在 GWT 中，为了在托管模式“开发模式”下运行应用程序，您可以将 get.codesvr 参数附加到 url 中，如下所示。
/?gwt.codesvr=127.0.0.1:9997
第一个问题是我想知道 GWT 如何知道何时启动 JVM 实例来提供 .class 文件而不是编译后的 JavaScript 文件？我似乎无法找到 GWT 在开发模式下如何工作。我确实在 com.google.gwt.devDevMode 中找到了 main( )。这个main()是如何调用的？
第二个问题是在文档中，它说 GWT devmode 与 Jetty 服务器一起运行，但是我在浏览器中看到了实际的 JavaScript。这个jetty服务器如何从客户端代码的.class文件输出JavaScript？
谢谢。
最佳答案
所有的魔法都是通过套接字和浏览器插件完成的。
Design: Out of Process Hosted Mode (OOPHM)
这是基本部分。
考虑以下 GWT 代码:
public class MyEntryPoint implements EntryPoint {
private static native int jsniMethod() /*-{
return 1;
}-*/;
public void onModuleLoad() {
jsniMethod();
}
}
JavaScript: the browser plugin sends a LoadModuleMessage with the module name.
Java: the hosted mode server receives the LoadModuleMessage, loads the module and invokes the onModuleLoad in the corresponding EntryPoints. In this case MyEntryPoint::onModuleLoad is called. When MyEntryPoint is compiled, a LoadJsniMessage is sent to create browser-side JavaScript functions for each JSNI method, then when onModuleLoad invokes jsniMethod an InvokeMessage is sent.
JavaScript: This is the key part of the example. The JavaScript engine is currently awaiting a return from the LoadModuleMessage it sent, but it must be in a position to invoke the call to MyEntryPoint::jsniMethod on the same thread. This is accomplished by having the thread enter a read-and-dispatch routine following every remote invocation. In this case, the thread receives the LoadJsniMessage and InvokeMessage messages, invokes jsniMethod and sends a ReturnMessage containing the value 1.
Java: The read-and-dispatch routine receives the ReturnMessage and knows to return from the call to jsniMethod. Having fully executed the onModuleLoad method it sends a ReturnMessage and falls back into a top level read-and-dispatch loop. (Since all calls originate from the browser's UI event dispatch, only the hosted mode server needs to remain in a read-and-dispatch routine during idle time. The browser simply returns control by exiting the JavaScript function that was originally called.)
关于java - GWT 中的代码服务器参数如何工作？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/18584387/