FME特色建设
（定义<特征内容地图>元素下映射规则）

A mapping rule[R1From the元件，一个元件相匹配Ë可能无法执行所有必要的映射Ë的子元素。在这种情况下，额外的映射规则匹配Ë’s children should be specified under the<功能内容地图>元素。

回想一下，当一个FME特征正在建设中（即，至少一个Feature mapping rule被激活），则特征搜索集只能包括从映射规则<功能内容地图>元素。当激活时,这些映射规则work on the current feature that is under construction; they do not specify the construction of a new FME feature.

Consider the following input XML document,points2.xml：

points2.xml

< ?xml version=”1.0”?>            

A mapping rule[R1下所定义的元件，相匹配的<点>element will have difficulty extracting information from all the元素。

[Recall that the extract expression does not currently support index access for the matched element’s children. All[R1是ble to do now, is to extract data from the first元素。

An extract expression defined in a mapping rule matching the<点>element will be unable to reach the otherelements, since itsexpression stringcan only refer to the first元素。To overcome this limitation, we need to define mapping rules in the<功能内容地图>元素匹配元素。

Let[R2是下的映射规则<功能内容地图>元素匹配元素。什么时候[R2activates it will suspend[R1，and work with the same FME feature that[R1创建。下面xfMap文件，feature_content.xmp，这是否正是：

feature_content.xmp

<？XML版本= “1.0”？> <！DOCTYPE xfMap SYSTEM “xfMap.dtd”> <！xfMap> <特征地图> <！ - 调用此映射规则R1  - > <映射匹配= “点”>   <特征内容地图> <！ - 调用此映射规则R2  - > <映射匹配= “彩色”> <属性> <属性> <名称> <字面EXPR =”色。 “/> <提取EXPR =” @类型 “/>  <值> <提取EXPR =” @值“/>      

什么时候thepoints2.xmlandfeature_content.xmp文档被送入XML阅读器中，FME具有输出是：

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Feature Type: '
Attribute: color.blue' has value 0.596'
属性：color.green”具有价值0.233'
Attribute: color.red' has value 0.324'
属性：XML_TYPE“具有价值xml_no_geom”
几何类型：未知（0）
=============================================================
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Feature Type: '
属性：color.blue”具有价值0.554'
Attribute: color.green' has value 0.948'
属性：color.red”具有价值0.874'
属性：XML_TYPE“具有价值xml_no_geom”
几何类型：未知（0）
=============================================================

这是发生了什么：

步		功能搜索的设置内容（步骤之后）	映射规则的状态[Rp（后工序）
1。	该Feature-search-set is initialized: No feature mapping rules are executing, so the mapping rules defined in在元素feature_content.xmpdocument are added to the feature-search-set.	{[R1}	[R1：de-activated [R2：de-activated
2。	XML读取器读取的开始标记<points>element: No mapping rules in the feature-search-set matches the <points>元素。该reader continues reading the contents of the元素。	{[R1}	[R1：de-activated [R2：de-activated
3。	该XML Reader reads the start-tag of a <point>element: 该mapping rule[R1in the feature-search-set matches the <point>元素。[R1被激活。[R1也是在执行中因状态<点>元件是当前上下文元素。 Since at least one feature mapping rule is activated (i.e.,[R1），特征搜索集的内容随后将默认为含有下的映射规则<特征化内容地图>element, in this case, it is just[R2。	{[R2}	[R1：activated, executing [R2：de-activated
4。	该XML Reader reads the start-tag of a <色>element: 该mapping rule[R2in the feature-search-set matches the <色>元素。[R2被激活。没有品牌的新FME功能创建因为[R2在被定义<Feature内容映射>元素。该element is also the context element so that[R1is suspended, and[R2现在执行。 该Feature mapping rule[R2具有<属性>element,[R2提供这些属性到正在构造的FME特征。	{[R2}	[R1：激活，悬浮 [R2：activated, executing
5。	该<色>元素结束标记被读取。Thiselement initially triggered the activation of[R2，所以[R2is de-activated (see the section titled映射规则状态). 该功能搜索集不会改变，因为有至少一个激活的Feature mapping rule，that is[R1。	{[R2}	[R1：activated, executing [R2：de-activated
6。	步4) and 5) are repeated for the next two <色>元素。	{[R2}	...
7。	该<point>元素结束标记被读取。 [R1被取消激活。XML读取器认为在建FME功能是完成时[R1de-activates, this is because[R1是Feature mapping rule在所定义的<Feature-map>元素。 NoFeature mapping rulesare activated, so the mapping rules defined in在元素feature_content.xmpdocument becomes the feature-search-set.	{[R1}	[R1：de-activated [R2：de-activated
8.	步骤3）至7）被重复用于第二<point>元素。	...	...
9.	该<points>元素结束标记被读取。该XML阅读器已经读完了输入的XML文档。	{}	[R1：de-activated [R2：de-activated

考虑另一个例子：

points3.xml

< ?xml version = " 1.0 " ?>        0.324 0.233 0.596           0.874 0.948 0.554    

feature_content2.xmp

< ?xml version="1.0">                                                          

什么时候thepoints3.xml，feature_content2.xmp文档输入到XML阅读器，下面的FME的特点是输出：

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
功能类型：myPoint_0'
Attribute: fill_color.blue' has value 0.596'
Attribute: fill_color.green' has value 0.233'
Attribute: fill_color.red' has value 0.324'
Attribute: location.x ' has value 10.0'
Attribute: location.y ' has value 0.0'
Attribute: outline_color.blue' has value 1.0'
Attribute: outline_color.green' has value 1.0'
属性：outline_color.red”具有值1.0'
属性：XML_TYPE“具有价值xml_no_geom”
几何类型：未知（0）
=============================================================
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
功能类型：myPoint_1'
Attribute: fill_color.blue' has value 0.554"'
属性：fill_color.green”具有价值0.948'
Attribute: fill_color.red' has value 0.874'
属性：location.x“具有价值5.0”
Attribute: location.y ' has value 5.0'
属性：outline_color.blue”具有值0.5'
属性：outline_color.green”具有值0.5'
Attribute: outline_color.red' has value 0.5'
属性：XML_TYPE“具有价值xml_no_geom”
几何类型：未知（0）
=============================================================