用schema对xml文件进行约束

<?xml version="1.0" encoding="UTF-8"?>

<teachers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns="http://www.example.org/teacher"
          xsi:schemaLocation="http://www.example.org/teacher teacher.xsd">
    <teacher id="234">
        <name>Jack</name>
        <age>28</age>
    </teacher>
    
    <teacher>
        <name>Tom</name>
        <age>34</age>
    </teacher>
</teachers>

<?xml version="1.0" encoding="UTF-8"?>

<schema xmlns="http://www.w3.org/2001/XMLSchema" 
        targetNamespace="http://www.example.org/teacher" 
        elementFormDefault="qualified">
    <element name="teachers">
        <complexType>
            <sequence maxOccurs="unbounded">
                <element name="teacher">
                    <complexType>
                        <sequence>
                            <element name="name" type="string"></element>
                            <element name="age" type="int"></element>
                        </sequence>
                        <attribute name="id" type="int"></attribute>
                    </complexType>
                </element>
            </sequence>
        </complexType>
    </element>
</schema>