简单使用
添加依赖
implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
新建接口和返回对象
interface GitHubService {
@GET("users/{user}/repos")
fun listRepos(@Path("user") user: String?): Call<List<Repo>>
}
data class Repo(
val allow_forking: Boolean,
...
val watchers_count: Int
)
data class Owner(
val avatar_url: String,
...
val url: String
)
在activity中调用
val retrofit = Retrofit.Builder()
.baseUrl("https://api.github.com/")
.addConverterFactory(GsonConverterFactory.create())
.build()
val service = retrofit.create(GitHubService::class.java)
val listRepos = service.listRepos("octocat")
listRepos.enqueue(object :Callback<List<Repo>> {
override fun onResponse(call: Call<List<Repo>>, response: Response<List<Repo>>) {
println("response: ${response.body()!![0].name}")
}
override fun onFailure(call: Call<List<Repo>>, t: Throwable) {
}
})
源码解读
从最后执行的enqueue方法进行分析： 点击enqueue(）方法进入一个call的接口类，无法知道知道他的具体实现， 往上寻找看service.listRepos("octocat")这个方法，发现listRepos方法也是接口里面的一个方法，继续往上寻找retrofit.create(GitHubService::class.java)，查看crete方法
public <T> T create(final Class<T> service) {
validateServiceInterface(service);
return (T)
Proxy.newProxyInstance(
service.getClassLoader(),
new Class<?>[] {service},
new InvocationHandler() {
private final Platform platform = Platform.get();
private final Object[] emptyArgs = new Object[0];
@Override
public @Nullable Object invoke(Object proxy, Method method, @Nullable Object[] args)
throws Throwable {
if (method.getDeclaringClass() == Object.class) {
return method.invoke(this, args);
}
args = args != null ? args : emptyArgs;
return platform.isDefaultMethod(method)
? platform.invokeDefaultMethod(method, service, proxy, args)
: loadServiceMethod(method).invoke(args);
}
});
}
进入validateServiceInterface方法
private void validateServiceInterface(Class<?> service) {
//判断是否接口
if (!service.isInterface()) {
throw new IllegalArgumentException("API declarations must be interfaces.");
}
Deque<Class<?>> check = new ArrayDeque<>(1);
//把接口添加进入队列
check.add(service);
while (!check.isEmpty()) {
Class<?> candidate = check.removeFirst();
//getTypeParameters()是指接口上的泛型
if (candidate.getTypeParameters().length != 0) {
StringBuilder message =
new StringBuilder("Type parameters are unsupported on ").append(candidate.getName());
if (candidate != service) {
message.append(" which is an interface of ").append(service.getName());
}
throw new IllegalArgumentException(message.toString());
}
//将父类的接口也添加到队列中
Collections.addAll(check, candidate.getInterfaces());
}
//是否提前解析
if (validateEagerly) {
Platform platform = Platform.get();
for (Method method : service.getDeclaredMethods()) {
if (!platform.isDefaultMethod(method) && !Modifier.isStatic(method.getModifiers())) {
loadServiceMethod(method);
}
}
}
}
service是GitHubService::class.java
validateServiceInterface方法主要是做一些验证，判断service是不是接口，有没有泛型，是否提前解析的判断等。
如果validateEagerly这个标志为true的时候 会提前进入这个方法来验证这个service和解析他。
分析Proxy.newProxyInstance()
(T)
Proxy.newProxyInstance(
service.getClassLoader(),
new Class<?>[] {service},
new InvocationHandler() {
private final Platform platform = Platform.get();
private final Object[] emptyArgs = new Object[0];
@Override
public @Nullable Object invoke(Object proxy, Method method, @Nullable Object[] args)
throws Throwable {
//是 Object 的方法，直接触发该方法
if (method.getDeclaringClass() == Object.class) {
return method.invoke(this, args);
}
args = args != null ? args : emptyArgs;
//是 default 方法，那么使用该 Java8 平台的方法执行
return platform.isDefaultMethod(method)
? platform.invokeDefaultMethod(method, service, proxy, args)
: loadServiceMethod(method).invoke(args);
}
});
Proxy类的静态方法newProxyInstance()方法返回的是实现了指定接口的实现类对象。
动态代理就是在运行时生成一个类，这个类会实现你指定的一组接口，而这个类没有.java文件，是在运行时生成的，你也不用去关心它是什么类型的，你只需要知道它实现了哪些接口
Proxy类的newInstance()方法有三个参数
- loader: 用哪个类加载器去加载代理对象
- interfaces:动态代理类需要实现的接口,可以是多个接口
- h:动态代理方法在执行时，会调用h里面的invoke方法去执行
InvocationHandler里面invoke方法的三个参数
- proxy：就是代理对象，newProxyInstance方法的返回对象
- method：调用的方法
- args: 方法中的参数
进入invoke方法发现是抽象类ServiceMethod里面的一个方法，往上寻找进入loadServiceMethod方法
ServiceMethod<?> loadServiceMethod(Method method) {
//从缓存中取
ServiceMethod<?> result = serviceMethodCache.get(method);
if (result != null) return result;
synchronized (serviceMethodCache) {
result = serviceMethodCache.get(method);
if (result == null) {
//创建一个新的ServiceMethod放入缓存
result = ServiceMethod.parseAnnotations(this, method);
serviceMethodCache.put(method, result);
}
}
return result;
}
进入ServiceMethod.parseAnnotations(this, method)方法
static <T> ServiceMethod<T> parseAnnotations(Retrofit retrofit, Method method) {
RequestFactory requestFactory = RequestFactory.parseAnnotations(retrofit, method);
Type returnType = method.getGenericReturnType();
if (Utils.hasUnresolvableType(returnType)) {
throw methodError(
method,
"Method return type must not include a type variable or wildcard: %s",
returnType);
}
if (returnType == void.class) {
throw methodError(method, "Service methods cannot return void.");
}
return HttpServiceMethod.parseAnnotations(retrofit, method, requestFactory);
}
进入parseAnnotations方法
static <ResponseT, ReturnT> HttpServiceMethod<ResponseT, ReturnT> parseAnnotations(
Retrofit retrofit, Method method, RequestFactory requestFactory) {
boolean isKotlinSuspendFunction = requestFactory.isKotlinSuspendFunction;
boolean continuationWantsResponse = false;
boolean continuationBodyNullable = false;
Annotation[] annotations = method.getAnnotations();
Type adapterType;
if (isKotlinSuspendFunction) {
Type[] parameterTypes = method.getGenericParameterTypes();
Type responseType =
Utils.getParameterLowerBound(
0, (ParameterizedType) parameterTypes[parameterTypes.length - 1]);
if (getRawType(responseType) == Response.class && responseType instanceof ParameterizedType) {
