为什么我不能在Apache POI中将一个工作簿链接到另一个工作簿？

时间：2017-10-01 00:49:44

标签： java excel charts apache-poi

我有一个包含一些数据的工作簿。我正在使用该工作簿并根据其他工作簿中的数据创建另一个带有折线图的工作簿。代码运行正常，但每当我打开图形文件时，我都会收到警告We can't update some of the links in your workbook right now。如果单击警告菜单中的Edit Links...按钮，则表明无法找到数据工作簿。如果我点击Change Source...，然后选择正确的工作簿，那么它可以正常工作。为什么是这样？ POI可以不保留两个文件之间的链接吗？

我的代码：

创建数据工作簿：

public static XSSFWorkbook createDataSpreadsheet(String name, long[] data) {
    XSSFWorkbook workbook = new XSSFWorkbook();
    XSSFSheet sheet = workbook.createSheet(name);

    int rowNumber = 0;
    for(int i = 1; i < data.length + 1; i++) {
        Row row = sheet.createRow(rowNumber++);

        int columnNumber = 0;
        row.createCell(columnNumber++).setCellValue(i);
        row.createCell(columnNumber++).setCellValue(data[i - 1]);
    }

    return workbook;
}

要创建图表工作簿：

public static XSSFWorkbook createLineChart(String name, XSSFWorkbook data) {
    XSSFWorkbook workbook = new XSSFWorkbook();

    XSSFSheet sheet = workbook.createSheet(name);

    XSSFDrawing drawing = sheet.createDrawingPatriarch();
    XSSFClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 0, 15, 15);
    XSSFChart lineChart = drawing.createChart(anchor);

    XSSFChartLegend legend = lineChart.getOrCreateLegend();
    legend.setPosition(LegendPosition.BOTTOM); 

    LineChartData chartData = lineChart.getChartDataFactory().createLineChartData();     
    ChartAxis bottomAxis = lineChart.getChartAxisFactory().createCategoryAxis(AxisPosition.BOTTOM);
    ValueAxis leftAxis = lineChart.getChartAxisFactory().createValueAxis(AxisPosition.LEFT);
    leftAxis.setCrosses(AxisCrosses.AUTO_ZERO);

    XSSFSheet dataSheet = data.getSheetAt(0);
    ChartDataSource<Number> xData = DataSources.fromNumericCellRange(dataSheet, new CellRangeAddress(0, dataSheet.getLastRowNum(), 0, 0));
    ChartDataSource<Number> yData = DataSources.fromNumericCellRange(dataSheet, new CellRangeAddress(0, dataSheet.getLastRowNum(), 1, 1));

    LineChartSeries chartSeries = chartData.addSeries(xData, yData);
    chartSeries.setTitle("A title");

    lineChart.plot(chartData, new ChartAxis[] { bottomAxis, leftAxis });

    return workbook;
}

1 个答案:

答案 0 :(得分：5)

直到现在才在XSSF中创建外部链接。有ExternalLinksTable但是如果你查看Uses of this Class，那么你会看到只提供阅读那些外部链接但不创建和写作。

所以我们需要处理低级对象。我们需要了解Office OpenXML *.xlsx ZIP存档中此外部链接的内部依赖关系。

以下工作只要两个工作簿都存储在同一目录中。

代码主要是您提供的代码，其中添加了一种方法，用于创建指向另一个工作簿中工作表的外部链接。这种方法使用的是低级对象，并不是很常用，但它应该显示原理。

您的代码的其他更改也会被评论。

import java.io.*;

