JasperReports is a Java library, and it is meant for Java developers who need to add reporting to their applications.

Introduction

In this post, we will create an excel report that is exposed over RESTful endpoint using Spring Boot. In a previous post we looked at how to expose Jasper PDF over REST.

Prerequisites

Project Structure

At the end of this guide our folder structure will look similar to the following:

.
|__src/
|  |__main/
|  |  |__java/
|  |  |  |__com/
|  |  |  |  |__juliuskrah/
|  |  |  |  |  |__jasper/
|  |  |  |  |  |  |__Application.java
|  |  |  |  |  |  |__ApplicationProperties.java
|  |  |  |  |  |  |__report/
|  |  |  |  |  |  |  |__JasperReportsService.java
|  |  |  |  |  |  |  |__ReportService.java
|  |  |  |  |  |  |__storage/
|  |  |  |  |  |  |  |__FileSystemStorageService.java
|  |  |  |  |  |  |  |__StorageException.java
|  |  |  |  |  |  |  |__StorageFileNotFoundException.java
|  |  |  |  |  |  |  |__StorageService.java
|  |  |  |  |  |  |__web/
|  |  |  |  |  |  |  |__rest/
|  |  |  |  |  |  |  |  |__ApplicationResource.java
|  |  |__resources/
|  |  |  |__reports/
|  |  |  |  |__pdf_rest_resource.jrxml
|  |  |  |  |__pdf_rest.jrxml
|  |  |  |__application.yaml
|  |  |  |__cherry.png
|  |  |  |__logo.png
|__pom.xml

How to complete this guide

To complete this guide, download (zip| tar.gz) and unzip the source repository for this guide.

Create Excel Report

Let us start by implementing a solution to generate excel in JasperReports:

file: src/main/java/com/juliuskrah/jasper/report/JasperReportsService.java 

@Component
public class JasperReportsService implements ReportService {
  // ...
  @Override
  public byte[] generatePDFReport(String inputFileName, Map<String, Object> params,
    JRDataSource dataSource) {
    byte[] bytes = null;
    JasperReport jasperReport = null;
    try {
      if (storageService.jasperFileExists(inputFileName)) {
        jasperReport = (JasperReport) JRLoader.loadObject(storageService.loadJasperFile(inputFileName));
      } else {
        var jrxml = storageService.loadJrxmlFile(inputFileName);
        jasperReport = JasperCompileManager.compileReport(jrxml);
        // Save the compiled report for use on next invocation
        JRSaver.saveObject(jasperReport, storageService.loadJasperFile(inputFileName));
      }
      JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport, params, dataSource);
      var input = new SimpleExporterInput(jasperPrint);
      try (var byteArray = new ByteArrayOutputStream()) {
        var output = new SimpleOutputStreamExporterOutput(byteArray);
        var exporter = new JRXlsxExporter();
        exporter.setExporterInput(input);
        exporter.setExporterOutput(output);
        exporter.exportReport();
        bytes = byteArray.toByteArray();
        output.close();
      } catch (IOException e) {
        // handle IO error
      }
      return bytes;
    } catch (JRException e) {
      // handle error
    }
    return bytes;
  }
}

Render the Excel REST Endpoint

We will create the REST endpoint:

file: src/main/java/com/juliuskrah/jasper/web/rest/ApplicationResource.java 

@RestController
public class ApplicationResource {
  // ...
  @GetMapping("/{username}")
  public ResponseEntity<byte[]> report(@PathVariable String username) {
    Map<String, Object> params = new HashMap<>();
    params.put("username", username);
    byte[] bytes = reportService.generatePDFReport("pdf_rest_resource", params);
    var contentDisposition = ContentDisposition.builder("attachment")
      .filename(username + ".xlsx").build();
    HttpHeaders headers = new HttpHeaders();
    headers.setContentDisposition(contentDisposition);
    return ResponseEntity
      .ok()
      // Specify content type as excel
      .header("Content-Type", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet; charset=UTF-8")
      // Tell browser to download Excel if it can
      .headers(headers) //
      .body(bytes);
  }
}

Now navigate to http://localhost:8080/:username to view your report.

Conclusion

In this post we learned how to generate Excel with JasperReports and serve it over HTTP with Spring Boot. As usual you can find the full example to this guide in the github repository. Until the next post, keep doing cool things :+1:.