关于用dom4j对xml的读取 - Java / Java EE

http://www.blogjava.net/bolo/archive/2009/01/04/221068.html
这是原文，里面有一个例子，我下载下来后导入到myeclipse里面去以后出现如下的错误提示，不知是何原因？
XML配置文件未加载成功，请检查
java.lang.ExceptionInInitializerError
Caused by: java.lang.RuntimeException: org.dom4j.DocumentException: null Nested exception: null
at com.demo.database.DataBaseConnect.load(DataBaseConnect.java:50)
at com.demo.database.DataBaseConnect.<clinit>(DataBaseConnect.java:36)
Caused by: org.dom4j.DocumentException: null Nested exception: null
at org.dom4j.io.SAXReader.read(SAXReader.java:484)
at org.dom4j.io.SAXReader.read(SAXReader.java:343)
at com.demo.database.DataBaseConnect.load(DataBaseConnect.java:46)
... 1 more

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DataBaseConnect.java
把这个类的代码贴出来看看

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package com.demo.database;

import java.io.InputStream;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.HashMap;
import java.util.List;

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

import com.demo.util.ClassUtils;
import com.demo.util.Constant;

/**
 * 数据库连接管理
 * @author 菠萝大象
 * @version 1.0
 */
public class DataBaseConnect {

private static Element coreMo