requestBodyConverter 不執行的解決辦法:
參數要使用@Body這種形式,否則 request 方法會不起作用。
在Retrofit中,無論是發送資料和接收資料,都是通過OKHttp的RequestBody和ResponseBody來實作的。在實際項目中,有時候原始的RequestBody或是ResponseBody并不能滿足我們的需求(如接口加密),就需要對它進行轉換。
在Retrofit通過build()方法獲得執行個體時,可以添加多個ConverterFactory,但要注意的是,添加的順序是有影響的。如下代碼:
.addConverterFactory(GsonConverterFactory.create())
看下源碼:
private final List<Converter.Factory> converterFactories;
public Builder addConverterFactory(Converter.Factory factory) {
converterFactories.add(checkNotNull(factory, "factory == null"));
return this;
}
按照retrofit的邏輯,是從前往後進行比對,如果比對上,就忽略後面的,直接使用。
int start = converterFactories.indexOf(skipPast) + 1;
for (int i = start, count = converterFactories.size(); i < count; i++) {
Converter.Factory factory = converterFactories.get(i);
Converter<?, RequestBody> converter =
factory.requestBodyConverter(type, parameterAnnotations, methodAnnotations, this);
if (converter != null) {
//noinspection unchecked
return
從上面的源碼中可以看到,當factory.requestBodyConverter傳回空時,表示沒有比對上,可使用下一個factory.
是以,當我們自定義converter的時候,需要進行條件判斷,符合我們一定規則的才能使用。
Retrofit官方給了以下幾個常用的轉換庫
- Gson: com.squareup.retrofit2:converter-gson
- Jackson: com.squareup.retrofit2:converter-jackson
- Moshi: com.squareup.retrofit2:converter-moshi
- Protobuf: com.squareup.retrofit2:converter-protobuf
- Wire: com.squareup.retrofit2:converter-wire
- Simple XML: com.squareup.retrofit2:converter-simplexml
- Scalars (primitives, boxed, and String): com.squareup.retrofit2:converter-scalars
Type
我們以建立protobuff為例。
Retrofit已經為我們提供了自定義ConverterFactory的接口,我們隻需要實作它給的接口即可。
public final class ProtoConverterFactory extends Converter.Factory
public static ProtoConverterFactory create() {
return new ProtoConverterFactory();
}
@Override
public Converter<ResponseBody, ?> responseBodyConverter(Type type, Annotation[] annotations,
Retrofit retrofit) {
//進行條件判斷,如果傳進來的Type不是class,則比對失敗
if (!(type instanceof Class<?>)) {
return null;
}
//進行條件判斷,如果傳進來的Type不是MessageLite的實作類,則也比對失敗
Class<?> c = (Class<?>) type;
if (!MessageLite.class.isAssignableFrom(c)) {
return null;
}
Parser<MessageLite> parser;
try {
Field field = c.getDeclaredField("PARSER");
//noinspection unchecked
parser = (Parser<MessageLite>) field.get(null);
} catch (NoSuchFieldException | IllegalAccessException e) {
throw new IllegalArgumentException(
"Found a protobuf message but " + c.getName() + " had no PARSER field.");
}
//傳回一個實作了Converter的類,
return new ProtoResponseBodyConverter<>(parser);
}
@Override
public Converter<?, RequestBody> requestBodyConverter(Type type,
Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) {
//進行條件判斷,如果傳進來的Type不是class,則比對失敗
if (!(type instanceof Class<?>)) {
return null;
}
//進行條件判斷,如果傳進來的Type不是MessageLite的實作類,則也比對失敗
if (!MessageLite.class.isAssignableFrom((Class<?>) type)) {
return null;
}
return new
注意在Convert的兩個泛型中,前一個類型是傳進來的對象類型,後一個類型是轉換後的對象類型。
final class ProtoRequestBodyConverter<T extends MessageLite> implements Converter<T, RequestBody> {
private static final MediaType MEDIA_TYPE = MediaType.parse("application/x-protobuf");
@Override public RequestBody convert(T value) throws IOException {
byte[] bytes = value.toByteArray();
return
final class ProtoResponseBodyConverter<T extends MessageLite>
implements Converter<ResponseBody, T> {
private final Parser<T> parser;
ProtoResponseBodyConverter(Parser<T> parser) {
this.parser = parser;
}
@Override public T convert(ResponseBody value) throws IOException {
try {
return parser.parseFrom(value.byteStream());
} catch (InvalidProtocolBufferException e) {
throw new RuntimeException(e); // Despite extending IOException, this is data mismatch.