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.usermodel.charts.*;
import org.apache.poi.ss.util.CellRangeAddress;

import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.xssf.model.ExternalLinksTable;

import org.apache.poi.openxml4j.opc.*;
import org.apache.poi.POIXMLDocumentPart;

import org.openxmlformats.schemas.spreadsheetml.x2006.main.ExternalLinkDocument;

import static org.apache.poi.POIXMLTypeLoader.DEFAULT_XML_OPTIONS;

public class CreateExcelLineChartDataAnotherWorkbook {

 private static String datawbname = "DataWB.xlsx";
 private static String chartwbname = "ChartWB.xlsx";

 public CreateExcelLineChartDataAnotherWorkbook() throws Exception {
  Workbook datawb = createDataSpreadsheet("ChartDataSheet");
  saveWorkbook(datawb, "/home/axel/Dokumente/"+datawbname);

  Workbook chartwb = createLineChart("ChartSheet", (XSSFWorkbook)datawb);
  saveWorkbook(chartwb, "/home/axel/Dokumente/"+chartwbname);
 }

 //your method only partially changed to have sample data
 public XSSFWorkbook createDataSpreadsheet(String name) {
  Workbook workbook = new XSSFWorkbook();
  Sheet sheet = workbook.createSheet(name);

  int rowNumber = 0;
  for(int i = 0; i < 20; i++) {
   Row row = sheet.createRow(rowNumber++);

   int columnNumber = 0;
   row.createCell(columnNumber++).setCellValue(Math.PI*i/10*2);
   row.createCell(columnNumber++).setCellValue(Math.sin(Math.PI*i/10*2));
  }

  return (XSSFWorkbook)workbook;
 }

 //method for saving the workbooks
 public void saveWorkbook(Workbook wb, String path) throws Exception {
  wb.write(new FileOutputStream(path));
  wb.close();
 }

 //your method changes are commented
 public XSSFWorkbook createLineChart(String name, XSSFWorkbook data) throws Exception {
  Workbook workbook = new XSSFWorkbook();

  //create the external link to datawbname
  int extwbid = 1;
  createExternalLinkToWorksheet((XSSFWorkbook)workbook, datawbname, "ChartDataSheet", "rId"+extwbid);

  Sheet sheet = workbook.createSheet(name);

  Drawing drawing = sheet.createDrawingPatriarch();
  ClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 0, 15, 15);
  Chart lineChart = drawing.createChart(anchor);

  ChartLegend legend = lineChart.getOrCreateLegend();
  legend.setPosition(LegendPosition.BOTTOM); 

  LineChartData chartData = lineChart.getChartDataFactory().createLineChartData();     
  ChartAxis bottomAxis = lineChart.getChartAxisFactory().createCategoryAxis(AxisPosition.BOTTOM);
  ValueAxis leftAxis = lineChart.getChartAxisFactory().createValueAxis(AxisPosition.LEFT);
  leftAxis.setCrosses(AxisCrosses.AUTO_ZERO);

  Sheet dataSheet = data.getSheetAt(0);
  ChartDataSource<Number> xData = DataSources.fromNumericCellRange(dataSheet, new CellRangeAddress(0, dataSheet.getLastRowNum(), 0, 0));
  ChartDataSource<Number> yData = DataSources.fromNumericCellRange(dataSheet, new CellRangeAddress(0, dataSheet.getLastRowNum(), 1, 1));

  LineChartSeries chartSeries = chartData.addSeries(xData, yData);
  chartSeries.setTitle("A title");

  lineChart.plot(chartData, new ChartAxis[] { bottomAxis, leftAxis });

  //since dataSheet is an external sheet, the formula in the org.openxmlformats.schemas.drawingml.x2006.chart.CTNumRef
  //must be prefixed with [1], where 1 is the Id of the linked workbook 
  String catref = ((XSSFChart)lineChart).getCTChart().getPlotArea().getLineChartArray(0).getSerArray(0).getCat().getNumRef().getF();
  ((XSSFChart)lineChart).getCTChart().getPlotArea().getLineChartArray(0).getSerArray(0).getCat().getNumRef().setF("[" + extwbid + "]" + catref);
  String valref = ((XSSFChart)lineChart).getCTChart().getPlotArea().getLineChartArray(0).getSerArray(0).getVal().getNumRef().getF();
  ((XSSFChart)lineChart).getCTChart().getPlotArea().getLineChartArray(0).getSerArray(0).getVal().getNumRef().setF("[" + extwbid + "]" + valref);

  return (XSSFWorkbook)workbook;
 }

 //method for creating a external link to a sheet in another workbook
 public void createExternalLinkToWorksheet(XSSFWorkbook workbook, String wbname, String sheetname, String rIdExtWb) throws Exception {
  OPCPackage opcpackage = workbook.getPackage();