responseType = Utils.getParameterUpperBound(0, (ParameterizedType) responseType);
continuationWantsResponse = true;
} else {
}
adapterType = new Utils.ParameterizedTypeImpl(null, Call.class, responseType);
annotations = SkipCallbackExecutorImpl.ensurePresent(annotations);
} else {
adapterType = method.getGenericReturnType();
}
CallAdapter<ResponseT, ReturnT> callAdapter =
createCallAdapter(retrofit, method, adapterType, annotations);
Type responseType = callAdapter.responseType();
if (responseType == okhttp3.Response.class) {
throw methodError(
method,
"'"
+ getRawType(responseType).getName()
+ "' is not a valid response body type. Did you mean ResponseBody?");
}
if (responseType == Response.class) {
throw methodError(method, "Response must include generic type (e.g., Response<String>)");
}
if (requestFactory.httpMethod.equals("HEAD") && !Void.class.equals(responseType)) {
throw methodError(method, "HEAD method must use Void as response type.");
}
Converter<ResponseBody, ResponseT> responseConverter =
createResponseConverter(retrofit, method, responseType);
okhttp3.Call.Factory callFactory = retrofit.callFactory;
if (!isKotlinSuspendFunction) {
return new CallAdapted<>(requestFactory, callFactory, responseConverter, callAdapter);
} else if (continuationWantsResponse) {
//noinspection unchecked Kotlin compiler guarantees ReturnT to be Object.
return (HttpServiceMethod<ResponseT, ReturnT>)
new SuspendForResponse<>(
requestFactory,
callFactory,
responseConverter,
(CallAdapter<ResponseT, Call<ResponseT>>) callAdapter);
} else {
//noinspection unchecked Kotlin compiler guarantees ReturnT to be Object.
return (HttpServiceMethod<ResponseT, ReturnT>)
new SuspendForBody<>(
requestFactory,
callFactory,
responseConverter,
(CallAdapter<ResponseT, Call<ResponseT>>) callAdapter,
continuationBodyNullable);
}
}
发现这个类继承至ServiceMethod这个类，同时还实现类invoke方法
HttpServiceMethod<ResponseT, ReturnT> extends ServiceMethod<ReturnT>
所以我们先分析invoke方法
@Override
final @Nullable ReturnT invoke(Object[] args) {
Call<ResponseT> call = new OkHttpCall<>(requestFactory, args, callFactory, responseConverter);
return adapt(call, args);
}
protected abstract @Nullable ReturnT adapt(Call<ResponseT> call, Object[] args);
发现最后又调用类一个抽象方法adapt
再次进入parseAnnotations方法
if (!isKotlinSuspendFunction) {
return new CallAdapted<>(requestFactory, callFactory, responseConverter, callAdapter);
} else if (continuationWantsResponse) {
return (HttpServiceMethod<ResponseT, ReturnT>)
new SuspendForResponse<>(
requestFactory,
callFactory,
responseConverter,
(CallAdapter<ResponseT, Call<ResponseT>>) callAdapter);
} else {
return (HttpServiceMethod<ResponseT, ReturnT>)
new SuspendForBody<>(
requestFactory,
callFactory,
responseConverter,
(CallAdapter<ResponseT, Call<ResponseT>>) callAdapter,
continuationBodyNullable);
}
因为没有使用挂起，所以进入new CallAdapted<>(requestFactory, callFactory, responseConverter, callAdapter)这个里面
static final class CallAdapted<ResponseT, ReturnT> extends HttpServiceMethod<ResponseT, ReturnT> {
private final CallAdapter<ResponseT, ReturnT> callAdapter;
CallAdapted(
RequestFactory requestFactory,
okhttp3.Call.Factory callFactory,
Converter<ResponseBody, ResponseT> responseConverter,
CallAdapter<ResponseT, ReturnT> callAdapter) {
super(requestFactory, callFactory, responseConverter);
this.callAdapter = callAdapter;
}
@Override
protected ReturnT adapt(Call<ResponseT> call, Object[] args) {
return callAdapter.adapt(call);
}
}
进入callAdapter.adapt(call) 发现是CallAdapter接口里面的一个方法。
进入OkHttpCall类发现他实现了Call这个接口，突然想起，调用 enqueue(）也是call接口
public void enqueue(final Callback<T> callback) {
Objects.requireNonNull(callback, "callback == null");
okhttp3.Call call;
Throwable failure;
synchronized (this) {
if (executed) throw new IllegalStateException("Already executed.");
executed = true;
call = rawCall;
failure = creationFailure;
if (call == null && failure == null) {
try {
//创建一个call出来
call = rawCall = createRawCall();
} catch (Throwable t) {
throwIfFatal(t);
failure = creationFailure = t;
}
}
}
if (failure != null) {
callback.onFailure(this, failure);
return;
}
if (canceled) {
call.cancel();
}
//这个call是okhttp的call
call.enqueue(
new okhttp3.Callback() {
@Override
public void onResponse(okhttp3.Call call, okhttp3.Response rawResponse) {
Response<T> response;
try {
// 解析返回的对象rawResponse是okhttp的对象，response是retrofit的
response = parseResponse(rawResponse);
} catch (Throwable e) {
throwIfFatal(e);
callFailure(e);
return;
}
try {
callback.onResponse(OkHttpCall.this, response);
} catch (Throwable t) {
throwIfFatal(t);
t.printStackTrace(); // TODO this is not great
}
}
@Override
public void onFailure(okhttp3.Call call, IOException e) {
callFailure(e);
}
private void callFailure(Throwable e) {
try {
callback.onFailure(OkHttpCall.this, e);
} catch (Throwable t) {
throwIfFatal(t);
t.printStackTrace(); // TODO this is not great
}
}
});
}
进入createRawCall方法创建一个call出来（来自okhttp3的call不是retrofit的）
private okhttp3.Call createRawCall() throws IOException {
okhttp3.Call call = callFactory.newCall(requestFactory.create(args));
if (call == null) {
throw new NullPointerException("Call.Factory returned null.");
}
return call;
}
最后通过okhttp的enqueue方法来进行网络请求。
大致的流程是这样的，但是有一个calladapter一直没有走完，从新回到parseAnnotations中，发现callAdapter是通过createCallAdapter方法创建的
CallAdapter<ResponseT, ReturnT> callAdapter =
createCallAdapter(retrofit, method, adapterType, annotations);
进入createCallAdapter方法
private static <ResponseT, ReturnT> CallAdapter<ResponseT, ReturnT> createCallAdapter(
Retrofit retrofit, Method method, Type returnType, Annotation[] annotations) {
try {
return (CallAdapter<ResponseT, ReturnT>) retrofit.callAdapter(returnType, annotations);
} catch (RuntimeException e) { // Wide exception range because factories are user code.
