Question

我正在尝试建立与Azure的ServiceBus的基本连接，并且在Azures示例代码中遇到了一些奇怪的东西让我想知道如何存储变量，因为我无法让它工作。

一个有效的例子：

client.OnMessage(message =>
{
    Console.WriteLine(String.Format("Message body: {0}", message.GetBody<String>()));
    Console.WriteLine(String.Format("Message id: {0}", message.MessageId));
});

如果我将其编辑成如下：

string test = string.Empty;
client.OnMessage(message =>
{
    test = String.Format("Message body: {0}", message.GetBody<String>());
});
Console.WriteLine("test: "+test); //outputs "test: "

它不再起作用了。输出将只是“测试：”。这不应该像这样工作还是我错过了什么？

提前致谢

Answer 1

您的问题是OnMessage是一个事件。消息到达时执行lambda表达式message => ...。

// keep a list if you need one.
var bag = new ConcurrentBag<string>();
// the string is allocated immediately.
string test = string.Empty;
// the client will execute the lambda when a message arrives.
client.OnMessage(message =>
{
    // this is executed when a message arrives.
    test = String.Format("Message body: {0}", message.GetBody<String>());

    // this will output the message when a message arrives, and 
    // the lambda expression executes.
    Console.WriteLine("test: "+test); //outputs "test: "

    // you could add the message to a list here.
    bag.Add(message.GetBody<string>());
});

// this line of code runs immediately, before the message arrives.
Console.WriteLine("test: "+test); //outputs "test: "

将变量存储在事件驱动的消息泵中？

1 个答案: