Creating SpringBoot RestAPIs to upload and download multiple CSV files to databases: MySQL and PostgreSQL is one of the most common question in the development world. Going through the tutorial post”SpringBoot Upload Download Multiple CSV files to MySQL/PostgreSQL”, I explain details how to do it by step to step with coding and give you 100% running source code. What we will do?
– I draw an overview diagram architecture of SpringBoot RestAPI Upload CSV Files.
– I use Spring Web to development Spring RestApis.
– I use ApacheCommon or Open CSV libraries to parse and read CSV files.
– I use SpringJPA to save data from CSV files to MySQL and PostgreSQL.
– I implement a SpringBoot Global Exception Handler when uploading with a very big files and fail.
– I use Ajax and Bootstrap to implement a frontend client to upload/download CSV files.
- Youtube Video Guide: SpringBoot Upload/Download CSV Files to Dabatase
- Overview – Springboot Upload Download Multiple CSV files to MySQL/PostgreSQL
- Create Project – SpringBoot RestAPIs Upload Download CSV file
- Implement Utils for Writing and Reading multiple CSV files
- Define Spring JPA repository
- Implement a CSV File Service
- Implement SpringBoot Upload CSV files RestApi
- Implement SpringBoot Download CSV file RestApi
- Configure MySQL/PostgreSQL database connection
- Test SpringBoot Upload Download RestAPIs with Rest-Client
- Implement SpringBoot Rest Exception Handler
- Tuning File Upload Limits
- Implement Ajax Client
- Integrative Testing SpringBoot Upload Download CSV files with Ajax Client
- Sourcecode
To do the tutorial “SpringBoot upload download CSV files to database”, we need prepare Java >= 8, Eclipse with SpringToolSuite, PostgreSQL and pgAdmin or MySQL, a RestClient (I use Advanced Rest Client).
Now let’s go!
Youtube Video Guide: SpringBoot Upload/Download CSV Files to Dabatase
Overview – Springboot Upload Download CSV files to MySQL/PostgreSQL
Here is an overview about workflow data of SpringBoot Upload/Download multiple Csv Files project:

– We implement an Ajax or use a Rest client to upload/download Csv files to/from SpringBoot application.
– For manipulating Csv files, we develop an Csv Utils class to write and read data from them.
– We implement a Csv File Service to do CRUD operations with MySQL/PostgreSQL that supported by SpringJPA Repository.
Here is an overview of “SpringBoot Upload Download multiple CSV files to database” project that we will implement in the tutorial:

controller
package implements Controller RestAPIs classes to upload/download Csv files from Ajax or a Rest-Clientrepository
package defines a CRUD JPA Repository:CustomerRepository
services
package implements a classCsvFileServices
with functions to store and retrieve Csv File’s datautils
package implements a classCsvUtils
with common functions for reading or writing data to/from Csv filesmodel
package defines a classCustomer
for mapping data between each CSV’s row with each database’s recorderrorhandler
package implements a classRestExceptionHandler
to handle an exception:file size exceeded
Create Project – SpringBoot RestAPIs Upload Download CSV file
We use Eclipse to create a “SpringBoot upload download file” project with a set of below dependencies:
spring-boot-starter-data-jpa
dependency is used to interact with PostgreSQL/MySQL databasepostgresql
ormysql-connector-java
drivers are used to connect with PostgreSQL/MySQL databasespring-boot-starter-web
dependency is used to implement Spring RestAPIs Controller
For writting and reading CSV files, we use dependency commons-csv
of org.apache.commons
or use dependency opencsv
of com.opencsv
In the tutorial, we mainly do a demo with MySQL database, so here is the details of necessary dependencies in pom.xml
file:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.commons/commons-csv -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-csv</artifactId>
<version>1.8</version>
</dependency>
<dependency>
<groupId>com.opencsv</groupId>
<artifactId>opencsv</artifactId>
<version>4.5</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
Implement Utils for Writing and Reading multiple CSV files
Using OpenCsv to Read/Write data to CSV file
We create class OpenCsvUtil.java
to read/write csv file with 2 methods:
parseCsvFile(InputStream is)
is used to read csv filecustomersToCsv(Writer writer, List
is used to write object list to csv writercustomers)

