poi 获取excel中图片(转载)

转载:http://fansfirst2008.iteye.com/blog/1138189 

javaapachecodeexcel 

先贴代码,再解释与疑问(这段代码是我努力了半天的结果)

 

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.List;

import org.apache.poi.hssf.usermodel.HSSFClientAnchor;
import org.apache.poi.hssf.usermodel.HSSFPicture;
import org.apache.poi.hssf.usermodel.HSSFPictureData;
import org.apache.poi.hssf.usermodel.HSSFShape;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.PictureData;
import org.apache.poi.ss.usermodel.WorkbookFactory;

public class ReadPicturesFromExcel {

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

        InputStream inp = new FileInputStream(
                "D:\\Users\\Fancy1_Fan\\桌面\\work\\test.xls");
        HSSFWorkbook workbook = (HSSFWorkbook) WorkbookFactory.create(inp);

        List<HSSFPictureData> pictures = workbook.getAllPictures();
        HSSFSheet sheet = (HSSFSheet) workbook.getSheetAt(0);
        
        
        int i = 0;
        for (HSSFShape shape : sheet.getDrawingPatriarch().getChildren()) {
            HSSFClientAnchor anchor = (HSSFClientAnchor) shape.getAnchor();

            if (shape instanceof HSSFPicture) {
                HSSFPicture pic = (HSSFPicture) shape;
                int row = anchor.getRow1();
                System.out.println(i + "--->" + anchor.getRow1() + ":"
                        + anchor.getCol1());
                int pictureIndex = pic.getPictureIndex()-1;
                HSSFPictureData picData = pictures.get(pictureIndex);

                System.out.println(i + "--->" + pictureIndex);
                savePic(row, picData);
            }
            i++;
        }
    }

    private static void savePic(int i, PictureData pic) throws Exception {

        String ext = pic.suggestFileExtension();

        byte[] data = pic.getData();
        if (ext.equals("jpeg")) {
            FileOutputStream out = new FileOutputStream(
                    "D:\\Users\\Fancy1_Fan\\桌面\\work\\pict" + i + ".jpg");
            out.write(data);
            out.close();
        }
        if (ext.equals("png")) {
            FileOutputStream out = new FileOutputStream(
                    "D:\\Users\\Fancy1_Fan\\桌面\\work\\pict" + i + ".png");
            out.write(data);
            out.close();
        }
    }

}

　　

 

 

  思路:

        1.获得所有图片---->

        2.得到sheet DrawingPatriarch的所有shape--->

        3.获得shape的anchor --->

        4.获得picture的pictureIndex(这个很关键)------->

        5.最后假定pictureIndex就是allPictures中图片的位置,从而获得这张picture的data信息.

  问题:

         对于最后的假定没有官方文档的支持,所以有待测试.但是简单测试结果是ok的!

 

  对于假定的证明:

         官方文档向excel添加图片的流程是:

         1.调用workbook的addPicture,并且返回此pictureIndex------>

         2.然后创建一个ClientAnchor--------->

         3.最后通过这个pictureIndex和Anchor把它绘到sheet上

    由此可见pictureIndex,ClientAnchor以及pictureData是一一对应的关系,只要能够关联这三者,就可以获得

    Excel中picture的完整信息了.

    然而根据poi的api,只能单独获得picture,或者包含pictureIndex和anchor的HSSFPicture,并没有把它们关联在一起.

 

 

    查看源码发现 HSSFWorkbook只不过是一个外观类,或者适配器类,low level工作类为InternalWorkbook

 

/**
   * this is the reference to the low level Workbook object
   */

  private InternalWorkbook workbook;

 

    查看InternalWorkbook有api如下

 

public EscherBSERecord getBSERecord(int pictureIndex) {
      return escherBSERecords.get(pictureIndex-1);
  }

  此处表明:如果能获得InternalWorkbook对象和pictureIndex,就可以获得图片数据和信息.但是没法通过 HSSFWorkbook对象获得InternalWorkbook对象,因为如下:(此方法为包访问)

 

InternalWorkbook getWorkbook() {
      return workbook;
  }

 

  但是观察InternalWorkbook可以发现,如图:

 

private List<EscherBSERecord> escherBSERecords;

 保存图像数据的底层是一个List有序的集合.以及根据getBSERecord方法,就推断出picutreIndex就是表示picture在List里面的下标.

 

 

以上仅仅是个人的见解,由于对于poi的整体设计理念并没有把握,所以对于以上问题暂时找不到没有一个合理的解释.