目标是能够等待 dart 代码在 javascript 上下文中处理并接收其输出，但我无法做到。我无法等待 dart:js (code1)。我可以等待我们……
目标是能够等待 dart 代码在 javascript 上下文中处理并接收其输出，但我无法做到这一点。
我无法使用 dart:js (code1) 等待。我可以使用 flutter_js(code2) 等待。flutter_js 的问题在于它不适用于 flutter web。
是否可以使用 dart:js 或其他适用于 flutter web 的软件包来等待？
我发现这个堆栈溢出是类似的::
如何在 Flutter 中异步调用 JavaScript？
如何在 Flutter Web 中从异步 JS 函数获取回调或返回值到 Dart？
https://github.com/dart-lang/sdk/issues/50530
第二和第三个链接正是我在寻找的，但我不明白答案是什么。
非常感谢任何帮助/
代码1::
import 'package:flutter/material.dart';
import 'dart:js' as js;
import 'package:flutter/material.dart';
class JsCompilerUtil {
Future<bool?> process_client_script({
required String script,
required Map<String, dynamic> current,
}) async {
js.JsObject jsObject = js.JsObject.jsify(current);
js.context['c'] = jsObject;
// js.context['c'] = current;
var result = js.context.callMethod("eval", [script]);
return result;
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key});
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
JsCompilerUtil jsCompilerUtil = JsCompilerUtil();
@override
void initState() {
// TODO: implement initState
super.initState();
*initialize*data();
}
Future<void> *initialize*data() async {
String script = """
console.log("Hi from js, this is the inputed name: "+c.name);
var res = c.dummyWait();
console.log("res:")
""";
Map<String, dynamic> current = {
"name": "Juan",
"dummyWait": dummyWait
};
final res = await jsCompilerUtil.process_client_script(script: script, current: current);
}
@override
Widget build(BuildContext context) {
return SizedBox();
}
Future<String> dummyWait() async {
print("dummyWait()\n");
await Future.delayed(const Duration(seconds: 1));
return 'MESSAGE FROM DART';
}
}
代码1的输出::
Restarted application in 28ms.
The debugEmulateFlutterTesterEnvironment getter is deprecated and will be removed in a future release. Please use `debugEmulateFlutterTesterEnvironment` from `dart:ui_web` instead.
Hi from js, this is the inputed name: Juan
dummyWait()
res:
代码2：
import 'package:flutter/material.dart';
import 'package:flutter_js/flutter_js.dart';
import 'dart:convert';
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key});
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
late JavascriptRuntime flutterJs;
@override
void initState() {
super.initState();
flutterJs = getJavascriptRuntime();
_setupJavaScriptBridge();
}
void _setupJavaScriptBridge() {
flutterJs.onMessage('dummyAwait', (args) async {
String result = await dummyAwaitFunction();
return result;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('JavaScript in Dart'),
),
body: Center(
child: ElevatedButton(
onPressed: _logic,
child: Text('Run JavaScript'),
),
),
);
}
Future<void> _logic() async {
String result = await runJavaScript();
print("JavaScript result: $result");
}
Future<String> runJavaScript() async {
// Dart map
final current = {"name": "juan"};
// Convert Dart map to JSON string
String jsonString = jsonEncode(current);
// JavaScript script to parse JSON string, call Dart function, and print result
String script = '''
var current = JSON.parse('$jsonString');
async function waitForDart() {
var res = await sendMessage('dummyAwait');
console.log("INSDE OF JS: " + res);
return res;
}
waitForDart();
''';
// Evaluate JavaScript script
JsEvalResult jsResult = await flutterJs.evaluateAsync(script);
return jsResult.stringResult;
}
Future<String> dummyAwaitFunction() async {
await Future.delayed(const Duration(seconds: 1));
return 'MESSAGE FROM DART';
}
}
我正在尝试创建一个 zip 文件，并通过分段上传路由将该 zip 文件上传到 AWS S3。但是，我遇到了一个问题，即文件成功生成，但内容
我正在尝试创建一个 zip 文件并通过分段上传路由将该 zip 文件上传到 AWS S3。但是，我遇到一个问题，即文件成功生成，但文件内的内容被损坏。
这是我尝试取消存档文件时遇到的错误：
Archive: test2MB.zip
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
unzip: cannot find zipfile directory in one of test2MB.zip or
test2MB.zip.zip, and cannot find test2MB.zip.ZIP, period.
以下是我为此编写的代码片段
private Single<List<CompletedPart>> zipAndUploadZipParts(String uploadId) {
List<Single<CompletedPart>> uploadPartObservables = new ArrayList<>();
final int[] partNumber = {Constants.START_PART_NUMBER};
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ZipOutputStream zipOutputStream = new ZipOutputStream(byteArrayOutputStream);
return zipMetadata(zipOutputStream)
.andThen(uploadZipPart(byteArrayOutputStream, uploadPartObservables, partNumber, uploadId)
.onErrorResumeNext(error -> {
this.contextRx.log().error(String.format("placeholder", partNumber[0], this.logIdentifier, error.getMessage()), error);
return Completable.error(new RuntimeException("Placeholder"));
}))
.andThen(finalizeZipUpload(uploadPartObservables, zipOutputStream, byteArrayOutputStream));
}
private Completable zipMetadata(ZipOutputStream zipOutputStream) {
return Completable.create(emitter -> {
try {
ZipEntry metadataEntry = new ZipEntry(Constants.METADATA_FILE_NAME);
zipOutputStream.putNextEntry(metadataEntry);
zipOutputStream.write(this.catalogObjectsMetadata.getBytes());
zipOutputStream.closeEntry();
emitter.onComplete();
} catch (IOException exception) {
this.contextRx.log().error(String.format(Constants.LOG_ERROR_ZIPPING_METADATA, this.logIdentifier, exception.getMessage()), exception);
emitter.onError(new RuntimeException(String.format(Constants.ERROR_ZIPPING_METADATA)));
}
});
}
private Completable uploadZipPart(ByteArrayOutputStream byteArrayOutputStream, List<Single<CompletedPart>> uploadPartObservables, int[] partNumber, String uploadId) {
return Completable.create(emitter -> {
try {
byte[] zipData = byteArrayOutputStream.toByteArray();
uploadPartObservables.add(uploadPart(zipData, partNumber[0]++, uploadId));
byteArrayOutputStream.reset();
this.contextRx.log().info(String.format("Uploaded part %d for uploadId %s", partNumber[0] - 1, uploadId));
emitter.onComplete();
} catch (Exception exception) {
emitter.onError(exception);
}
});
}
private Single<List<CompletedPart>> finalizeZipUpload(List<Single<CompletedPart>> uploadPartObservables, ZipOutputStream zipOutputStream, ByteArrayOutputStream byteArrayOutputStream) {
return Single.defer(() -> {
try {
zipOutputStream.finish();
} catch (IOException e) {
return Single.error(new RuntimeException("Error finishing zip output stream", e));
} finally {
try {
zipOutputStream.close();
} catch (IOException e) {
return Single.error(new RuntimeException("Error closing zip output stream", e));
}
try {
byteArrayOutputStream.close();
} catch (IOException e) {
return Single.error(new RuntimeException("Error closing byte array output stream", e));
}
}
return Single.merge(uploadPartObservables)
.toList()
.doOnSuccess(parts -> this.contextRx.log().info(String.format(Constants.ALL_PARTS_UPLOADED, this.logIdentifier, parts)))
.onErrorReturnItem(new ArrayList<>());
});
}
有人可以指导一下我的代码出了什么问题，导致我的 zip 文件损坏吗？
压缩文件中的内容不应该被损坏。