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