我正在使用POI（）的流式工作表编写大型Excel表（超过一百万条记录），但我得到java.lang.OutOfMemoryError: Java heap space。这是我的代码：
public void exportExcel() {
try {
SXSSFWorkbook workbook = new SXSSFWorkbook();
Sheet sheet = workbook.createSheet();
List<Oject> list = dao.getList();
Cell cell = null;
if (!list.isEmpty()) {
Row row = sheet.createRow(0);
cell = row.createCell(0);
cell.setCellValue("s1");
cell = row.createCell(1);
cell.setCellValue("s2");
cell = row.createCell(2);
cell.setCellValue("s3");
cell = row.createCell(3);
cell.setCellValue("s4");
cell = row.createCell(4);
cell.setCellValue("s5");
cell = row.createCell(5);
cell.setCellValue("s6");
cell = row.createCell(6);
cell.setCellValue("s7");
cell = row.createCell(7);
cell.setCellValue("s8");
cell = row.createCell(8);
cell.setCellValue("s9");
cell = row.createCell(9);
cell.setCellValue("s10");
cell = row.createCell(10);
cell.setCellValue("s11");
cell = row.createCell(11);
cell.setCellValue("s12");
cell = row.createCell(12);
cell.setCellValue("s13");
cell = row.createCell(13);
cell.setCellValue("s14");
cell = row.createCell(14);
cell.setCellValue("s15");
cell = row.createCell(15);
cell.setCellValue("s16");
cell = row.createCell(16);
cell.setCellValue("s17");
cell = row.createCell(17);
cell.setCellValue("s18");
cell = row.createCell(18);
cell.setCellValue("s19");
cell = row.createCell(19);
cell.setCellValue("s20");
cell = row.createCell(20);
cell.setCellValue("s21");
cell = row.createCell(21);
cell.setCellValue("s22");
cell = row.createCell(22);
cell.setCellValue("s23");
cell = row.createCell(23);
cell.setCellValue("s24");
cell = row.createCell(24);
cell.setCellValue("s25");
cell = row.createCell(25);
cell.setCellValue("s26");
cell = row.createCell(26);
cell.setCellValue("s27");
cell = row.createCell(27);
cell.setCellValue("s28");
cell = row.createCell(28);
cell.setCellValue("s29");
cell = row.createCell(29);
cell.setCellValue("s30");
cell = row.createCell(30);
cell.setCellValue("s31");
cell = row.createCell(31);
cell.setCellValue("s32");
cell = row.createCell(32);
cell.setCellValue("s33");
cell = row.createCell(33);
cell.setCellValue("s34");
cell = row.createCell(34);
cell.setCellValue("s35");
cell = row.createCell(35);
cell.setCellValue("s36");
cell = row.createCell(36);
cell.setCellValue("s37");
for (int i = 0; i < list.size(); i++) {
row = sheet.createRow(i + 1);
cell = row.createCell(0);
if (list.get(i).getOne == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getOne);
}
cell = row.createCell(1);
if (list.get(i).getTwo() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getTwo());
}
cell = row.createCell(2);
if (list.get(i).getThree() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getThree());
}
cell = row.createCell(3);
if (list.get(i).getFour() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getFour().toString());
}
cell = row.createCell(4);
if (list.get(i).getFive() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getFive());
}
cell = row.createCell(5);
if (list.get(i).getSix() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getSix());
}
cell = row.createCell(6);
if (list.get(i).getSeven() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getSeven());
}
cell = row.createCell(7);
if (list.get(i).getEight() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getEight());
}
cell = row.createCell(8);
if (list.get(i).getNine() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getNine());
}
cell = row.createCell(9);
if (list.get(i).getTen() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getTen().toString());
}
cell = row.createCell(10);
if (list.get(i).getD() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getD());
}
cell = row.createCell(11);
if (list.get(i).getF() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getF().toString());
}
cell = row.createCell(12);
if (list.get(i).getV() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getV().toString());
}
cell = row.createCell(13);
if (list.get(i).getVa() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getVa().toString());
}
cell = row.createCell(14);
if (list.get(i).getFo() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getFo().toString());
}
cell = row.createCell(15);
if (list.get(i).getVar() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getVar().toString());
}
cell = row.createCell(16);
if (list.get(i).getVarm() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getVarm().toString());
}
cell = row.createCell(17);
if (list.get(i).getFor() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getFor().toString());
}
cell = row.createCell(18);
if (list.get(i).getVarp() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getVarp().toString());
}
cell = row.createCell(19);
if (list.get(i).getVau() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getVau().toString());
}
cell = row.createCell(20);
if (list.get(i).getFoi() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getFoi().toString());
}
cell = row.createCell(21);
if (list.get(i).getVaro() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getVaro());
}
cell = row.createCell(22);
if (list.get(i).getVo() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getvo().toString());
}
cell = row.createCell(23);
if (list.get(i).getF5() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getF5().toString());
}
cell = row.createCell(24);
if (list.get(i).getV5() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getV5().toString());
}
cell = row.createCell(25);
if (list.get(i).getVm5() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getVm5().toString());
}
cell = row.createCell(26);
if (list.get(i).getDo() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getDo().toString());
}
cell = row.createCell(27);
if (list.get(i).getDmow() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getDmow().toString());
}
cell = row.createCell(28);
if (list.get(i).getCut() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getCut());
}
cell = row.createCell(29);
if (list.get(i).getDre() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getDre().toString());
}
cell = row.createCell(30);
if (list.get(i).getCli() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getCli());
}
cell = row.createCell(31);
if (list.get(i).getDn() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getDn().toString());
}
cell = row.createCell(32);
if (list.get(i).getCod() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getCod());
}
cell = row.createCell(33);
if (list.get(i).getCk() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getCk());
}
cell = row.createCell(34);
if (list.get(i).getRem() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getRem().toString());
}
cell = row.createCell(35);
if (list.get(i).getPs() == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getPs().toString());
}
cell = row.createCell(36);
if (list.get(i).getTyp) == null) {
cell.setCellValue("");
} else {
cell.setCellValue(list.get(i).getTyp().toString());
}
}
}
FacesContext facesContext = FacesContext.getCurrentInstance();
ExternalContext externalContext = facesContext.getExternalContext()
externalContext.setResponseContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
externalContext.setResponseHeader("Content-Disposition", "attachment; filename=\"Lim_" + new Date().toString() + ".xlsx\"");
workbook.write(externalContext.getResponseOutputStream());
facesContext.responseComplete();
workbook.dispose();
} catch (Exception e) {
FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR, "Error", null));
e.printStackTrace();
}
}
我需要了解问题，因为列表的大小是变化的，我的堆大小是512m
答案 0 :(得分：2)
使用SXSSFWorkbook workbook = new SXSSFWorkbook(100);
创建流式工作簿时，您隐式指定无限行访问权限。这通常不是你想写的。我建议在构造函数中添加一个整数参数，例如
1这应该会大大减少内存消耗。您甚至可以使用{{1}}作为数字，只要您只按顺序写行。