Java用POI读取excel文件，报异常：NotOLE2FileException: Invalid header signature； read xxx, expected 0xE11AB1A1

背景： 系统支持excel的两种文件上传 xlsx 和 xls 

问题：今天上传了一个 xlsx的文档 ，系统错误为

org.apache.poi.openxml4j.exceptions.OLE2NotOfficeXmlFileException: The supplied data appears to be in the OLE2 Format. 
You are calling the part of POI that deals with OOXML (Office Open XML) Documents. You need to call a different part of POI
 to process this data (eg HSSF instead of XSSF)
	at org.apache.poi.openxml4j.opc.internal.ZipHelper.verifyZipHeader(ZipHelper.java:147) ~[poi-ooxml-4.1.0.jar!/:4.1.0]
	at org.apache.poi.openxml4j.opc.internal.ZipHelper.openZipStream(ZipHelper.java:175) ~[poi-ooxml-4.1.0.jar!/:4.1.0]
	at org.apache.poi.openxml4j.opc.ZipPackage.(ZipPackage.java:104) ~[poi-ooxml-4.1.0.jar!/:4.1.0]
	at org.apache.poi.openxml4j.opc.OPCPackage.open(OPCPackage.java:301) ~[poi-ooxml-4.1.0.jar!/:4.1.0]
	at org.apache.poi.ooxml.util.PackageHelper.open(PackageHelper.java:37) ~[poi-ooxml-4.1.0.jar!/:4.1.0]
	at org.apache.poi.xssf.usermodel.XSSFWorkbook.(XSSFWorkbook.java:303) ~[poi-ooxml-4.1.0.jar!/:4.1.0

正常系统逻辑处理为：

  private Workbook getWorkbook(String filePath, InputStream is) throws IOException {
        String fileExt = this.fileExt(filePath);

        return "xlsx".equals(fileExt) ? new XSSFWorkbook(is) : "xls".equals(fileExt) ? new HSSFWorkbook(is) : null;
    }

这是线上一个问题，客户说上传错误 但是不肯将文件发我们，通过分析错误原因 看到，是后缀名称和解析方式出了问题，

也就是手动修改文件名后不匹配导致的。

找到原因就好说了，尝试catch里面处理异常

  if( "xlsx".equals(fileExt)){
            try {
                workbook = new XSSFWorkbook(is);
            }catch (Exception e){
                log.error("我草，xlsx是手动改的后缀 而不是通过另存为的方式");
                workbook = new HSSFWorkbook(is);
            }
        } else if ("xls".equals(fileExt) ){
            try {
                workbook = new HSSFWorkbook(is);
            }catch (Exception e){
                log.error("我草，xls是手动改的后缀 而不是通过另存为的方式");
                workbook = new XSSFWorkbook(is);
            }
        }

尝试仍然不好用，其实这种事指标不治本，文件的本身字节码并没有改变，但是通过改变workboor获取方式，仍是存在问题的。

再次优化一下，使用工厂模式创建Workbook：

        // 通过文件流工厂方式来处理 
        Workbook workbook = WorkbookFactory.create(is);

看一下POI的源码:

public static Workbook create(InputStream inp, String password) throws IOException, InvalidFormatException, EncryptedDocumentException {
        InputStream is = FileMagic.prepareToCheckMagic(inp);
        FileMagic fm = FileMagic.valueOf(is);
        switch(fm) {
        case OLE2:
            NPOIFSFileSystem fs = new NPOIFSFileSystem(is);
            return create(fs, password);
        case OOXML:
            return new XSSFWorkbook(OPCPackage.open(is));
        default:
            throw new InvalidFormatException("Your InputStream was neither an OLE2 stream, nor an OOXML stream");
        }
    }

通过debug调试 可得出

xlsx 对应的FileMagic为 OOXML
xls 对应的FileMagic为 OLE2

FileMagic 类的代码可参考如下：

public enum FileMagic {
    /** OLE2 / BIFF8+ stream used for Office 97 and higher documents */
    OLE2(HeaderBlockConstants._signature),
    /** OOXML / ZIP stream */
    OOXML(OOXML_FILE_HEADER),
    /** XML file */
    XML(RAW_XML_FILE_HEADER),
    /** BIFF2 raw stream - for Excel 2 */
    BIFF2(new byte[]{
        0x09, 0x00, // sid=0x0009
        0x04, 0x00, // size=0x0004
        0x00, 0x00, // unused
        0x70, 0x00  // 0x70 = multiple values
    }),
    /** BIFF3 raw stream - for Excel 3 */
    BIFF3(new byte[]{
     // 省略
}

 

OLE2类型的orkbook实现方式：

里面有个password 默认为 null ,但是我也没有找到 何时调用password不为空的时候 估计是预留的吧，有兴趣的可以自己看看

 // 第一步先转化为POIFSFileSystem 
POIFSFileSystem fs = new POIFSFileSystem(is);
 // 第二步调用this.create(fs, password);
  public static Workbook create(final DirectoryNode root, String password) throws IOException {
        // Encrypted OOXML files go inside OLE2 containers, is this one?
        if (root.hasEntry(Decryptor.DEFAULT_POIFS_ENTRY)) {
            InputStream stream = null;
            try {
                stream = DocumentFactoryHelper.getDecryptedStream(root, password);

                return createXSSFWorkbook(stream);
            } finally {
                IOUtils.closeQuietly(stream);

                // as we processed the full stream already, we can close the filesystem here
                // otherwise file handles are leaked
                root.getFileSystem().close();
            }
        }

        // If we get here, it isn't an encrypted PPTX file
        // So, treat it as a regular HSLF PPT one
        boolean passwordSet = false;
        if (password != null) {
            Biff8EncryptionKey.setCurrentUserPassword(password);
            passwordSet = true;
        }
        try {
            return createHSSFWorkbook(root);
        } finally {
            if (passwordSet) {
                Biff8EncryptionKey.setCurrentUserPassword(null);
            }
        }
    }             

OOXML类型的orkbook实现方式：

private static Workbook createWorkbook(String factoryClass, Object[] args) throws IOException, EncryptedDocumentException {
        try {
            Class clazz = WorkbookFactory.class.getClassLoader().loadClass(factoryClass);
            Class[] argsClz = new Class[args.length];
            int i=0;
            for (Object o : args) {
                Class c = o.getClass();
                if (Boolean.class.isAssignableFrom(c)) {
                    c = boolean.class;
                } else if (InputStream.class.isAssignableFrom(c)) {
                    c = InputStream.class;
                } else if (File.class.isAssignableFrom(c)) {
                    c = File.class;
                }
                argsClz[i++] = c;
            }
            Method m = clazz.getMethod("createWorkbook", argsClz);
            return (Workbook)m.invoke(null, args);
        } catch (InvocationTargetException e) {
            Throwable t = e.getCause();
            if (t instanceof IOException) {
                throw (IOException)t;
            } else if (t instanceof EncryptedDocumentException) {
                throw (EncryptedDocumentException)t;
            } else if (t instanceof OldFileFormatException) {
                throw (OldFileFormatException)t;
            } else if (t instanceof RuntimeException) {
                throw (RuntimeException)t;
            } else {
                throw new IOException(t.getMessage(), t);
            }
        } catch (Exception e) {
            throw new IOException(e);
        }
    }