POI操作Excel报错java.lang.NoSuchMethodError
1、检查报错日志如下
2、定位错误
1、可能是编码出问题，检查编码
3、生成EXCEL文件类是否有如下编码：
response.setContentType("application/x-msdownload");
response.setCharacterEncoding("utf-8");
response.setHeader("Content-Disposition", "attachment;filename=" + new String( fileName.getBytes("gb2312"), "ISO8859-1" ));
4、检查导入poi的包是否存在多个版本，删除多余版本。
5、<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>3.17</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml-schemas</artifactId>
<version>3.17</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.17</version>
</dependency>
6、如果不确定自己引用的是哪个包，可以用一下代码检测class文件走哪个jar包
7、检测class文件代码：
ClassLoader classloader =
org.apache.poi.poifs.filesystem.POIFSFileSystem.class.getClassLoader();
URL res = classloader.getResource(
"org/apache/poi/poifs/filesystem/POIFSFileSystem.class");
String path = res.getPath();
System.out.println("POI Core came from " + path);
classloader = org.apache.poi.POIXMLDocument.class.getClassLoader();
res = classloader.getResource("org/apache/poi/POIXMLDocument.class");
path = res.getPath();
System.out.println("POI OOXML came from " + path);
classloader = org.apache.poi.hslf.HSLFSlideShow.class.getClassLoader();
res = classloader.getResource("org/apache/poi/hslf/HSLFSlideShow.class");
path = res.getPath();
System.out.println("POI Scratchpad came from " + path);
8、将旧的jar从Java build path中删除掉，把workspace里面的包删了再把project clean一下，然后重新部署。