老师为什么我都xml文档用schema限制后，运行xpath查询结果就不显示？？？

<?xml version="1.0" encoding="UTF-8"?>
<!-- 人力资源管理系统 -->
<hr xmlns="http://www.w3school.com.cn"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.w3school.com.cn  hr2.xsd">
    <employee id="e001">
        <name>张三</name>
        <age>31</age>
        <salary>4000</salary>
        <department>
            <dname>会计部</dname>
            <address>xx大厦-B103</address>
        </department>
    </employee>
    <employee id="e002">
        <name>李四</name>
        <age>41</age>
        <salary>5000</salary>
        <department>
            <dname>工程部</dname>
            <address>xx大厦-B303</address>
        </department>
    </employee>
    <employee id="e003">
        <name>王五</name>
        <age>55</age>
        <salary>10000</salary>
        <department>
            <dname>公关部</dname>
            <address>xx大厦-A001</address>
        </department>
    </employee>
</hr>

package com.mason.dom4j;
 
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
 
import java.util.List;
 
public class XPathTestor {
    public static void main(String[] args) {
        XPathTestor xPathTestor=new XPathTestor();
        xPathTestor.xpath("/hr/employee");
    }
 
    public void xpath(String xpathExp) {
        //传入参数为xPath表达式
        String file = "C:\\Users\\Mason\\IdeaProjects\\untitled\\src\\hr.xml";
        SAXReader reader = new SAXReader();
        try {
            Document document = reader.read(file);
            List<Node>nodes= document.selectNodes(xpathExp);
            for (Node node:nodes){
                Element emp=(Element) node;
                System.out.println(emp.elementText("name"));
                System.out.println(emp.elementText("age"));
                System.out.println(emp.elementText("salary"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

运行成功没用报错，但就是不显示结果！！这是为什么呢?

但我后来把xml的Schema限制删了之后↓

<?xml version="1.0" encoding="UTF-8"?>
<!-- 人力资源管理系统 -->
<hr>
    <employee id="e001">
        <name>张三</name>
        <age>31</age>
        <salary>4000</salary>
        <department>
            <dname>会计部</dname>
            <address>xx大厦-B103</address>
        </department>
    </employee>
    <employee id="e002">
        <name>李四</name>
        <age>41</age>
        <salary>5000</salary>
        <department>
            <dname>工程部</dname>
            <address>xx大厦-B303</address>
        </department>
    </employee>
    <employee id="e003">
        <name>王五</name>
        <age>55</age>
        <salary>10000</salary>
        <department>
            <dname>公关部</dname>
            <address>xx大厦-A001</address>
        </department>
    </employee>
</hr>

这样就可以正常显示出xpath后的结果，这是为什么呢？

MasonM 2019-03-23

源自：XML入门 3-8 XPath实验室

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3回答

好帮手慕阿满回答被采纳获得+3积分 2019-03-25 16:08:29

同学你好，同学需要修改一下xml和xsd文件的头部，修改后xml文件的头部如：

1 2	`<hr` `xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"` `xsi:noNamespaceSchemaLocation="hr.xsd">`

xsd文件的头部，如：

1	`<xs:schema` `xmlns:xs="http://www.w3.org/2001/XMLSchema">`

这样就可以读取schema约束的xml文档了。

如果我的回答解决了你的疑惑，请采纳。祝：学习愉快~

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MasonM 提问者 #1

老师为什么要这样改?这跟W3school官网的引用约束不同喔?

2019-03-25 16:10:46
好帮手慕阿满回复提问者 MasonM #2

同学你好，xml文件中存在命名空间导致document.selectNodes() 没有结果，所以修改一下就可以了。祝：学习愉快~

2019-03-25 19:10:42

提问者 MasonM 2019-03-24 15:13:40

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           targetNamespace="http://www.w3school.com.cn"
           xmlns="http://www.w3school.com.cn"
           elementFormDefault="qualified">
    <xs:element name="hr">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="employee" minOccurs="1" maxOccurs="10">
                    <xs:complexType>
                        <xs:sequence>
                            <xs:element name="name" type="xs:string"></xs:element>
                            <xs:element name="age" type="xs:integer"></xs:element>
                            <xs:element name="salary" type="xs:integer"></xs:element>
                            <xs:element name="department">
                                <xs:complexType>
                                    <xs:sequence>
                                        <xs:element name="dname" type="xs:string"></xs:element>
                                        <xs:element name="address" type="xs:string"></xs:element>
                                    </xs:sequence>
                                </xs:complexType>
                            </xs:element>
                        </xs:sequence>
                        <xs:attribute name="id" type="xs:string" use="required"></xs:attribute>
                    </xs:complexType>
                </xs:element>
            </xs:sequence>
        </xs:complexType>
    </xs:element>
</xs:schema>