文件输出后的xml-schema失效

<?xml version="1.0" encoding="UTF-8"?>
<teaching-plan
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:noNamespaceSchemaLocation="plan.xsd">
	<course id="a1">
		<course-name>大学英语</course-name>
		<course-hour>20</course-hour>
		<exam-form>考试</exam-form>
	</course>
	<course id="a2">
		<course-name>高等数学</course-name>
		<course-hour>70</course-hour>
		<exam-form>考试</exam-form>
	</course>
	<course id="a3">
		<course-name>计算机应用基础</course-name>
		<course-hour>108</course-hour>
		<exam-form>上机考试</exam-form>
	</course>
</teaching-plan>

<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema">
	<element name="teaching-plan">
		<complexType>
			<sequence>
				<element name="course" maxOccurs="100">
					<complexType>
						<sequence>
							<element name="course-name" type="string"></element>
							<element name="course-hour">
								<simpleType>
									<restriction base="integer">
										<minInclusive value="20"></minInclusive>
										<maxInclusive value="110"></maxInclusive>
									</restriction>
								</simpleType>
							</element>
							<element name="exam-form" type="string"></element>
						</sequence>
						<attribute name="id" type="string" use="required"></attribute>
					</complexType>
				</element>
			</sequence>
		</complexType>
	</element>
</schema>

package com.imooc.dom4j;

import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.List;

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class planWriter {
	public void writerXml(){
		String flie="E:\\xml\\lXml\\bin\\plan-schema.xml";
//		String flie1="E:\\xml\\lXml\\bin\\plan-schema1.xml";
		SAXReader reader=new SAXReader();
		try {
			Document document=reader.read(flie);
			Element root=document.getRootElement();
			Element course=root.addElement("course");
			course.addAttribute("id", "a5");
			course.addElement("course-name").setText("我不喜欢的语文");
			course.addElement("course-hour").setText("24");
			course.addElement("exam-form").setText("考试");
			Writer writer=new OutputStreamWriter(new FileOutputStream(flie),"UTF-8");
			document.write(writer);
			writer.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public void readerXml() {
		String flie="E:\\xml\\lXml\\bin\\plan-schema.xml";
//		String flie1="E:\\xml\\lXml\\bin\\plan-schema1.xml";
		SAXReader reader=new SAXReader();
		try {
			Document document=reader.read(flie);
			Element root=document.getRootElement();
			List<Element> Course=root.elements("course");
			for(Element course:Course) {
			Attribute att=course.attribute("id");
			System.out.println(att.getText());
			System.out.println(course.elementText("course-name"));
			System.out.println(course.elementText("course-hour"));
			System.out.println(course.elementText("exam-form"));
			}
		} catch (DocumentException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		planWriter pw=new planWriter();
		pw.writerXml();
		pw.readerXml();
	}

}

图一为没输出前的状态

图二为输出后的状态.为何输出后的xml-shema失效了