MyEclipse報錯：

Warning: Caught exception attempting to use SAX to load a SAX XMLReader

Warning: Exception was: java.lang.ClassNotFoundException: org/apache/xerces/parsers/SAXParser

Warning: I will print the stack trace then carry on using the default SAX parser

java.lang.ClassNotFoundException: org/apache/xerces/parsers/SAXParser

at org.xml.sax.helpers.XMLReaderFactory.loadClass(Unknown Source)

at org.xml.sax.helpers.XMLReaderFactory.createXMLReader(Unknown Source)

at org.dom4j.io.SAXHelper.createXMLReader(SAXHelper.java:83)

at org.dom4j.io.SAXReader.createXMLReader(SAXReader.java:894)

at org.dom4j.io.SAXReader.getXMLReader(

at org.dom4j.io.SAXReader.read(SAXReader.java:435)

at org.dom4j.io.SAXReader.read(SAXReader.java:343)

at com.bjpowernode.drp.util.XmlConfigReader.<init>(XmlConfigReader.java:38)

at com.bjpowernode.drp.util.XmlConfigReader.getInstance(XmlConfigReader.java:58)

at com.bjpowernode.drp.util.DbUtil.getConnection(

at com.bjpowernode.drp.util.IdGenerator.generate(IdGenerator.java:34)

at com.bjpowernode.drp.util.IdGenerator.main(IdGenerator.java:79)

org.dom4j.DocumentException: SAX2 driver class org.apache.xerces.parsers.SAXParser not found Nested exception: SAX2 driver class org.apache.xerces.parsers.SAXParser not found

at org.dom4j.io.SAXReader.read(SAXReader.java:484)

at org.dom4j.io.SAXReader.read(SAXReader.java:343)

at com.bjpowernode.drp.util.XmlConfigReader.<init>(XmlConfigReader.java:38)

at com.bjpowernode.drp.util.XmlConfigReader.getInstance(XmlConfigReader.java:58)

at com.bjpowernode.drp.util.DbUtil.getConnection(DbUtil.java:37)

at com.bjpowernode.drp.util.IdGenerator.generate(IdGenerator.java:34)

at com.bjpowernode.drp.util.IdGenerator.main(IdGenerator.java:79)

Nested exception:

java.lang.ClassNotFoundException: org/apache/xerces/parsers/SAXParser

at org.dom4j.io.SAXHelper.createXMLReader(SAXHelper.java:98)

at org.dom4j.io.SAXReader.createXMLReader(SAXReader.java:894)

at org.dom4j.io.SAXReader.getXMLReader(SAXReader.java:715)

at org.dom4j.io.SAXReader.read(SAXReader.java:435)

at org.dom4j.io.SAXReader.read(SAXReader.java:343)

at com.bjpowernode.drp.util.XmlConfigReader.<init>(XmlConfigReader.java:38)

at com.bjpowernode.drp.util.XmlConfigReader.getInstance(XmlConfigReader.java:58)

at com.bjpowernode.drp.util.DbUtil.getConnection(DbUtil.java:37)

at com.bjpowernode.drp.util.IdGenerator.generate(IdGenerator.java:34)

at com.bjpowernode.drp.util.IdGenerator.main(IdGenerator.java:79)

Nested exception: java.lang.ClassNotFoundException: org/apache/xerces/parsers/SAXParser

at org.dom4j.io.SAXHelper.createXMLReader(SAXHelper.java:98)

at org.dom4j.io.SAXReader.createXMLReader(SAXReader.java:894)

at org.dom4j.io.SAXReader.getXMLReader(SAXReader.java:715)

at org.dom4j.io.SAXReader.read(SAXReader.java:435)

at org.dom4j.io.SAXReader.read(SAXReader.java:343)

at com.bjpowernode.drp.util.XmlConfigReader.<init>(XmlConfigReader.java:38)

at com.bjpowernode.drp.util.XmlConfigReader.getInstance(XmlConfigReader.java:58)

at com.bjpowernode.drp.util.DbUtil.getConnection(DbUtil.java:37)

at com.bjpowernode.drp.util.IdGenerator.generate(IdGenerator.java:34)

at com.bjpowernode.drp.util.IdGenerator.main(IdGenerator.java:79)

Exception in thread "main" java.lang.NullPointerException

at java.lang.Class.forName0(Native Method)

at java.lang.Class.forName(Class.java:169)

at com.bjpowernode.drp.util.DbUtil.getConnection(DbUtil.java:38)

at com.bjpowernode.drp.util.IdGenerator.generate(IdGenerator.java:34)

at com.bjpowernode.drp.util.IdGenerator.main(IdGenerator.java:79)

 解決方法：引入xercesImpl.jar

xml-apis.jar
xercesImpl.jar
    解析XML檔案，對映檔案是XML格式，資料庫配置檔案也可以是XML格式。解析XML的技術可以分為兩類那就是SAX和DOM。實現解析XML檔案的功能很方便，我們可以通過下載第三方的一些工具包如xml-apis.jar和 xercesImpl.jar等，也可以使用JDK自帶的工具類DocumentBuilderFactory、DocumentBuilder、 Document、Element等等。通過這些類我們可以把XML檔案的資訊讀入記憶體並通過類中的某些方法獲取指定節點的名字、值、屬性名、屬性值這些資訊。

      java 系統之中使用的是JDom,Xerces解析器解析XML。在1.4之前，屬於java的擴充套件部分，而在1.5之後，已經加入到了JDK之中了。