岂料我受到了挫伤，scanner.hasNextLine()一直为false，于是我百思不得姐啊，经过调试发现，Scanner内部有java.nio.charset.UnmappableCharacterException，就百度了一下，没找到答案，google访问不了，想起公司的网络是香港的，就远程上去，还好在*上找到了答案。O(∩_∩)O~~
原来用改动下面一行就OK啦，不解释，你懂的，不懂就去*。
Scanner scanner=new Scanner(new File(filePath),"UTF-8");
Java Code：
public void output(String filePath) throws FileNotFoundException{Scanner scanner=new Scanner(new File(filePath));String str=null;while(scanner.hasNextLine()){str=scanner.nextLine();if(str.indexOf("FileName")>0){System.out.println(str.substring(str.indexOf(">")+1, str.lastIndexOf("<")));}}scanner.close();}
File content：
<File><MediaFileType>0</MediaFileType><FileName>周杰伦 - 爱在西元前.mp3</FileName><FilePath>D:\music\</FilePath><FileSize>5623610</FileSize><Duration>234292</Duration><Hash>0589341ba15528a4c63e36c49a3c0e45</Hash><Lyric>E:\KuGou\Lyric\周杰伦 - 爱在西元前-0589341ba15528a4c63e36c49a3c0e45.krc</Lyric><Bitrate>192004</Bitrate><MandatoryBitrate>0</MandatoryBitrate></File>
Java Code after modify：
public void output(String filePath) throws FileNotFoundException{Scanner scanner=new Scanner(new File(filePath),"UTF-8");//Always explicitly pass a charset when working with textString str=null;while(scanner.hasNextLine()){str=scanner.nextLine();if(str.indexOf("FileName")>0)System.out.println(str.substring(str.indexOf(">")+1, str.lastIndexOf("<")));}//It‘s better to check IOException when working with Scanner(PS:find UnmappableCharacterException took me more time,finally by debug to found )IOException ioException = scanner.ioException();if (ioException != null) {ioException.printStackTrace();}scanner.close();}