java导出excel（解决导出几万条数据内存溢出的问题）

import java.io.BufferedOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class Test {
    public static void main(String[] args) {
    	System.out.println(System.currentTimeMillis());
        StringBuffer sb = new StringBuffer();
        try {
            DataOutputStream rafs = new DataOutputStream(
                    new BufferedOutputStream(new FileOutputStream(new File(
                            "d://test.xlsx"))));
            sb.append("<?xml version=\"1.0\"?>");
            sb.append("\n");
            sb.append("<?mso-application progid=\"Excel.Sheet\"?>");
            sb.append("\n");
            sb.append("<Workbook xmlns=\"urn:schemas-microsoft-com:office:spreadsheet\"");
            sb.append("\n");
            sb.append("  xmlns:o=\"urn:schemas-microsoft-com:office:office\"");
            sb.append("\n");
            sb.append(" xmlns:x=\"urn:schemas-microsoft-com:office:excel\"");
            sb.append("\n");
            sb.append(" xmlns:ss=\"urn:schemas-microsoft-com:office:spreadsheet\"");
            sb.append("\n");
            sb.append(" xmlns:html=\"http://www.w3.org/TR/REC-html40\">");
            sb.append("\n");
            sb.append(" <Styles>\n");
            sb.append("  <Style ss:ID=\"Default\" ss:Name=\"Normal\">\n");
            sb.append("   <Alignment ss:Vertical=\"Center\"/>\n");
            sb.append("   <Borders/>\n");
            sb.append("   <Font ss:FontName=\"宋体\" x:CharSet=\"134\" ss:Size=\"12\"/>\n");
            sb.append("   <Interior/>\n");
            sb.append("   <NumberFormat/>\n");
            sb.append("   <Protection/>\n");
            sb.append("  </Style>\n");
            sb.append(" </Styles>\n");
//             int sheetcount = 0;
            int recordcount = 100000;
            int currentRecord = 0;
            int total = 100000;
            int col = 10;
            sb.append("<Worksheet ss:Name=\"Sheet0\">");
            sb.append("\n");
            sb.append("<Table ss:ExpandedColumnCount=\"" + col
                    + "\" ss:ExpandedRowCount=\"" + total
                    + "\" x:FullColumns=\"1\" x:FullRows=\"1\">");
            sb.append("\n");
            for (int i = 0; i < total; i++) {
                if ((currentRecord == recordcount
                        || currentRecord > recordcount || currentRecord == 0)
                        && i != 0) {// 一个sheet写满
                    currentRecord = 0;
                    rafs.write(sb.toString().getBytes());
                    sb.setLength(0);
                    sb.append("</Table>");
                    sb.append("<WorksheetOptions xmlns=\"urn:schemas-microsoft-com:office:excel\">");
                    sb.append("\n");
                    sb.append("<ProtectObjects>False</ProtectObjects>");
                    sb.append("\n");
                    sb.append("<ProtectScenarios>False</ProtectScenarios>");
                    sb.append("\n");
                    sb.append("</WorksheetOptions>");
                    sb.append("\n");
                    sb.append("</Worksheet>");
                    sb.append("<Worksheet ss:Name=\"Sheet" + i / recordcount
                            + "\">");
                    sb.append("\n");
                    sb.append("<Table ss:ExpandedColumnCount=\"" + col
                            + "\" ss:ExpandedRowCount=\"" + recordcount
                            + "\" x:FullColumns=\"1\" x:FullRows=\"1\">");
                    sb.append("\n");
                }
                sb.append("<Row>");
                for (int j = 0; j < col; j++) {
                	if(i==0) sb.append("<Cell><Data ss:Type=\"String\">标题"+j+"</Data></Cell>");
                	else sb.append("<Cell><Data ss:Type=\"String\">c"+i+"&"+j+"</Data></Cell>"); 

                    sb.append("\n");
                }
                sb.append("</Row>");
                if (i % 5000 == 0) {
                    rafs.write(sb.toString().getBytes("utf-8"));  //注意编码
                    rafs.flush();
                    sb.setLength(0);
                }
                sb.append("\n");
                currentRecord++;
            }
            rafs.write(sb.toString().getBytes());
            sb.setLength(0);
            sb.append("</Table>");
            sb.append("<WorksheetOptions xmlns=\"urn:schemas-microsoft-com:office:excel\">");
            sb.append("\n");
            sb.append("<ProtectObjects>False</ProtectObjects>");
            sb.append("\n");
            sb.append("<ProtectScenarios>False</ProtectScenarios>");
            sb.append("\n");
            sb.append("</WorksheetOptions>");
            sb.append("\n");
            sb.append("</Worksheet>");
            sb.append("</Workbook>");
            sb.append("\n");
            rafs.write(sb.toString().getBytes());
            rafs.flush();
            rafs.close();
            System.out.println(System.currentTimeMillis());
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}