接着上一篇的内容接着讲
上一篇我们说到了retrofit的初始化
这一篇我们将讲述retrofit的调用过程
public interface GitHubService {
@GET("users/{user}/repos")
Call<List<Repo>> listRepos(@Path("user") String user);
}
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://api.github.com/")
.build();
GitHubService service = retrofit.create(GitHubService.class);
接下来就是讲讲retrofit.create(class);
public <T> T create(final Class<T> service) {
Utils.validateServiceInterface(service);
if (validateEagerly) {
eagerlyValidateMethods(service);
}
return (T) Proxy.newProxyInstance(service.getClassLoader(), new Class<?>[] { service },
new InvocationHandler() {
private final Platform platform = Platform.get();
@Override public Object invoke(Object proxy, Method method, @Nullable Object[] args)
throws Throwable {
// If the method is a method from Object then defer to normal invocation.
if (method.getDeclaringClass() == Object.class) {
return method.invoke(this, args);
}
if (platform.isDefaultMethod(method)) {
return platform.invokeDefaultMethod(method, service, proxy, args);
}
ServiceMethod<Object, Object> serviceMethod =
(ServiceMethod<Object, Object>) loadServiceMethod(method);
OkHttpCall<Object> okHttpCall = new OkHttpCall<>(serviceMethod, args);
return serviceMethod.callAdapter.adapt(okHttpCall);
}
});
}
我们看下第一行代码
Utils.validateServiceInterface(service);
//Utils.java
static <T> void validateServiceInterface(Class<T> service) {
if (!service.isInterface()) {
throw new IllegalArgumentException("API declarations must be interfaces.");
}
// Prevent API interfaces from extending other interfaces. This not only avoids a bug in
// Android (http://b.android.com/58753) but it forces composition of API declarations which is
// the recommended pattern.
if (service.getInterfaces().length > 0) {
throw new IllegalArgumentException("API interfaces must not extend other interfaces.");
}
}
如果Service不是接口或者Service继承了其他接口会抛出IllegalArgumentException异常
好啦再看看
if (validateEagerly) {
eagerlyValidateMethods(service);
}
我找了两圈，没发现初始化validateEagerly的，所以validateEagerly应该是默认值false；看注释貌似是控制预加载注解的，也就是说默认不加载，等到调用时才加载，那么我们先略过预加载，等后面看到加载的时候再搞一搞
return (T) Proxy.newProxyInstance(service.getClassLoader(), new Class<?>[] { service },
new InvocationHandler() {
private final Platform platform = Platform.get();
@Override public Object invoke(Object proxy, Method method, @Nullable Object[] args)
throws Throwable {
// If the method is a method from Object then defer to normal invocation.
if (method.getDeclaringClass() == Object.class) {
return method.invoke(this, args);
}
if (platform.isDefaultMethod(method)) {
return platform.invokeDefaultMethod(method, service, proxy, args);
}
ServiceMethod<Object, Object> serviceMethod =
(ServiceMethod<Object, Object>) loadServiceMethod(method);
OkHttpCall<Object> okHttpCall = new OkHttpCall<>(serviceMethod, args);
return serviceMethod.callAdapter.adapt(okHttpCall);
}
});
create 方法return了一个动态代理对象，什么是动态代理？自行百度，这里不讲。
我们知道 调用动态代理对象的时候，都会被InvocationHandler拦截，最后执行InvocationHandler invoke()方法；
也就是说下面这段代码
public interface GitHubService {
@GET("users/{user}/repos")
Call<List<Repo>> listRepos(@Path("user") String user);
}
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://api.github.com/")
.build();
GitHubService service = retrofit.create(GitHubService.class);
当调用retrofit.create(GitHubService.class)时，会生成一个GitHubService的对象，而调用生成的GitHubService对象的每个方法时，都会调用到InvocationHandler. invoke(),
那么我们来看看这个invoke()方法
new InvocationHandler() {
private final Platform platform = Platform.get();
@Override public Object invoke(Object proxy, Method method, @Nullable Object[] args)
throws Throwable {
// If the method is a method from Object then defer to normal invocation.
