J2EE使用注解导出Excel
上次不好意思。发这个贴没写完。被弄为隐藏帖了。

使用注解导出Excel主要使用了POI包和反射原理，使得导出段可以灵活配置，并且不需要额外的配置文件
1：注解代码：

import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;/** * @author 1097877378 * */@Target(value = ElementType.METHOD)@Retention(value = RetentionPolicy.RUNTIME)public @interface ExportColumn {/** * 列名 */public String[] name() default {};//为什么用数组，大家想一下/** * 格式化字符串 */public String format() default "";/** * 导出次序 */public int order() default 0; }

2：在需要导出的DTO或实体中对需要导出的字段配置导出注解
示例：

import java.sql.Date;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.SequenceGenerator;import javax.persistence.Table;import =ExportColumn;public class Users  {private Long id;private String name;private String password;private Date birthday;public Long getId() {return id;}@ExportColumn(name={"姓名"})public String getName() {return name;}@ExportColumn(name={"密码"})public String getPassword() {return password;}@ExportColumn(format="%1$tY-%1$tm-%1$td", name={"生日"})public Date getBirthday() {return birthday;}        ...省略get,set

3：导出类，利用反射原理：

import java.io.IOException;import java.io.OutputStream;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.Arrays;import java.util.Comparator;import java.util.List;import javax.servlet.http.HttpServletResponse;import org.apache.poi.hssf.usermodel.HSSFWorkbook;import org.apache.poi.ss.usermodel.Cell;import org.apache.poi.ss.usermodel.Row;import org.apache.poi.ss.usermodel.Sheet;import ExportColumn;public class ExportExcelUtil {/** * 导出Excel文件到输出流 * @param response * @throws IOException */public static <T> void exportExcel(List<T> data, String fileName, HttpServletResponse response) throws Exception {response.reset();//fileName = URLEncoder.encode(fileName, "UTF-8");//only IEfileName = new String(fileName.getBytes("GBK"), "ISO-8859-1");//IE and FireFoxresponse.setHeader("Content-disposition", "attachment; filename=" + fileName + ".xls");// 设定输出文件头           response.setContentType("application/msexcel");// 定义输出类型         HSSFWorkbook workbook = createWorkbook(data);        OutputStream os = response.getOutputStream();// 取得输出流           workbook.write(os);        os.flush();        os.close();    }private static <T> HSSFWorkbook createWorkbook(List<T> data) throws SecurityException, IllegalArgumentException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {HSSFWorkbook workbook = new HSSFWorkbook(); Sheet sheet = workbook.createSheet("sheet1"); {createHeader(sheet, data.get(0));createBody(sheet, data);}return workbook;}private static <T> void createHeader(Sheet sheet, T dataRow) {Row header = sheet.createRow(0);Method[] methods = dataRow.getClass().getMethods();Arrays.sort(methods, new Comparator<Method>() {public int compare(Method o1, Method o2) {return o1.getName().compareTo(o2.getName());}});int cellindex = 0;for(Method method : methods) {//取得DTO的导出列if (method.isAnnotationPresent(ExportColumn.class)) {ExportColumn export = method.getAnnotation(ExportColumn.class);String[] titles = export.name();Cell headerCell = header.createCell(cellindex);headerCell.setCellValue(titles[0]);cellindex ++;}}}private static <T> void createBody(Sheet sheet, List<T> data) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {if (!data.isEmpty()) {int rowindex = 1;for (T datarow : data) {Row sheetrow = sheet.createRow(rowindex);Method[] methods = datarow.getClass().getMethods();Arrays.sort(methods, new Comparator<Method>() {public int compare(Method o1, Method o2) {return o1.getName().compareTo(o2.getName());}});int cellindex = 0;for(Method method : methods) {//取得DTO的导出列if (method.isAnnotationPresent(ExportColumn.class)) {Object cellvalue = (Object)method.invoke(datarow);Cell sheetcell = sheetrow.createCell(cellindex);if (null != cellvalue) {ExportColumn export = method.getAnnotation(ExportColumn.class);String cellstr = cellvalue.toString();if (!export.format().equals("")){cellstr = String.format(export.format(), cellvalue);//按注解格式化}sheetcell.setCellValue(cellstr);}cellindex ++;}}rowindex ++;}}}}

4： 搞定：导出时执行
得到Users 的list
ExportExcelUtil.exportExcel(usersList, "人员信息表", response);

这个是个比较老的版本，现在已经把注解和ExportExcelUtil升级了，不过还没有高强度测试。。
欢迎大家提出意见