我写的程序老是出现这么错误，百思无果，复制老师的代码之后依然出现该错误（后面就连Xml内容都一样）。以下是错误

java.net.MalformedURLException: unknown protocol: g

at java.net.URL.<init>(URL.java:600)

at java.net.URL.<init>(URL.java:490)

at java.net.URL.<init>(URL.java:439)

at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(XMLEntityManager.java:620)

at com.sun.org.apache.xerces.internal.impl.XMLVersionDetector.determineDocVersion(XMLVersionDetector.java:148)

at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:805)

at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:770)

at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)

at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:243)

at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)

at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:177)

at com.imooc.dom.Domtext.kjtext(Domtext.java:26)

at com.imooc.dom.Domtext.main(Domtext.java:132)