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 IE
		fileName = new String(fileName.getBytes("GBK"), "ISO-8859-1");//IE and FireFox
		response.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 Com