如何将GWT方法作为参数传递给Javascript函数？ [英] How to pass a GWT method as a parameter into a Javascript function?

问题描述

概述

• 有一个名为 private void handleError ）


• 有一个JSNI Javascript函数调用： private native void registerErrorHandler（）


• 原生javascript函数调用第三方Javascript库中的另一个函数： foo.attachEvent（EventName，handlerReference）;





功能



我需要将GWT方法作为函数参数放到 foo.attachEvent（）函数中，我尝试了几种方法：



foo.attachEvent（Error，registerErrorHandler）; - >
TypeMismatchException



foo.attachEvent Error，this。@ package.foo :: registerErrorHandler（））; - >
TypeMismatchException



  var handler = this。@ package.foo :: registerErrorHandler（）（）; 
 foo.attachEvent（Error，handler）; 
  

- >
TypeMismatchException





纯Javascript>





当我用纯JavaScript写这篇文章时，它正在工作：



 函数handleError（）{
 alert（Error）; 
} 
函数registerErrorHandler（）{
 var event =Error; 
 var handler = handleError; 
 
 foo.attachEvent（event，handler）; 
} 
  

如何将其实现到GWT中？我有很多问题完全理解Javascript - Java对象转换。我将 handleError 函数引用理解为 JavaScriptObject ，但我无法使用该信息来处理它。 / p> 解析方案

您的代码需要如下所示:(只有一个时间大括号，因此函数不会执行...）

  var handler = this。@ package.foo :: registerErrorHandler（）; 
 foo.attachEvent（Error，handler）; 
  

但是你也想要做的是将你的函数封装在$ entry函数中，这样你的未捕获的异常处理程序将起作用：

  var handler = this。@ package.foo :: registerErrorHandler（）; 
 foo.attachEvent（Error，$ entry（handler））; 
  

你总是可以做的是构建一个直接调用你的gwt函数的js函数：

  var that = this; 
 var handler = function（）{
。@ package.foo :: registerErrorHandler（）（）; 
}; 
 foo.attachEvent（Error，$ entry（handler））; 
  

Overview

• There is a GWT method called: private void handleError()
• There is a JSNI Javascript function called: private native void registerErrorHandler()
• The native javascript function calls another function from a third party Javascript library: foo.attachEvent("EventName", handlerReference);

Functionality

I need to pass the GWT method as a function parameter into the foo.attachEvent() function, i tried several approaches:

foo.attachEvent("Error", registerErrorHandler); -> TypeMismatchException

foo.attachEvent("Error", [e-mail]::registerErrorHandler()); -> TypeMismatchException

var handler = [e-mail]::registerErrorHandler()();
foo.attachEvent("Error", handler);

-> TypeMismatchException

Plain Javascript

When I write this in plain Javascript, it's working:

function handleError() {
    alert("Error");
}
function registerErrorHandler() {
    var event = "Error";
    var handler = handleError;

    foo.attachEvent (event, handler);
}

How can I implement that into GWT? I am having a lot of problems completely understanding the Javascript - Java Objects conversion. I understand the handleError function reference as a JavaScriptObject, but I am not able to get it working with that information.

解决方案

you code needs to look like this: (there are only one time braces, therefore the function is not executed...)

var handler = [e-mail]::registerErrorHandler();
foo.attachEvent("Error", handler);

but what you also want to do is wrap your function in the $entry function so that your uncaught exception handler will work:

var handler = [e-mail]::registerErrorHandler();
foo.attachEvent("Error", $entry(handler));

What you can always do is build a js function that directly calls your gwt function:

var that = this;
var handler = function(){
    [e-mail]::registerErrorHandler()();
};
foo.attachEvent("Error", $entry(handler));

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