} finally
Annotation
在有一些情況,僅僅通過type來進行判斷,資訊是不夠的,還需要額外的參數。這時我們就可以利用後面兩個參數來進行。
我們先看requestBodyConverter的函數簽名。
public Converter<?, RequestBody> requestBodyConverter(Type type,
顯然,parameterAnnoatations是指在定義接口的參數上的注解。如下面的MyType:
@GET("applist/mini-appcenter/")
Call<MiniAppCenterPojo> getMiniApp(@Query("offsets") @TypeString String
定義在方法上的注釋就是methodAnnotations
@TypeString
@GET("applist/mini-appcenter/")
Call<MiniAppCenterPojo> getMiniApp(@Query("offsets");
我們就可以通過對這些注解的判斷來進行自定義Converter的比對。
@Documented
@Target(PARAMETER)
@Retention(RUNTIME)
public @interface TypeString{
public class StringConverterFactory extends Converter.Factory
@Override
public Converter<ResponseBody, ?> responseBodyConverter(Type type, Annotation[] annotations,
Retrofit retrofit) {
if (!(type instanceof Class<?>)) {
return null;
}
for( Annotation annotation :annotations) {
if( annotation instanceof TypeString) {
return new StringResponseConverter();
}
}
return null;
}
@Override
public Converter<?, RequestBody> requestBodyConverter(Type type,
Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) {
if (!(type instanceof Class<?>)) {
return null;
}
for( Annotation annotation :parameterAnnotations) {
if( annotation instanceof TypeString) {
return new StringRequestConverter();
}
}
return null;
}
public static class StringResponseConverter implements Converter<ResponseBody, String> {
@Override
public String convert(ResponseBody value) throws IOException {
return value.string();
}
}
public static class StringRequestConverter implements Converter<String, RequestBody> {
@Override
public RequestBody convert(String value) throws IOException {
return RequestBody.create(MediaType.parse("application/octet-stream"), value);
}
}
}
下面再看一個基于Gson的自定義ConverterFactory。
如果我們對安全性要求比較高,或者編碼不太一樣的話,預設的GsonConverterFactory就不行了,我們就需要自定義ConverterFactory。
代碼如下:
public final class DecodeConverterFactory extends Converter.Factory
public static DecodeConverterFactory create() {
return create(new Gson());
}
public static DecodeConverterFactory create(Gson gson) {
return new DecodeConverterFactory(gson);
}
private final Gson gson;
private DecodeConverterFactory(Gson gson) {
if (gson == null) throw new NullPointerException("gson == null");
this.gson = gson;
}
@Override
public Converter<ResponseBody, ?> responseBodyConverter(Type type, Annotation[] annotations, Retrofit retrofit) {
TypeAdapter<?> adapter = gson.getAdapter(TypeToken.get(type));
return new DecodeResponseBodyConverter<>(adapter);
}
@Override
public Converter<?, RequestBody> requestBodyConverter(Type type, Annotation[] annotations,Retrofit retrofit) {
TypeAdapter<?> adapter = gson.getAdapter(TypeToken.get(type));
return new
然後我們需要自定義responseBodyConverter和requestBodyConverter,這裡我們發送請求的時候不需要加密,接收請求的時候需要解密,具體代碼如下:
public class DecodeResponseBodyConverter<T> implements Converter<ResponseBody, T> {
private final TypeAdapter<T> adapter;
DecodeResponseBodyConverter(TypeAdapter<T> adapter) {
this.adapter = adapter;
}
@Override
public T convert(ResponseBody value) throws IOException {
//解密字元串
return adapter.fromJson(EncryptUtils.decode(value.string()));
}
}
public class DecodeRequestBodyConverter<T> implements Converter<T, RequestBody> {
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<T> adapter;
DecodeRequestBodyConverter(Gson gson,TypeAdapter<T> 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.flush();
return
需要注意的是:adapter.fromJson(EncryptUtils.decode(value.string())) 中EncryptUtils.decode(value.string())傳回類型必須是json字元串,否則會報錯。
參考文章:
http://caiyao.name/2016/01/13/Retrofit%E4%BD%BF%E7%94%A8%E4%B9%8B%E8%87%AA%E5%AE%9A%E4%B9%89Converter/
可能遇到的問題:
when required parameters have string and file together, retrofit 2.2.0 do not work
requestBodyConverter 不執行的解決辦法:
參數要使用@Body這種形式,否則 request 方法會不起作用。
例如:
@POST("/index/index/sms_code")
Observable<BaseResopnse> sms_code(@Body String
/**
* Returns a {@link Converter} for converting {@code type} to an HTTP request body, or null if
* {@code type} cannot be handled by this factory. This is used to create converters for types
* specified by {@link Body @Body}, {@link Part @Part}, and {@link PartMap @PartMap}
* values.
*/
public @Nullable Converter<?, RequestBody> requestBodyConverter(Type type,
Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) {
return null;
}