throw methodError(method, e, "Unable to create call adapter for %s", returnType);
}
}
继续进入callAdapter方法
public CallAdapter<?, ?> callAdapter(Type returnType, Annotation[] annotations) {
return nextCallAdapter(null, returnType, annotations);
}
继续进入nextCallAdapter
public CallAdapter<?, ?> nextCallAdapter(
@Nullable CallAdapter.Factory skipPast, Type returnType, Annotation[] annotations) {
Objects.requireNonNull(returnType, "returnType == null");
Objects.requireNonNull(annotations, "annotations == null");
int start = callAdapterFactories.indexOf(skipPast) + 1;
for (int i = start, count = callAdapterFactories.size(); i < count; i++) {
CallAdapter<?, ?> adapter = callAdapterFactories.get(i).get(returnType, annotations, this);
if (adapter != null) {
return adapter;
}
}
StringBuilder builder =
new StringBuilder("Could not locate call adapter for ").append(returnType).append(".\n");
if (skipPast != null) {
builder.append(" Skipped:");
for (int i = 0; i < start; i++) {
builder.append("\n * ").append(callAdapterFactories.get(i).getClass().getName());
}
builder.append('\n');
}
builder.append(" Tried:");
for (int i = start, count = callAdapterFactories.size(); i < count; i++) {
builder.append("\n * ").append(callAdapterFactories.get(i).getClass().getName());
}
throw new IllegalArgumentException(builder.toString());
}
进入callAdapterFactories类中查看什么时候初始化
Retrofit(
okhttp3.Call.Factory callFactory,
HttpUrl baseUrl,
List<Converter.Factory> converterFactories,
List<CallAdapter.Factory> callAdapterFactories,
@Nullable Executor callbackExecutor,
boolean validateEagerly) {
this.callFactory = callFactory;
this.baseUrl = baseUrl;
this.converterFactories = converterFactories; // Copy+unmodifiable at call site.
this.callAdapterFactories = callAdapterFactories; // Copy+unmodifiable at call site.
this.callbackExecutor = callbackExecutor;
this.validateEagerly = validateEagerly;
}
查看Retrofit是在那里创建的
return new Retrofit(
callFactory,
baseUrl,
unmodifiableList(converterFactories),
unmodifiableList(callAdapterFactories),
callbackExecutor,
validateEagerly);
}
找到callAdapterFactories赋值的地方
// Make a defensive copy of the adapters and add the default Call adapter.
List<CallAdapter.Factory> callAdapterFactories = new ArrayList<>(this.callAdapterFactories);
//给工厂添加值
callAdapterFactories.addAll(platform.defaultCallAdapterFactories(callbackExecutor));
进入defaultCallAdapterFactories
List<? extends CallAdapter.Factory> defaultCallAdapterFactories(
@Nullable Executor callbackExecutor) {
DefaultCallAdapterFactory executorFactory = new DefaultCallAdapterFactory(callbackExecutor);
return hasJava8Types
? asList(CompletableFutureCallAdapterFactory.INSTANCE, executorFactory)
: singletonList(executorFactory);
}
进入DefaultCallAdapterFactory查看get方法
final class DefaultCallAdapterFactory extends CallAdapter.Factory {
private final @Nullable Executor callbackExecutor;
DefaultCallAdapterFactory(@Nullable Executor callbackExecutor) {
this.callbackExecutor = callbackExecutor;
}
@Override
public @Nullable CallAdapter<?, ?> get(
Type returnType, Annotation[] annotations, Retrofit retrofit) {
if (getRawType(returnType) != Call.class) {
return null;
}
if (!(returnType instanceof ParameterizedType)) {
throw new IllegalArgumentException(
"Call return type must be parameterized as Call<Foo> or Call<? extends Foo>");
}
final Type responseType = Utils.getParameterUpperBound(0, (ParameterizedType) returnType);
final Executor executor =
Utils.isAnnotationPresent(annotations, SkipCallbackExecutor.class)
? null
: callbackExecutor;
return new CallAdapter<Object, Call<?>>() {
@Override
public Type responseType() {
return responseType;
}
@Override
public Call<Object> adapt(Call<Object> call) {
return executor == null ? call : new ExecutorCallbackCall<>(executor, call);
}
};
}
}
进入ExecutorCallbackCall类中
static final class ExecutorCallbackCall<T> implements Call<T> {
//Executor只是一个接口，它是Java／Android线程池框架的基础
final Executor callbackExecutor;
final Call<T> delegate;
ExecutorCallbackCall(Executor callbackExecutor, Call<T> delegate) {
this.callbackExecutor = callbackExecutor;
this.delegate = delegate;
}
@Override
public void enqueue(final Callback<T> callback) {
Objects.requireNonNull(callback, "callback == null");
//就是那个okhttp3.call
delegate.enqueue(
new Callback<T>() {
@Override
public void onResponse(Call<T> call, final Response<T> response) {
//切一下线程再去执行
callbackExecutor.execute(
() -> {
if (delegate.isCanceled()) {
callback.onFailure(ExecutorCallbackCall.this, new IOException("Canceled"));
} else {
callback.onResponse(ExecutorCallbackCall.this, response);
}
});
}
@Override
public void onFailure(Call<T> call, final Throwable t) {
callbackExecutor.execute(() -> callback.onFailure(ExecutorCallbackCall.this, t));
}
});
}
}
查看一下callbackExecutor
final Executor executor =
Utils.isAnnotationPresent(annotations, SkipCallbackExecutor.class)
? null
: callbackExecutor;
发现defaultCallAdapterFactories是一个传入的参数
List<? extends CallAdapter.Factory> defaultCallAdapterFactories(
@Nullable Executor callbackExecutor) {
DefaultCallAdapterFactory executorFactory = new DefaultCallAdapterFactory(callbackExecutor);
return hasJava8Types
? asList(CompletableFutureCallAdapterFactory.INSTANCE, executorFactory)
: singletonList(executorFactory);
}
又回到这里
// Make a defensive copy of the adapters and add the default Call adapter.
