apache的xmlbeans项目中自带demo（名称为Validation）的一个小错误

这个例子中包含几个文件，分别是todolist.xsd,todolist.xml,Validation.java,ValidationTest.java

下面分别复制其代码：
Validation.java：
/*   Copyright 2004 The Apache Software Foundation
*
*   Licensed under the Apache License, Version 2.0 (the "License");
*   you may not use this file except in compliance with the License.
*   You may obtain a copy of the License at
*
*       http://www.apache.org/licenses/LICENSE-2.0
*
*   Unless required by applicable law or agreed to in writing, software
*   distributed under the License is distributed on an "AS IS" BASIS,
*   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*   See the License for the specific language governing permissions and
*  limitations under the License.
*/

package org.apache.xmlbeans.samples.validation;

import org.apache.xmlbeans.*;
import org.apache.xmlbeans.samples.validation.todolist.*;
import org.apache.xmlbeans.samples.validation.todolist.TodolistDocument.Todolist;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;

/**
* A sample to illustrate two means for validating XML against schema
* using features of the XMLBeans API. The features illustrated are:
*
* - Validating after changes by using the XmlObject.validate method.
* This method is exposed by types generated by compiling schema. The
* validate method validates instances against all aspects of schema.
* Also, with this method you can specify a Collection instance to
* capture errors that occur during validation.
*
* - Validating "on the fly" using the XmlOptions.VALIDATE_ON_SET constant.
* This option prompts XMLBeans to validate XML against simple schema types
* <em>as you set them</em>, rather than by expressly calling for validation.
* You can set this option by calling XmlOptions.setValidateOnSet, then
* specifying the XmlOptions instance as a parameter when creating
* a new instance from schema or parsing an existing one.
*
* Note that it is also possible to validate instances from the
* command line by using tools you'll find in the bin directory of the
* XMLBeans distribution.
*/
public class Validation
{
    private static XmlOptions m_validationOptions;

    /**
     * Receives a todo list XML instance, twice rendering it invalid
     * and validating it using the XMLBeans API.
     *
     * @param args An array in which the first item is a
     * path to the XML instance file.
     */
    public static void main(String[] args)
    {
        Validation thisSample = new Validation();
       
        // Use the validate method to validate an instance after
        // updates.
        boolean isValidAfterChanges = thisSample.isValidAfterChanges(args[0]);
       
        // Use the VALIDATE_ON_SET option to validate an instance
        // as updates are made.
        boolean isValidOnTheFly = thisSample.isValidOnTheFly(args[0]);
    }

    /**
     * Illustrates use of the validate method by making changes to incoming
     * XML that invalidate the XML, then validating the instance and
     * printing resulting error messages.
     *
     * Because this code is designed to generate invalid XML, it
     * returns false when successful.
     *
     * @param xmlPath A path to the XML instance file.
     * @return <code>true if the XML is valid after changes;
     * otherwise, <code>false</code>.
     */
    public boolean isValidAfterChanges(String xmlPath)
    {
        System.out.println("Validating after changes: \n");
        // Set up the validation error listener.
        ArrayList validationErrors = new ArrayList();
        m_validationOptions = new XmlOptions();
        m_validationOptions.setErrorListener(validationErrors);

        TodolistDocument todoList = (TodolistDocument)parseXml(xmlPath, null);

        // Schema defines the <name> element as required (minOccurs = '1').
        // So this statement renders the XML invalid because it sets the
        // <name> element to nil.
        todoList.getTodolist().getItemArray(0).setName(null);

        // During validation, errors are added to the ArrayList for
        // retrieval and printing by the printErrors method.
        boolean isValid = todoList.validate(m_validationOptions);

        if (!isValid)
        {
            printErrors(validationErrors);
        }
        return isValid;
    }

    /**
     * Illustrates the "validate on set" feature, which validates XML
     * for simple types on the fly. As XML for those types is "set" through
     * accessors generated by compiling schema, XMLBeans checks the XML's
     * validity. The code here uses generated types to retrieve the first
     * <item> in a <todolist>, then update the <item>'s id attribute. The code
     * throws an exception when it tries to set an id attribute value that
     * is too high.
     *
     * Because this code is designed to generate invalid XML, it
     * returns false when successful.
     *
     * @param xmlPath A path to the XML instance file.
     * @return <code>true</code> if valid XML is successfully created;
     * otherwise, <code>false</code>.
     */
    public boolean isValidOnTheFly(String xmlPath)
    {
        System.out.println("Validating on-the-fly: \n");
        m_validationOptions = new XmlOptions();
        m_validationOptions.setValidateOnSet();
       
        TodolistDocument todoList = (TodolistDocument)parseXml(xmlPath, m_validationOptions);
        Todolist list = todoList.getTodolist();
        ItemType firstItem = list.getItemArray(0);

        // Schema defines the <id> element as allowing values up to 100. So
        // this line throws an exception because it invalidates the XML the
        // code is updating.
        firstItem.setId(8587);
       
