case1输入没有任何不同（如果NULL是一个问题，那么错误消息将表明这一点）。

因为该输入不受信任（它来自第三方服务器？）您应该在解析调用周围添加一些错误处理代码，以便考虑输入格式错误的可能性。至少，在失败时记录接收到的输入会立即清楚地表明您没有接收到预期的数组。