java - Apache POI XSSFWorkbook 为文件抛出 NullPointerException

Question

我已经用类似的问题检查了这里的所有可能的问题，但没有一个解决方案有效。我觉得我错过了一些非常明显的东西，但我就是看不到它。

我在 Windows 10 上，使用 Eclipse 2019，以及最新的 Apache POI jar 文件(不是 maven)和 xmlbeans 版本 3.1.0。我想读取一个 xlsx 文件，但是每次我运行我的代码(这是我在多个网站和视频上看到使用并成功运行的基本示例)时，我在创建工作簿的行收到“NullPointerException” :

import java.io.File;
//import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
//import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class excelImportTest {


    public static void main (String args[]) throws IOException, InvalidFormatException {

      // Linking file to Workbook
      // ****Where exception is called every time****
      XSSFWorkbook wb = new XSSFWorkbook(new File("C:\\Users\\Owner\\Downloads\\TestData.xlsx"));

      // Pulling sheet from Workbook
      XSSFSheet sheet = wb.getSheetAt(0);

      // Get iterator to all the rows in current sheet
      Iterator<Row> rowIterator = sheet.iterator();

      // Traversing over each row of XLSX file
      while (rowIterator.hasNext()) {
          Row row = rowIterator.next();

          // For each row, iterate through each columns
          Iterator<Cell> cellIterator = row.cellIterator();

          while (cellIterator.hasNext()) {
              Cell cell = cellIterator.next();
              switch(cell.getCellType()) {
              case STRING:
                  System.out.print(cell.getStringCellValue() + "\t");
                  break;
              case NUMERIC:
                  System.out.print(cell.getNumericCellValue() + "\t");
                  break;
              case BOOLEAN:
                  System.out.print(cell.getBooleanCellValue() + "\t");
                  break;
              default :
              }
          }
      }
      wb.close();

这是我收到的异常:

Exception in thread "main" java.lang.ExceptionInInitializerError
    at sun.misc.Unsafe.ensureClassInitialized(Native Method)
    at sun.reflect.UnsafeFieldAccessorFactory.newFieldAccessor(Unknown Source)
    at sun.reflect.ReflectionFactory.newFieldAccessor(Unknown Source)
    at java.lang.reflect.Field.acquireFieldAccessor(Unknown Source)
    at java.lang.reflect.Field.getFieldAccessor(Unknown Source)
    at java.lang.reflect.Field.get(Unknown Source)
    at org.apache.xmlbeans.XmlBeans.typeSystemForClassLoader(XmlBeans.java:775)
    at org.openxmlformats.schemas.drawingml.x2006.main.ThemeDocument.<clinit>(Unknown Source)
    at org.openxmlformats.schemas.drawingml.x2006.main.ThemeDocument$Factory.parse(Unknown Source)
    at org.apache.poi.xssf.model.ThemesTable.<init>(ThemesTable.java:86)
    at org.apache.poi.ooxml.POIXMLFactory.createDocumentPart(POIXMLFactory.java:61)
    at org.apache.poi.ooxml.POIXMLDocumentPart.read(POIXMLDocumentPart.java:684)
    at org.apache.poi.ooxml.POIXMLDocument.load(POIXMLDocument.java:180)
    at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:288)
    at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:325)
    at excelImportTest.main(excelImportTest.java:62)
Caused by: java.lang.RuntimeException: Could not instantiate SchemaTypeSystemImpl (java.lang.reflect.InvocationTargetException): is the version of xbean.jar correct?
    at schemaorg_apache_xmlbeans.system.sD023D6490046BA0250A839A9AD24C443.TypeSystemHolder.loadTypeSystem(Unknown Source)
    at schemaorg_apache_xmlbeans.system.sD023D6490046BA0250A839A9AD24C443.TypeSystemHolder.<clinit>(Unknown Source)
    ... 16 more
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    ... 18 more
Caused by: java.lang.NullPointerException
    at org.apache.xmlbeans.impl.schema.ClassLoaderResourceLoader.getResourceAsStream(ClassLoaderResourceLoader.java:33)
    at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl$XsbReader.getLoaderStream(SchemaTypeSystemImpl.java:2249)
    at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl$XsbReader.<init>(SchemaTypeSystemImpl.java:1522)
    at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl.initFromHeader(SchemaTypeSystemImpl.java:273)
    at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl.<init>(SchemaTypeSystemImpl.java:185)
    ... 22 more

我已经尝试了所有我能想到的选项组合和我在网上找到的建议:

我创建了一个单独的 FileInputStream(new File(...))，并运行了一个 if 语句来查看它是否为空。这返回了“not null”，但是当它到达

上方的行时我仍然得到异常

我尝试使用嵌套的 new FileInputStream(new File(...)) 格式运行该行，并收到相同的错误

我一直在使用 try-catch 块来处理异常，但在中止程序之前它似乎没有标记异常

我尝试使用包含 Apache-POI 的 OCPPackage.open(new File(...)) 方法，并得到相同的错误

我是否遗漏了任何明显的方法，或者这是否源于我的设置中的其他问题？

编辑

由于看起来我的问题可能出在我引用的 .jar 文件中，以下是我作为文件构建路径的一部分的内容:

Answer 1

我认为您没有正确添加 jar 。

首先去这个网址:https://archive.apache.org/dist/poi/release/bin/并下载 poi-bin-4.1.2-20200217.zip从那里。

现在解压缩 zip 并将这个 jars 添加到你的项目中，用红色标记。







我已经测试了您的代码及其工作原理。

import java.io.File;
import java.io.IOException;
import java.util.Iterator;

import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class Testing {
    public static void main(String args[]) throws IOException, InvalidFormatException {

        // Linking file to Workbook
        // ****Where exception is called every time****
        XSSFWorkbook wb = new XSSFWorkbook(new File("C:\\Users\\Anish\\Downloads\\TestData.xlsx"));

        System.out.println("Workbook loaded");

        // Pulling sheet from Workbook
        XSSFSheet sheet = wb.getSheetAt(0);

        // Get iterator to all the rows in current sheet
        Iterator<Row> rowIterator = sheet.iterator();

        // Traversing over each row of XLSX file
        while (rowIterator.hasNext()) {
            Row row = rowIterator.next();

            // For each row, iterate through each columns
            Iterator<Cell> cellIterator = row.cellIterator();

            while (cellIterator.hasNext()) {
                Cell cell = cellIterator.next();
                switch (cell.getCellType()) {
                case STRING:
                    System.out.print(cell.getStringCellValue() + "\t");
                    break;
                case NUMERIC:
                    System.out.print(cell.getNumericCellValue() + "\t");
                    break;
                case BOOLEAN:
                    System.out.print(cell.getBooleanCellValue() + "\t");
                    break;
                default:
                }
            }
        }
        wb.close();

    }
}

输出 :



现在，如果您在项目中使用maven。那么，您不需要在类路径上添加jar。

简单地，在 pom.xml 中添加这个依赖项.

<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi</artifactId>
    <version>4.1.2</version>
</dependency>
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>4.1.2</version>
</dependency>