if (method.getDeclaringClass() == Object.class) {
return method.invoke(this, args);
}
if (platform.isDefaultMethod(method)) {
return platform.invokeDefaultMethod(method, service, proxy, args);
}
ServiceMethod<Object, Object> serviceMethod =
(ServiceMethod<Object, Object>) loadServiceMethod(method);
OkHttpCall<Object> okHttpCall = new OkHttpCall<>(serviceMethod, args);
return serviceMethod.callAdapter.adapt(okHttpCall);
}
}
当调用的method属于Object时，执行method.invoke(this, args);，也即是原来object的操作并return
当调用的method是默认方法时，执行默认方法调用，并return；
当调用的method属于Object也不是默认方法时，执行
ServiceMethod<Object, Object> serviceMethod =
(ServiceMethod<Object, Object>) loadServiceMethod(method);
OkHttpCall<Object> okHttpCall = new OkHttpCall<>(serviceMethod, args);
return serviceMethod.callAdapter.adapt(okHttpCall);
接下来我们看看loadServiceMethod()的实现
ServiceMethod<?, ?> loadServiceMethod(Method method) {
ServiceMethod<?, ?> result = serviceMethodCache.get(method);
if (result != null) return result;
synchronized (serviceMethodCache) {
result = serviceMethodCache.get(method);
if (result == null) {
result = new ServiceMethod.Builder<>(this, method).build();
serviceMethodCache.put(method, result);
}
}
return result;
}
serviceMethodCache是一个ServiceMethod缓存，以method为key的一个map，当serviceMethodCache中存在对应key的ServiceMethod则return，不存在则通过ServiceMethod. Builder生成一个，并put到cache里，再return，
我们看看
ServiceMethod.Builder()的代码
Builder(Retrofit retrofit, Method method) {
this.retrofit = retrofit;
this.method = method;
//方法的注解
this.methodAnnotations = method.getAnnotations();
//方法参数类型
this.parameterTypes = method.getGenericParameterTypes();
//方法参数注解
this.parameterAnnotationsArray = method.getParameterAnnotations();
}
public ServiceMethod build() {
//创建一个CallAdapter
callAdapter = createCallAdapter();
responseType = callAdapter.responseType();
if (responseType == Response.class || responseType == okhttp3.Response.class) {
throw methodError("'"
+ Utils.getRawType(responseType).getName()
+ "' is not a valid response body type. Did you mean ResponseBody?");
}
responseConverter = createResponseConverter();
for (Annotation annotation : methodAnnotations) {
parseMethodAnnotation(annotation);
}
if (httpMethod == null) {
throw methodError("HTTP method annotation is required (e.g., @GET, @POST, etc.).");
}
if (!hasBody) {
if (isMultipart) {
throw methodError(
"Multipart can only be specified on HTTP methods with request body (e.g., @POST).");
}
if (isFormEncoded) {
throw methodError("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; p < parameterCount; p++) {
Type parameterType = parameterTypes[p];
if (Utils.hasUnresolvableType(parameterType)) {
throw parameterError(p, "Parameter type must not include a type variable or wildcard: %s",
parameterType);
}
Annotation[] parameterAnnotations = parameterAnnotationsArray[p];
if (parameterAnnotations == null) {
throw parameterError(p, "No Retrofit annotation found.");
}
parameterHandlers[p] = parseParameter(p, parameterType, parameterAnnotations);
}
if (relativeUrl == null && !gotUrl) {
throw methodError("Missing either @%s URL or @Url parameter.", httpMethod);
}
if (!isFormEncoded && !isMultipart && !hasBody && gotBody) {
throw methodError("Non-body HTTP method cannot contain @Body.");
}
if (isFormEncoded && !gotField) {
throw methodError("Form-encoded method must contain at least one @Field.");
}
if (isMultipart && !gotPart) {
throw methodError("Multipart method must contain at least one @Part.");
}
return new ServiceMethod<>(this);
}
private CallAdapter<T, R> createCallAdapter() {
//被调用方法返回值类型
Type returnType = method.getGenericReturnType();
//当返回值类型为无法解析类型时
if (Utils.hasUnresolvableType(returnType)) {
throw methodError(
"Method return type must not include a type variable or wildcard: %s", returnType);
}
//当返回值类型为void时
if (returnType == void.class) {
throw methodError("Service methods cannot return void.");
}
//获取方法的注解列表
Annotation[] annotations = method.getAnnotations();
try {
//noinspection unchecked
//最终调用了 retrofit.callAdapte方法
return (CallAdapter<T, R>) retrofit.callAdapter(returnType, annotations);
} catch (RuntimeException e) { // Wide exception range because factories are user code.