        // This line will not be reached.
        return todoList.validate();
    }

    /**
     * Receives the collection containing errors found during
     * validation and print the errors to the console.
     *
     * @param validationErrors The validation errors.
     */
    public void printErrors(ArrayList validationErrors)
    {
        System.out.println("Errors discovered during validation: \n");
        Iterator iter = validationErrors.iterator();
        while (iter.hasNext())
        {
            System.out.println(">> " + iter.next() + "\n");
        }
    }

    /**
     * <p>Creates a File from the XML path provided in main arguments, then
     * parses the file's contents into a type generated from schema.</p>
     * <p/>
     * <p>Note that this work might have been done in main. Isolating it here
     * makes the code separately available from outside this class.</p>
     *
     * @param xmlFilePath A path to XML based on the schema in inventory.xsd.
     * @return An instance of a generated schema type that contains the parsed
     *         XML.
     */
    public XmlObject parseXml(String xmlFilePath, XmlOptions validationOptions)
    {
        File xmlFile = new File(xmlFilePath);
        XmlObject xml = null;
        try
        {
            xml = XmlObject.Factory.parse(xmlFile, validationOptions);
        } catch (XmlException e)
        {
            e.printStackTrace();
        } catch (IOException e)
        {
            e.printStackTrace();
        }
        return xml;
    }
}

ValidationTest.java:
/*   Copyright 2004 The Apache Software Foundation
*
*   Licensed under the Apache License, Version 2.0 (the "License");
*   you may not use this file except in compliance with the License.
*   You may obtain a copy of the License at
*
*       http://www.apache.org/licenses/LICENSE-2.0
*
*   Unless required by applicable law or agreed to in writing, software
*   distributed under the License is distributed on an "AS IS" BASIS,
*   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*   See the License for the specific language governing permissions and
*  limitations under the License.
*/

package org.apache.xmlbeans.samples.validation;

import org.apache.xmlbeans.samples.validation.Validation;

/**
* A class with which to test the Validation sample.
*/
public class ValidationTest
{
    /**
     * Tests the Validation sample.
     */
    public static void main(String[] args)
    {
        // all we're checking for is that the sample doesn't throw anything.
        // a real sample test might assert something more interesting.
        Validation sample = new Validation();
        // Use the validate method to validate an instance after
        // updates.
        boolean isValidAfterChanges = sample.isValidAfterChanges(args[0]);
        assert !isValidAfterChanges;
       
        // Use the VALIDATE_ON_SET option to validate an instance
        // as updates are made.
        boolean isValidOnTheFly = sample.isValidOnTheFly(args[0]);       
        assert !isValidOnTheFly;
    }
}


todolist.xml:
<?xml version="1.0" encoding="UTF-8"?>
<!--
Copyright 2004 The Apache Software Foundation

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<todolist xmlns="http://xmlbeans.apache.org/samples/validation/todolist">
    <item id="001">
      <name>Buy a south Pacific island.</name>
      <description>Contingent on inheriting lots of money.</description>
      <due_by>2005-05-01T23:36:28</due_by>
      <action>someday_maybe_defer</action>
    </item>
    <item id="002">
      <name>Get that new PowerBook I've been eyeing.</name>
      <description>Resulting productivity increase will be exponential!</description>
      <due_by>2005-05-01T23:36:28</due_by>
      <action>do</action>
    </item>
    <item id="003">
      <name>Clean the garage.</name>
      <description>Remove at least enough junk so that my bicycle fits.</description>
      <due_by>2005-05-30T23:36:28</due_by>
      <action>delegate</action>
    </item>
</todolist>

todolist.xsd:
<?xml version="1.0" encoding="UTF-8"?>
<!--
Copyright 2004 The Apache Software Foundation

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<xs:schema targetNamespace="http://xmlbeans.apache.org/samples/validation/todolist" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://xmlbeans.apache.org/samples/validation/todolist" elementFormDefault="qualified">
<xs:element name="todolist">
<xs:complexType>
<xs:sequence>
<xs:element name="item" type="itemType" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:complexType name="itemType">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="description" type="xs:string" minOccurs="0"/>
<xs:element name="due_by" type="xs:dateTime" minOccurs="0"/>
<xs:element name="action" type="actionType"/>
</xs:sequence>
<xs:attribute name="id" type="idType"/>
</xs:complexType>
<xs:simpleType name="nameType">
<xs:restriction base="xs:string">
<xs:maxLength value="50"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="idType">
<xs:restriction base="xs:int">
<xs:maxExclusive value="100"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="actionType">
<xs:restriction base="xs:string">
<xs:enumeration value="do"/>
<xs:enumeration value="delegate"/>
<xs:enumeration value="someday_maybe_defer"/>
<xs:enumeration value="toss"/>
<xs:enumeration value="incubate"/>
<xs:enumeration value="file"/>
</xs:restriction>
</xs:simpleType>
</xs:schema>

其中错误的地方在todolist.xsd,红色标记处（xs:string），这个错误导致
          <xs:simpleType name="nameType">
<xs:restriction base="xs:string">
<xs:maxLength value="50"/>
</xs:restriction>
</xs:simpleType>
无效。应该将其改为：nameType