  //creating /xl/externalLinks/externalLink1.xml having link to externalBook with external sheetName
  PackagePartName partname = PackagingURIHelper.createPartName("/xl/externalLinks/externalLink1.xml");
  PackagePart part = opcpackage.createPart(partname, "application/vnd.openxmlformats-officedocument.spreadsheetml.externalLink+xml");
  POIXMLDocumentPart externallinkstable = new POIXMLDocumentPart(part) {
   @Override
   protected void commit() throws IOException {
    PackagePart part = getPackagePart();
    OutputStream out = part.getOutputStream();
    try {
     ExternalLinkDocument doc = ExternalLinkDocument.Factory.parse(
      "<externalLink xmlns=\"http://schemas.openxmlformats.org/spreadsheetml/2006/main\">"
     +"<externalBook xmlns:r=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships\" r:id=\""+ rIdExtWb + "\">"
     +"<sheetNames><sheetName val=\"" + sheetname + "\"/></sheetNames>"
     +"</externalBook>"
     +"</externalLink>"
     );
     doc.save(out, DEFAULT_XML_OPTIONS);
     out.close();
    } catch (Exception ex) {
     ex.printStackTrace();
    }; 
   }
  };
  //creating the relation to the external workbook in /xl/externalLinks/_rels/externalLink1.xml.rels
  PackageRelationship packrelship = part.addRelationship(new java.net.URI(wbname), TargetMode.EXTERNAL, "http://schemas.openxmlformats.org/officeDocument/2006/relationships/externalLinkPath", rIdExtWb);

  //creating the relation to /xl/externalLinks/externalLink1.xml in /xl/_rels/workbook.xml.rels
  String rIdExtLink = "rId" + (workbook.getRelationParts().size()+1);
  workbook.addRelation(rIdExtLink, XSSFRelation.EXTERNAL_LINKS, externallinkstable);

  //creating the <externalReferences><externalReference .../> in /xl/workbook.xml
  workbook.getCTWorkbook().addNewExternalReferences().addNewExternalReference().setId(rIdExtLink);

 }

 public static void main(String[] args) throws Exception {
  CreateExcelLineChartDataAnotherWorkbook mainObject = new CreateExcelLineChartDataAnotherWorkbook();
 }

}

我的新代码提供了一个类MyXSSFWorkbook，它通过为链接的工作簿和工作表创建XSSFWorkbook的方法扩展了ExternalLinksTable。此代码确实创建了ExternalLinksTable，并使用反射将此ExternalLinksTable添加到ExternalLinksTable中的XSSFWorkbook列表中。因此，可以进一步使用工作簿。

该方法只需要链接工作簿和链接表的名称。它管理自己的ID。它返回ExternalLinksTable的Id（作为/xl/externalLinks/externalLink1.xml中的1。因此，此Id可用作公式中的外部工作簿引用（作为[1]ChartDataSheet!$A$1:$A$20中的1）。

import java.io.*;