package com.loizenai.updownloadcsv.utils;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import com.loizenai.updownloadcsv.model.Customer;
import com.opencsv.CSVWriter;
import com.opencsv.bean.ColumnPositionMappingStrategy;
import com.opencsv.bean.CsvToBean;
import com.opencsv.bean.CsvToBeanBuilder;
import com.opencsv.bean.StatefulBeanToCsv;
import com.opencsv.bean.StatefulBeanToCsvBuilder;
/**
* Copyright by https://loizenai.com
*
* @author loizenai.com
*/
public class OpenCsvUtil {
public static List<Customer> parseCsvFile(InputStream is) {
String[] CSV_HEADER = { "id", "name", "address", "age" };
Reader fileReader = null;
CsvToBean<Customer> csvToBean = null;
List<Customer> customers = new ArrayList<Customer>();
try {
fileReader = new InputStreamReader(is);
ColumnPositionMappingStrategy<Customer> mappingStrategy = new ColumnPositionMappingStrategy<Customer>();
mappingStrategy.setType(Customer.class);
mappingStrategy.setColumnMapping(CSV_HEADER);
csvToBean = new CsvToBeanBuilder<Customer>(fileReader).withMappingStrategy(mappingStrategy).withSkipLines(1)
.withIgnoreLeadingWhiteSpace(true).build();
customers = csvToBean.parse();
return customers;
} catch (Exception e) {
System.out.println("Reading CSV Error!");
e.printStackTrace();
} finally {
try {
fileReader.close();
} catch (IOException e) {
System.out.println("Closing fileReader/csvParser Error!");
e.printStackTrace();
}
}
return customers;
}
public static void customersToCsv(Writer writer, List<Customer> customers) {
String[] CSV_HEADER = { "id", "name", "address", "age" };
StatefulBeanToCsv<Customer> beanToCsv = null;
try {
// write List of Objects
ColumnPositionMappingStrategy<Customer> mappingStrategy =
new ColumnPositionMappingStrategy<Customer>();
mappingStrategy.setType(Customer.class);
mappingStrategy.setColumnMapping(CSV_HEADER);
beanToCsv = new StatefulBeanToCsvBuilder<Customer>(writer)
.withMappingStrategy(mappingStrategy)
.withQuotechar(CSVWriter.NO_QUOTE_CHARACTER)
.build();
beanToCsv.write(customers);
} catch (Exception e) {
System.out.println("Writing CSV error!");
e.printStackTrace();
}
}
}
Using Apache Commons CSV to Read/Write data to CSV file
We create class OpenCsvUtil.java
to read/write csv file with 2 methods:
parseCsvFile(InputStream is)
is used to read csv filecustomersToCsv(Writer writer, List
is used to write object list to csv writercustomers)