List<CallAdapter.Factory> callAdapterFactories = new ArrayList<>(this.callAdapterFactories);
callAdapterFactories.addAll(platform.defaultCallAdapterFactories(callbackExecutor));
找到赋值的地方
Executor callbackExecutor = this.callbackExecutor;
if (callbackExecutor == null) {
callbackExecutor = platform.defaultCallbackExecutor();
}
进入defaultCallbackExecutor
@Nullable
Executor defaultCallbackExecutor() {
return null;
}
发现返回一个null 发现Platform这个类是一个平台相关类
private static Platform findPlatform() {
return "Dalvik".equals(System.getProperty("java.vm.name"))
? new Android() //
: new Platform(true);
}
于是找到Android里面的这个方法
static final class Android extends Platform {
Android() {
super(Build.VERSION.SDK_INT >= 24);
}
@Override
public Executor defaultCallbackExecutor() {
return new MainThreadExecutor();
}
@Nullable
@Override
Object invokeDefaultMethod(
Method method, Class<?> declaringClass, Object object, Object... args) throws Throwable {
if (Build.VERSION.SDK_INT < 26) {
throw new UnsupportedOperationException(
"Calling default methods on API 24 and 25 is not supported");
}
return super.invokeDefaultMethod(method, declaringClass, object, args);
}
static final class MainThreadExecutor implements Executor {
private final Handler handler = new Handler(Looper.getMainLooper());
@Override
public void execute(Runnable r) {
handler.post(r);
}
}
}
进入MainThreadExecutor中，突然发现原来切换是为了把返回值的处理切换到UI线程
static final class MainThreadExecutor implements Executor {
private final Handler handler = new Handler(Looper.getMainLooper());
@Override
public void execute(Runnable r) {
handler.post(r);
}
}
Okhttp3.Call是如何被创建出来的
private okhttp3.Call createRawCall() throws IOException {
okhttp3.Call call = callFactory.newCall(requestFactory.create(args));
if (call == null) {
throw new NullPointerException("Call.Factory returned null.");
}
return call;
}
进入ServiceMethod类的parseAnnotations
static <T> ServiceMethod<T> parseAnnotations(Retrofit retrofit, Method method) {
RequestFactory requestFactory = RequestFactory.parseAnnotations(retrofit, method);
Type returnType = method.getGenericReturnType();
if (Utils.hasUnresolvableType(returnType)) {
throw methodError(
method,
"Method return type must not include a type variable or wildcard: %s",
returnType);
}
if (returnType == void.class) {
throw methodError(method, "Service methods cannot return void.");
}
return HttpServiceMethod.parseAnnotations(retrofit, method, requestFactory);
}
进入parseAnnotations方法
static RequestFactory parseAnnotations(Retrofit retrofit, Method method) {
return new Builder(retrofit, method).build();
}
进入build方法
RequestFactory build() {
for (Annotation annotation : methodAnnotations) {
parseMethodAnnotation(annotation);
}
if (httpMethod == null) {
throw methodError(method, "HTTP method annotation is required (e.g., @GET, @POST, etc.).");
}
if (!hasBody) {
if (isMultipart) {
throw methodError(
method,
"Multipart can only be specified on HTTP methods with request body (e.g., @POST).");
}
if (isFormEncoded) {
throw methodError(
method,
"FormUrlEncoded can only be specified on HTTP methods with "
+ "request body (e.g., @POST).");
}
}
int parameterCount = parameterAnnotationsArray.length;
parameterHandlers = new ParameterHandler<?>[parameterCount];
for (int p = 0, lastParameter = parameterCount - 1; p < parameterCount; p++) {
parameterHandlers[p] =
parseParameter(p, parameterTypes[p], parameterAnnotationsArray[p], p == lastParameter);
}
if (relativeUrl == null && !gotUrl) {
throw methodError(method, "Missing either @%s URL or @Url parameter.", httpMethod);
}
if (!isFormEncoded && !isMultipart && !hasBody && gotBody) {
throw methodError(method, "Non-body HTTP method cannot contain @Body.");
}
if (isFormEncoded && !gotField) {
throw methodError(method, "Form-encoded method must contain at least one @Field.");
}
if (isMultipart && !gotPart) {
throw methodError(method, "Multipart method must contain at least one @Part.");
}
return new RequestFactory(this);
}
进入parseMethodAnnotation方法
private void parseMethodAnnotation(Annotation annotation) {
if (annotation instanceof DELETE) {
parseHttpMethodAndPath("DELETE", ((DELETE) annotation).value(), false);
} else if (annotation instanceof GET) {
parseHttpMethodAndPath("GET", ((GET) annotation).value(), false);
} else if (annotation instanceof HEAD) {
parseHttpMethodAndPath("HEAD", ((HEAD) annotation).value(), false);
} else if (annotation instanceof PATCH) {
parseHttpMethodAndPath("PATCH", ((PATCH) annotation).value(), true);
} else if (annotation instanceof POST) {
parseHttpMethodAndPath("POST", ((POST) annotation).value(), true);
} else if (annotation instanceof PUT) {
parseHttpMethodAndPath("PUT", ((PUT) annotation).value(), true);
} else if (annotation instanceof OPTIONS) {
parseHttpMethodAndPath("OPTIONS", ((OPTIONS) annotation).value(), false);
} else if (annotation instanceof HTTP) {
HTTP http = (HTTP) annotation;
parseHttpMethodAndPath(http.method(), http.path(), http.hasBody());
} else if (annotation instanceof retrofit2.http.Headers) {
String[] headersToParse = ((retrofit2.http.Headers) annotation).value();
if (headersToParse.length == 0) {
throw methodError(method, "@Headers annotation is empty.");
}
headers = parseHeaders(headersToParse);
} else if (annotation instanceof Multipart) {
if (isFormEncoded) {
throw methodError(method, "Only one encoding annotation is allowed.");
}
isMultipart = true;
} else if (annotation instanceof FormUrlEncoded) {
if (isMultipart) {
throw methodError(method, "Only one encoding annotation is allowed.");
}
isFormEncoded = true;
}
}
parseHttpMethodAndPath方法主要是记录注解的一些行为
private void parseHttpMethodAndPath(String httpMethod, String value, boolean hasBody) {
if (this.httpMethod != null) {
throw methodError(
method,
"Only one HTTP method is allowed. Found: %s and %s.",
this.httpMethod,
httpMethod);
}
this.httpMethod = httpMethod;
this.hasBody = hasBody;
if (value.isEmpty()) {
return;
}
// Get the relative URL path and existing query string, if present.
