Java对Excel文件的读写操作可由jxl.jar或poi.jar实现，这里使用jxl.jar完成对Excel文件的导出。

一、将Excel文件导出在本地

步骤：
  创建文件 -> 创建工作簿 -> 创建Sheet -> 加入数据 -> 写入文件。

示意图

`
package cn.exporttoexceldemo;

import jxl.Workbook;
import jxl.write.Label;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;

import java.io.File;

public class ExportExcelToLocal {
public static void main(String[] args) {
String title[] = {"工号","姓名","部门"};
String content[][] = {
{"001","乔峰","财务部"},
{"002","段誉","销售部"},
{"003","虚竹","采购部"},
{"004","张无忌","研发部"},
{"005","黄蓉","人力资源部"}
};
//1.创建一个文件
File file = new File("D:\ExportExcelToLocal.xls");
try {
//2.创建WritableWorkbook工作簿对象，并将其接入创建的文件
WritableWorkbook writableWorkbook = Workbook.createWorkbook(file);

        //3.创建一个Sheet，第一个参数是sheet的名称，第二个参数是索引号
        //（可通过WritableFont、WritableCellFormat等方法对单元格的属性进行设置）
        WritableSheet writableSheet = writableWorkbook.createSheet("sheet1", 0);

        //4.在sheet中加入数据
        for (int i = 0; i < title.length; i++) { //标题行
            writableSheet.addCell(new Label(i,0,title[i])); //new Label(列号，行号，内容)
        }
        for (int i = 0; i < content.length; i++) { //内容
            for (int j = 0; j < content[0].length; j++){
                writableSheet.addCell(new Label(j, i+1, content[i][j]));
            }
        }

        //5.对WritableWorkbook对象执行写入操作
        writableWorkbook.write();
        writableWorkbook.close(); //关闭writableWorkbook

    }catch (Exception e){
        e.printStackTrace();
    }

}

}
`

生成的excel文件的内容

  实现生成并由浏览器下载Excel文件的功能有两种方式：1.先将Excel文件导出在服务器磁盘上，再由客户端下载；2.直接导出至输出流，由浏览器下载为Excel文件。这里演示直接将数据内容导出至输出流，完成由浏览器下载为Excel文件的功能。

步骤：定义输出流 ->定义工作簿-> 输出流接入网络响应 -> 工作簿接入输出流 -> 创建sheet -> 加入数据 -> 写入输出流。

示意图

示例：将指定数组的数据导出至输出流，由浏览器下载为Excel文件，文件名为‘ExportExcelToClient.xls’。

实现程序

`
package cn.exporttoexceldemo;

import jxl.Workbook;
import jxl.write.Label;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

@WebServlet("/ExportExcelToClientServlet")
public class ExportExcelToClientServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    String title[] = {"工号","姓名","部门"};
    String content[][] = {
            {"001","乔峰","财务部"},
            {"002","段誉","销售部"},
            {"003","虚竹","采购部"},
            {"004","张无忌","研发部"},
            {"005","黄蓉","人力资源部"}
    };
    String fileName = "ExportExcelToClient.xls"; //定义文件名
    //设置编码
    response.setContentType("application/vnd.ms-excel;charset=UTF-8");
    try {
        if (request.getHeader("User-Agent").toUpperCase().indexOf("MSIE") > 0){ //IE浏览器
            fileName = URLEncoder.encode(fileName,"UTF-8");
        }else {
            fileName = new String(fileName.getBytes("UTF-8"),"ISO8859-1");
        }
        response.setHeader("Content-Disposition", "p_w_upload; filename="+fileName);
    }catch (UnsupportedEncodingException e){
        e.printStackTrace();
    }
    //1.定义一个输出流对象
    ServletOutputStream servletOutputStream = null;

    //2.定义一个WritableWorkbook工作簿对象
    WritableWorkbook writableWorkbook = null;

    try {
        //3.将输出流对象接入响应端response
        servletOutputStream = response.getOutputStream();

        //4.将工作簿对象接入输出流对象
        writableWorkbook = Workbook.createWorkbook(servletOutputStream);

        //5.创建一个Sheet，第一个参数是sheet的名称，第二个参数是索引号
        WritableSheet writableSheet = writableWorkbook.createSheet("sheet1",0);
        
        //6.在sheet中加入数据
        for (int i = 0; i < title.length; i++) { //标题行
            writableSheet.addCell(new Label(i,0,title[i]));
        }
        for (int i = 0; i < content.length; i++) { //内容
            for (int j = 0; j < content[0].length; j++){
                writableSheet.addCell(new Label(j, i+1, content[i][j]));
            }
        }

        //7.对工作簿对象执行写入操作
        writableWorkbook.write();
        servletOutputStream.flush();
    }catch (Exception e){
        e.printStackTrace();
    }finally {
        try {
            writableWorkbook.close();
            servletOutputStream.close();
        }catch (Exception e1){
            e1.printStackTrace();
        }
    }

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    this.doPost(request, response);
}

}
`

生成的excel文件的内容

End.