Retrofit 是一個用於 Android 和 Java 平臺的類型安全的網絡請求框架，項目的網絡模塊是使用Retrofit框架封裝的；html
開發過程當中，使用了第三方的sdk，要將第三方輸出的數據上傳給服務端，可是sdk輸出的+通過Url encode傳輸給服務端，服務端url decode以後就成了空格。。。java
在線對輸出的數據進行url 編解碼沒有問題，最終編解碼結果都是和原始數據相同，因此開始排查Retrofit底層對url encode的實現git
背景
代碼中使用Retrofit框架封裝的網絡請求以下：github
@FormUrlEncoded
@POST("user/upload")
Observable<Response<Boolean>> upload(@Field(value = "data", encoded = true) String data);
原覺得encoded=true表示要進行url encode，本着逐個排除法先encoded設置爲false，這下應該就不進行url encode了嘛，結果發現改爲false以後，服務端返回成功了，什麼？將網絡請求打印發現，url的body仍然進行編碼了，這是爲何呢安全
而後將encoded=true，encoded=false狀況下的數據打印出來，發現除了+的編碼不一樣，其餘均相同，網絡搜索沒有找到緣由，只能一步步去查看Retrofit源碼了網絡
//原始數據 /gAAAAAAAAD+AAAAAAAAAP4AAAAAAAAA //encoded = true %2FgAAAAAAAAD+AAAAAAAAAP4AAAAAAAAA //encoded = false %2FgAAAAAAAAD%2BAAAAAAAAAP4AAAAAAAAA
根據源碼調查緣由
Retrofit，註解FormUrlEncoded將網絡請求自動設置成application/x-www-form-urlencoded，對註解的Field數據進行Url 編碼app
/**
* Denotes that the request body will use form URL encoding. Fields should be declared as
* parameters and annotated with {@link Field @Field}.
* <p>
* Requests made with this annotation will have {@code application/x-www-form-urlencoded} MIME
* type. Field names and values will be UTF-8 encoded before being URI-encoded in accordance to
* <a href="http://tools.ietf.org/html/rfc3986">RFC-3986</a>.
*/
@Documented
@Target(METHOD)
@Retention(RUNTIME)
public @interface FormUrlEncoded {
}
好了這裏沒有疑問，使用這個註解就已經自動會對Field註解的form數據進行Url編碼了，那爲何還會有encoded參數呢？框架
@Documented
@Target(PARAMETER)
@Retention(RUNTIME)
public @interface Field {
String value();
/** Specifies whether the {@linkplain #value() name} and value are already URL encoded. */
boolean encoded() default false;
}
根據Field的註解說明，encoded參數表示是value是否已經Url編碼過了，那這個就好理解了，encoded=true表示value數據已經進行過Url 編碼了，那爲何打印出來的數據中除了加號其餘數據仍是進行Url編碼了呢？ui
只能接下來繼續看了this
RequestFactory對註解進行解析
//對註解FormUrlEncoded的解析，使用使用POST，PUT，PATCH的http方法中（hasBody=true）
if (annotation instanceof FormUrlEncoded) {
if (isMultipart) {
throw methodError(method, "Only one encoding annotation is allowed.");
}
isFormEncoded = true;
}
//對註解Field的解析
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();
}
//若是使用了FormUrlEncoded註解而未用（Field註解或FieldMap註解），就會報錯
if (isFormEncoded && !gotField) {
throw methodError(method, "Form-encoded method must contain at least one @Field.");
}
RequestFactory中會建立RequestBuilder，下面就查看RequestBuilder對Url編碼相關的處理了
構造方法裏若是isFormEncoded=true就會建立okhttp3.FormBody實例
if (isFormEncoded) {
// Will be set to 'body' in 'build'.
formBuilder = new FormBody.Builder();
} else if (isMultipart) {
// Will be set to 'body' in 'build'.
multipartBuilder = new MultipartBody.Builder();
multipartBuilder.setType(MultipartBody.FORM);
}
//若是encoded=true就會調進formBuilder實例的addEncoded方法中
void addFormField(String name, String value, boolean encoded) {
if (encoded) {
formBuilder.addEncoded(name, value);
} else {
formBuilder.add(name, value);
}
}
接下來就走進okttp的源碼裏了，最終的URL編碼是由okhttp源碼實現
FormBody的對應接口實現
//encoded=false會走進此方法中url編碼
fun add(name: String, value: String) = apply {
names += name.canonicalize(
encodeSet = FORM_ENCODE_SET,
plusIsSpace = true,
charset = charset
)
values += value.canonicalize(
encodeSet = FORM_ENCODE_SET,
plusIsSpace = true,
charset = charset
)
}
//encoded=true會走進此方法中進行url編碼
fun addEncoded(name: String, value: String) = apply {
names += name.canonicalize(
encodeSet = FORM_ENCODE_SET,
alreadyEncoded = true,
plusIsSpace = true,
charset = charset
)
values += value.canonicalize(
encodeSet = FORM_ENCODE_SET,
alreadyEncoded = true,
plusIsSpace = true,
charset = charset
)
}
//在HttpUrl類中
/**
* Returns a substring of `input` on the range `[pos..limit)` with the following
* transformations:
*
* * Tabs, newlines, form feeds and carriage returns are skipped.