throw methodError(e, "Unable to create call adapter for %s", returnType);
}
}
在build中可以看到首先create一个CallAdapter，我们之前知道，这个callAdapter的目的是将，将CallAdapter<T, R>R类型转换为T类型（如，rxjavaAdapter，将call<T>转换为Observable<T>）
那么继续让我们看 retrofit.callAdapte()方法
public CallAdapter<?, ?> callAdapter(Type returnType, Annotation[] annotations) {
return nextCallAdapter(null, returnType, annotations);
}
/**
* Returns the {@link CallAdapter} for {@code returnType} from the available {@linkplain
* #callAdapterFactories() factories} except {@code skipPast}.
*
* @throws IllegalArgumentException if no call adapter available for {@code type}.
*/
public CallAdapter<?, ?> nextCallAdapter(@Nullable CallAdapter.Factory skipPast, Type returnType,
Annotation[] annotations) {
checkNotNull(returnType, "returnType == null");
checkNotNull(annotations, "annotations == null");
int start = adapterFactories.indexOf(skipPast) + 1;
for (int i = start, count = adapterFactories.size(); i < count; i++) {
CallAdapter<?, ?> adapter = adapterFactories.get(i).get(returnType, annotations, this);
if (adapter != null) {
return adapter;
}
}
那么adapterFactories这个是什么？还记得之前说过，如果没有设置adapterFactorie，默认使用platform.defaultCallAdapterFactory()嘛？（Retrofit.Builder.build()方法中），我们之前也说过android 的默认CallAdapterFactory是ExecutorCallAdapterFactory；
那么让我们看看ExecutorCallAdapterFactory的get方法
@Override
public CallAdapter<?, ?> get(Type returnType, Annotation[] annotations, Retrofit retrofit) {
if (getRawType(returnType) != Call.class) {
return null;
}
final Type responseType = Utils.getCallResponseType(returnType);
return new CallAdapter<Object, Call<?>>() {
@Override public Type responseType() {
return responseType;
}
@Override public Call<Object> adapt(Call<Object> call) {
return new ExecutorCallbackCall<>(callbackExecutor, call);
}
};
}
之前也说过，ExecutorCallAdapterFactory只处理返回值为Call<?>的其他返回null，结合nextCallAdapter函数，可以看出，遍历找到一个不为null的，也即是找到一个处理Call的adapter，如果他是Observable<?>类型的，那么
ExecutorCallAdapterFactory就没办法处理，这个时候就得RxjavaAdapterFactory出马，
我们接着看build方法的代码
if (responseType == Response.class || responseType == okhttp3.Response.class) {
throw methodError("'"
+ Utils.getRawType(responseType).getName()
+ "' is not a valid response body type. Did you mean ResponseBody?");
}
如果call的泛型类型是Retrofit.Response或者okhttp3.Response
抛出一个异常
responseConverter = createResponseConverter();
接下来看下
private Converter<ResponseBody, T> createResponseConverter() {
Annotation[] annotations = method.getAnnotations();
try {
return retrofit.responseBodyConverter(responseType, annotations);
} catch (RuntimeException e) { // Wide exception range because factories are user code.
throw methodError(e, "Unable to create converter for %s", responseType);
}
}
没错，又跳到retrofit类里了，((⊙﹏⊙)b，写文章的时候跳来跳去累死了)
让我们继续看看responseBodyConverter的代码
/**
* Returns a {@link Converter} for {@link ResponseBody} to {@code type} from the available
* {@linkplain #converterFactories() factories}.
*
* @throws IllegalArgumentException if no converter available for {@code type}.
