Flutter 如何从dart流中的回调函数中生成值
我在颤振应用程序中定义了以下流:Flutter 如何从dart流中的回调函数中生成值,flutter,dart,Flutter,Dart,我在颤振应用程序中定义了以下流: static Stream<String> downloadIdentifiers() async* { try { yield "test"; final directory = await getApplicationDocumentsDirectory(); Response response; Dio dio = new Dio(); response = await
static Stream<String> downloadIdentifiers() async* {
try {
yield "test";
final directory = await getApplicationDocumentsDirectory();
Response response;
Dio dio = new Dio();
response = await dio.download(
MyConstants.identifiersUrl,
join(directory.path, "identifiers.json"),
onReceiveProgress: (int received, int total) {
print("$received / $total");
},
);
yield join(directory.path, "identifiers.json");
} catch (ex) {
throw ex;
}
}
静态流下载标识符()异步*{
试一试{
产量“测试”;
最终目录=等待getApplicationDocumentsDirectory();
反应;
Dio Dio=新的Dio();
response=等待dio.download(
MyConstants.IdentifierURL,
join(directory.path,“identifiers.json”),
onReceiveProgress:(收到整数,总计整数){
打印(“$received/$total”);
},
);
产生连接(directory.path,“identifiers.json”);
}捕获(ex){
掷骰子;
}
}
我正在使用下载
我想将下载进度的信息输出到我的流中,但是onReceiveProgress
上的回调函数只接受一个常规函数作为回调函数
如何获取流中要产生的接收/总字节的信息
谢谢大家! 谢谢你的回答。
在他的帮助下,我终于做到了:
static Stream<String> downloadIdentifiers() async* {
StreamController<String> streamController = new StreamController();
try {
final directory = await getApplicationDocumentsDirectory();
Dio dio = new Dio();
dio.download(
MyConstants.identifiersUrl,
join(directory.path, "identifiers.json"),
onReceiveProgress: (int received, int total) {
streamController.add("$received / $total");
print("$received / $total");
},
).then((Response response) {
streamController.add("Download finished");
})
.catchError((ex){
streamController.add(ex.toString());
})
.whenComplete((){
streamController.close();
});
yield* streamController.stream;
} catch (ex) {
throw ex;
}
}
静态流下载标识符()异步*{
StreamController StreamController=新的StreamController();
试一试{
最终目录=等待getApplicationDocumentsDirectory();
Dio Dio=新的Dio();
下载(
MyConstants.IdentifierURL,
join(directory.path,“identifiers.json”),
onReceiveProgress:(收到整数,总计整数){
streamController.add(“$received/$total”);
打印(“$received/$total”);
},
).然后((响应){
streamController.add(“下载完成”);
})
.catchError((例如){
streamController.add(例如toString());
})
.完成时(){
streamController.close();
});
产量*streamController.stream;
}捕获(ex){
掷骰子;
}
}
您可以使用,并直接向其中添加元素。