POI实现Excel报表导出

1.导入Apache POI的JAR包
POI JAR 包（Apache官网中可以直接下载）

2.熟悉常用对象

对象	作用
HSSFSheet	excel的表单
HSSFRow	excel的行
HSSFCell	excel的格子单元
HSSFFont	excel字体
HSSFDataFormat	日期格式
HSSFHeader	sheet头
HSSFFooter	sheet尾
HSSFCellStyle	cell样式
HSSFDateUtil	日期
HSSFPrintSetup	打印
HSSFErrorConstants	错误信息表

3、上代码：

package com.pzoom.xiaochen.excel;

import java.io.OutputStream;
import java.util.ArrayList;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.hssf.util.HSSFColor;

public class ExcelFileGenerator {

    private final int SPLIT_COUNT = 15; //Excel每个工作表的行数

    private ArrayList fieldName = null; //excel数据的抬头栏，即名称栏

    private ArrayList fieldData = null; //excel导出的实际数据

    private HSSFWorkbook workBook = null;//一个excel文件

    //有参构造器，限定了使用此类时，必须首先构建好两个list参数，并将所需数据放入上述两个list。
    //其中fieldName这个list可以使用泛型约束List<String>
    //fieldData这个可以使用泛型约束List<List<Object>>
    public ExcelFileGenerator(ArrayList fieldName, ArrayList fieldData) {
        this.fieldName = fieldName;
        this.fieldData = fieldData;
    }
    /**
     * @return HSSFWorkbook
     */
    public HSSFWorkbook createWorkbook() {
        workBook = new HSSFWorkbook();//创建一个工作簿
        int rows = fieldData.size();//清点出输入数据的行数
        int sheetNum = 0;//将工作表个数清零
        //根据数据的行数与每个工作表所能容纳的行数，求出需要创建工作表的个数
        if (rows % SPLIT_COUNT == 0) {
            sheetNum = rows / SPLIT_COUNT;
        } else {
            sheetNum = rows / SPLIT_COUNT + 1;
        }

        for (int i = 1; i <= sheetNum; i++) {
            HSSFSheet sheet = workBook.createSheet("Page " + i);//创建工作表
            HSSFRow headRow = sheet.createRow(0); //创建第一栏，抬头栏
            for (int j = 0; j < fieldName.size(); j++) {
                HSSFCell cell = headRow.createCell(j);//创建抬头栏单元格
                //设置单元格格式
                cell.setCellType(HSSFCell.CELL_TYPE_STRING);
                sheet.setColumnWidth(j, 6000);
                HSSFCellStyle style = workBook.createCellStyle();
                HSSFFont font = workBook.createFont();
                font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
                short color = HSSFColor.RED.index;
                font.setColor(color);
                style.setFont(font);
                //将数据填入单元格
                if(fieldName.get(j) != null){
                    cell.setCellStyle(style);
                    cell.setCellValue((String) fieldName.get(j));
                }else{
                    cell.setCellStyle(style);
                    cell.setCellValue("-");
                }
            }
            //创建数据栏单元格并填入数据
            for (int k = 0; k < (rows < SPLIT_COUNT ? rows : SPLIT_COUNT); k++) {
                if (((i - 1) * SPLIT_COUNT + k) >= rows)
                    break;
                HSSFRow row = sheet.createRow(k + 1);
                ArrayList rowList = (ArrayList) fieldData.get((i - 1)
                        * SPLIT_COUNT + k);
                for (int n = 0; n < rowList.size(); n++) {
                    HSSFCell cell = row.createCell( n);
                    if(rowList.get(n) != null){
                        cell.setCellValue((String) rowList.get(n).toString());
                    }else{
                        cell.setCellValue("");
                    }
                }
            }
        }
        return workBook;
    }
    //将信息写入输出流的方法。
    public void exportExcel(OutputStream os) throws Exception {
        workBook = createWorkbook();
        workBook.write(os);
        os.close();
    }
}

4、测试

@Test
    public void testExcel() throws Exception
    {
        ExcelFileGenerator generator = new ExcelFileGenerator(Lists.newArrayList("1","2","3"), Lists.newArrayList(Lists.newArrayList("aa","bb","cc"), Lists.newArrayList("dd","ee","ff")));
        generator.exportExcel(new FileOutputStream(new File("a.xls")));
    }