POI 生成excel(大数据量) SXSSF
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使用POI 的SXSSF (Streaming Usermodel API)生成较大的excel，同时开启压缩
1 import junit.framework.Assert;
2 import org.apache.poi.ss.usermodel.Cell;
3 import org.apache.poi.ss.usermodel.Row;
4 import org.apache.poi.ss.usermodel.Sheet;
5 import org.apache.poi.ss.usermodel.Workbook;
6 import org.apache.poi.ss.util.CellReference;
7 import org.apache.poi.xssf.streaming.SXSSFWorkbook;
8
9 public static void main(String[] args) throws Throwable {
10 SXSSFWorkbook wb = new SXSSFWorkbook(100); // keep 100 rows in memory, exceeding rows will be flushed to disk
11 Sheet sh = wb.createSheet();
12 for(int rownum = 0; rownum < 1000; rownum++){
13 Row row = sh.createRow(rownum);
14 for(int cellnum = 0; cellnum < 10; cellnum++){
15 Cell cell = row.createCell(cellnum);
16 String address = new CellReference(cell).formatAsString();
17 cell.setCellValue(address);
18 }
19
20 }
21
22 // Rows with rownum < 900 are flushed and not accessible
23 for(int rownum = 0; rownum < 900; rownum++){
24 Assert.assertNull(sh.getRow(rownum));
25 }
26
27 // ther last 100 rows are still in memory
28 for(int rownum = 900; rownum < 1000; rownum++){
29 Assert.assertNotNull(sh.getRow(rownum));
30 }
31
32 FileOutputStream out = new FileOutputStream("/temp/sxssf.xlsx");
33 wb.write(out);
34 out.close();
35
36 // dispose of temporary files backing this workbook on disk
37 wb.dispose();
38 }
遇到的问题：
错误是NPE错误，类似如下，原因是缺少字体或者环境变量未设置，需要安装"ttf-dejavu"字体，具体可以参考：
https://stackoverflow.com/questions/30626136/cannot-load-font-in-jre-8
https://www.jianshu.com/p/c05b5fc71bd0
1 java.lang.NullPointerException
2 at sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1264)
3 at sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:219)
4 at sun.awt.FontConfiguration.init(FontConfiguration.java:107)
5 at sun.awt.X11FontManager.createFontConfiguration(X11FontManager.java:774)
6 at sun.font.SunFontManager$2.run(SunFontManager.java:431)
7 at java.security.AccessController.doPrivileged(Native Method)
8 at sun.font.SunFontManager.<init>(SunFontManager.java:376)
9 at sun.awt.FcFontManager.<init>(FcFontManager.java:35)
10 at sun.awt.X11FontManager.<init>(X11FontManager.java:57)
11 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
12 at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
13 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
14 at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
15 at java.lang.Class.newInstance(Class.java:442)
16 at sun.font.FontManagerFactory$1.run(FontManagerFactory.java:83)
17 at java.security.AccessController.doPrivileged(Native Method)
18 at sun.font.FontManagerFactory.getInstance(FontManagerFactory.java:74)
19 at java.awt.Font.getFont2D(Font.java:495)
20 at java.awt.Font.canDisplayUpTo(Font.java:2080)
21 at java.awt.font.TextLayout.singleFont(TextLayout.java:470)
22 at java.awt.font.TextLayout.<init>(TextLayout.java:531)
23 at org.apache.poi.ss.util.SheetUtil.getDefaultCharWidth(SheetUtil.java:275)
24 at org.apache.poi.xssf.streaming.AutoSizeColumnTracker.<init>(AutoSizeColumnTracker.java:117)
25 at org.apache.poi.xssf.streaming.SXSSFSheet.<init>(SXSSFSheet.java:79)
26 at org.apache.poi.xssf.streaming.SXSSFWorkbook.createAndRegisterSXSSFSheet(SXSSFWorkbook.java:656)
27 at org.apache.poi.xssf.streaming.SXSSFWorkbook.createSheet(SXSSFWorkbook.java:677)
28 at org.apache.poi.xssf.streaming.SXSSFWorkbook.createSheet(SXSSFWorkbook.java:83)
还有一种，easyexcel，没用过，可以参考https://github.com/alibaba/easyexcel
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