java 导出Excel 大数据量，自己经验总结！

出处： http://lyjilu.iteye.com/

分析导出实现代码，XLSX支持：

/**
     * 生成<span style="white-space: normal; background-color: #ffffff;">XLSX</span>,2007版本的excel,每个sheet无6.5W的行数限制，但是到了一定数量，可能内存溢出，
     * 次方法适合在预计10W以下的数据导出时使用,本机测试，14W可以导出。列数量在8列左右
     *
     * @param fileOut
     *            输出流
     * @param sheetMap
     *            要设置的数据信息
     * @throws SQLException
     */
    public static void createXSLXByResultSet(OutputStream fileOut, WriteXLSBean... beans)
            throws SQLException {
        try {
            //重点 Workbook
            Workbook wb = new XSSFWorkbook();
            for (int i = 0, len = beans.length; i < len; i++) {
                WriteXLSBean xlsBean = beans[i];
                Sheet sheet = wb.createSheet(xlsBean.getSheetName());
                ResultSet rs = xlsBean.getRs();
                ResultSetMetaData rsmd = rs.getMetaData();
                TypeHandlerRegistry tr = BeanContext.tr;
                Map<String, String> th = xlsBean.getTh();
                int index = 0;
                while (rs.next()) {
                    long t1 = System.currentTimeMillis();
                    org.apache.poi.ss.usermodel.Row row = sheet
                            .createRow(index);
                    for (int j = 0, numberOfColumns = rsmd.getColumnCount(); j < numberOfColumns; j++) {
                        String key = rsmd.getColumnLabel(j + 1).toLowerCase();
                        if (th.containsKey(key)) {
                            TypeHandler<?> type = tr.getTypeHandler(JdbcType
                                    .forCode(rsmd.getColumnType(j + 1)));
                            Object obj = type.getResult(rs, key);
                            row.createCell(j).setCellValue(obj == null ? ""
                                    : obj.toString());
                        }
                    }
                    System.out.println(index + " :"
                            + (System.currentTimeMillis() - t1));
                    index++;
                }
            }
            //重点 Workbook
            wb.write(fileOut);
        } catch (IOException e) {
            e.printStackTrace();
            throw new ServiceRunTimeException("生产xls文档错误", e);
        } finally {
 
        }
    }

在上面 标注了重点的两处，分别是：

1.构建一个Excel对象

2.将该对象写入一个OutPutStream

而在构建过程中，没有地方写入OutPutSteam ,也就是说必须在内存中构建整个 Excel，才能进行写出操作，在大数据量情况下，这样将导致所有数据加载到内存中，而不能输出，导致最后 内存溢出。