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.usermodel.charts.*;
import org.apache.poi.ss.util.CellRangeAddress;

import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.xssf.model.ExternalLinksTable;

import org.apache.poi.openxml4j.opc.*;
import org.apache.poi.POIXMLDocumentPart;

import org.openxmlformats.schemas.spreadsheetml.x2006.main.ExternalLinkDocument;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTExternalReferences;

import static org.apache.poi.POIXMLTypeLoader.DEFAULT_XML_OPTIONS;

import java.lang.reflect.Field;

import java.util.List;
import java.util.ArrayList;

public class CreateExcelLineChartExternalLinksTable {

 private static String datawbname = "DataWB.xlsx";
 private static String chartwbname = "ChartWB.xlsx";

 public CreateExcelLineChartExternalLinksTable() throws Exception {
  Workbook datawb = createDataSpreadsheet("ChartDataSheet");
  saveWorkbook(datawb, "/home/axel/Dokumente/"+datawbname);

  Workbook chartwb = createLineChart("ChartSheet", (XSSFWorkbook)datawb);
  saveWorkbook(chartwb, "/home/axel/Dokumente/"+chartwbname);
 }

 //your method only partially changed to have sample data
 public XSSFWorkbook createDataSpreadsheet(String name) {
  Workbook workbook = new XSSFWorkbook();
  Sheet sheet = workbook.createSheet(name);

  int rowNumber = 0;
  for(int i = 0; i < 20; i++) {
   Row row = sheet.createRow(rowNumber++);

   int columnNumber = 0;
   row.createCell(columnNumber++).setCellValue(Math.PI*i/10*2);
   row.createCell(columnNumber++).setCellValue(Math.sin(Math.PI*i/10*2));
  }

  return (XSSFWorkbook)workbook;
 }

 //method for saving the workbooks
 public void saveWorkbook(Workbook wb, String path) throws Exception {
  wb.write(new FileOutputStream(path));
  wb.close();
 }

 //your method changes are commented
 public XSSFWorkbook createLineChart(String name, XSSFWorkbook data) throws Exception {
  Workbook workbook = new MyXSSFWorkbook();

  Sheet sheet = workbook.createSheet(name);

  Drawing drawing = sheet.createDrawingPatriarch();
  ClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 0, 15, 15);
  Chart lineChart = drawing.createChart(anchor);

  ChartLegend legend = lineChart.getOrCreateLegend();
  legend.setPosition(LegendPosition.BOTTOM); 

  LineChartData chartData = lineChart.getChartDataFactory().createLineChartData();     
  ChartAxis bottomAxis = lineChart.getChartAxisFactory().createCategoryAxis(AxisPosition.BOTTOM);
  ValueAxis leftAxis = lineChart.getChartAxisFactory().createValueAxis(AxisPosition.LEFT);
  leftAxis.setCrosses(AxisCrosses.AUTO_ZERO);

  Sheet dataSheet = data.getSheetAt(0);
  ChartDataSource<Number> xData = DataSources.fromNumericCellRange(dataSheet, new CellRangeAddress(0, dataSheet.getLastRowNum(), 0, 0));
  ChartDataSource<Number> yData = DataSources.fromNumericCellRange(dataSheet, new CellRangeAddress(0, dataSheet.getLastRowNum(), 1, 1));

  LineChartSeries chartSeries = chartData.addSeries(xData, yData);
  chartSeries.setTitle("A title");

  lineChart.plot(chartData, new ChartAxis[] { bottomAxis, leftAxis });

  //create the ExternalLinksTable for the linked workbook and sheet
  int extLinksId = ((MyXSSFWorkbook)workbook).createExternalLinksTableWbSheet(datawbname, "ChartDataSheet");
System.out.println(((XSSFWorkbook)workbook).getExternalLinksTable());