int question = value.indexOf('?');
if (question != -1 && question < value.length() - 1) {
// Ensure the query string does not have any named parameters.
String queryParams = value.substring(question + 1);
Matcher queryParamMatcher = PARAM_URL_REGEX.matcher(queryParams);
if (queryParamMatcher.find()) {
throw methodError(
method,
"URL query string "%s" must not have replace block. "
+ "For dynamic query parameters use @Query.",
queryParams);
}
}
this.relativeUrl = value;
this.relativeUrlParamNames = parsePathParameters(value);
}
parseParameter这个方法对参数做分析
private @Nullable ParameterHandler<?> parseParameter(
int p, Type parameterType, @Nullable Annotation[] annotations, boolean allowContinuation) {
ParameterHandler<?> result = null;
if (annotations != null) {
for (Annotation annotation : annotations) {
ParameterHandler<?> annotationAction =
parseParameterAnnotation(p, parameterType, annotations, annotation);
if (annotationAction == null) {
continue;
}
if (result != null) {
throw parameterError(
method, p, "Multiple Retrofit annotations found, only one allowed.");
}
result = annotationAction;
}
}
if (result == null) {
if (allowContinuation) {
try {
if (Utils.getRawType(parameterType) == Continuation.class) {
isKotlinSuspendFunction = true;
return null;
}
} catch (NoClassDefFoundError ignored) {
}
}
throw parameterError(method, p, "No Retrofit annotation found.");
}
return result;
}
parseParameterAnnotation方法会针对接口上的那些注解参数进行分析和记录
private ParameterHandler<?> parseParameterAnnotation(
int p, Type type, Annotation[] annotations, Annotation annotation) {
if (annotation instanceof Url) {
validateResolvableType(p, type);
if (gotUrl) {
throw parameterError(method, p, "Multiple @Url method annotations found.");
}
if (gotPath) {
throw parameterError(method, p, "@Path parameters may not be used with @Url.");
}
if (gotQuery) {
throw parameterError(method, p, "A @Url parameter must not come after a @Query.");
}
if (gotQueryName) {
throw parameterError(method, p, "A @Url parameter must not come after a @QueryName.");
}
if (gotQueryMap) {
throw parameterError(method, p, "A @Url parameter must not come after a @QueryMap.");
}
if (relativeUrl != null) {
throw parameterError(method, p, "@Url cannot be used with @%s URL", httpMethod);
}
gotUrl = true;
if (type == HttpUrl.class
|| type == String.class
|| type == URI.class
|| (type instanceof Class && "android.net.Uri".equals(((Class<?>) type).getName()))) {
return new ParameterHandler.RelativeUrl(method, p);
} else {
throw parameterError(
method,
p,
"@Url must be okhttp3.HttpUrl, String, java.net.URI, or android.net.Uri type.");
}
} else if (annotation instanceof Path) {
validateResolvableType(p, type);
if (gotQuery) {
throw parameterError(method, p, "A @Path parameter must not come after a @Query.");
}
if (gotQueryName) {
throw parameterError(method, p, "A @Path parameter must not come after a @QueryName.");
}
if (gotQueryMap) {
throw parameterError(method, p, "A @Path parameter must not come after a @QueryMap.");
}
if (gotUrl) {
throw parameterError(method, p, "@Path parameters may not be used with @Url.");
}
if (relativeUrl == null) {
throw parameterError(
method, p, "@Path can only be used with relative url on @%s", httpMethod);
}
gotPath = true;
Path path = (Path) annotation;
String name = path.value();
validatePathName(p, name);
Converter<?, String> converter = retrofit.stringConverter(type, annotations);
return new ParameterHandler.Path<>(method, p, name, converter, path.encoded());
} else if (annotation instanceof Query) {
validateResolvableType(p, type);
Query query = (Query) annotation;
String name = query.value();
boolean encoded = query.encoded();
Class<?> rawParameterType = Utils.getRawType(type);
gotQuery = true;
if (Iterable.class.isAssignableFrom(rawParameterType)) {
if (!(type instanceof ParameterizedType)) {
throw parameterError(
method,
p,
rawParameterType.getSimpleName()
+ " must include generic type (e.g., "
+ rawParameterType.getSimpleName()
+ "<String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) type;
Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
Converter<?, String> converter = retrofit.stringConverter(iterableType, annotations);
return new ParameterHandler.Query<>(name, converter, encoded).iterable();
} else if (rawParameterType.isArray()) {
Class<?> arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
Converter<?, String> converter =
retrofit.stringConverter(arrayComponentType, annotations);
return new ParameterHandler.Query<>(name, converter, encoded).array();
} else {
Converter<?, String> converter = retrofit.stringConverter(type, annotations);
return new ParameterHandler.Query<>(name, converter, encoded);
}
} else if (annotation instanceof QueryName) {
validateResolvableType(p, type);
QueryName query = (QueryName) annotation;
boolean encoded = query.encoded();
Class<?> rawParameterType = Utils.getRawType(type);
gotQueryName = true;
if (Iterable.class.isAssignableFrom(rawParameterType)) {
if (!(type instanceof ParameterizedType)) {
throw parameterError(
method,
p,
rawParameterType.getSimpleName()
+ " must include generic type (e.g., "
+ rawParameterType.getSimpleName()
+ "<String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) type;
Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
Converter<?, String> converter = retrofit.stringConverter(iterableType, annotations);
return new ParameterHandler.QueryName<>(converter, encoded).iterable();
} else if (rawParameterType.isArray()) {
Class<?> arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
Converter<?, String> converter =
retrofit.stringConverter(arrayComponentType, annotations);
return new ParameterHandler.QueryName<>(converter, encoded).array();
} else {
Converter<?, String> converter = retrofit.stringConverter(type, annotations);
return new ParameterHandler.QueryName<>(converter, encoded);
}
} else if (annotation instanceof QueryMap) {
validateResolvableType(p, type);
