英文:
How to serialize Go structures using protocol buffers and use them in Dart over Ajax
问题
如果您在我的服务器上有大量的键入数据存储在SQL数据库中，您想要如何使用Protocol Buffers将这些数据发送到Dart客户端？
英文:
If you have a large amount of typed data in an sql database on my server, how do you send this data to a dart client using protocol buffers?
答案1
得分: 13
首先，在计算机上安装 protoc，使用以下命令：
sudo apt-get install protobuf-compiler
然后从 https://code.google.com/p/goprotobuf/ 安装 Go Protocol Buffer 库。Dart 版本可以在这里找到：https://github.com/dart-lang/dart-protoc-plugin。
下一步是编写一个包含要发送的消息定义的 .proto 文件。可以在这里找到示例：https://developers.google.com/protocol-buffers/docs/proto。
例如：
message Car {
required string make = 1;
required int32 numdoors = 2;
}
然后使用 protoc 工具为该 proto 文件编译一个 Go 文件和一个 Dart 文件。
在 Go 中创建一个 Car 对象时，记得使用提供的类型：
c := new(Car)
c.Make = proto.String("Citroën")
c.Numdoors = proto.Int32(4)
然后，你可以将该对象通过 http.ResponseWriter 发送如下：
binaryData, err := proto.Marshal(c)
if err != nil {
// 处理错误
}
w.Write(binaryData)
在 Dart 代码中，你可以按如下方式获取信息：
void getProtoBuffer() {
HttpRequest.request("http://my.url.com", responseType: "arraybuffer").then( (request) {
Uint8List buffer = new Uint8List.view(request.response, 0, (request.response as ByteBuffer).lengthInBytes); // 这是对 dart2js 的一个修复，因为存在一个 bug
Car c = new Car.fromBuffer(buffer);
print(c);
});
}
如果一切正常，你现在应该在 Dart 应用程序中拥有一个 Car 对象 
英文:
First install protoc on your computer using
sudo apt-get install protobuf-compiler
Then install the go protocol buffer library from <https://code.google.com/p/goprotobuf/>. The dartlang version can be found here: <https://github.com/dart-lang/dart-protoc-plugin>.
The next step is to write a .proto file containing a definition of the message to be sent. examples can be found here: <https://developers.google.com/protocol-buffers/docs/proto>.
For example:
message Car {
required string make = 1;
required int32 numdoors = 2;
}
Then use the protoc tool to compile a go file and a dart file for this proto file.
To create a Car object in go, remember to use the types provided:
c := new(Car)
c.Make = proto.String("Citroën")
c.Numdoors = proto.Int32(4)
Then you can send the object over an http.ResponseWriter, w as follows:
binaryData, err := proto.Marshal(c)
if err != nil {
// do something with error
}
w.Write(binaryData)
In the Dart code, you can fetch the information as follows:
void getProtoBuffer() {
HttpRequest.request("http://my.url.com", responseType: "arraybuffer").then( (request) {
Uint8List buffer = new Uint8List.view(request.response, 0, (request.response as ByteBuffer).lengthInBytes); // this is a hack for dart2js because of a bug
Car c = new Car.fromBuffer(buffer);
print(c);
});
}
If everything worked, you should now have a Car object in your Dart application
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