为文件抛出NullPointerException的Apache POI XSSFWorkbook

Question

我已经用类似的问题检查了这里的每一个可能的问题，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，但我就是看不出来。

我在Windows10上，使用Eclipse2019，以及最新的Apache POI jar文件（不是maven)，其中包含xmlbeans版本3.1.0。我想读取一个xlsx文件，但每次运行代码（这是一个基本的示例，我已经在多个网站和视频中成功地使用并运行）时，我都会在创建工作簿的行处收到一个“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();

以下是我收到的异常：

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

我已经尝试了我能想到的每一种选择组合和我在网上找到的建议：

• 我创建了一个单独的FileInputStream（new File(...))，并运行一个if语句查看它是否为null。这返回了“not null”，但是当它到达
上面的行时，我仍然得到了异常
• 我尝试使用嵌套的新FileInputStream（new File(...))运行该行格式，并收到相同的错误
• 我一直在为异常使用try-catch块，但它似乎没有在中止程序之前标记异常
• 我尝试使用Apache-POI包含的ocppackage.open（new File（...））方法，并得到相同的错误

Answer 1

我想你没有正确地添加罐子。

首先转到这个url:https://archive.apache.org/dist/poi/release/bin/并从那里下载poi-bin-4.1.2-20200217.zip。

现在提取zip并将这些jar添加到用红色标记的项目中。

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();

    }
}

<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>