


How PHP uses the xmllint command to process xml and html, xmllintxml_PHP tutorial
PHP uses the xmllint command to process xml and html, xmllintxml
The example in this article describes how PHP uses the xmllint command to process xml and html. Share it with everyone for your reference. The specific analysis is as follows:
xmllint is a very convenient tool for processing and verifying xml and processing html. Under Linux, you can use this command as long as libxml2 is installed. First, let’s take a look at an example of processing HTML using the --html and --xpath parameters:
An example is as follows:
In the above example, only the content of the text part is obtained by extracting the result (ul#csstb) after querying the ownership of the IP address on 123cha. The result after executing the above script statement is as follows:
[Your query]:8.8.8.8
Main data of this site:
USA>
Auxiliary data of this site: Google Public DNS provided:hypo
United States Google’s free Google Public DNS provides: zwstar reference data 1: United States
Reference data two: United States
1. --format
This parameter is used to format the xml so that it has good readability.
Suppose there is xml (person.xml) with the following content:
2. --noblanks
Contrary to --format, sometimes in order to save transmission volume, we want to remove the blanks in xml. In this case, we can use the --noblanks command. Assume that the content of xml (person.xml) is as follows
3. --schema
Use scheam to verify the correctness of xml files (XML Schema is an XML-based DTD replacement) Assume that there are xml files (person.xml) and scheam files (person.xsd). The contents are as follows
person.xml
Copy code
person.xsd
Copy code
按如下命令执行后的结果是:
person.xml validates
注:默认情况下,验证后会输出验证的文件内容,可以使用 --noout选项去掉此输出,这样我们可以只得到最后的验证结果。
person.xml validates
下面我们改动person.xml,使这份文件age字段和sex都是不符合xsd定义的。
person.xml:4: element age: Schemas validity error : Element 'age': 'not age' is not a valid value of the atomic type 'xs:integer'.
person.xml:5: element sex: Schemas validity error : Element 'sex': [facet 'enumeration'] The value 'test' is not an element of the set {'male', 'female'}.
person.xml:5: element sex: Schemas validity error : Element 'sex': 'test' is not a valid value of the local atomic type.
person.xml fails to validate
可以看到xmllint成功的报出了错误!
4、 关于--schema的输出
在讲输出之前先看下面一个场景,假如你想通过php执行xmllint然后拿到返回结果,你的代码通常应该是这个样子valid.php
exec($command, $output, $retval);
//出错时返回值不为0
if ($retval != 0){
var_dump($output);
}
else{
echo "yeah!";
}
We keep the errors in person.xml above.
Execute this code and you will find that the output you get is not an error, but array(0) {}, amazing!
Why is this happening?
Because of xmllint --schema, if an error occurs during verification, the error message will not be displayed through the standard output (stdout), but through the standard error (stderr).
The output parameter of exec can only get the content displayed by the standard output (stdout).
Therefore, in order to get the error message, we need to redirect standard error to standard output and modify the code accordingly:
Execute valid.php again and get the error message successfully!
Examples are as follows:
First create an xml document, named po.xml, with the following content:
Then the schema file written for po.xml is named po.xsd and the content is as follows:
Copy code
The code is as follows:
Purchase order schema for Example.com.
Copyright 2000 Example.com. All rights reserved.
使用 xmllint 对 po.xml 文件进行校验:
希望本文所述对大家的PHP程序设计有所帮助。

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