Question

以下代码是一个创建xlsx blob的测试程序使用Apache POI并解压缩blob（xlsx是zip格式）检查一些值。该代码基于Stack Overflow 问题，但我无法解压缩工作正常。对此的要求是文件系统不能感动，所以我们诉诸溪流。

问题在于行

int size = (int) entry.getSize();

总是产生-1。但是，请参阅

之前的评论

zipInput.closeEntry();

对于进一步进入该计划的变化，但似乎不正确。

我们不想使用POI本身来读取xlsx文件因为我们正在测试POI似乎不存在的问题与Apache Struts合作，我们希望消除我们使用独立于Struts的POI的方式是罪魁祸首。一旦这个测试通过，如果问题Struts 报告仍然存在，我们知道要看Struts本身而不是我们使用POI的方式。

/**
 * Short, Self Contained, Correct Example of
 * 1) creating an xlsx blob with test data;
 * 2) sending it to a stream;
 * 3) unzipping the xlsx;
 * 4) checking the worksheet's xml file for
 * correct test values.
 * Heavily inlined from two other properly factored
 * files, one POI wrapper and one JUnit test case
 * (although the test is not a "unit test" since it
 * only tests third party library integration)
 * DEPENDENCIES
 * 1) poi-3.8.jar
 * 2) poi-ooxml-3.8.jar
 * 3) xmlbeans-2.6.0.jar
 * 4) dom4j-1.6.1.jar
 * 5) poi-ooxml-schemas-3.8.jar
 * Other solutions attempted:
 * 1) commons-compress: always returned byte array of proper size
 * but containing all zeros.
 * Note that we do NOT want to use the filesystem. This exercise's
 * purpose is to create dynamically generated xlsx files delivered
 * via HTTP. The filesystem is never involved.
 */
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class CreateWorkbook
{
    public static void main(String[] args) throws IOException
    {
        // create the data to place into workbook
        List<List<String>> resultset = new ArrayList<List<String>>();
        List<String> row = new ArrayList<String>();
        row.add("A1");
        row.add("B1");
        row.add("C1");
        resultset.add(row);
        row = new ArrayList<String>();
        row.add("A2");
        row.add("B2");
        row.add("C2");
        resultset.add(row);
        row = new ArrayList<String>();
        row.add("A3");
        row.add("B3");
        row.add("C3");
        resultset.add(row);
        // create POI workbook and fill it with resultSet
        XSSFWorkbook workbook = new XSSFWorkbook();
        Sheet s = workbook.createSheet();
        for (int i = 0; i < resultset.size(); i++)
        {
            List<String> record = resultset.get(i);
            Row r = s.createRow(i);
            for (int j = 0; j < record.size(); j++)
                r.createCell(j).setCellValue(record.get(j));
        }
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        workbook.write(out);
        out.flush();
        // retrieve workbook's data into a string and
        // test if the cell values (a1,b2,c3,etc) appear
        ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
        // xlsx is a zipped archive so we need to unzip
        ZipInputStream zipInput = new ZipInputStream(in);
        assert zipInput.available() == 1;
        ZipEntry entry = zipInput.getNextEntry();
        assert entry != null;
        while (entry != null)
        {
            // since this "if" condition passes during execution we
            // know that the stream contains a zip archive with
            // an entry called "xl/worksheets/sheet1.xml". Therefore,
            // ZipEntry retrieval appears to work correctly and the
            // archive has at least a partially correct zip format.
            if (entry.getName().equals("xl/worksheets/sheet1.xml"))
            {
                int size = (int) entry.getSize();
                // ==============================================
                // always fails, reports -1
                assert size > 0 : size;
                // ==============================================
                byte[] bytes = new byte[size];
                int readbytes = zipInput.read(bytes, 0, size);
                assert readbytes > 0 : readbytes;
                // nothing after this line has been tested
                StringBuilder builder = new StringBuilder();
                for (int i = 0; i < size; i++)
                    builder.append(Character.toString((char) bytes[i]));
                String xml = builder.toString();
                assert xml.contains("A1");
                assert xml.contains("B2");
                assert xml.contains("C3");
                break;
            }
            // Swapping the order of these two lines actually
            // causes the program to go further, with size = 678
            // and failing at the readbytes assertion rather than
            // the size assertion.
            // I thought swapping would mess everything up since
            // the entry would be closed immediately after obtaining
            // it.
            zipInput.closeEntry();
            entry = zipInput.getNextEntry();
        }
        zipInput.close();
        in.close();
    }
}

Answer 1

你并不完全适合使用Zip。

试试这个代码段：

        if (entry.getName().equals("xl/worksheets/sheet1.xml"))
        {
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            IOUtils.copy(zipInput, bos);
            String xml = bos.toString();
            assert xml.contains("A1");
            assert xml.contains("B2");
            assert xml.contains("C3");
            break;
        }

使用java.util.zip。*解压缩使用Apache POI创建的xlsx blob时失败

1 个答案: