如何在Dart中下载图片并将其正确转换为base64? [英] How to download picture and convert to base64 correctly in Dart?
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问题描述
我正在努力下载图片,然后将其显示在页面上。打印的base64编码的字符串看起来有误;它与例如 http://www.freeformatter.com/base64-encoder.html 结果。
I'm in struggle with downloading a picture and then showing it on a page. Printed base64-encoded string looks wrong; it's not identical with e.g. http://www.freeformatter.com/base64-encoder.html result.
这是我的代码:
HttpRequest.request(_url).then((HttpRequest response) {
String contentType = response.getResponseHeader('Content-Type');
if (_supportedContentType(contentType)) {
List bytes = new Utf8Encoder().convert(response.responseText);
String header = 'data:$contentType;base64,';
String base64 = CryptoUtils.bytesToBase64(bytes);
String image = "${header}${base64}";
me.avatar = image;
print(image);
}
}
推荐答案
设置响应类型时,您将获得二进制数据
When you set the responseType you get binary data
import 'dart:html' show HttpRequest;
import 'dart:convert' show base64;
import 'dart:typed_data' show Uint8List, ByteBuffer;
main() {
HttpRequest
.request("Zacharie_Noterman_-_Monkey_business.jpg",
responseType: "arraybuffer")
.then((HttpRequest response) {
String contentType = response.getResponseHeader('Content-Type');
var list = new Uint8List.view((response.response as ByteBuffer));
String header = 'data:$contentType;base64,';
String base64 = base64.encode(list);
String image = "${header}${base64}";
// me.avatar = image;
print(image);
//}
});
}
结果:
data:image / png; base64,/ 9j / 4AAQSkZJRgABAQEAYABgAAD ....
data:image/png;base64,/9j/4AAQSkZJRgABAQEAYABgAAD....
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