Creating a downloadable csv file from an HTML table via java
If you have a <table> on your website and you’d like users to be able to download the content of that table to a csv file via java, I’ve got you covered. We’ll need HTML, JavaScript, Java, and the jsoup Java HTML parser.
Add a button on your page
<button id="download">Download</button>
Add an empty form to your page that posts to your controller action
<form id="myForm" method="post" action="/csvExport">
<input id="reportData" type="hidden" name="policyDetails" />
</form>
JavaScript to grab the HTML
document.getElementById("download").onclick = function () {
let theData = document.getElementById("reportData");
// this gets the first table on the screen and pulls the HTML, but you can target by id, class, etc
theData.value = document.getElementsByClassName("table")[0].outerHTML;
document.getElementById("myForm").submit();
};
Add jsoup to your build file. Use the latest version.
compile 'org.jsoup:jsoup:1.13.1'
Create a java controller
@PostMapping(value = "/csvExport", produces = MediaType.APPLICATION_OCTET_STREAM_VALUE)
public ResponseEntity<ByteArrayResource> export(@RequestParam("policyDetails") String policyDetails) {
try {
String csvText = generateExcel(policyDetails);
ByteArrayInputStream bais = new ByteArrayInputStream(csvText.getBytes());
byte[] byteArray = IOUtils.toByteArray(bais);
HttpHeaders headers = new HttpHeaders();
headers.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=cat.csv");
return ResponseEntity.ok()
.headers(headers)
.contentLength(byteArray.length)
.contentType(MediaType.APPLICATION_OCTET_STREAM)
.body(new ByteArrayResource(byteArray));
} catch (Exception e) {
// log and redirect user to an error page
}
}
public String generateExcel(String policyDetails) {
StringBuilder sb = new StringBuilder();
try {
Document doc = Jsoup.parseBodyFragment(policyDetails);
Elements rows = doc.getElementsByTag("tr");
// loop through all the tr
for (Element row : rows) {
// loop through all the td
Elements cells = row.getElementsByTag("td");
for (Element cell : cells) {
sb.append(cell.text().concat(","));
}
// add a line separator
sb.append("\n");
}
} catch (Exception e) {
e.getStackTrace();
}
return sb.toString();
}