什麽是DTO，為什麽要DTO？
　　數據傳輸對象，簡單的來說就是用戶在數據庫的操作中涉及到了多表的屬性，pojo中單獨的類不能作為傳輸對象。因為他只對應了操作中的一部分屬性，比如有學生表（姓名，學號，班級號）班級表（班級號，班級名）。當你查詢某學生的班級名時，單獨的學生類和班級類都不足以代表他們。因此就需要我們的dto，dto當你需要什麽屬性你就定義什麽屬性，僅作為一個傳輸對象。

　　JXL的用法workbook

　　可寫表格與只讀表格

　　讀取exce

import java.io.File;

import jxl.Cell;
import jxl.Hyperlink;
import jxl.Sheet;
 
import jxl.Workbook;
/**
 * 讀取excel
 * @author Administrator
 *
 */
public class Test {
    public static void main(String[] args) throws Exception {
        Workbook book = Workbook.getWorkbook(new File("aa.xls"));
        Sheet sheet = book.getSheet("first");
        int rows = sheet.getRows();
        
 
int cols = sheet.getColumns();
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                System.out.print(sheet.getCell(j, i).getContents()+"\t");
            }
            System.out.println();
        }
        Cell cell = sheet.getCell(0, 0);
        Hyperlink[] links 
 
= sheet.getHyperlinks();
        System.out.println(links.length);
        for (int i = 0; i < links.length; i++) {
            System.out.println(links[i].getURL().toString());
        }
    }

}

　　寫入excel

package cn.zkingsoft;

import java.io.File;
import java.net.URL;

import jxl.Workbook;
import jxl.write.Label;
import jxl.write.Number;
import jxl.write.WritableHyperlink;
import jxl.write.WritableImage;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;

/**
 * 寫入excel
 * @author Administrator
 *
 */
public class Test2 {
	public static void main(String[] args)  throws Exception{
		WritableWorkbook book = Workbook.createWorkbook(new File("classmate.xls"));
		WritableSheet sheet  = book.createSheet("0913A", 0);
		sheet.addCell(new Label(0,0,"黃傳名"));
		sheet.addCell(new Label(0,1,"45.89"));
		sheet.addCell(new Number(1,1,45.89d));
		sheet.addImage(new WritableImage(2,2,5,10,new File("_logo_8.png")));
		sheet.addHyperlink(new WritableHyperlink(0,3,new URL("https://www.baidu.com")));
		book.write();
		book.close();
	}

}

分層開發之DTO和JXL讀取excel寫入excel