[英]How to use DTD ENTITY external reference in log4j.xml
I tried to use entities from external dtd file. 我试图使用外部dtd文件中的实体。
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"
[<!ENTITY logHome SYSTEM "log4j-entity.dtd">]
>
log4j-entity.dtd log4j的-entity.dtd
<?xml version="1.0" encoding="UTF-8"?>
<!ENTITY logHome "/root/crm_test/">
I tried to use the entity values in attribute values like this. 我试图在这样的属性值中使用实体值。
<param name="File" value="&logHome;log/info.log"/>
I get this errror: 我得到这个错误:
The external entity reference "&logHome;" is not permitted in an attribute value.
How can I do this? 我怎样才能做到这一点?
Note: 注意:
This thing works.. 这件事有效..
<!ENTITY logHome "/root/crm_test/">
You need to make the entity inside the internal subset a parameter entity and then reference it. 您需要将内部子集中的实体作为参数实体,然后引用它。
Change: 更改:
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"
[<!ENTITY logHome SYSTEM "log4j-entity.dtd">]
>
to: 至:
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd" [
<!ENTITY % logHome SYSTEM "log4j-entity.dtd">
%logHome;
]>
The XML specs specifically forbid the use of external entities in attribute values. XML规范明确禁止在属性值中使用外部实体。 See here: http://www.w3.org/TR/2004/REC-xml-20040204/#forbidden
见这里: http : //www.w3.org/TR/2004/REC-xml-20040204/#forbidden
The following are forbidden, and constitute fatal errors: [...] a reference to an external entity in an attribute value.
以下是禁止的,并构成致命错误:[...]在属性值中引用外部实体。
So the answer is: XML won't let you do what you're trying to do. 所以答案是:XML不会让你做你想做的事情。 You might, however, get a similar effect if you ran your XML through an XSLT processor and applied transformations as needed.
但是,如果通过XSLT处理器运行XML并根据需要应用转换,则可能会产生类似的效果。
There are a couple things wrong here. 这里有一些错误。
logHome
for two different things (an external entity containing declarations, which should as Daniel Haley points out be a parameter entity) and an internal entity whose replacement text names a directory. logHome
用于两个不同的事物(包含声明的外部实体,应该像Daniel Haley指出的那样是一个参数实体)和一个内部实体,其替换文本命名一个目录。 &logHome;
&logHome;
的引用&logHome;
in the attribute value is understood to be a reference to the resource whose URI is " log4j-entity.dtd
". log4j-entity.dtd
”的资源的引用。 ?The simplest way to achieve what you want would be to declare the logHome
entity in the internal subset: ?实现所需内容的最简单方法是在内部子集中声明
logHome
实体:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd" [
<!ENTITY logHome "/root/crm_test/">
]>
If you really want the declaration of logHome
to be external, it might be less confusing to use a different name for the parameter entity: 如果您真的希望
logHome
的声明是外部的,那么为参数实体使用不同的名称可能不那么令人困惑:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd" [
<!ENTITY % logHomeDeclaration SYSTEM "log4j-entity.dtd">
%logHomeDeclaration;
]>
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