Class<?> rawParameterType = Utils.getRawType(type);
gotQueryMap = true;
if (!Map.class.isAssignableFrom(rawParameterType)) {
throw parameterError(method, p, "@QueryMap parameter type must be Map.");
}
Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
if (!(mapType instanceof ParameterizedType)) {
throw parameterError(
method, p, "Map must include generic types (e.g., Map<String, String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) mapType;
Type keyType = Utils.getParameterUpperBound(0, parameterizedType);
if (String.class != keyType) {
throw parameterError(method, p, "@QueryMap keys must be of type String: " + keyType);
}
Type valueType = Utils.getParameterUpperBound(1, parameterizedType);
Converter<?, String> valueConverter = retrofit.stringConverter(valueType, annotations);
return new ParameterHandler.QueryMap<>(
method, p, valueConverter, ((QueryMap) annotation).encoded());
} else if (annotation instanceof Header) {
validateResolvableType(p, type);
Header header = (Header) annotation;
String name = header.value();
Class<?> rawParameterType = Utils.getRawType(type);
if (Iterable.class.isAssignableFrom(rawParameterType)) {
if (!(type instanceof ParameterizedType)) {
throw parameterError(
method,
p,
rawParameterType.getSimpleName()
+ " must include generic type (e.g., "
+ rawParameterType.getSimpleName()
+ "<String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) type;
Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
Converter<?, String> converter = retrofit.stringConverter(iterableType, annotations);
return new ParameterHandler.Header<>(name, converter).iterable();
} else if (rawParameterType.isArray()) {
Class<?> arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
Converter<?, String> converter =
retrofit.stringConverter(arrayComponentType, annotations);
return new ParameterHandler.Header<>(name, converter).array();
} else {
Converter<?, String> converter = retrofit.stringConverter(type, annotations);
return new ParameterHandler.Header<>(name, converter);
}
} else if (annotation instanceof HeaderMap) {
if (type == Headers.class) {
return new ParameterHandler.Headers(method, p);
}
validateResolvableType(p, type);
Class<?> rawParameterType = Utils.getRawType(type);
if (!Map.class.isAssignableFrom(rawParameterType)) {
throw parameterError(method, p, "@HeaderMap parameter type must be Map.");
}
Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
if (!(mapType instanceof ParameterizedType)) {
throw parameterError(
method, p, "Map must include generic types (e.g., Map<String, String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) mapType;
Type keyType = Utils.getParameterUpperBound(0, parameterizedType);
if (String.class != keyType) {
throw parameterError(method, p, "@HeaderMap keys must be of type String: " + keyType);
}
Type valueType = Utils.getParameterUpperBound(1, parameterizedType);
Converter<?, String> valueConverter = retrofit.stringConverter(valueType, annotations);
return new ParameterHandler.HeaderMap<>(method, p, valueConverter);
} else if (annotation instanceof Field) {
validateResolvableType(p, type);
if (!isFormEncoded) {
throw parameterError(method, p, "@Field parameters can only be used with form encoding.");
}
Field field = (Field) annotation;
String name = field.value();
boolean encoded = field.encoded();
gotField = true;
Class<?> rawParameterType = Utils.getRawType(type);
if (Iterable.class.isAssignableFrom(rawParameterType)) {
if (!(type instanceof ParameterizedType)) {
throw parameterError(
method,
p,
rawParameterType.getSimpleName()
+ " must include generic type (e.g., "
+ rawParameterType.getSimpleName()
+ "<String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) type;
Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
Converter<?, String> converter = retrofit.stringConverter(iterableType, annotations);
return new ParameterHandler.Field<>(name, converter, encoded).iterable();
} else if (rawParameterType.isArray()) {
Class<?> arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
Converter<?, String> converter =
retrofit.stringConverter(arrayComponentType, annotations);
return new ParameterHandler.Field<>(name, converter, encoded).array();
} else {
Converter<?, String> converter = retrofit.stringConverter(type, annotations);
return new ParameterHandler.Field<>(name, converter, encoded);
}
} else if (annotation instanceof FieldMap) {
validateResolvableType(p, type);
if (!isFormEncoded) {
throw parameterError(
method, p, "@FieldMap parameters can only be used with form encoding.");
}
Class<?> rawParameterType = Utils.getRawType(type);
if (!Map.class.isAssignableFrom(rawParameterType)) {
throw parameterError(method, p, "@FieldMap parameter type must be Map.");
}
Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
if (!(mapType instanceof ParameterizedType)) {
throw parameterError(
method, p, "Map must include generic types (e.g., Map<String, String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) mapType;
Type keyType = Utils.getParameterUpperBound(0, parameterizedType);
if (String.class != keyType) {
throw parameterError(method, p, "@FieldMap keys must be of type String: " + keyType);
}
Type valueType = Utils.getParameterUpperBound(1, parameterizedType);
Converter<?, String> valueConverter = retrofit.stringConverter(valueType, annotations);
gotField = true;
return new ParameterHandler.FieldMap<>(
method, p, valueConverter, ((FieldMap) annotation).encoded());
} else if (annotation instanceof Part) {
validateResolvableType(p, type);
if (!isMultipart) {
throw parameterError(
method, p, "@Part parameters can only be used with multipart encoding.");
}
Part part = (Part) annotation;
gotPart = true;
String partName = part.value();
Class<?> rawParameterType = Utils.getRawType(type);
if (partName.isEmpty()) {
if (Iterable.class.isAssignableFrom(rawParameterType)) {
if (!(type instanceof ParameterizedType)) {
throw parameterError(
method,
p,
rawParameterType.getSimpleName()