  //since dataSheet is an external sheet, the formula in the org.openxmlformats.schemas.drawingml.x2006.chart.CTNumRef
  //must be prefixed with [1], where 1 is the Id of the linked workbook 
  String catref = ((XSSFChart)lineChart).getCTChart().getPlotArea().getLineChartArray(0).getSerArray(0).getCat().getNumRef().getF();
  ((XSSFChart)lineChart).getCTChart().getPlotArea().getLineChartArray(0).getSerArray(0).getCat().getNumRef().setF("["+extLinksId+"]" + catref);
  String valref = ((XSSFChart)lineChart).getCTChart().getPlotArea().getLineChartArray(0).getSerArray(0).getVal().getNumRef().getF();
  ((XSSFChart)lineChart).getCTChart().getPlotArea().getLineChartArray(0).getSerArray(0).getVal().getNumRef().setF("["+extLinksId+"]" + valref);

  return (XSSFWorkbook)workbook;
 }

 public static void main(String[] args) throws Exception {
  CreateExcelLineChartExternalLinksTable mainObject = new CreateExcelLineChartExternalLinksTable();
 }

 //class which extends XSSFWorkbook and provides a method for creating ExternalLinksTable for linked workbook and sheet
 private class MyXSSFWorkbook extends XSSFWorkbook {

  //method for creating ExternalLinksTable for linked workbook and sheet
  //returns the Id of this ExternalLinksTable
  int createExternalLinksTableWbSheet(String wbname, String sheetname) throws Exception {

   List<ExternalLinksTable> elternallinkstablelist = getExternalLinksTable();
   int extLinksId = 1;
   if (elternallinkstablelist != null) extLinksId = elternallinkstablelist.size()+1;

   OPCPackage opcpackage = getPackage();

   //creating /xl/externalLinks/externalLink1.xml having link to externalBook with external sheetName
   PackagePartName partname = PackagingURIHelper.createPartName("/xl/externalLinks/externalLink"+extLinksId+".xml");
   PackagePart part = opcpackage.createPart(partname, "application/vnd.openxmlformats-officedocument.spreadsheetml.externalLink+xml");

   OutputStream out = part.getOutputStream();
   ExternalLinkDocument doc = ExternalLinkDocument.Factory.parse(
     "<externalLink xmlns=\"http://schemas.openxmlformats.org/spreadsheetml/2006/main\">"
    +"<externalBook xmlns:r=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships\" r:id=\"rId1\">"
    +"<sheetNames><sheetName val=\"" + sheetname + "\"/></sheetNames>"
    +"</externalBook>"
    +"</externalLink>"
   );
   doc.save(out, DEFAULT_XML_OPTIONS);
   out.close();

   //creating the relation to the external workbook in /xl/externalLinks/_rels/externalLink1.xml.rels
   PackageRelationship packrelship = part.addRelationship(new java.net.URI(wbname), TargetMode.EXTERNAL, "http://schemas.openxmlformats.org/officeDocument/2006/relationships/externalLinkPath", "rId1");

   ExternalLinksTable externallinkstable = new ExternalLinksTable(part);

   //creating the relation to /xl/externalLinks/externalLink1.xml in /xl/_rels/workbook.xml.rels
   String rIdExtLink = "rId" + (getRelationParts().size()+1);
   addRelation(rIdExtLink, XSSFRelation.EXTERNAL_LINKS, externallinkstable);

   //creating the <externalReferences><externalReference .../> in /xl/workbook.xml
   CTExternalReferences externalreferences = getCTWorkbook().getExternalReferences();
   if (externalreferences == null) externalreferences = getCTWorkbook().addNewExternalReferences();
   externalreferences.addNewExternalReference().setId(rIdExtLink);

   Field externalLinksField = XSSFWorkbook.class.getDeclaredField("externalLinks"); 
   externalLinksField.setAccessible(true);
   @SuppressWarnings("unchecked") //we know the problem and expect runtime error if it possibly occurs
   List<ExternalLinksTable> externalLinks = (ArrayList<ExternalLinksTable>)externalLinksField.get(this);
   if (externalLinks == null) {
    externalLinks = new ArrayList<ExternalLinksTable>();
    externalLinks.add(externallinkstable);
    externalLinksField.set(this, externalLinks);
   } else {
    externalLinks.add(externallinkstable);
   }

   return extLinksId;
  }
 }
}
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