package com.loizenai.updownloadcsv.utils;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVPrinter;
import org.apache.commons.csv.CSVRecord;
import org.springframework.web.multipart.MultipartFile;
import com.loizenai.updownloadcsv.model.Customer;
public class ApacheCommonsCsvUtil {
private static String csvExtension = "csv";
public static void customersToCsv(Writer writer, List<Customer> customers) throws IOException {
try (CSVPrinter csvPrinter = new CSVPrinter(writer,
CSVFormat.DEFAULT.withHeader("id", "name", "address", "age"));) {
for (Customer customer : customers) {
List<String> data = Arrays.asList(String.valueOf(customer.getId()), customer.getName(),
customer.getAddress(), String.valueOf(customer.getAge()));
csvPrinter.printRecord(data);
}
csvPrinter.flush();
} catch (Exception e) {
System.out.println("Writing CSV error!");
e.printStackTrace();
}
}
public static List<Customer> parseCsvFile(InputStream is) {
BufferedReader fileReader = null;
CSVParser csvParser = null;
List<Customer> customers = new ArrayList<Customer>();
try {
fileReader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
csvParser = new CSVParser(fileReader,
CSVFormat.DEFAULT.withFirstRecordAsHeader().withIgnoreHeaderCase().withTrim());
Iterable<CSVRecord> csvRecords = csvParser.getRecords();
for (CSVRecord csvRecord : csvRecords) {
Customer customer = new Customer(Long.parseLong(csvRecord.get("id")), csvRecord.get("name"),
csvRecord.get("address"), Integer.parseInt(csvRecord.get("age")));
customers.add(customer);
}
} catch (Exception e) {
System.out.println("Reading CSV Error!");
e.printStackTrace();
} finally {
try {
fileReader.close();
csvParser.close();
} catch (IOException e) {
System.out.println("Closing fileReader/csvParser Error!");
e.printStackTrace();
}
}
return customers;
}
public static boolean isCSVFile(MultipartFile file) {
String extension = file.getOriginalFilename().split("\\.")[1];
if(!extension.equals(csvExtension)) {
return false;
}
return true;
}
}
Define Spring JPA repository
In the tutorial “SpringBoot RestAPIs Upload Download CSV file”, to do CRUD operations with MySQL/PostgreSQL database, we define a simple CustomerRepository
interface that extends the org.springframework.data.repository.CrudRepository
:
package com.loizenai.updownloadcsv.repository;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import com.loizenai.updownloadcsv.model.Customer;
/**
*
* Copyright by https://loizenai.com
* @author loizenai.com
*
*/
@Repository
public interface CustomerRepository extends CrudRepository<Customer, Long>{
}
See related article: How to integrate SpringBoot 2.x with PostgreSQL database using Spring JPA
Implement a CSV File Service
We create a CSV File Service CsvFileServices
to do 2 tasks:
- Store data to database with supported API:
store(MultipartFile file)
- Load data from database to a CSV file with supported API
ByteArrayInputStream loadFile()
CsvFileServices
class uses the Spring JPA repository CustomerRepository
to interact with database and use the utility functions of CsvUtils
class to manipulate data with Csv files.
Here is coding details:
package com.loizenai.updownloadcsv.service;
import java.io.IOException;
import java.io.InputStream;
import java.io.Writer;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.loizenai.updownloadcsv.model.Customer;
import com.loizenai.updownloadcsv.repository.CustomerRepository;
import com.loizenai.updownloadcsv.utils.ApacheCommonsCsvUtil;
/**
*
* Copyright https://loizenai.com
* @author loizenai.com
*/
@Service
public class CsvFileServices {
@Autowired
CustomerRepository customerRepository;
// Store Csv File's data to database
public void store(InputStream file) {
try {
// Using ApacheCommons Csv Utils to parse CSV file
List<Customer> lstCustomers = ApacheCommonsCsvUtil.parseCsvFile(file);
// Using OpenCSV Utils to parse CSV file
// List<Customer> lstCustomers = OpenCsvUtil.parseCsvFile(file);
// Save customers to database
customerRepository.saveAll(lstCustomers);
} catch(Exception e) {
throw new RuntimeException("FAIL! -> message = " + e.getMessage());
}
}
// Load Data to CSV File
public void loadFile(Writer writer) throws IOException {
try {
List<Customer> customers = (List<Customer>) customerRepository.findAll();
// Using ApacheCommons Csv Utils to write Customer List objects to a Writer
ApacheCommonsCsvUtil.customersToCsv(writer, customers);
// Using Open CSV Utils to write Customer List objects to a Writer
// OpenCsvUtil.customersToCsv(writer, customers);
} catch(Exception e) {
throw new RuntimeException("Fail! -> Message = " + e.getMessage());
}
}
}
* Note: org.springframework.stereotype.Service
indicates that an annotated class is a Service
Implement SpringBoot Upload CSV files RestApi
We create a UploadCsvRestApi.java
controller class to do upload a single and multiple csv files with 2 api methods:

Upload single CSV file
We create a posting API /api/upload/csv/single
for uploading a single Csv file, and here is a signature detail:
@PostMapping("/single")
public Response uploadSingleCSVFile(@RequestParam("csvfile") MultipartFile csvfile) {
...
}
The function uploadSingleCSVFile
does the 2 main taks:
- Validated task: check name and type of requested file before processing
- Store CSV file data to database
@PostMapping("/single")
public Response uploadSingleCSVFile(@RequestParam("csvfile") MultipartFile csvfile) {
Response response = new Response();
// Checking the upload-file's name before processing
if (csvfile.getOriginalFilename().isEmpty()) {
response.addMessage(new Message(csvfile.getOriginalFilename(),
"No selected file to upload! Please do the checking", "fail"));
return response;
}
// checking the upload file's type is CSV or NOT
if(!ApacheCommonsCsvUtil.isCSVFile(csvfile)) {
response.addMessage(new Message(csvfile.getOriginalFilename(), "Error: this is not a CSV file!", "fail"));
return response;
}
try {
// save file data to database
csvFileServices.store(csvfile.getInputStream());
response.addMessage(new Message(csvfile.getOriginalFilename(), "Upload File Successfully!", "ok"));
} catch (Exception e) {
response.addMessage(new Message(csvfile.getOriginalFilename(), e.getMessage(), "fail"));
}
return response;
}
Upload multiple CSV files
We create a posting API /api/upload/csv/multiple
for uploading multiple Csv files, and here is a signature detail:
@PostMapping("/multiple") public Response uploadMultipleFiles(@RequestParam("csvfiles") MultipartFile[] csvfiles) { ... }
The function uploadMultipleFiles
does the 2 main taks:
- Validated task: check names and type of all requested files before processing them
- Store Csv files’ data to database
@PostMapping("/multiple")
public Response uploadMultipleFiles(@RequestParam("csvfiles") MultipartFile[] csvfiles) {
Response response = new Response();
/*
* Filtering files had been selected for uploading (the files having names)
*/
MultipartFile[] readyUploadedFiles = Arrays.stream(csvfiles)
.filter(x -> !StringUtils.isEmpty(x.getOriginalFilename())).toArray(MultipartFile[]::new);
/*
* Checking whether having at least one file had been selected for uploading
*/
if (readyUploadedFiles.length == 0) {
response.addMessage(new Message("", "No selected file to upload!", "fail"));
return response;
}
/*
* Checking uploaded files are CSV files or NOT
*/
String notCsvFiles = Arrays.stream(csvfiles).filter(x -> !ApacheCommonsCsvUtil.isCSVFile(x))
.map(x -> x.getOriginalFilename()).collect(Collectors.joining(" , "));
if (!StringUtils.isEmpty(notCsvFiles)) {
response.addMessage(new Message(notCsvFiles, "Not Csv Files", "fail"));
return response;
}
/*
* Do the uploading
*/
for (MultipartFile file : readyUploadedFiles) {
try {
csvFileServices.store(file.getInputStream());
response.addMessage(new Message(file.getOriginalFilename(), "Upload Successfully!", "ok"));
} catch (Exception e) {
response.addMessage(new Message(file.getOriginalFilename(), e.getMessage(), "fail"));
}
}
return response;
}
The UploadCsvRestApi
uses the CsvFileServices
service to store Csv files’ data to database.
@RestController
is a convenience annotation that is itself annotated with @Controller
and @ResponseBody
The returned class Response
contains a set of necessary information to return back to requested client.

Here is coding details of Response
class:
package com.loizenai.updownloadcsv.message;
import java.util.ArrayList;
import java.util.List;
/**
* Copyright by https://loizenai.com
* @author loizenai.com
*
*/
public class Response {
private List<Message> messages = null;
private List<FileInfo> fileInfos = null;
private Error error = null;
private String errStatus = "";
public Response() {
this.messages = new ArrayList<Message>();
}
public Response(List<FileInfo> fileInfos) {
this.fileInfos = fileInfos;
}
public Response(String errStatus, Error err) {
this.errStatus = errStatus;
this.error = err;
}
public void addFileInfo(FileInfo file) {
this.fileInfos.add(file);
}
Implement SpringBoot Download CSV file RestApi
We implement a rest controller DownloadCsvRestAPI
having a http GET downloadFile()
API method with URL /api/download/csv/
to load all entities from database and serve them as a Csv file back to requested client.