+ " must include generic type (e.g., "
+ rawParameterType.getSimpleName()
+ "<String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) type;
Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
if (!MultipartBody.Part.class.isAssignableFrom(Utils.getRawType(iterableType))) {
throw parameterError(
method,
p,
"@Part annotation must supply a name or use MultipartBody.Part parameter type.");
}
return ParameterHandler.RawPart.INSTANCE.iterable();
} else if (rawParameterType.isArray()) {
Class<?> arrayComponentType = rawParameterType.getComponentType();
if (!MultipartBody.Part.class.isAssignableFrom(arrayComponentType)) {
throw parameterError(
method,
p,
"@Part annotation must supply a name or use MultipartBody.Part parameter type.");
}
return ParameterHandler.RawPart.INSTANCE.array();
} else if (MultipartBody.Part.class.isAssignableFrom(rawParameterType)) {
return ParameterHandler.RawPart.INSTANCE;
} else {
throw parameterError(
method,
p,
"@Part annotation must supply a name or use MultipartBody.Part parameter type.");
}
} else {
Headers headers =
Headers.of(
"Content-Disposition",
"form-data; name="" + partName + """,
"Content-Transfer-Encoding",
part.encoding());
if (Iterable.class.isAssignableFrom(rawParameterType)) {
if (!(type instanceof ParameterizedType)) {
throw parameterError(
method,
p,
rawParameterType.getSimpleName()
+ " must include generic type (e.g., "
+ rawParameterType.getSimpleName()
+ "<String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) type;
Type iterableType = Utils.getParameterUpperBound(0, parameterizedType);
if (MultipartBody.Part.class.isAssignableFrom(Utils.getRawType(iterableType))) {
throw parameterError(
method,
p,
"@Part parameters using the MultipartBody.Part must not "
+ "include a part name in the annotation.");
}
Converter<?, RequestBody> converter =
retrofit.requestBodyConverter(iterableType, annotations, methodAnnotations);
return new ParameterHandler.Part<>(method, p, headers, converter).iterable();
} else if (rawParameterType.isArray()) {
Class<?> arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
if (MultipartBody.Part.class.isAssignableFrom(arrayComponentType)) {
throw parameterError(
method,
p,
"@Part parameters using the MultipartBody.Part must not "
+ "include a part name in the annotation.");
}
Converter<?, RequestBody> converter =
retrofit.requestBodyConverter(arrayComponentType, annotations, methodAnnotations);
return new ParameterHandler.Part<>(method, p, headers, converter).array();
} else if (MultipartBody.Part.class.isAssignableFrom(rawParameterType)) {
throw parameterError(
method,
p,
"@Part parameters using the MultipartBody.Part must not "
+ "include a part name in the annotation.");
} else {
Converter<?, RequestBody> converter =
retrofit.requestBodyConverter(type, annotations, methodAnnotations);
return new ParameterHandler.Part<>(method, p, headers, converter);
}
}
} else if (annotation instanceof PartMap) {
validateResolvableType(p, type);
if (!isMultipart) {
throw parameterError(
method, p, "@PartMap parameters can only be used with multipart encoding.");
}
gotPart = true;
Class<?> rawParameterType = Utils.getRawType(type);
if (!Map.class.isAssignableFrom(rawParameterType)) {
throw parameterError(method, p, "@PartMap parameter type must be Map.");
}
Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
if (!(mapType instanceof ParameterizedType)) {
throw parameterError(
method, p, "Map must include generic types (e.g., Map<String, String>)");
}
ParameterizedType parameterizedType = (ParameterizedType) mapType;
Type keyType = Utils.getParameterUpperBound(0, parameterizedType);
if (String.class != keyType) {
throw parameterError(method, p, "@PartMap keys must be of type String: " + keyType);
}
Type valueType = Utils.getParameterUpperBound(1, parameterizedType);
if (MultipartBody.Part.class.isAssignableFrom(Utils.getRawType(valueType))) {
throw parameterError(
method,
p,
"@PartMap values cannot be MultipartBody.Part. "
+ "Use @Part List<Part> or a different value type instead.");
}
Converter<?, RequestBody> valueConverter =
retrofit.requestBodyConverter(valueType, annotations, methodAnnotations);
PartMap partMap = (PartMap) annotation;
return new ParameterHandler.PartMap<>(method, p, valueConverter, partMap.encoding());
} else if (annotation instanceof Body) {
validateResolvableType(p, type);
if (isFormEncoded || isMultipart) {
throw parameterError(
method, p, "@Body parameters cannot be used with form or multi-part encoding.");
}
if (gotBody) {
throw parameterError(method, p, "Multiple @Body method annotations found.");
}
Converter<?, RequestBody> converter;
try {
converter = retrofit.requestBodyConverter(type, annotations, methodAnnotations);
} catch (RuntimeException e) {
// Wide exception range because factories are user code.
throw parameterError(method, e, p, "Unable to create @Body converter for %s", type);
}
gotBody = true;
return new ParameterHandler.Body<>(method, p, converter);
} else if (annotation instanceof Tag) {
validateResolvableType(p, type);
Class<?> tagType = Utils.getRawType(type);
for (int i = p - 1; i >= 0; i--) {
ParameterHandler<?> otherHandler = parameterHandlers[i];
if (otherHandler instanceof ParameterHandler.Tag
&& ((ParameterHandler.Tag) otherHandler).cls.equals(tagType)) {
throw parameterError(
method,
p,
"@Tag type "
+ tagType.getName()
+ " is duplicate of parameter #"
+ (i + 1)
+ " and would always overwrite its value.");
}
}
return new ParameterHandler.Tag<>(tagType);
}
return null; // Not a Retrofit annotation.
}
接着再createRawCall里面拼装成一个okhttp3.call
private okhttp3.Call createRawCall() throws IOException {
okhttp3.Call call = callFactory.newCall(requestFactory.create(args));
if (call == null) {
throw new NullPointerException("Call.Factory returned null.");
}
return call;
}
进入create方法
okhttp3.Request create(Object[] args) throws IOException {
@SuppressWarnings("unchecked") // It is an error to invoke a method with the wrong arg types.
