一般公司的服务器返回数据比较规律如下：
statusCode 状态码
message 各种提醒
result 结果
public class BaseData implements Serializable { public T result; public int code; public String msg; public T getResult() { return result; } public void setResult(T result) { this.result = result; } public int getCode() { return code; } public void setCode(int code) { this.code = code; } public String getMsg() { return msg; } public void setMsg(String msg) { this.msg = msg; } }
有的公司成功返回：
{ "code":200, "msg":"SUCCESS", "result": { “name”:"测试账号", "vip":"0"} }
失败返回：
{ "code":300, "msg":"该手机号无效，请确认手机号码", "result":""}
此时result即可能是String又可能是Object对于以下这种写法肯定不能同时解析：
@FormUrlEncoded@POST("service/AppServiceInterface")Observable> login( @Field("mobile") String mobile, @Field("vCode") String vCode);
常见封装：
Retrofit retrofit = new Retrofit.Builder() .baseUrl(baseUrl) .client(mOkHttpClient) .addCallAdapterFactory(RxJava2CallAdapterFactory.create()) .addConverterFactory(GsonConverterFactory.create()) .build();
这里用的是GsonConverterFactory
这样就会在解析的时候报一个JsonSyntaxException异常
网上其他解决方法都是自定义一个异常，然后在onError（）中进行String类型的判断，这样岂不是要该很多很多网络请求么？那么就可以用下面的方法来优雅的解决这个问题：
打开GsonConverterFactory可以看到：
public final class GsonConverterFactory extends Converter.Factory { /** * Create an instance using a default {@link Gson} instance for conversion. Encoding to JSON and * decoding from JSON (when no charset is specified by a header) will use UTF-8. */ public static GsonConverterFactory create() { return create(new Gson()); } /** * Create an instance using {@code gson} for conversion. Encoding to JSON and * decoding from JSON (when no charset is specified by a header) will use UTF-8. */ @SuppressWarnings("ConstantConditions") // Guarding public API nullability. public static GsonConverterFactory create(Gson gson) { if (gson == null) throw new NullPointerException("gson == null"); return new GsonConverterFactory(gson); } private final Gson gson; private GsonConverterFactory(Gson gson) { this.gson = gson; } @Override public Converter responseBodyConverter(Type type, Annotation[] annotations, Retrofit retrofit) { TypeAdapter adapter = gson.getAdapter(TypeToken.get(type)); return new GsonResponseBodyConverter<>(gson, adapter); } @Override public Converter requestBodyConverter(Type type, Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) { TypeAdapter adapter = gson.getAdapter(TypeToken.get(type)); return new GsonRequestBodyConverter<>(gson, adapter); }}
这里面有两个类：
GsonResponseBodyConverter.java
final class GsonResponseBodyConverter implements Converter { private final Gson gson; private final TypeAdapter adapter; GsonResponseBodyConverter(Gson gson, TypeAdapter adapter) { this.gson = gson; this.adapter = adapter; } @Override public T convert(ResponseBody value) throws IOException { JsonReader jsonReader = gson.newJsonReader(value.charStream()); try { return adapter.read(jsonReader); } finally { value.close(); } }}
GsonRequestBodyConverter.java
final class GsonRequestBodyConverter implements Converter { private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8"); private static final Charset UTF_8 = Charset.forName("UTF-8"); private final Gson gson; private final TypeAdapter adapter; GsonRequestBodyConverter(Gson gson, TypeAdapter adapter) { this.gson = gson; this.adapter = adapter; } @Override public RequestBody convert(T value) throws IOException { Buffer buffer = new Buffer(); Writer writer = new OutputStreamWriter(buffer.outputStream(), UTF_8); JsonWriter jsonWriter = gson.newJsonWriter(writer); adapter.write(jsonWriter, value); jsonWriter.close(); return RequestBody.create(MEDIA_TYPE, buffer.readByteString()); }}
其中GsonResponseBodyConverter中的convert方法抛出了一个异常
我们是可以catch到的，那问题就变得简单了，既然能抓取到，就地解决。问题是这个类我们改不掉，那么索性就直接自定义吧。我们是代码的搬运工：
