问题

目前我正在尝试通过Apache Camel（2.25.1）轮询读取一个Excel文件。
这意味着该方法通过String获取文件内容：

@Handler
public void processFile(@Body String body) {

为了读取Excel文件，我使用Apache POI和POI-ooxml（均为4.1.2版本）。

然而，直接使用String：

WorkbookFactory.create(new ByteArrayInputStream(body.getBytes(Charset.forName("UTF-8"))))

会抛出"java.io.IOException: ZIP entry size is too large or invalid"。

使用其他编码的String：

WorkbookFactory.create(new ByteArrayInputStream(body.getBytes()))
会抛出"org.apache.poi.openxml4j.exceptions.NotOfficeXmlFileException: No valid entries or contents found, this is not a valid OOXML (Office Open XML) file"。

此外，我尝试过：

File file = exchange.getIn().getBody(File.class);
Workbook workbook = new XSSFWorkbook(new FileInputStream(file));

可能是因为文件是从FTP服务器读取的，会抛出java.io.FileNotFoundException：无效的文件路径。

然而，下面的代码可以工作：

URL url = new URL(fileFtpPath);
URLConnection urlc = url.openConnection();
InputStream ftpIs = urlc.getInputStream();
Workbook workbook = new XSSFWorkbook(ftpIs);

但我更倾向于不自己连接到FTP服务器，因为Camel已经读取了文件并且所需的Excel内容可用（在String body中）。
是否有任何方法可以使用Apache POI从String中读取Excel文件的内容？

@Handler
public void processFile(@Body String body) {

WorkbookFactory.create(new ByteArrayInputStream(body.getBytes(Charset.forName("UTF-8"))))

WorkbookFactory.create(new ByteArrayInputStream(body.getBytes()))

File file = exchange.getIn().getBody(File.class);
Workbook workbook = new XSSFWorkbook(new FileInputStream(file));

URL url = new URL(fileFtpPath);
URLConnection urlc = url.openConnection();
InputStream ftpIs = urlc.getInputStream();
Workbook workbook = new XSSFWorkbook(ftpIs);

答案1

得分: 0

我有我的路由在XML中，所以我使用Groovy来处理Excel文件，也许你会发现它有帮助。

import org.apache.poi.ss.usermodel.WorkbookFactory

def workbook = WorkbookFactory.create(request.getBody(File.class))
def sheet = workbook.getSheetAt(0)
...

还有另一种方法，通常用于处理大型Excel文件，我们在处理流时会使用。要走这条路，我们应该从org.apache.poi.xssf.eventusermodel实现XSSFSheetXMLHandler.SheetContentsHandler：

你可以在这个SO问题中找到原始POI示例的副本，由于某种原因，它最近已从poi svn中删除。如果你感兴趣，我的Groovy版本看起来像这样：

import org.apache.poi.openxml4j.opc.OPCPackage
import org.apache.poi.ooxml.util.SAXHelper
import org.apache.poi.xssf.eventusermodel.XSSFReader
import org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler
import org.apache.poi.xssf.eventusermodel.ReadOnlySharedStringsTable
import org.apache.poi.hssf.usermodel.HSSFDataFormatter
import org.xml.sax.InputSource

class MyHandler implements XSSFSheetXMLHandler.SheetContentsHandler {
    ...
}

def pkg = OPCPackage.open(request.getBody(InputStream.class))
def xssfReader = new XSSFReader(pkg)
def sheetParser = SAXHelper.newXMLReader()

def handler = new XSSFSheetXMLHandler(xssfReader.getStylesTable(), null, new ReadOnlySharedStringsTable(pkg), MyHandler, new HSSFDataFormatter(), false)
sheetParser.setContentHandler(handler)
sheetParser.parse(new InputSource(xssfReader.getSheetsData().next()))

<details>
<summary>英文:</summary>

I have my routes in XML, so I use groovy to process excel files, perhaps you may find it helpful

import org.apache.poi.ss.usermodel.WorkbookFactory

def workbook = WorkbookFactory.create(request.getBody(File.class))
def sheet = workbook.getSheetAt(0)
...

There is another approach usually using for large excel files where we are dealing with a stream. To go this way we should implement `XSSFSheetXMLHandler.SheetContentsHandler` from `org.apache.poi.xssf.eventusermodel`   
You could find a copy of the original POI example in this [SO question][1], for some reason it was recently deleted from [poi svn][2]. If you are interested, my groovy version looks like this

import org.apache.poi.openxml4j.opc.OPCPackage
import org.apache.poi.ooxml.util.SAXHelper
import org.apache.poi.xssf.eventusermodel.XSSFReader
import org.apache.poi.xssf.eventusermodel.XSSFSheetXMLHandler
import org.apache.poi.xssf.eventusermodel.ReadOnlySharedStringsTable
import org.apache.poi.hssf.usermodel.HSSFDataFormatter
import org.xml.sax.InputSource

class MyHandler implements XSSFSheetXMLHandler.SheetContentsHandler {
...
}

def pkg = OPCPackage.open(request.getBody(InputStream.class))
def xssfReader = new XSSFReader(pkg)
def sheetParser = SAXHelper.newXMLReader()

def handler = new XSSFSheetXMLHandler(xssfReader.getStylesTable(), null, new ReadOnlySharedStringsTable(pkg), MyHandler, new HSSFDataFormatter(), false)
sheetParser.setContentHandler(handler)
sheetParser.parse(new InputSource(xssfReader.getSheetsData().next()))

  [1]: https://stackoverflow.com/questions/51447162/reading-big-xls-and-xlsx-files
  [2]: https://svn.apache.org/repos/asf/poi/trunk/src/examples/

</details>



# 答案2
**得分**: 0

你可以直接将消息体转换为InputStream，然后将其传递给XSSFWorkbook构造函数。

```java
Exchange exchange = consumerTemplate.receive("file://C:/ftp/?noop=true", pollCount);
InputStream stream = exchange.getIn().getBody(InputStream.class);

XSSFWorkbook workbook = new XSSFWorkbook(stream);

XSSFSheet sheet = workbook.getSheetAt(0);

        Exchange exchange = consumerTemplate.receive("file://C:/ftp/?noop=true", pollCount);
    	InputStream stream = exchange.getIn().getBody(InputStream.class);

    	XSSFWorkbook workbook = new XSSFWorkbook(stream);
    	       	
    	XSSFSheet sheet = workbook.getSheetAt(0);