Spring Boot Beispiel zum Herunterladen von Datei vom Server

Question

Ich habe eine Spring Boot-Webanwendung und ich brauche ein Beispiel, wie Sie eine Datei vom Server herunterladen.

Danke, R.

Answer 1

Dieses Beispiel, das ich für meinen Fall gearbeitet gefunden:

@Controller 
@RequestMapping(value = "/") 
public class HomeController { 

    @RequestMapping(value = "/download", method = RequestMethod.GET) 
    public StreamingResponseBody getSteamingFile(HttpServletResponse response) throws IOException { 

     response.setContentType("text/html;charset=UTF-8"); 
     response.setHeader("Content-Disposition", "attachment; filename=\"webpage.html\""); 
     InputStream inputStream = new FileInputStream(new File("C:\\MyWebPage\\webpage.html")); 

     return outputStream -> { 
      int nRead; 
      byte[] data = new byte[1024]; 
      while ((nRead = inputStream.read(data, 0, data.length)) != -1) { 
       outputStream.write(data, 0, nRead); 
      } 
      inputStream.close(); 
     }; 
    } 
} 

Answer 2

Ich habe this laufende Projekt von SpringBoot. Unten ist ein Teil des Codes, der xlsx Datei ausgibt.

WebController.java

@RequestMapping(value = {"/excel"}, method = RequestMethod.GET) 

    public void excel(HttpServletResponse response, @RequestParam("email") String email) { 

     try { 
      Query query = new Query(); 
      query.addCriteria(Criteria.where("email").is(email)); 

      if(email.equals("")) 
       query=new Query(); 

      List<MQTT_Server_Detail> list = mongoTemplate.find(query, MQTT_Server_Detail.class, "owner"); 

      response.addHeader("Content-disposition", "attachment; filename=Door.xlsx"); 
      response.setContentType("application/vnd.ms-excel"); 

      Workbook workbook = new XSSFWorkbook(); 
      workbook.createSheet("owner"); 
      workbook.setSheetName(0, "Owner"); 
      Sheet sheet = workbook.getSheetAt(0); 

      sheet.createRow(0); 
      sheet.getRow(0).createCell(0).setCellValue("Owner Email"); 
      sheet.getRow(0).createCell(1).setCellValue("Topic"); 
      sheet.getRow(0).createCell(2).setCellValue("Device Name"); 
      sheet.getRow(0).createCell(3).setCellValue("Device ID"); 

      Row row; 
      int num = 1; 

      for (MQTT_Server_Detail a : list) { 
       Devices devices = getDevice(a.getEmail()); 

       for (int i = 0; i < devices.getDevicesID().size(); i++) { 
        row = sheet.createRow(num++); 
        row.createCell(0).setCellValue(a.getEmail()); 
        row.createCell(1).setCellValue(a.getTopic()); 
        row.createCell(2).setCellValue((String) devices.getDevicesName().get(i)); 
        row.createCell(3).setCellValue((String) devices.getDevicesID().get(i)); 
       } 

      } 

      sheet = workbook.createSheet("Users"); 

      row = sheet.createRow(0); 
      row.createCell(0).setCellValue("Name"); 
      row.createCell(1).setCellValue("Device"); 
      row.createCell(2).setCellValue("CardID"); 
      row.createCell(3).setCellValue("Email"); 
      row.createCell(4).setCellValue("Mobile"); 
      row.createCell(5).setCellValue("Blocked"); 
      row.createCell(6).setCellValue("Last in Date"); 
      row.createCell(7).setCellValue("Last in Time"); 
      row.createCell(8).setCellValue("Last out Date"); 
      row.createCell(9).setCellValue("Last out Time"); 
      row.createCell(10).setCellValue("Owner"); 

      Criteria criteria[] = new Criteria[list.size()]; 

      for (int i = 0; i < list.size(); i++) { 
       criteria[i] = Criteria.where("owner").is(list.get(i).getEmail()); 
      } 

      List<Users_POJO> users_pojoList; 

      if (list.size() == 0) 
       users_pojoList = new ArrayList<>(); 
      else 
       users_pojoList = mongoTemplate.find(new Query().addCriteria(new Criteria().orOperator(criteria)), 
         Users_POJO.class, "users"); 


      for (int i = 0; i < users_pojoList.size(); i++) { 
       row = sheet.createRow(i + 1); 
       row.createCell(0).setCellValue(users_pojoList.get(i).getName()); 
       row.createCell(1).setCellValue(users_pojoList.get(i).getDevice()); 
       row.createCell(2).setCellValue(users_pojoList.get(i).getCard_id()); 
       row.createCell(3).setCellValue(users_pojoList.get(i).getEmail()); 
       row.createCell(4).setCellValue(users_pojoList.get(i).getMobile()); 
       row.createCell(5).setCellValue(users_pojoList.get(i).getBlocked()); 
       row.createCell(6).setCellValue(users_pojoList.get(i).getLast_in_date()); 
       row.createCell(7).setCellValue(users_pojoList.get(i).getLast_in_time()); 
       row.createCell(8).setCellValue(users_pojoList.get(i).getLast_out_date()); 
       row.createCell(9).setCellValue(users_pojoList.get(i).getLast_out_time()); 
       row.createCell(10).setCellValue(users_pojoList.get(i).getOwner()); 

      } 

      sheet = workbook.createSheet("Logs"); 
      row = sheet.createRow(0); 
      row.createCell(0).setCellValue("CardID"); 
      row.createCell(1).setCellValue("Device"); 
      row.createCell(2).setCellValue("Date"); 
      row.createCell(3).setCellValue("Time"); 
      row.createCell(4).setCellValue("Count"); 

      criteria = new Criteria[users_pojoList.size()]; 
      for (int i = 0; i < users_pojoList.size(); i++) { 
       criteria[i] = Criteria.where("card_id").is(users_pojoList.get(i).getCard_id()); 
      } 
      query = new Query(); 
      query.addCriteria(new Criteria().orOperator(criteria)); 

      List<Log_POJO> log_pojoList; 

      if (users_pojoList.size() == 0) 
       log_pojoList = new ArrayList<>(); 
      else 
       log_pojoList = mongoTemplate.find(query, Log_POJO.class, "logs"); 


      for (int i = 0; i < log_pojoList.size(); i++) { 
       row = sheet.createRow(i + 1); 
       row.createCell(0).setCellValue(log_pojoList.get(i).getCard_id()); 
       row.createCell(1).setCellValue(log_pojoList.get(i).getDevice()); 

       String date = log_pojoList.get(i).getDay() + "-" + log_pojoList.get(i).getMonth() + "-" + log_pojoList.get(i).getYear(); 
       row.createCell(2).setCellValue(date); 

       String time = log_pojoList.get(i).getHour() + "-" + log_pojoList.get(i).getMin() + "-" + log_pojoList.get(i).getSec(); 
       row.createCell(3).setCellValue(time); 

       row.createCell(4).setCellValue(log_pojoList.get(i).getSerial_no()); 

      } 
      workbook.write(response.getOutputStream()); 

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

    } 

Kurz gesagt, müssen Sie dies tun:

response.addHeader("Content-disposition", "attachment; filename=Door.xlsx"); 
response.setContentType("application/vnd.ms-excel"); 
//get the outputstream of response and write data to it