Here is coding:
package com.loizenai.updownloadcsv.controller;
import java.io.IOException;
import javax.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import com.loizenai.updownloadcsv.service.CsvFileServices;
/**
* Copyright https://loizenai.com
* @author loizenai.com
*
*/
@RestController
public class DownloadCsvRestApi {
@Autowired
CsvFileServices csvFileService;
/*
* Download CSV Files
*/
@GetMapping("/api/download/csv/")
public void downloadFile(HttpServletResponse response) throws IOException {
response.setContentType("text/csv");
response.setHeader("Content-Disposition", "attachment; filename=customers.csv");
csvFileService.loadFile(response.getWriter());
}
}
With above coding, the API returns a file that has name is customers.csv
, type is text/csv
(CSV file type) and status code is 200
(.ok()
) for successfully processing.
Configure MySQL/PostgreSQL database connection
In the SpringBoot project, we need interact with database to do CRUD operation to save/retrieve data from CSV file to database, so now we need to add database configuration in application.properties
file.
– For PostgreSQL connection, you follow below configuration formatting:
## PostgreSQL
spring.datasource.url=jdbc:postgresql://localhost:5432/loizenaidb
spring.datasource.username=postgres
spring.datasource.password=123
#drop & create table again, good for testing, comment this in production
spring.jpa.hibernate.ddl-auto=create
– For MySQL connection, you follow below configuration formatting:
spring.datasource.url=jdbc:mysql://localhost:3306/loizenaidb
spring.datasource.username=root
spring.datasource.password=12345
spring.jpa.generate-ddl=true
Test SpringBoot Upload Download RestAPIs with Rest-Client
We use Advanced Rest Client to test the Upload/Download RestAPIs.
For testing, we prepare 3 Csv files as below content:



SpringBoot Upload a Single CSV File
We create a POST request to URL http://localhost:8080/api/upload/csv/single
that has a body with multipart/form-data
content type and includes 1 Csv file as below:

Run the “SpringBoot Upload Download CSV Files” project then send the POST request, we get a response successfully as below details:

Checking database, we get a customer table with 5 records as below:

SpringBoot Upload Multiple CSV Files
We create a POST request to URL http://localhost:8080/api/upload/csv/multiple
that has a body with multipart/form-data
content type and includes 2 Csv files as below:

We get a response successfully as below details:

Checking MySQL/PostgreSQL database, Now customer
table has 15 records as below:

SpringBoot Download Data as a Single CSV file
Do a GET request to retrieve a CSV file from URL http://localhost:8080/api/download/csv/
:

SpringBoot test a big CSV File Uploading
We do a big CSV file uploading to SpringBoot RestApi:

We get a 500 error response with an exception message throwed from SpringBoot server:
org.apache.tomcat.util.http.fileupload.impl.SizeLimitExceededException: the request was rejected because its size (45422988) exceeds the configured maximum (10485760)
at org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl.init(FileItemIteratorImpl.java:150) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl.getMultiPartStream(FileItemIteratorImpl.java:194) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl.findNextItem(FileItemIteratorImpl.java:213) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl.(FileItemIteratorImpl.java:131) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.tomcat.util.http.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:255) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:279) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.connector.Request.parseParts(Request.java:2870) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.connector.Request.getParts(Request.java:2772) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
at org.apache.catalina.connector.RequestFacade.getParts(RequestFacade.java:1098) ~[tomcat-embed-core-9.0.33.jar:9.0.33]
This is a Maximum upload size exceeded
exception. How to catch and handle the exception? We go to the next session for a right solution.
Implement SpringBoot Rest Exception Handler
For handling the Maximum upload size exceeded
exception, we create a RestExceptionHandler
class that extends the ResponseEntityExceptionHandler
class.
package com.loizenai.updownloadcsv.errorhandler;
import javax.servlet.http.HttpServletRequest;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartException;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
import com.loizenai.updownloadcsv.message.Error;
import com.loizenai.updownloadcsv.message.Response;
/**
*
* Copyright by https://loizenai.com
* @author loizenai.com
*
*/
@ControllerAdvice
public class RestExceptionHandler extends ResponseEntityExceptionHandler {
// Catch file size exceeded exception!
@SuppressWarnings({ "rawtypes", "unchecked" })
@ExceptionHandler(MultipartException.class)
@ResponseBody
ResponseEntity<Response> handleControllerException(HttpServletRequest request, Throwable ex) {
HttpStatus status = getStatus(request);
Error err = new Error("0x123", ex.getMessage());
Response res = new Response("error", err);
return new ResponseEntity(res, status);
}
private HttpStatus getStatus(HttpServletRequest request) {
Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
if (statusCode == null) {
return HttpStatus.INTERNAL_SERVER_ERROR;
}
return HttpStatus.valueOf(statusCode);
}
}
org.springframework.web.bind.annotation.ControllerAdvice
is a specialization of @Component
for classes that declare @ExceptionHandler
, @InitBinder
, or @ModelAttribute
methods to be shared across multiple @Controller
classes.
org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler
is a convenient base class for @ControllerAdvice
classes that wish to provide centralized exception handling across all @RequestMapping
methods through @ExceptionHandler
methods. This base class provides an @ExceptionHandler
method for handling internal Spring MVC exceptions. This method returns a ResponseEntity
for writing to the response with a message converter. (refer Spring docs)
Tuning File Upload Limits
We can tune Spring Boot’s auto-configured MultipartConfigElement
with property settings. We add the following properties to your existing properties settings (in application.properties
file):
spring.servlet.multipart.max-file-size=4096KB spring.servlet.multipart.max-request-size=4096KB
The multipart settings are constrained as follows:
spring.http.multipart.max-file-size
is set to 4096KB, meaning total file size cannot exceed 4096KB.spring.http.multipart.max-request-size
is set to 4096KB, meaning total request size for a multipart/form-data cannot exceed 4096KB.
Implement Ajax Client
Implement Upload Download Html Form
I use Bootstrap framework to create Html view for uploadload and download CSV files as below structure:

The view clearly has 3 difference row:
- the first row includes a html form for uploading a single csv file
- the second row includes a html form for uploading multiple csv files
- the final row includes a link used to download a csv files
Here is coding:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Upload Download CSV File Example</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js"></script>
<script src="/js/ajaxupdownloadcsv.js"></script>
</head>
<body>
<div class="container">
<div class="row">
<div class="col-sm-7" style="background-color:#e6fffa; padding:10px; border-radius:3px">
<h3>Upload Single CSV File</h3>
<form id="uploadSingleFileForm">
<div class="form-group">
<label class="control-label" for="csvfile">Choose a Csv File:</label>
<input type="file" class="form-control"
placeholder="Choose a upload file" id="csvfile" name="csvfile" required></input>
</div>
<button type="submit" class="btn btn-danger" id="btnUploadSingleFileSubmit">Submit</button>
</form>
<div id="response" style="display:none">
</div>
</div>
</div>
<hr>
<div class="row">
<div class="col-sm-7" style="background-color:#e6fffa; padding:10px; border-radius:3px">
<h3>Upload Multiple Files</h3>
<form id="uploadMultipleFilesForm">
<div class="form-group">
<label class="control-label" for="csvfiles">Choose CSV Files:</label>
<input type="file" class="form-control"
placeholder="Choose upload files" id="csvfiles" name="csvfiles" multiple required></input>
</div>
<button type="submit" class="btn btn-danger" id="btnUploadMultipleFilesSubmit">Submit</button>
</form>
<div id="responses" style="display:none">
</div>
</div>
</div>
<hr>
<div class="row">
<div class="col-sm-7">
<a href="/api/download/csv/" class="btn btn-primary" role="button" id="downloadcsvfile">Download CSV File</a>
</div>
</div>
</div>
</body>
</html>
We save the .html
file in static folder under src/main/resources
folder of SpringBoot project as index.html
name.
Implement Ajax Upload CSV files
We continue to implement an Ajax script to upload the data-form:
/**
* Copyright by https://loizenai.com
* Author: loizenai.com
*/
$(document).ready(function() {
/**
* Upload single file to SpringBoot
* at RestAPI: /api/upload/csv/single
*/
$("#uploadSingleFileForm").submit(function(evt) {
evt.preventDefault();
var formData = new FormData($(this)[0]);
$.ajax({
url : '/api/upload/csv/single',
type : 'POST',
data : formData,
async : false,
cache : false,
contentType : false,
enctype : 'multipart/form-data',
processData : false,
success : function(response) {
$("#response").empty();
if(response.errStatus !== "error"){
var displayInfo = response.messages[0].filename + " : " + response.messages[0].message + "<br>";
$("#response").append(displayInfo);
// add some css
$("#response").css("display", "block");
$("#response").css("background-color", "#e6e6ff");
$("#response").css("border", "solid 1px black");
$("#response").css("border-radius", "3px");
$("#response").css("margin", "10px");
$("#response").css("padding", "10px");
}else{
$("#response").css("display", "none");
var error = response.error.errDesc;
alert(error);
}
},
error: function(e){
alert("Fail! " + e);
}
});
return false;
});
/**
* Upload single file to SpringBoot
* at RestAPI: /api/upload/csv/multiple
*/
$("#uploadMultipleFilesForm").submit(function(evt) {
evt.preventDefault();
var formData = new FormData($(this)[0]);
$.ajax({
url : '/api/upload/csv/multiple',
type : 'POST',
data : formData,
async : false,
cache : false,
contentType : false,
enctype : 'multipart/form-data',
processData : false,
success : function(response) {
$("#responses").empty();
if(response.errStatus !== "error"){
var displayInfo = "<ul>";
for(var i=0; i<response.messages.length; i++){
displayInfo += "<li>" + response.messages[i].filename
+ " : " + response.messages[i].message
+ "</li>";
}
$("#responses").append(displayInfo + "</ul>");
$("#responses").css("display", "block");
// add some css
$("#responses").css("background-color", "#e6e6ff");
$("#responses").css("border", "solid 1px black");
$("#responses").css("border-radius", "3px");
$("#responses").css("margin", "10px");
$("#responses").css("padding", "10px");
}else{
$("#responses").css("display", "none");
var error = response.error.errDesc;
alert(error);
}
},
error: function(e){
alert("Fail! " + e);
}
});
return false;
});
})
The above script has 2 main functions:
$("#uploadSingleFileForm").submit(function(evt)
is used to upload a single csv file$("#uploadMultipleFilesForm").submit(function(evt)
is used to upload multiple csv files
Integrative Testing SpringBoot Upload Download CSV files with Ajax Client
Testcase – Upload Single CSV file

Network log:

Testcase – Upload Multiple CSV files

Network log:

Testcase – Download CSV file

Network Logs:

Sourcecode
All features of sourcecode for the tutorial SpringBoot RestAPIs Upload Download Multiple CSV files to MySQL/PostgreSQL with Ajax + RestClient:
- Backend
- Upload Single CSV File RestAPI
- Upload Multiple CSV Files RestAPI
- Download all data as a single CSV file
- Frontend
- Html Upload Single File Form
- Html Upload Multiple Files Form
- JQuery Ajax to download all data as a single CSV file
– GitHub Sourcecode for “SpringBoot Upload Download CSV files to MySQL/PostgreSQL”:
SpringBoot CSV Upload Download csv-Files – GitHub Sourcecode
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