*/
public <T> Converter<ResponseBody, T> responseBodyConverter(Type type, Annotation[] annotations) {
return nextResponseBodyConverter(null, type, annotations);
}
/**
* Returns a {@link Converter} for {@link ResponseBody} to {@code type} from the available
* {@linkplain #converterFactories() factories} except {@code skipPast}.
*
* @throws IllegalArgumentException if no converter available for {@code type}.
*/
public <T> Converter<ResponseBody, T> nextResponseBodyConverter(
@Nullable Converter.Factory skipPast, Type type, Annotation[] annotations) {
checkNotNull(type, "type == null");
checkNotNull(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) {
//noinspection unchecked
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());
}
调用nextResponseBodyConverter时 Converter.Factory传的是null所以start=0；还记得在我们new 一个Retrofit.Builder的时候，add进去的BuiltInConverters嘛？我们之前说过BuiltInConverters只能处理requestBody，和ResponseBody，其他返回为null，所以Call<ResponseBody>/Observable<ResponseBody>或者Call<requestBody>/Observable<requestBody> 就会匹配到BuiltInConverters，由BuiltInConverters处理，那么问题来了，如果我想处理Call<String>呢？emmmmm..你得自定义一个Converter.Factory，将Response body转换成String或者其他对象，(例如GsonConverterFactory)
继续看build()代码
for (Annotation annotation : methodAnnotations) {
parseMethodAnnotation(annotation);
}
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);
if (!Void.class.equals(responseType)) {
throw methodError("HEAD method must use Void as response type.");
}
} 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("@Headers annotation is empty.");
}
headers = parseHeaders(headersToParse);
} else if (annotation instanceof Multipart) {
if (isFormEncoded) {
throw methodError("Only one encoding annotation is allowed.");
}
isMultipart = true;
} else if (annotation instanceof FormUrlEncoded) {
if (isMultipart) {
throw methodError("Only one encoding annotation is allowed.");
}
isFormEncoded = true;
}
}
private void parseHttpMethodAndPath(String httpMethod, String value, boolean hasBody) {
if (this.httpMethod != null) {
throw methodError("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("URL query string \"%s\" must not have replace block. "
+ "For dynamic query parameters use @Query.", queryParams);
}
}
this.relativeUrl = value;
this.relativeUrlParamNames = parsePathParameters(value);
}
这里的代码略多，我们用get来举例子，其余原理类似
parseHttpMethodAndPath("GET", ((GET) annotation).value(), false);
private void parseHttpMethodAndPath(String httpMethod, String value, boolean hasBody) {
···
···
···
this.relativeUrl = value;
this.relativeUrlParamNames = parsePathParameters(value);
}
/**
* Gets the set of unique path parameters used in the given URI. If a parameter is used twice
* in the URI, it will only show up once in the set.
*/
static Set<String> parsePathParameters(String path) {
Matcher m = PARAM_URL_REGEX.matcher(path);
Set<String> patterns = new LinkedHashSet<>();
while (m.find()) {
patterns.add(m.group(1));
}
return patterns;
}
官网例子
@GET("users/{user}/repos")
Call<List<Repo>> listRepos(@Path("user") String user);
最终会调到parsePathParameters，并且将所有{?}的参数名用正则表达式找出来，并且保存在ServiceMethod.relativeUrlParamNames中
我们继续看ServiceMethod.Builder.build()代码
int parameterCount = parameterAnnotationsArray.length;
parameterHandlers = new ParameterHandler<?>[parameterCount];
for (int p = 0; p < parameterCount; p++) {
Type parameterType = parameterTypes[p];
if (Utils.hasUnresolvableType(parameterType)) {
throw parameterError(p, "Parameter type must not include a type variable or wildcard: %s",
parameterType);
}
Annotation[] parameterAnnotations = parameterAnnotationsArray[p];
if (parameterAnnotations == null) {
throw parameterError(p, "No Retrofit annotation found.");
}
parameterHandlers[p] = parseParameter(p, parameterType, parameterAnnotations);
}
parameterAnnotationsArray是参数注解数组，参数有注解的最后都调用了parseParameter(),
private ParameterHandler<?> parseParameter(
int p, Type parameterType, Annotation[] annotations) {
ParameterHandler<?> result = null;
for (Annotation annotation : annotations) {
ParameterHandler<?> annotationAction = parseParameterAnnotation(
p, parameterType, annotations, annotation);
if (annotationAction == null) {
continue;
}
if (result != null) {
throw parameterError(p, "Multiple Retrofit annotations found, only one allowed.");
}
result = annotationAction;
}
if (result == null) {
throw parameterError(p, "No Retrofit annotation found.");
}
return result;
}
private ParameterHandler<?> parseParameterAnnotation(
int p, Type type, Annotation[] annotations, Annotation annotation) {
if (annotation instanceof Url) {
if (gotUrl) {
throw parameterError(p, "Multiple @Url method annotations found.");
}
if (gotPath) {
throw parameterError(p, "@Path parameters may not be used with @Url.");
}
if (gotQuery) {
throw parameterError(p, "A @Url parameter must not come after a @Query");
}
if (relativeUrl != null) {
throw parameterError(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();
} else {
throw parameterError(p,
