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[英]How can i get the path of client side download location in java servlet or jsp?
[英]how can i download an excel file from server side to client side using jsp servlet
我正在實現一個Web應用程序,需要將數據庫數據下載到excel中。 我將所有數據檢索到excel中,並保存在服務器端,但是如何將excel下載到客戶端?
我已經完成了以下代碼:
row = spreadsheet.createRow(p);
cell = row.createCell(1);
cell.setCellValue(m);
cell = row.createCell(2);
cell.setCellValue(emp_code);
cell = row.createCell(3);
cell.setCellValue(card_no);
// ... more code
String root = getServletContext().getRealPath("/");
File path = new File(root + "/Downloads/ExcellFile");
f="/salary_Report.xls";
String n=path+f;
System.out.println(" File name"+f);
if (!path.exists()) {
boolean status = path.mkdirs();
}
FileOutputStream output = new FileOutputStream(new File(path+f));
workbook.write(output);
output.close();
之后,我將如何下載該Excel文件?
使用通用的這樣的方法創建一個ExcelService
類。 此方法可以用於寫入文件(這對於測試以及是否需要在服務器端存儲文件很有用),也可以使用此方法稍后再寫入servlet的輸出流。
還要注意,每個方法負責關閉資源 ,它已經打開(和只是資源) - writeToXlsx(OutputStream)
的Workbook
, writeToXlsx(String)
的OutputStream
。
/**
* Create an Excel file (as OutputStream) with your data
*
* @param output The OutputStream to which the method should write.
* It must be opened before!
* Notice that although it is an <em>output</em> of the method,
* it is provided as an <em>input</em> parameter.
* The idea is: "Give me the data, and here is the place
* you should put them to."
* @throws IOException
*/
public void writeToXlsx(OutputStream output) throws IOException {
try (final Workbook wb = new XSSFWorkbook();) {
final Sheet sheet = wb.createSheet(...);
// your code here to fill the sheet
wb.write(output);
}
}
為了您的方便(和測試),您可以創建一個寫入文件的特定方法。 但是,這不是客戶端應用程序要使用的方法!
/**
* Create an Excel file (as file) with your data.
*
* @param outputFile The name of the output file.
* @throws IOException
*/
public void writeToXlsx(String outputFile) throws IOException {
try (OutputStream output = new FileOutputStream(new File(outputFile))) {
writeToXlsx(output);
}
}
您的servlet可能看起來像這樣。 它使用您創建的服務。
@WebServlet("/content/data")
public class DataServlet extends HttpServlet {
private static final long serialVersionUID = ....;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
writeHeader(response);
writeBody(response);
}
private void writeBody(HttpServletResponse response) throws IOException {
// Each servlet has the output stream which is directly
// streamed to the client browser as the response:
final OutputStream output = response.getOutputStream();
// Now your service creates the data and writes them to the
// output stream:
final ExcelService service = new ExcelService();
service.writeToXlsx(output);
// To be sure that nothing is lost:
output.flush();
}
private void writeHeader(HttpServletResponse response) {
// Here you tell the browser that the result is not HTML, but Excel.
// The browser uses this information to open an application
// associated in the client operating system with this type
// of data.
response.setContentType("application/ms-excel");
// The browser will pass this information to Excel
// which will consider this as the file name
response.setHeader("Content-Disposition", "attachment; filename=MyData.xlsx");
}
}
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