java如何生成客户端文件？

Question

刚写了一个程序，用户在访问的时候可以查询数据库中的数据然后直接生成一个excel文件到指定的文件夹中，但是在服务器上发布之后，直接把文件生成在服务器上了，我想要客户在使用我的网站时使用这个功能直接返回他一个excel文件，这个怎么实现的，表达的有些不清晰。。大家将就一下哈

Answer 1

response返回 生成excel，在用户浏览器弹出窗口让用户自己选择打开还是另存为。

Answer 2

先生成excel 然后返回文件下载地址。

Answer 3

把excel文件内容直接写到response的输出流中

Answer 4

直接让他下载你生成的excel
给你看点代码吧..
Action:
/**
 * 员工信息导出excel
 */
@SuppressWarnings("unchecked")
public String exportEmployeeExcel() {
DataGrid g = employeeService.gainEmployeeList(employee);
List<Employee> list = g.getRows();
excelStream = employeeService.exportEmployeeExcel(list);// 导出excel表格
return "exportEmployeeExcel";
}service:
/**
 * 员工信息导出excel
 */
@SuppressWarnings("unchecked")
public String exportEmployeeExcel() {
DataGrid g = employeeService.gainEmployeeList(employee);
List<Employee> list = g.getRows();
excelStream = employeeService.exportEmployeeExcel(list);// 导出excel表格
return "exportEmployeeExcel";
}struts2配置文件<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
<struts>
<package name="employee" extends="basePackage">
<action name="employeeExport" class="com.gx.employee.action.EmployeeAction">
<result name="exportEmployeeExcel" type="stream">   
                 <param name="contentType">   
                     application/vnd.ms-excel   
                 </param>   
                 <param name="inputName">excelStream</param>   
                 <param name="contentDisposition">   
                     filename="employee.xls"  
                 </param>   
                 <param name="bufferSize">1024</param>   
             </result>
</action>
</package>
</struts>

Answer 5

Service: 上面那个贴错了
/**
 * 导出员工信息
 */
@Override
public InputStream exportEmployeeExcel(List<?> list) {
if(list==null){
throw new SystemException("list is null in exportEmployeeExcel method,it mustn't be null.");
}
ByteArrayOutputStream out = new ByteArrayOutputStream();   
putDataOnOutputStream(out,list);   
return new ByteArrayInputStream(out.toByteArray());   
}

private void putDataOnOutputStream(OutputStream os,List<?> list) {
if(list==null)
throw new SystemException("list is null in exportEmployeeExcel method,it mustn't be null.");

WritableWorkbook workbook;
try {
workbook = Workbook.createWorkbook(os);
WritableSheet sheet = workbook.createSheet("Sheet1", 0);
sheet.getSettings().setDefaultColumnWidth(20);
sheet.addCell(new jxl.write.Label(0, 0, "id"));
sheet.addCell(new jxl.write.Label(1, 0, "姓名"));
sheet.addCell(new jxl.write.Label(2, 0, "性别"));
sheet.addCell(new jxl.write.Label(3, 0, "年龄"));
sheet.addCell(new jxl.write.Label(4, 0, "编号"));
sheet.addCell(new jxl.write.Label(5, 0, "手机号"));
sheet.addCell(new jxl.write.Label(6, 0, "身份证号"));
sheet.addCell(new jxl.write.Label(7, 0, "级别"));
sheet.addCell(new jxl.write.Label(8, 0, "部门"));
sheet.addCell(new jxl.write.Label(9, 0, "家庭地址"));
sheet.addCell(new jxl.write.Label(10, 0, "入职时间"));
sheet.addCell(new jxl.write.Label(11, 0, "离职时间"));
sheet.addCell(new jxl.write.Label(12, 0, "是否在职"));
sheet.addCell(new jxl.write.Label(13, 0, "备注"));
        //循环遍历到数据集
        for(int i= 0;i<list.size();i++){
         Employee e = (Employee) list.get(i);
         sheet.addCell(new jxl.write.Label(0,i+1 ,e.getId()+""));
         sheet.addCell(new jxl.write.Label(1,i+1 ,e.getName()));
         sheet.addCell(new jxl.write.Label(2,i+1 ,e.getGender()==1?"男":"女"));
         sheet.addCell(new jxl.write.Label(3,i+1 ,e.getAge()+""));
         sheet.addCell(new jxl.write.Label(4,i+1 ,e.getBn()));
         sheet.addCell(new jxl.write.Label(5,i+1 ,e.getMobile()));
         sheet.addCell(new jxl.write.Label(6,i+1 ,e.getIdCard()));
         sheet.addCell(new jxl.write.Label(7,i+1 ,e.getLevelName()));
         sheet.addCell(new jxl.write.Label(8,i+1 ,e.getDepartmentName()));
         sheet.addCell(new jxl.write.Label(9,i+1 ,e.getAddress()));
         sheet.addCell(new jxl.write.Label(10,i+1 ,CommonUtil.getDate(e.getCreateTime())));
         sheet.addCell(new jxl.write.Label(11,i+1 ,CommonUtil.getDate(e.getLeaveTime())));
         sheet.addCell(new jxl.write.Label(12,i+1 ,e.getStatus()==1?"在职":"离职"));
         sheet.addCell(new jxl.write.Label(13,i+1 ,e.getRe()));
        }
workbook.write();
workbook.close();
} catch (Exception e) {
logger.error("putDataOnOutputStream has some error:",e);
throw new SystemException("putDataOnOutputStream has some error:",e);
}
}