Retrofit2源码解析03-OkHttpCall.enqueue

清疚 2023-10-17 16:45 66阅读 0赞

接下来我们来分析下OkHttpCall.enqueue，OkHttpCall也是继承自Retrofit的call，并在内部调用OkHttp3.Call.enqueue。

public void enqueue(final Callback<T> callback) {
        
            //...
            call.enqueue(new okhttp3.Callback() {
        
              @Override public void onResponse(okhttp3.Call call, okhttp3.Response rawResponse)
                  throws IOException {
        
                Response<T> response;
                try {
        
                  response = parseResponse(rawResponse);
                } catch (Throwable e) {
        
                  callFailure(e);
                  return;
                }
                callSuccess(response);
              }
        
              @Override public void onFailure(okhttp3.Call call, IOException e) {
        
                try {
        
                  callback.onFailure(OkHttpCall.this, e);
                } catch (Throwable t) {
        
                  t.printStackTrace();
                }
              }
        
              private void callFailure(Throwable e) {
        
                try {
        
                  callback.onFailure(OkHttpCall.this, e);
                } catch (Throwable t) {
        
                  t.printStackTrace();
                }
              }
        
              private void callSuccess(Response<T> response) {
        
                try {
        
                  callback.onResponse(OkHttpCall.this, response);
                } catch (Throwable t) {
        
                  t.printStackTrace();
                }
              }
            });
        }

主要来看parseResponse，这里会根据不同的状态码，来做不同的操作。

Response<T> parseResponse(okhttp3.Response rawResponse) throws IOException {
        
            ResponseBody rawBody = rawResponse.body();
            
            // Remove the body's source (the only stateful object) so we can pass the response along.
            rawResponse = rawResponse.newBuilder()
                .body(new NoContentResponseBody(rawBody.contentType(), rawBody.contentLength()))
                .build();
            
            int code = rawResponse.code();
            if (code < 200 || code >= 300) {
        
              try {
        
                // Buffer the entire body to avoid future I/O.
                ResponseBody bufferedBody = Utils.buffer(rawBody);
                return Response.error(bufferedBody, rawResponse);
              } finally {
        
                rawBody.close();
              }
            }
            
            if (code == 204 || code == 205) {
        
              return Response.success(null, rawResponse);
            }
            
            ExceptionCatchingRequestBody catchingBody = new ExceptionCatchingRequestBody(rawBody);
            try {
        
              T body = serviceMethod.toResponse(catchingBody);
              return Response.success(body, rawResponse);
            } catch (RuntimeException e) {
        
              // If the underlying source threw an exception, propagate that rather than indicating it was
              // a runtime exception.
              catchingBody.throwIfCaught();
              throw e;
            }
        }

如果一切顺利，会调用serviceMethod.toResponse

T toResponse(ResponseBody body) throws IOException {
        
            return responseConverter.convert(body);
        }

在这里，会调用responseConverter的convert方法。  
这里的responseConverter就是Retrofit Build创建过程中，  
以GsonConverterFactory为例，代码如下。

final class GsonResponseBodyConverter<T> implements Converter<ResponseBody, T> {
        
            private final Gson gson;
            private final TypeAdapter<T> adapter;
            
            GsonResponseBodyConverter(Gson gson, TypeAdapter<T> 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();
            }
        }

#### 总结 ####

OkHttpCall.enqueue就是回去调用OkHttp，当成功回调时，会调用responseConverter的convert方法，进行数据类型的转换，比如GsonResponseBoyConverter，就会把ResponseBody中的流转换为JsonReader，在转化为相应的对象类型。

#### 其他 ####

文中Retrofit的源码是Retrofit2.1.0