根据运行环境不用，可能内存溢出的 情况不同

根据情况，如果数据量达到10W以上，建议使用

1、多个Excel，每个Excel一个Sheet,因为所有Sheet都是Workbook的组成部分。如果不分多个Excel,即使分Sheet也没用，

2、每个Excel中列数适中，比如： 5W行每个Excel档，实现分多次导出和分页查询原理一样

3、对多个Excel导出到一个临时目录，并通过程序压缩，然后提供给客户下载

2003版通过数据库结果存到List中，然后进行生产：Table 就是List Row 是Map

/**
     * 生产xls,2003版本的excel,每个sheet有6.5W的行数限制
     *
     * @param fileOut
     *            输出流，未关闭
     * @param sheetMap
     *            要导出的数据信息
     */
    public static void createXSLByMap(OutputStream fileOut, Map<String, Table<Row<String, Object>>> sheetMap) {
        try {
            HSSFWorkbook wb = new HSSFWorkbook();
            Set<String> keys = sheetMap.keySet();
            for (Iterator<String> iterator = keys.iterator(); iterator
                    .hasNext();) {
                String SheetKey = iterator.next();
                Sheet sheet = wb.createSheet(SheetKey);
                List<Row<String, Object>> sheetRows = sheetMap.get(SheetKey);
                for (int i = 0, len = sheetRows.size(); i < len; i++) {
                    Map<String, Object> cellMap = sheetRows.get(i);
                    Set<String> cellSet = cellMap.keySet();
                    org.apache.poi.ss.usermodel.Row row = sheet.createRow(i);
                    int j = 0;
                    for (Iterator<String> iterCell = cellSet.iterator(); iterCell
                            .hasNext(); j++) {
                        String cellKey = iterCell.next();
                        Object obj = cellMap.get(cellKey);
                        row.createCell(j).setCellValue(obj == null ? ""
                                : obj.toString());
                    }
                }
            }
            wb.write(fileOut);
        } catch (IOException e) {
            e.printStackTrace();
            throw new ServiceRunTimeException("生产xls文档错误", e);
        } finally {
        }
    }

新版本 POI+office 2007版本excel可以导出几十万条而不内存溢出，详细见：

导出大量数据到 excel 的 xlsx文件

static String src="abcdefafslfelgtryjukjhgfdadertjDSFGHJKJGHFERTUIOabcdefafslfelgtryjukjhgfdadertjDSFGHJKdertjDSFGHJKJGHFERTUIOabcdefafslfelgtryjukjhgfdadertjDSFGHJKJGHFERTUIO";
    public static void main(String[] args) throws Throwable {
        SXSSFWorkbook wb = new SXSSFWorkbook(100); // 这里100是在内存中的数量，如果大于此数量时，会写到硬盘，以避免在内存导致内存溢出
        Sheet sh = wb.createSheet();
        for (int rownum = 0; rownum < 1000000; rownum++) {
            Row row = sh.createRow(rownum);
            for (int cellnum = 0; cellnum < 10; cellnum++) {
                Cell cell = row.createCell(cellnum);
                String address = new CellReference(cell).formatAsString();
                cell.setCellValue(address+src.substring(rownum%10*10+1, (rownum%10+1)*10));
            }
        }
        File file = new File("F:/aa.xlsx");
        file.createNewFile();
        FileOutputStream out = new FileOutputStream(file);
        wb.write(out);
        out.close();
    }

内存使用情况：

根据以上前辈经验，自己在结果自身需求考虑，整合出一个工具。解决了excle表.xls格式行数65535行的限制。我实现的形式是导出一张表，里面有多页aaarticlea/png;base64,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" alt="" />（我是已65000为一页）

这里是用反射来使用所有传入进行的实体的属性的值。这里只针对String和基本数据类型。如有自己定义的类型需要自己加上。

package com.tommy.fundation.util;
 
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
 
public class RelectUtil {
    public static <T> List<Object> reflectEntity(T model,Class<?> cals) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, SecurityException, NoSuchFieldException{
        List<Object> list = new ArrayList<Object>();
        Field[] field = model.getClass().getDeclaredFields();        //获取实体类的所有属性，返回Field数组
        for(int j=0 ; j<field.length ; j++){     //遍历所有属性
            String nam = field[j].getName();    //获取属性的名字
            String name = nam;
            name  = name.substring(0,1).toUpperCase()+name.substring(1);
            String type = field[j].getGenericType().toString();    //获取属性的类型
 
            if(type.equals("class java.lang.String")){   //如果type是类类型，则前面包含"class "，后面跟类名
                Method m = model.getClass().getMethod("get"+name);
                String value = (String) m.invoke(model);    //调用getter方法获取属性值
                if(value != null){
                   list.add(value);
                }else{
                    list.add("");
                }
            }
 
            if(type.equals("class java.lang.Integer")){
                Method m = model.getClass().getMethod("get"+name);
                Integer value = (Integer) m.invoke(model);
                if(value != null){
                    list.add(value);
                }else{
                    list.add("");
                }
            }
 
            if(type.equals("class java.lang.Short")){
                Method m = model.getClass().getMethod("get"+name);
                Short value = (Short) m.invoke(model);
                if(value != null){
                    list.add(value);
                }else{
                    list.add("");
                }
            }       
 