ParameterHandler<Object>[] handlers = (ParameterHandler<Object>[]) parameterHandlers;
int argumentCount = args.length;
if (argumentCount != handlers.length) {
throw new IllegalArgumentException(
"Argument count ("
+ argumentCount
+ ") doesn't match expected count ("
+ handlers.length
+ ")");
}
RequestBuilder requestBuilder =
new RequestBuilder(
httpMethod,
baseUrl,
relativeUrl,
headers,
contentType,
hasBody,
isFormEncoded,
isMultipart);
if (isKotlinSuspendFunction) {
// The Continuation is the last parameter and the handlers array contains null at that index.
argumentCount--;
}
List<Object> argumentList = new ArrayList<>(argumentCount);
for (int p = 0; p < argumentCount; p++) {
argumentList.add(args[p]);
handlers[p].apply(requestBuilder, args[p]);
}
return requestBuilder.get().tag(Invocation.class, new Invocation(method, argumentList)).build();
}
因为有类前面的各种记录，在这里可以很方便的创建出来okhttp3.call这个对象
数据的解析
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) {
rawBody.close();
return Response.success(null, rawResponse);
}
ExceptionCatchingResponseBody catchingBody = new ExceptionCatchingResponseBody(rawBody);
try {
//数据解析
T body = responseConverter.convert(catchingBody);
return Response.success(body, rawResponse);
} catch (RuntimeException e) {
catchingBody.throwIfCaught();
throw e;
}
}
发现convert是一个接口，跟踪responseConverter查看在哪里赋值的
OkHttpCall(
RequestFactory requestFactory,
Object[] args,
okhttp3.Call.Factory callFactory,
Converter<ResponseBody, T> responseConverter) {
this.requestFactory = requestFactory;
this.args = args;
this.callFactory = callFactory;
this.responseConverter = responseConverter;
}
在OkHttpCall被创建的时候进行赋值
HttpServiceMethod(
RequestFactory requestFactory,
okhttp3.Call.Factory callFactory,
Converter<ResponseBody, ResponseT> responseConverter) {
this.requestFactory = requestFactory;
this.callFactory = callFactory;
this.responseConverter = responseConverter;
}
@Override
final @Nullable ReturnT invoke(Object[] args) {
Call<ResponseT> call = new OkHttpCall<>(requestFactory, args, callFactory, responseConverter);
return adapt(call, args);
}
查看HttpServiceMethod创建的位置
CallAdapted(
RequestFactory requestFactory,
okhttp3.Call.Factory callFactory,
Converter<ResponseBody, ResponseT> responseConverter,
CallAdapter<ResponseT, ReturnT> callAdapter) {
super(requestFactory, callFactory, responseConverter);
this.callAdapter = callAdapter;
}
CallAdapted是在parseAnnotations这个方法中创建的
static <ResponseT, ReturnT> HttpServiceMethod<ResponseT, ReturnT> parseAnnotations(
Retrofit retrofit, Method method, RequestFactory requestFactory) {
...
if (!isKotlinSuspendFunction) {
return new CallAdapted<>(requestFactory, callFactory, responseConverter, callAdapter);
} else if (continuationWantsResponse) {
//noinspection unchecked Kotlin compiler guarantees ReturnT to be Object.
return (HttpServiceMethod<ResponseT, ReturnT>)
new SuspendForResponse<>(
requestFactory,
callFactory,
responseConverter,
(CallAdapter<ResponseT, Call<ResponseT>>) callAdapter);
} else {
//noinspection unchecked Kotlin compiler guarantees ReturnT to be Object.
return (HttpServiceMethod<ResponseT, ReturnT>)
new SuspendForBody<>(
requestFactory,
callFactory,
responseConverter,
(CallAdapter<ResponseT, Call<ResponseT>>) callAdapter,
continuationBodyNullable);
}
}
查看responseConverter的赋值的地方
Converter<ResponseBody, ResponseT> responseConverter =
createResponseConverter(retrofit, method, responseType);
进入createResponseConverter方法
private static <ResponseT> Converter<ResponseBody, ResponseT> createResponseConverter(
Retrofit retrofit, Method method, Type responseType) {
Annotation[] annotations = method.getAnnotations();
try {
return retrofit.responseBodyConverter(responseType, annotations);
} catch (RuntimeException e) { // Wide exception range because factories are user code.
throw methodError(method, e, "Unable to create converter for %s", responseType);
}
}
进入responseBodyConverter方法
public <T> Converter<ResponseBody, T> responseBodyConverter(Type type, Annotation[] annotations) {
return nextResponseBodyConverter(null, type, annotations);
}
进入nextResponseBodyConverter方法
public <T> Converter<ResponseBody, T> nextResponseBodyConverter(
@Nullable Converter.Factory skipPast, Type type, Annotation[] annotations) {
Objects.requireNonNull(type, "type == null");
Objects.requireNonNull(annotations, "annotations == null");
int start = converterFactories.indexOf(skipPast) + 1;
for (int i = start, count = converterFactories.size(); i < count; i++) {
Converter<ResponseBody, ?> converter =
converterFactories.get(i).responseBodyConverter(type, annotations, this);
if (converter != null) {
return (Converter<ResponseBody, T>) converter;
}
}
StringBuilder builder =
new StringBuilder("Could not locate ResponseBody converter for ")
.append(type)
.append(".\n");
if (skipPast != null) {
builder.append(" Skipped:");
for (int i = 0; i < start; i++) {
builder.append("\n * ").append(converterFactories.get(i).getClass().getName());
}
builder.append('\n');
}
builder.append(" Tried:");
for (int i = start, count = converterFactories.size(); i < count; i++) {
builder.append("\n * ").append(converterFactories.get(i).getClass().getName());
}
throw new IllegalArgumentException(builder.toString());
}
流程和上面的有点类似了。
val retrofit = Retrofit.Builder()
.baseUrl("https://api.github.com/")
.addConverterFactory(GsonConverterFactory.create())
.build()
addConverterFactory(GsonConverterFactory.create())，如果在创建的时候添加这行就可以用gson解析了。
最后
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