最近发现retrofit2的Call的enqueue 方法竟然出现了耗时操作，这究竟是为何呢？下面是一个百度人脸识别接口
/**
* 百度M:N人脸识别
*/
@POST
@FormUrlEncoded
Call<BaiduMultiSearchFaceResp> searchMultiFacesByBaiDu(@Url String url,
@Field("image") String image,
@Field("image_type") String imageType,
@Field("group_id_list") String groupIdList,
@Field("liveness_control") String livenessControl,
@Field("max_face_num") Integer maxFaceNum,
@Field("max_user_num") String maxUserNum,
@Field("match_threshold") String matchThreshold);
OkHttpCall 作为的Call的实现之一,而enqueue方法最关键地方在于调用了createRawCall()创建了RealCall对象，看看是否createRawCall耗时了。
private okhttp3.Call createRawCall() throws IOException {
okhttp3.Call call = serviceMethod.toCall(args);
if (call == null) {
throw new NullPointerException("Call.Factory returned null.");
}
return call;
}
接着是toCall() ,很明显这是在构建请求参数啊
/** Builds an HTTP request from method arguments. */
okhttp3.Call toCall(@Nullable Object... args) throws IOException {
RequestBuilder requestBuilder = new RequestBuilder(httpMethod, baseUrl, relativeUrl, headers,
contentType, hasBody, isFormEncoded, isMultipart);
@SuppressWarnings("unchecked") // It is an error to invoke a method with the wrong arg types.
ParameterHandler<Object>[] handlers = (ParameterHandler<Object>[]) parameterHandlers;
int argumentCount = args != null ? args.length : 0;
if (argumentCount != handlers.length) {
throw new IllegalArgumentException("Argument count (" + argumentCount
+ ") doesn't match expected count (" + handlers.length + ")");
}
for (int p = 0; p < argumentCount; p++) {
handlers[p].apply(requestBuilder, args[p]);
}
return callFactory.newCall(requestBuilder.build());
}
handlers[p].apply(requestBuilder, args[p]); 这是在处理请求参数，继续看看它的实现,apply 是 ParameterHandler 是一个抽象方法,像 Body、Field、Query等都实现了。而我的接口使用Field 所以查看Field apply的实现
@Override void apply(RequestBuilder builder, @Nullable T value) throws IOException {
if (value == null) return; // Skip null values.
String fieldValue = valueConverter.convert(value);
if (fieldValue == null) return; // Skip null converted values
builder.addFormField(name, fieldValue, encoded);
}
}
看来问题出在 addFormField 上了
void addFormField(String name, String value, boolean encoded) {
if (encoded) {
formBuilder.addEncoded(name, value);
} else {
formBuilder.add(name, value);
}
}
add 作了什么神奇的操作
public Builder add(String name, String value) {
if (name == null) throw new NullPointerException("name == null");
if (value == null) throw new NullPointerException("value == null");
names.add(HttpUrl.canonicalize(name, FORM_ENCODE_SET, false, false, true, true, charset));
values.add(HttpUrl.canonicalize(value, FORM_ENCODE_SET, false, false, true, true, charset));
return this;
}
public Builder addEncoded(String name, String value) {
if (name == null) throw new NullPointerException("name == null");
if (value == null) throw new NullPointerException("value == null");
names.add(HttpUrl.canonicalize(name, FORM_ENCODE_SET, true, false, true, true, charset));
values.add(HttpUrl.canonicalize(value, FORM_ENCODE_SET, true, false, true, true, charset));
return this;
}
add 一个对象到list 不该耗时啊，再看看HttpUrl.canonicalize
static String canonicalize(String input, int pos, int limit, String encodeSet,
boolean alreadyEncoded, boolean strict, boolean plusIsSpace, boolean asciiOnly,
Charset charset) {
int codePoint;
for (int i = pos; i < limit; i += Character.charCount(codePoint)) {
codePoint = input.codePointAt(i);
if (codePoint < 0x20
|| codePoint == 0x7f
|| codePoint >= 0x80 && asciiOnly
|| encodeSet.indexOf(codePoint) != -1
|| codePoint == '%' && (!alreadyEncoded || strict && !percentEncoded(input, i, limit))
|| codePoint == '+' && plusIsSpace) {
// Slow path: the character at i requires encoding!
Buffer out = new Buffer();
out.writeUtf8(input, pos, i);
canonicalize(out, input, i, limit, encodeSet, alreadyEncoded, strict, plusIsSpace,
asciiOnly, charset);
return out.readUtf8();
}
}
// Fast path: no characters in [pos..limit) required encoding.
return input.substring(pos, limit);
}
static void canonicalize(Buffer out, String input, int pos, int limit, String encodeSet,
boolean alreadyEncoded, boolean strict, boolean plusIsSpace, boolean asciiOnly,
Charset charset) {
Buffer encodedCharBuffer = null; // Lazily allocated.
int codePoint;
for (int i = pos; i < limit; i += Character.charCount(codePoint)) {
codePoint = input.codePointAt(i);
if (alreadyEncoded
&& (codePoint == '\t' || codePoint == '\n' || codePoint == '\f' || codePoint == '\r')) {
// Skip this character.
} else if (codePoint == '+' && plusIsSpace) {
// Encode '+' as '%2B' since we permit ' ' to be encoded as either '+' or '%20'.
out.writeUtf8(alreadyEncoded ? "+" : "%2B");
} else if (codePoint < 0x20
|| codePoint == 0x7f
|| codePoint >= 0x80 && asciiOnly
|| encodeSet.indexOf(codePoint) != -1
|| codePoint == '%' && (!alreadyEncoded || strict && !percentEncoded(input, i, limit))) {
// Percent encode this character.
if (encodedCharBuffer == null) {
encodedCharBuffer = new Buffer();
}
if (charset == null || charset.equals(Util.UTF_8)) {
encodedCharBuffer.writeUtf8CodePoint(codePoint);
} else {
encodedCharBuffer.writeString(input, i, i + Character.charCount(codePoint), charset);
}
while (!encodedCharBuffer.exhausted()) {
int b = encodedCharBuffer.readByte() & 0xff;
out.writeByte('%');
out.writeByte(HEX_DIGITS[(b >> 4) & 0xf]);
out.writeByte(HEX_DIGITS[b & 0xf]);
}
} else {
// This character doesn't need encoding. Just copy it over.
out.writeUtf8CodePoint(codePoint);
}
}
}
事情就很明显了！？？？
Call<BaiduMultiSearchFaceResp> call = getServer().searchMultiFacesByBaiDu(BaiduFaceApiHelper.getApiFaceMultiSearch(),
imageParam, Constants.BaiDuSupportImageType.BASE64, schoolId, "NONE", CameraPreviewLayout.MAX_FACE_NUM,
"1", "80");
没错，当请求参数是一个很大的字符串时（BASE64编码），canonicalize 就会卡主线程了。
问题关键找到了，问题也很好解决了。