Retrofit.png
ServiceMethod是retrofit的核心之一。它的作用是将请求接口方法中的请求参数、请求方式等等，封装成java对象以供请求使用，所以它的重要性不言而喻。
final class ServiceMethod {
// Upper and lower characters, digits, underscores, and hyphens, starting with a character.
1 static final String PARAM = "[a-zA-Z][a-zA-Z0-9_-]*";
static final Pattern PARAM_URL_REGEX = Pattern.compile("\\{(" + PARAM + ")\\}");
static final Pattern PARAM_NAME_REGEX = Pattern.compile(PARAM);
final okhttp3.Call.Factory callFactory;
final CallAdapter callAdapter;
private final HttpUrl baseUrl;
private final Converter responseConverter;
private final String httpMethod;
private final String relativeUrl;
private final Headers headers;
private final MediaType contentType;
private final boolean hasBody;
private final boolean isFormEncoded;
private final boolean isMultipart;
2 private final ParameterHandler[] parameterHandlers;
public ServiceMethod build() {
3 callAdapter = createCallAdapter();
4 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?");
}
5 responseConverter = createResponseConverter();
6 for (Annotation annotation : methodAnnotations) {
parseMethodAnnotation(annotation);
}
'判断请求方法注解是否添加'
...
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.");
}
7 parameterHandlers[p] = parseParameter(p, parameterType, parameterAnnotations);
}
'判断url、请求体等是否添加'
...
return new ServiceMethod<>(this);
}
通过标记1到2之间的成员变量可以看出，
ServiceMethod就是请求接口方法的一个包装类，它将请求方法转换成了一个java对象。
methodAnnotations：请求的注解
parameterTypes：参数类型
parameterAnnotationsArray：参数的具体内容
...3:
private CallAdapter createCallAdapter() {
Type returnType = method.getGenericReturnType();
if (Utils.hasUnresolvableType(returnType)) {
throw methodError(
"Method return type must not include a type variable or wildcard: %s", returnType);
}
if (returnType == void.class) {
throw methodError("Service methods cannot return void.");
}
Annotation[] annotations = method.getAnnotations();
try {
//noinspection unchecked
return (CallAdapter) 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);
}
}
通过返回类型和注解获取到对应的网络适配器,下面这段代码是此结论的具体实现：
(CallAdapterRetrofit中的nextCallAdapter方法
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;
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;
}
}
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(adapterFactories.get(i).getClass().getName());
}
builder.append('\n');
}
builder.append(" Tried:");
for (int i = start, count = adapterFactories.size(); i < count; i++) {
builder.append("\n * ").append(adapterFactories.get(i).getClass().getName());
}
throw new IllegalArgumentException(builder.toString());
}
从1中看到从Retrofit中adapterFactories中取出我们设置的适配器并返回
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
创建retrofit时设置的rxjava适配器。上面createCallAdapter返回就是这个。
- 5.createResponseConverter与createCallAdapter实现基本类似，不设置默认返回的是gson转换器
- 6.遍历方法的注解，设置请求类型、请求头、请求格式等：
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;
}
}
- 7.解析方法参数