Spring Boot example how to download file from server - spring-boot

Question

I have a Spring Boot web application and I need an example of how to download a file from the server.
Thanks,
R.

Answer 1

I have this running project of SpringBoot. Below is a part of code which outputs xlsx file.
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();
}
}
In short, you have to do this:
response.addHeader("Content-disposition", "attachment; filename=Door.xlsx");
response.setContentType("application/vnd.ms-excel");
//get the outputstream of response and write data to it

Answer 2

Spring Boot download file from server
#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();
};
}
}