"@Url must be okhttp3.HttpUrl, String, java.net.URI, or android.net.Uri type.");
}
} else if (annotation instanceof Path) {
if (gotQuery) {
throw parameterError(p, "A @Path parameter must not come after a @Query.");
}
if (gotUrl) {
throw parameterError(p, "@Path parameters may not be used with @Url.");
}
if (relativeUrl == null) {
throw parameterError(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<>(name, converter, path.encoded());
} else if (annotation instanceof Query) {
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(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) {
QueryName query = (QueryName) annotation;
boolean encoded = query.encoded();
Class<?> rawParameterType = Utils.getRawType(type);
gotQuery = true;
if (Iterable.class.isAssignableFrom(rawParameterType)) {
if (!(type instanceof ParameterizedType)) {
throw parameterError(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) {
Class<?> rawParameterType = Utils.getRawType(type);
if (!Map.class.isAssignableFrom(rawParameterType)) {
throw parameterError(p, "@QueryMap parameter type must be Map.");
}
Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
if (!(mapType instanceof ParameterizedType)) {
throw parameterError(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(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<>(valueConverter, ((QueryMap) annotation).encoded());
} else if (annotation instanceof Header) {
Header header = (Header) annotation;
String name = header.value();
Class<?> rawParameterType = Utils.getRawType(type);
if (Iterable.class.isAssignableFrom(rawParameterType)) {
if (!(type instanceof ParameterizedType)) {
throw parameterError(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) {
Class<?> rawParameterType = Utils.getRawType(type);
if (!Map.class.isAssignableFrom(rawParameterType)) {
throw parameterError(p, "@HeaderMap parameter type must be Map.");
}
Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
if (!(mapType instanceof ParameterizedType)) {
throw parameterError(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(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<>(valueConverter);
} else if (annotation instanceof Field) {
if (!isFormEncoded) {
throw parameterError(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(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) {
if (!isFormEncoded) {
throw parameterError(p, "@FieldMap parameters can only be used with form encoding.");
}
Class<?> rawParameterType = Utils.getRawType(type);
if (!Map.class.isAssignableFrom(rawParameterType)) {
throw parameterError(p, "@FieldMap parameter type must be Map.");
}
Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
if (!(mapType instanceof ParameterizedType)) {
throw parameterError(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(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<>(valueConverter, ((FieldMap) annotation).encoded());
} else if (annotation instanceof Part) {
if (!isMultipart) {
throw parameterError(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(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(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(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(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(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(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<>(headers, converter).iterable();
} else if (rawParameterType.isArray()) {
Class<?> arrayComponentType = boxIfPrimitive(rawParameterType.getComponentType());
if (MultipartBody.Part.class.isAssignableFrom(arrayComponentType)) {
throw parameterError(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<>(headers, converter).array();
} else if (MultipartBody.Part.class.isAssignableFrom(rawParameterType)) {
throw parameterError(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<>(headers, converter);
}
}
} else if (annotation instanceof PartMap) {
if (!isMultipart) {
throw parameterError(p, "@PartMap parameters can only be used with multipart encoding.");
}
gotPart = true;
Class<?> rawParameterType = Utils.getRawType(type);
if (!Map.class.isAssignableFrom(rawParameterType)) {
throw parameterError(p, "@PartMap parameter type must be Map.");
}
Type mapType = Utils.getSupertype(type, rawParameterType, Map.class);
if (!(mapType instanceof ParameterizedType)) {
throw parameterError(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(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(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<>(valueConverter, partMap.encoding());
} else if (annotation instanceof Body) {
if (isFormEncoded || isMultipart) {
throw parameterError(p,
"@Body parameters cannot be used with form or multi-part encoding.");
}
if (gotBody) {
throw parameterError(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(e, p, "Unable to create @Body converter for %s", type);
}
gotBody = true;
return new ParameterHandler.Body<>(converter);
}
return null; // Not a Retrofit annotation.
