ColdFusion中的cfcatch的类型 [英] Type of cfcatch in ColdFusion

问题描述

我只是使用 cftry / cfcatch 块来处理任何异常。采取这个简单的例外：

 < cftry& 
< cfset abc = 1/0> 
< cfcatch> 
< cfdump var =＃cfcatch.getClass（）。getName（）＃> 
< cfdump var =＃isStruct（cfcatch）＃> 
< cfdump var =＃isObject（cfcatch）＃> 
< cfdump var =＃structKeyExists（cfcatch，'type'）＃> 
< / cfcatch> 
< / cftry> 
  

并且上面的代码输出如下：

  coldfusion.runtime.DivideByZeroException 
 NO 
 YES 
 YES 
  

我的问题是：

为什么 structKeyExists cfcatch 不是类型 struct ？

并且在转储 cfcatch 时，它似乎是一个 struct 。

任何建议。

解决方案

）

添加到Miguel-F对CF的typelessness的意见...根据文档， IsStruct 使用以下规则（强调我的）：

是ColdFusion结构或是实现java.lang.Map接口的Java
对象。如果变量中的对象是用户定义的函数（UDF），则返回值
为False。

CFCatch 不符合该条件。因此，为什么 IsStruct 返回false。

如果你转储 cfcatch 对象，并检查类层次结构，你会看到它实际上实现为 java.lang.Exception 的子类：

  coldfusion.runtime.DivideByZeroException 
 coldfusion.runtime.ExpressionException 
 coldfusion.runtime.NeoException 
 java.lang.RuntimeException 
 java.lang.Exception 
 java.lang.Throwable 
 java.lang.Object 
  

...不 coldfusion.runtime.struct 即CF结构：

  coldfusion.runtime.Struct 
 coldfusion.util.FastHashtable 
 coldfusion.util.CaseInsensitiveMap 
 java.lang.Object 
  

因此，如Miguel-F所说可以像结构（可以是最复杂的对象），技术上不是 CF结构，这解释了为什么IsStruct返回false。

另外，可以使用点表示法访问其属性的原因，如CF结构，可能是因为cfcatch类使用 set_PropertyName_（value）方法，如果一个Java类符合
JavaBeans模式。因此，您可以通过
直接引用该属性来设置或获取属性，而不必显式调用方法。

例如，您可以使用以下命令访问cfcatch的message属性：

  cfcatch.message 
  
 
 
 
 ..而不是调用该属性的getter方法：
  cfcatch.getMessage（）
  
 
I am simply using a cftry/cfcatch block for handling any exception. Take this simple exception:
<cftry>
  <cfset abc = 1/0>
  <cfcatch>
    <cfdump var="#cfcatch.getClass().getName()#">
    <cfdump var="#isStruct(cfcatch)#">
    <cfdump var="#isObject(cfcatch)#">
    <cfdump var="#structKeyExists(cfcatch, 'type')#">
  </cfcatch>
</cftry>
And the above code's output is like this:
coldfusion.runtime.DivideByZeroException 
NO 
YES 
YES
My question is: 

Why structKeyExists is not throwing an error as cfcatch is not of type struct? 

And on dumping cfcatch it seems like it is a struct. 

Any suggestions.
解决方案
(Too long for comments..)

Adding to Miguel-F's comments about CF's "typelessness"... according to the documentation, IsStruct uses the following rules (emphasis mine):

  
Returns True, if variable is a ColdFusion structure or is a Java
  object that implements the java.lang.Map interface. The return value
  is False if the object in variable is a user-defined function (UDF).
CFCatch does not meet that criteria. Hence why IsStruct returns false. 

If you dump the cfcatch object, and examine the class hierarchy, you will see it is actually implemented as a subclass of java.lang.Exception:
coldfusion.runtime.DivideByZeroException
coldfusion.runtime.ExpressionException
coldfusion.runtime.NeoException
java.lang.RuntimeException
java.lang.Exception
java.lang.Throwable
java.lang.Object 
... not coldfusion.runtime.struct ie CF structure:
coldfusion.runtime.Struct
coldfusion.util.FastHashtable
coldfusion.util.CaseInsensitiveMap
java.lang.Object 
So as Miguel-F said, though it can be used like a structure (as can most complex object), technically it is not a CF structure, which explains why IsStruct returns false.

As an aside, the reason you can access its properties using dot notation, like with CF structures, is probably because the cfcatch class uses the JavaBean pattern:

  
ColdFusion can automatically invoke get_PropertyName_() and
  set_PropertyName_(value) methods if a Java class conforms to the
  JavaBeans pattern. As a result, you can set or get the property by
  referencing it directly, without having to explicitly invoke a method.
So for example, you can access the "message" property of cfcatch using:
     cfcatch.message
.. instead of invoking its "getter" method for that property:
     cfcatch.getMessage()


                        
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