*
* * In queries, ' ' is encoded to '+' and '+' is encoded to "%2B".
*
* * Characters in `encodeSet` are percent-encoded.
*
* * Control characters and non-ASCII characters are percent-encoded.
*
* * All other characters are copied without transformation.
*
* @param alreadyEncoded true to leave '%' as-is; false to convert it to '%25'.
* @param strict true to encode '%' if it is not the prefix of a valid percent encoding.
* @param plusIsSpace true to encode '+' as "%2B" if it is not already encoded.
* @param unicodeAllowed true to leave non-ASCII codepoint unencoded.
* @param charset which charset to use, null equals UTF-8.
*/
internal fun String.canonicalize(
pos: Int = 0,
limit: Int = length,
encodeSet: String,
alreadyEncoded: Boolean = false,
strict: Boolean = false,
plusIsSpace: Boolean = false,
unicodeAllowed: Boolean = false,
charset: Charset? = null
): String {
var codePoint: Int
var i = pos
while (i < limit) {
codePoint = codePointAt(i)
if (codePoint < 0x20 ||
codePoint == 0x7f ||
codePoint >= 0x80 && !unicodeAllowed ||
codePoint.toChar() in encodeSet ||
codePoint == '%'.toInt() &&
(!alreadyEncoded || strict && !isPercentEncoded(i, limit)) ||
codePoint == '+'.toInt() && plusIsSpace) {
// Slow path: the character at i requires encoding!
val out = Buffer()
out.writeUtf8(this, pos, i)
out.writeCanonicalized(
input = this,
pos = i,
limit = limit,
encodeSet = encodeSet,
alreadyEncoded = alreadyEncoded,
strict = strict,
plusIsSpace = plusIsSpace,
unicodeAllowed = unicodeAllowed,
charset = charset
)
return out.readUtf8()
}
i += Character.charCount(codePoint)
}
// Fast path: no characters in [pos..limit) required encoding.
return substring(pos, limit)
}
private fun Buffer.writeCanonicalized(
input: String,
pos: Int,
limit: Int,
encodeSet: String,
alreadyEncoded: Boolean,
strict: Boolean,
plusIsSpace: Boolean,
unicodeAllowed: Boolean,
charset: Charset?
) {
var encodedCharBuffer: Buffer? = null // Lazily allocated.
var codePoint: Int
var i = pos
while (i < limit) {
codePoint = input.codePointAt(i)
if (alreadyEncoded && (codePoint == '\t'.toInt() || codePoint == '\n'.toInt() ||
codePoint == '\u000c'.toInt() || codePoint == '\r'.toInt())) {
// Skip this character.
} else if (codePoint == '+'.toInt() && plusIsSpace) {
// Encode '+' as '%2B' since we permit ' ' to be encoded as either '+' or '%20'.
writeUtf8(if (alreadyEncoded) "+" else "%2B")
} else if (codePoint < 0x20 ||
codePoint == 0x7f ||
codePoint >= 0x80 && !unicodeAllowed ||
codePoint.toChar() in encodeSet ||
codePoint == '%'.toInt() &&
(!alreadyEncoded || strict && !input.isPercentEncoded(i, limit))) {
// Percent encode this character.
if (encodedCharBuffer == null) {
encodedCharBuffer = Buffer()
}
if (charset == null || charset == UTF_8) {
encodedCharBuffer.writeUtf8CodePoint(codePoint)
} else {
encodedCharBuffer.writeString(input, i, i + Character.charCount(codePoint), charset)
}
while (!encodedCharBuffer.exhausted()) {
val b = encodedCharBuffer.readByte().toInt() and 0xff
writeByte('%'.toInt())
writeByte(HEX_DIGITS[b shr 4 and 0xf].toInt())
writeByte(HEX_DIGITS[b and 0xf].toInt())
}
} else {
// This character doesn't need encoding. Just copy it over.
writeUtf8CodePoint(codePoint)
}
i += Character.charCount(codePoint)
}
結論
好了，由上面代碼可發現alreadyEncoded=true時，+並不會被編碼，因此緣由到這裏就找到了錯誤，客戶端的+號數據由於將encoded=true沒有被編碼，在服務端進行url 解碼後加號對應成空格，這也就是爲何服務端解析失敗了
if (codePoint == '+'.toInt() && plusIsSpace) {
// Encode '+' as '%2B' since we permit ' ' to be encoded as either '+' or '%20'.
writeUtf8(if (alreadyEncoded) "+" else "%2B")
}
默認encoded爲false，由okhttp底層進行url 編碼，但若是你想要本身對數據進行url編碼，將encoded設置爲true，不然不須要設置此參數，以下：
@FormUrlEncoded
@POST("user/upload")
Observable<Response<Boolean>> upload(@Field(value = "data") String data);
Retrofit和okhttp的源碼地址
