使用Retrofit2将文件上传到AWS S3预签名URL [英] Upload a file to AWS S3 pre-signed URL using Retrofit2

问题描述

我正在尝试使用预先签名的URL将文件上传到Amazon的S3.我从服务器生成了URL，该服务器生成了URL&将其作为JSON对象的一部分发送给我.我将URL作为字符串获取，如下所示:

I'm trying to upload a file to Amazon's S3 using a pre-signed URL. I get the URL from a server which generates the URL & sends it to me as part of a JSON object. I get the URL as a String, something like this:

不幸的是，当我将其传递给Retrofit2时，它修改了String并试图将其制成URL.我已经设置了encoding=true，它可以解决大多数问题，但不能完全解决.我知道字符串按原样工作.我已经在Postman&中尝试过得到成功的回应.

Unfortunately, when I pass this to Retrofit2, it modifies the String attempting to make it into a URL. I've set encoding=true which took care of most of the problem but not completely. I know the String works as it is. I've tried it in Postman & get a successful response.

首先，我尝试将整个字符串(除了我作为baseUrl剪切掉的字符串外)整体放入路径

1st I tried just putting the String (except for what I cut out as baseUrl) as a whole into the Path

public interface UpdateImageInterface {
    @PUT("{url}")
    Call<Void> updateImage(@Path(value="url", encoded=true) String url, Body RequestBody image);
}

呼叫代码:

    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://com-example-mysite.s3-us-east-1.amazonaws.com/userFolder/")
            .build();

    UpdateImageInterface imageInterface = retrofit.create(UpdateImageInterface.class);
    // imageUrl is "ImageName..."
    Call<Void> call = imageInterface.updateImage(imageUrl, requestFile);

除?"外，此方法大部分有效(在"ImageName"之后)转换为％3F".这会导致请求失败/400.

This works mostly except the the '?' (after "ImageName") get converted to "%3F". This causes a Bad Request / 400.

我的下一个尝试是使用Retrofit2创建查询，然后将整个String(带有多个查询)转储到查询中.

My next attempt was to create a query with Retrofit2 but then dump the whole String (with multiple queries) into the query.

public interface UpdateImageInterface {
    @PUT("ImageName")
    Call<Void> updateProfilePhoto(@Query(value="X-Amz-Security-Token", encoded = true) String token, @Body RequestBody image);
}

呼叫代码:

    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl("https://com-example-mysite.s3-us-east-1.amazonaws.com/userFolder/")
            .build();

    UpdateImageInterface imageInterface = retrofit.create(UpdateImageInterface.class);
    // imageUrl is "xxfooxx..."
    Call<Void> call = imageInterface.updateImage(imageUrl, requestFile);

得到?"正确呈现，但所有的'&'更改为％26"

This gets the '?' rendered correctly but all of the '&' get changed to "%26"

最后，我尝试在baseUrl()中传递整个String，但是由于结尾处没有'/'而给出了IllegalArgumentException.

Lastly I tried passing the whole String in baseUrl() but that gives an IllegalArgumentException for not having '/' on the end.

我知道我可以解析预签名的URL来进行多个查询&在应进行查询的情况下，将它们组装在Retrofit2中，但我想避免这种处理.

I know that I could parse the pre-signed URL to make multiple queries & assemble them in Retrofit2 as queries should be done but I'd like to avoid that processing.

要重述该问题:

是否有一种方法可以使用Retrofit2轻松地(无需进行大量的字符串分析)将带有预签名URL的文件上传到S3?

Is there a way to easily (without heavy String parsing) upload a file to S3 with a pre-signed URL using Retrofit2?

推荐答案

在同事的帮助下，这是解决方案.

With help from a colleague, this is the solution.

public interface UpdateImageInterface {
    @PUT
    Call<Void> updateImage(@Url String url, @Body RequestBody image);
}

呼叫代码:

    String CONTENT_IMAGE = "image/jpeg";

    File file = new File(localPhotoPath);    // create new file on device
    RequestBody requestFile = RequestBody.create(MediaType.parse(CONTENT_IMAGE), file);

    /* since the pre-signed URL from S3 contains a host, this dummy URL will
     * be replaced completely by the pre-signed URL.  (I'm using baseURl(String) here
     * but see baseUrl(okhttp3.HttpUrl) in Javadoc for how base URLs are handled
     */
    Retrofit retrofit = new Retrofit.Builder()
        .baseUrl("http://www.dummy.com/")
        .build();

    UpdateImageInterface imageInterface = retrofit.create(UpdateImageInterface.class);
    // imageUrl is the String as received from AWS S3
    Call<Void> call = imageInterface.updateImage(imageUrl, requestFile);

Javadoc 获取有关@Url(类网址)的信息& baseUrl()(Retrofit.Builder类)

Javadoc for info on @Url (class Url) & baseUrl() (class Retrofit.Builder)

MediaType是 OkHttp 库中的类，通常与Retrofit(两者都来自正方形).可以在Javadoc中找到有关传递给parse方法的常量的信息.

MediaType is a class in the OkHttp library that is often used with Retrofit (both from Square). Info about constants passed to the parse method can be found in the Javadoc.

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