            if(type.equals("class java.lang.Double")){
                Method m = model.getClass().getMethod("get"+name);
                Double value = (Double) m.invoke(model);
                if(value != null){
                    list.add(value);
                }else{
                    list.add("");
                }
            }                  
 
            if(type.equals("class java.lang.Boolean")){
                Method m = model.getClass().getMethod("get"+name);
                Boolean value = (Boolean) m.invoke(model);
                if(value != null){
                    list.add(value);
                }else{
                    list.add("");
                }
            }
 
            if(type.equals("class java.util.Date")){
                Method m = model.getClass().getMethod("get"+name);
                Date value = (Date) m.invoke(model);
                if(value != null){
                    list.add(value);
                }else{
                    list.add("");
                }
            }
        }
        return list;
    }
}

下面将是重点实现导出excel表

package com.tommy.fundation.util;
 
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
 
import javax.servlet.http.HttpServletResponse;
 
import org.apache.poi.hssf.record.formula.functions.T;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
 
@SuppressWarnings("hiding")
public class ExportExcel<T> {
    /**
     * 导出多张excel表,解决xls格式行数65535的限制
     * @author OnlyOne
     * @param response
     * @param list 需要处理的list数据集合
     * @throws Exception
     */
    @SuppressWarnings("deprecation")
    public void doExcel(HttpServletResponse response,List<T> list,String fileName) throws Exception {
         OutputStream os = response.getOutputStream();//获取输出流
        response.reset();
        // 设置下载头部信息。Content-disposition为属性名。attachment表示以附件方式下载，如果要在页面中打开，则改为inline。filename为文件名
        response.setHeader("Content-disposition", "attachment; filename=excell.xls");
        response.setContentType("application/msexcel");
 
        Map<Integer, List<T>> sheetMap = daData(list);
        HSSFWorkbook wb = new HSSFWorkbook();
        Set<Integer> keys = sheetMap.keySet();
        for (Iterator<Integer> iterator = keys.iterator(); iterator.hasNext();) {
            Integer SheetKey = iterator.next();
            HSSFSheet sheet = wb.createSheet((fileName+SheetKey).toString());
            List<T> sheetRows = sheetMap.get(SheetKey);
            for (int i = 0, len = sheetRows.size(); i < len; i++) {
                T en = (T) sheetRows.get(i);
                List<Object> dataList = RelectUtil.<T>reflectEntity(en, en.getClass());
                HSSFRow row = sheet.createRow(i);
                row.createCell(0).setCellValue(String.valueOf(i));
                for(int m=0; m<dataList.size(); m++){
                    row.createCell(m+1).setCellValue(dataList.get(m).toString());
                }
            }
        }
        wb.write(os);
    }
    /**
     * 此方法将数据集合按65000个进行分割成多个子集合
     * @author OnlyOne
     * @param list 需要处理的list数据集合
     * @return
     */
    public Map<Integer, List<T>> daData(List<T> list){
        int count = list.size()/65000;
        int yu = list.size() % 65000;
        Map<Integer, List<T>> map = new HashMap<Integer, List<T>>();
        for (int i = 0; i <= count; i++) {
            List<T> subList = new ArrayList<T>();
            if (i == count) {
                subList = list.subList(i * 65000, 65000 * i + yu);
            } else {
                subList = list.subList(i * 65000, 65000 * (i + 1)-1);
            }
            map.put(i, subList);
        }
        return map;
    }
}

在Java中调用的方式

@RequestMapping(value = "/doExcel", method = RequestMethod.GET)
public void doExcel(HttpServletResponse response,HttpServletRequest request) throws Exception {
        List<Enrolltg> list  = enrolltgService.findAll();
        new ExportExcel<Enrolltg>().doExcel(response, list, "黑白淡奶");
    }

大功搞成，以后再也不会为了数据量太大而导不出来烦恼了！！！

需要的包 poi-3.2-FINAL-20081019.jar