生成Excel报告供下载（Struts2）

1，Struts2配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
    "http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
	<package name="base" extends="struts-default" namespace="/">
		<action name="download" class="ivan.test.action.OutputExcelAction">
			<!-- EXCEL 模板所在位置 -->
			<param name="templatePosition">/template.xls</param>
			<result type="stream" name="success">
				<!-- 下载文件的类型,假如下载的是其他的，但你又不知道是什么格式，可以去 tomcat\conf\web.xml下找 -->
				<param name="contentType">application/vnd.ms-excel</param>
				<!-- 返回流 excelStream为action中的流变量名称 -->
				<param name="inputName">excelStream</param>
				<!-- attachment 这个位置的参数挺特殊的，可以设置成下载时，是否出现个下载提示框，或者直接下载之类的，怎么设置忘了，那个小本子找不到了 
					fileName指定生成的文件名字(这种方式合适动态生成文件名，比如做报表时，一般都要说是几月的统计数据之类)为action中变量 -->
				<param name="contentDisposition">
					attachment;filename=${excelFileName}
				</param>
				<param name="bufferSize">1024</param>
			</result>
		</action>
	</package>
</struts>

2，Action类

package ivan.test.action;

import ivan.test.demo.ExcelUtil;

import java.io.InputStream;
import java.util.Map;

public class OutputExcelAction extends BaseAction {

	private static final long serialVersionUID = 1L;
	// output 输出流变量
	private InputStream excelStream;
	// output 下载文件名
	private String excelFileName;
	// injection 模板路径
	private String templatePosition;

	@Override
	public String execute() throws Exception {
		String templatePath = httpApplication.getRealPath("/")
				+ "WEB-INF/classes" + templatePosition;

		Map<String, Object> map = ExcelUtil.getExcelMap(templatePath);
		excelStream = (InputStream) map.get("excelStream");
		excelFileName = (String) map.get("excelFileName");
		return SUCCESS;
	}

	public InputStream getExcelStream() {
		return excelStream;
	}

	public void setExcelStream(InputStream excelStream) {
		this.excelStream = excelStream;
	}

	public String getExcelFileName() {
		return excelFileName;
	}

	public void setExcelFileName(String excelFileName) {
		this.excelFileName = excelFileName;
	}

	public String getTemplatePosition() {
		return templatePosition;
	}

	public void setTemplatePosition(String templatePosition) {
		this.templatePosition = templatePosition;
	}

}

3，生成Excel的输入流与Excel的名字

package ivan.test.demo;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

public class ExcelUtil {

	public static Map<String, Object> getExcelMap(String template)
			throws Exception {
		ByteArrayOutputStream os = null;
		try {
			// 读取模板
			HSSFWorkbook workbook = new HSSFWorkbook(new FileInputStream(
					template));

			// 按照业务逻辑写入Excel表
			HSSFSheet sheet = workbook.getSheet("firstSheet");
			for (int i = 1; i < 10; i++) {
				HSSFRow row = sheet.createRow(i);
				for (int j = 0; j < 10; j++) {
					HSSFCell cell = row.createCell(j);
					cell.setCellType(HSSFCell.CELL_TYPE_STRING);
					cell.setCellValue("(" + i + " , " + j + ")");
				}
			}

			// 获取Excel名字与Excel的InputStream流
			os = new ByteArrayOutputStream();
			workbook.write(os);
			InputStream excelStream = new ByteArrayInputStream(os.toByteArray());
			String excelFileName = "text.xls";

			// 加载到Map，并返回Map
			Map<String, Object> excelMap = new HashMap<String, Object>();
			excelMap.put("excelFileName", excelFileName);
			excelMap.put("excelStream", excelStream);
			return excelMap;
		} catch (Exception e) {
			System.out.println("异常.............");
			throw e;
		} finally {
			if (os != null) {
				os.close();
			}
		}
	}
}