TtGsonConverterFactory.java
public class TtGsonConverterFactory extends Converter.Factory { private final Gson gson; private TtGsonConverterFactory(Gson gson) { this.gson = gson; } /** * Create an instance using a default {@link Gson} instance for conversion. Encoding to JSON and * decoding from JSON (when no charset is specified by a header) will use UTF-8. */ public static TtGsonConverterFactory create() { return create(new Gson()); } /** * Create an instance using {@code gson} for conversion. Encoding to JSON and * decoding from JSON (when no charset is specified by a header) will use UTF-8. */ @SuppressWarnings("ConstantConditions") // Guarding public API nullability. public static TtGsonConverterFactory create(Gson gson) { if (gson == null) throw new NullPointerException("gson == null"); return new TtGsonConverterFactory(gson); } @Override public Converter responseBodyConverter(Type type, Annotation[] annotations, Retrofit retrofit) { TypeAdapter adapter = gson.getAdapter(TypeToken.get(type)); return new TtGsonResponseBodyConverter<>(gson, adapter); } @Override public Converter requestBodyConverter(Type type, Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) { TypeAdapter adapter = gson.getAdapter(TypeToken.get(type)); return new TtGsonRequestBodyConverter<>(gson, adapter); }}
TtGsonRequestBodyConverter.java
public class TtGsonRequestBodyConverter implements Converter { private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8"); private static final Charset UTF_8 = Charset.forName("UTF-8"); private final Gson gson; private final TypeAdapter adapter; TtGsonRequestBodyConverter(Gson gson, TypeAdapter adapter) { this.gson = gson; this.adapter = adapter; } @Override public RequestBody convert(T value) throws IOException { Buffer buffer = new Buffer(); Writer writer = new OutputStreamWriter(buffer.outputStream(), UTF_8); JsonWriter jsonWriter = gson.newJsonWriter(writer); adapter.write(jsonWriter, value); jsonWriter.close(); return RequestBody.create(MEDIA_TYPE, buffer.readByteString()); }}
TtGsonResponseBodyConverter.java
public class TtGsonResponseBodyConverter implements Converter { private final Gson gson; private final TypeAdapter adapter; TtGsonResponseBodyConverter(Gson gson, TypeAdapter adapter) { this.gson = gson; this.adapter = adapter; } @Override public T convert(ResponseBody value) throws IOException { String responseValue = value.string(); JsonReader jsonReader; try { MediaType mediaType = value.contentType(); Charset charset = mediaType != null ? mediaType.charset(UTF_8) : UTF_8; InputStream inputStream = new ByteArrayInputStream(responseValue.getBytes()); jsonReader = gson.newJsonReader(new InputStreamReader(inputStream, charset)); return adapter.read(jsonReader); } catch (JsonSyntaxException e) { String result = responseValue.replace(",\"result\":\"\"", ""); MediaType mediaType = value.contentType(); Charset charset = mediaType != null ? mediaType.charset(UTF_8) : UTF_8; InputStream inputStream = new ByteArrayInputStream(result.getBytes()); jsonReader = gson.newJsonReader(new InputStreamReader(inputStream, charset)); return adapter.read(jsonReader); } finally { value.close(); } }}
然后一句话替换掉：
Retrofit retrofit = new Retrofit.Builder() .baseUrl(baseUrl) .client(mOkHttpClient) .addCallAdapterFactory(RxJava2CallAdapterFactory.create()) .addConverterFactory(TtGsonConverterFactory.create()) .build();
这里注意了，我们在catch中把这个请求下来的数据中包含 ,"result":"" 这一段替换没了，那不就爽歪歪了么，照样解析，只不过result = null而已，并不影响我们的判断，也不用自己抛异常在onError中处理，简单粗暴，至于MediaType、Charset、InputStream为什么这样写我也不知道为什么，我充当了个代码的搬运工而已。有知道的大神不妨给解释一下吧，谢谢！
参考资料：https://www.jianshu.com/p/06f4d3dd7e8e
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