我有一个简单的枚举：
public enum Season {
@Serializedname("0")
AUTUMN,@Serializedname("1")
SPRING;
}
从某个版本开始,GSON就能够解析这些枚举.为了确保,我这样做了：
final String s = gson.toJson(Season.AUTUMN);
它按我的预期工作.输出为“0”.所以,我尝试在我的Retrofit服务中使用它：
@GET("index.PHP?page[api]=test")
Observable<List<Month>> getMonths(@Query("season_lookup") Season season);
/*...some files later...*/
service.getMonths(Season.AUTUMN);
并且还添加了日志以确定其结果：
HttpLoggingInterceptor httpLoggingInterceptor = new HttpLoggingInterceptor();
httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient httpClient = new OkHttpClient.Builder()
.addInterceptor(httpLoggingInterceptor)
.build();
但它失败了. @Query完全忽略@Serializedname并改为使用.toString(),所以日志显示为… / index.PHP？page [api] = test& season_lookup = AUTUMN.
我跟踪了Retrofit源代码并找到了带有行的文件RequestFactoryParser：
Converter<?,String> converter =
retrofit.stringConverter(parameterType,parameterannotations);
action = new RequestAction.Query<>(name,converter,encoded);
似乎,就像它根本不关心枚举一样.在这些行之前,它将rawParameterType.isArray()测试为数组或Iterable.class.isAssignableFrom(),仅此而已.
改造实例创建是：
retrofit = new Retrofit.Builder()
.baseUrl(ApiConstants.API_ENDPOINT)
.client(httpClient)
.addConverterFactory(GsonConverterFactory.create(gson))
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
.build();
gson是GsonBuilder().create().我偷看了源代码,其中有枚举的预定义ENUM_TypeAdapters.ENUM_FACTORY,所以我保持原样.
问题是我该怎么办,以防止在我的枚举上使用toString()并使用@Serializedname？我将toString()用于其他目的.
解决方法
正如@DawidSzydło所提到的,我在Retrofit中误解了Gson的用法.它仅用于响应/请求解码/编码,但不用于@Query / @ Url / @ Path e.t.c.对于他们来说,Retrofit使用Converter.Factory将任何类型转换为String.
以下是将@Serializedname作为任何Enum的值传递给Retrofit服务时自动使用的代码.
以下是将@Serializedname作为任何Enum的值传递给Retrofit服务时自动使用的代码.
转换器：
public class EnumRetrofitConverterFactory extends Converter.Factory {
@Override
public Converter<?,String> stringConverter(Type type,Annotation[] annotations,Retrofit retrofit) {
Converter<?,String> converter = null;
if (type instanceof Class && ((Class<?>)type).isEnum()) {
converter = value -> EnumUtils.GetSerializednameValue((Enum) value);
}
return converter;
}
}
EnumUtils：
public class EnumUtils {
@Nullable
static public <E extends Enum<E>> String GetSerializednameValue(E e) {
String value = null;
try {
value = e.getClass().getField(e.name()).getAnnotation(Serializedname.class).value();
} catch (NoSuchFieldException exception) {
exception.printstacktrace();
}
return value;
}
}
改造创造：
retrofit = new Retrofit.Builder()
.baseUrl(ApiConstants.API_ENDPOINT)
.client(httpClient)
.addConverterFactory(GsonConverterFactory.create(gson))
.addConverterFactory(new EnumRetrofitConverterFactory())
.addCallAdapterFactory(RxJavaCallAdapterFactory.create())
.build();
08.18更新添加kotlin类似物：
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val httpLoggingInterceptor = HttpLoggingInterceptor()
httpLoggingInterceptor.level = HttpLoggingInterceptor.Level.BODY
val httpClient = OkHttpClient.Builder()
.addInterceptor(httpLoggingInterceptor)
.build()
val gson = GsonBuilder().create()
val retrofit = Retrofit.Builder()
.baseUrl(Api.ENDPOINT)
.client(httpClient)
.addConverterFactory(GsonConverterFactory.create(gson))
.addConverterFactory(EnumConverterFactory())
.build()
val service = retrofit.create(Api::class.java)
service.getMonths(Season.AUTUMN).enqueue(object : Callback<List<String>> {
override fun onFailure(call: Call<List<String>>?,t: Throwable?) {
/* ignore */
}
override fun onResponse(call: Call<List<String>>?,response: Response<List<String>>?) {
/* ignore */
}
})
}
}
class EnumConverterFactory : Converter.Factory() {
override fun stringConverter(type: Type?,annotations: Array<out Annotation>?,retrofit: Retrofit?): Converter<*,String>? {
if (type is Class<*> && type.isEnum) {
return Converter<Any?,String> { value -> getSerializednameValue(value as Enum<*>) }
}
return null
}
}
fun <E : Enum<*>> getSerializednameValue(e: E): String {
try {
return e.javaClass.getField(e.name).getAnnotation(Serializedname::class.java).value
} catch (exception: NoSuchFieldException) {
exception.printstacktrace()
}
return ""
}
enum class Season {
@Serializedname("0")
AUTUMN,@Serializedname("1")
SPRING
}
interface Api {
@GET("index.PHP?page[api]=test")
fun getMonths(@Query("season_lookup") season: Season): Call<List<String>>
companion object {
const val ENDPOINT = "http://127.0.0.1"
}
}
在日志中,您将看到：
D/OkHttp: --> GET http://127.0.0.1/index.PHP?page[api]=test&season_lookup=0 D/OkHttp: --> END GET D/OkHttp: <-- HTTP Failed: java.net.ConnectException: Failed to connect to /127.0.0.1:80
使用的依赖项是：
implementation 'com.squareup.retrofit2:retrofit:2.4.0' implementation 'com.google.code.gson:gson:2.8.5' implementation 'com.squareup.okhttp3:logging-interceptor:3.11.0' implementation 'com.squareup.retrofit2:converter-gson:2.4.0'