}
还是拿官网例子
@GET("users/{user}/repos")
Call<List<Repo>> listRepos(@Path("user") String user);
@Path("user") String user
parseParameterAnnotation()调用的时候，annotation isinstanceof Path
前面三个判断变量初始值为false，最终执行的是以下代码
gotPath = true;
Path path = (Path) annotation;
String name = path.value();
validatePathName(p, name);
Converter<?, String> converter = retrofit.stringConverter(type, annotations);
return new ParameterHandler.Path<>(name, converter, path.encoded());
我们来看下retrofit.stringConverter
public <T> Converter<T, String> stringConverter(Type type, Annotation[] annotations) {
checkNotNull(type, "type == null");
checkNotNull(annotations, "annotations == null");
for (int i = 0, count = converterFactories.size(); i < count; i++) {
Converter<?, String> converter =
converterFactories.get(i).stringConverter(type, annotations, this);
if (converter != null) {
//noinspection unchecked
return (Converter<T, String>) converter;
}
}
// Nothing matched. Resort to default converter which just calls toString().
//noinspection unchecked
return (Converter<T, String>) BuiltInConverters.ToStringConverter.INSTANCE;
}
这里我们可以看出，如果找不到stringConverter，则调用BuiltInConverters.ToStringConverter，
static final class ToStringConverter implements Converter<Object, String> {
static final ToStringConverter INSTANCE = new ToStringConverter();
@Override public String convert(Object value) {
return value.toString();
}
}
ToStringConverter的代码很简单就是讲Object 转换为String，从这里我们就明白了，
@GET("users/{user}/repos")
Call<List<Repo>> listRepos(@Path("user") String user);
的user是可以是任意类型的，只要重写它的tostring方法即可
ok，回归主线，parseParameterAnnotation()调用之后，将@Path解析成
new ParameterHandler.Path
static final class Path<T> extends ParameterHandler<T> {
private final String name;
private final Converter<T, String> valueConverter;
private final boolean encoded;
Path(String name, Converter<T, String> valueConverter, boolean encoded) {
this.name = checkNotNull(name, "name == null");
this.valueConverter = valueConverter;
this.encoded = encoded;
}
@Override void apply(RequestBuilder builder, @Nullable T value) throws IOException {
if (value == null) {
throw new IllegalArgumentException(
"Path parameter \"" + name + "\" value must not be null.");
}
builder.addPathParam(name, valueConverter.convert(value), encoded);
}
}
//RequestBuilder.java
void addPathParam(String name, String value, boolean encoded) {
if (relativeUrl == null) {
// The relative URL is cleared when the first query parameter is set.
throw new AssertionError();
}
relativeUrl = relativeUrl.replace("{" + name + "}", canonicalizeForPath(value, encoded));
}
最后，参数解析所有的信息都放入到了全局数据parameterHandlers中，每个parameterHandlers[i]都包含了各个参数的所有注解解析信息。
至此return 一个ServiceMethod
接下来我们回归InvocationHandler. invoke(),
OkHttpCall<Object> okHttpCall = new OkHttpCall<>(serviceMethod, args);
return serviceMethod.callAdapter.adapt(okHttpCall);
我们来看看，OkHttpCall的源码...O__O "…额okhttpCall就是Call的代理类，负责处理http请求，好像没什么好讲，我就不讲了，本文到此结束
