运行报这个错是为什么？

源自：2-2 使用 DOM 解析 XML 文件的属性名和属性值

[Fatal Error] books.xml:1:42: The encoding declaration is required in the text declaration.

org.xml.sax.SAXParseException: The encoding declaration is required in the text declaration.

at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:249)

at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:284)

at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:180)

at com.imooc.DomTest.main(DomTest.java:28)

提问者：粒子酱 2016-09-14 10:33