How to read a user-submitted file using Fileinputstream?

Question

I would like the user to send a file . xls to the system and from this would be created a database. The method I have is working, but the parameter that Fileinputstream receives is a String indicating the file path. Only the system will be used by different machines and the uploaded file will have different paths.

What I would like to know is how I make the user choose, from his machine, the file that should be read by the system, rather than the system picking the file from a specific path (static).

Follows the method:

public void convertePlanilhaEmAlunos() {

        try {

            // ALTERAR O PATH DE ACORDO COM O LOCAL DA PLANILHA
            FileInputStream file = new FileInputStream(
                    "C:\\Users\\Desktop\\teste.xls");

            // Get the workbook instance for XLS file
            XSSFWorkbook workbook = new XSSFWorkbook(file);

            // Get first sheet from the workbook
            XSSFSheet sheet = workbook.getSheetAt(0);

            Iterator<Row> rowIterator = sheet.iterator();

            while (rowIterator.hasNext()) {

                Row row = rowIterator.next();
                if (row.getRowNum() < 7) {
                    continue;
                }

                for (@SuppressWarnings("unused")
                Cell cell : row) {
                    aluno.setNome(String.valueOf(row.getCell(0)));
                    aluno.setDataNascimento(String.valueOf(row.getCell(1)));
                    aluno.setRg(String.valueOf(row.getCell(2)));
                    aluno.setNomeMae(String.valueOf(row.getCell(3)));
                    aluno.setRgMae(String.valueOf(row.getCell(4)));
                    aluno.setNomePai(String.valueOf(row.getCell(5)));
                    aluno.setCurso(String.valueOf(row.getCell(6)));
                    aluno.setTurma(String.valueOf(row.getCell(7)));

                }

                if (aluno.getNome() == "") {
                    break;
                }

                System.out.println(aluno.getNome());

                criaAluno();

                aluno = new Aluno();

            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Answer 1

You can add the primefaces library to your project and use the Uploadfile component to do this. Download the primefaces library directly on the website: http://www.primefaces.org/

On your website it will look like this:

<h:form enctype="multipart/form-data">
  <p:growl id="messages" showDetail="true" />

  <p:fileUpload value="#{fileUploadView.file}" mode="simple" disabled="true" />

  <p:commandButton value="Submit" ajax="false" actionListener="#{fileUploadView.upload}" disabled="true" />
</h:form>

And in Java it will stay like this:

public class FileUploadView {

private UploadedFile file;

public UploadedFile getFile() {
    return file;
}

public void setFile(UploadedFile file) {
    this.file = file;
}

public void upload() {
    if(file != null) {
        FacesMessage message = new FacesMessage("Succesful", file.getFileName() + " is uploaded.");
        FacesContext.getCurrentInstance().addMessage(null, message);
    }
}

}

With that you can make this upload easier and in the object itself "Uploadedfile" you can search for its path.

Answer 2

One of the builders XSSFWorkbook gets a InputStream as parameter. That being said, you can change the FileInputStream by a type of InputStream serve you better, like the BufferedInputStream or any other.

It depends on your need and how the user will send the file to the server. I believe the file already arrives at the server as InputStream and so you can pass it directly to the builder of XSSFWorkbook.