No external libraries required. Cons: Verbose code; requires manual handling of streams and connections. 2. Using Apache Commons IO
import java.io.BufferedInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.net.URL; import java.net.HttpURLConnection; public class CSVDownloader { public static void downloadCSV(String fileURL, String savePath) throws IOException { URL url = new URL(fileURL); HttpURLConnection httpConn = (HttpURLConnection) url.openConnection(); int responseCode = httpConn.getResponseCode(); if (responseCode == HttpURLConnection.HTTP_OK) { try (BufferedInputStream in = new BufferedInputStream(httpConn.getInputStream()); FileOutputStream fileOutputStream = new FileOutputStream(savePath)) { byte[] dataBuffer = new byte[1024]; int bytesRead; while ((bytesRead = in.read(dataBuffer, 0, 1024)) != -1) { fileOutputStream.write(dataBuffer, 0, bytesRead); } System.out.println("CSV Downloaded successfully!"); } } else { System.out.println("No file to download. Server replied HTTP code: " + responseCode); } httpConn.disconnect(); } } Use code with caution.
import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class ReportController { @GetMapping("/download-csv") public ResponseEntity downloadCSV() { String csvData = "ID,Name,Email\n1,John Doe,john@example.com\n2,Jane Smith,jane@example.com"; byte[] output = csvData.getBytes(); return ResponseEntity.ok() .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=report.csv") .contentType(MediaType.parseMediaType("text/csv")) .contentLength(output.length) .body(output); } } Use code with caution.
No external libraries required. Cons: Verbose code; requires manual handling of streams and connections. 2. Using Apache Commons IO
import java.io.BufferedInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.net.URL; import java.net.HttpURLConnection; public class CSVDownloader { public static void downloadCSV(String fileURL, String savePath) throws IOException { URL url = new URL(fileURL); HttpURLConnection httpConn = (HttpURLConnection) url.openConnection(); int responseCode = httpConn.getResponseCode(); if (responseCode == HttpURLConnection.HTTP_OK) { try (BufferedInputStream in = new BufferedInputStream(httpConn.getInputStream()); FileOutputStream fileOutputStream = new FileOutputStream(savePath)) { byte[] dataBuffer = new byte[1024]; int bytesRead; while ((bytesRead = in.read(dataBuffer, 0, 1024)) != -1) { fileOutputStream.write(dataBuffer, 0, bytesRead); } System.out.println("CSV Downloaded successfully!"); } } else { System.out.println("No file to download. Server replied HTTP code: " + responseCode); } httpConn.disconnect(); } } Use code with caution. download a csv file in java
import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class ReportController { @GetMapping("/download-csv") public ResponseEntity downloadCSV() { String csvData = "ID,Name,Email\n1,John Doe,john@example.com\n2,Jane Smith,jane@example.com"; byte[] output = csvData.getBytes(); return ResponseEntity.ok() .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=report.csv") .contentType(MediaType.parseMediaType("text/csv")) .contentLength(output.length) .body(output); } } Use code with caution. No external libraries required