How to download pdf file and redirect to home page in Spring mvc

Question

Following code just work fine there is no error in it but not work as required..

problem 1: I want to download pdf file and redirect to home page(url:../).when ever i nevigate to url(../admin/generate_pdf)

problem 2:when ever i uncomment the commented line in Pdfdemo.java it gives me an error 404 page not found.

Pdfdemo.java

public class Pdfdemos {
    private static String USER_PASSWORD = "password";
    private static String OWNER_PASSWORD = "lokesh";

        public String generate_pdf() {
            try {
                String file_name="d:\\sanjeet7.pdf";
                Document document= new Document();
                PdfWriter writer=PdfWriter.getInstance(document, new FileOutputStream(file_name));

//              writer.setEncryption(USER_PASSWORD.getBytes(),
//                          OWNER_PASSWORD.getBytes(), PdfWriter.ALLOW_PRINTING |PdfWriter.ALLOW_ASSEMBLY|
//                          PdfWriter.ALLOW_COPY|
//                          PdfWriter.ALLOW_DEGRADED_PRINTING|
//                          PdfWriter.ALLOW_FILL_IN|
//                          PdfWriter.ALLOW_MODIFY_ANNOTATIONS|
//                          PdfWriter.ALLOW_MODIFY_CONTENTS|
//                          PdfWriter.ALLOW_SCREENREADERS|
//                          PdfWriter.ALLOW_ASSEMBLY|
//                          PdfWriter.ENCRYPTION_AES_128, 0);


                document.open();
                document.add(new Paragraph(" "));document.add(new Paragraph(" "));
                String days_in_week[]= {"monday","tuesday","webnesday","thursday","friday","saturday"};
                int period=8;
                String user="springstudent";
                String pass="springstudent";
                String jdbcUrl="jdbc:mysql://localhost:3306/web_customer_tracker?useSSL=false";
                String driver="com.mysql.jdbc.Driver";
                Connection myconn=DriverManager.getConnection(jdbcUrl,user,pass);
                PreparedStatement ps=null;
                ResultSet rs=null;
                String query="select * from class_t";
                ps=myconn.prepareStatement(query);
                rs=ps.executeQuery();
                while(rs.next()) {
                    Paragraph para=new Paragraph("Time table for class"+rs.getString("class")+rs.getString("section"));
                    document.add(para);
                    System.out.println(rs.getInt("id"));
                    PdfPTable table=new PdfPTable(period+1);
                    for(int i=0;i<days_in_week.length;i++) {

                        for(int j=0;j<period+1;j++) {

                            if(j==5) {
                                table.addCell("recess");
                            }else {

                                table.addCell("this is "+j);
                            }


                        }


                    }
                    document.add(table);
                    document.newPage();

                }
                document.close();
                System.out.println("finish");





            return file_name;

            }catch(Exception e) {
                System.out.println(e);
            }
            return null;


        }

}

Generate_pdf_controller.java

@Controller
@RequestMapping("/admin/generate_pdf")
public class Generate_pdf_Controller {


    @GetMapping("/online")
    public String generating_pdf(Model theModel) {
        System.out.println("hello");
        CustomerServiceImpl pal=new CustomerServiceImpl();
        Pdfdemos pal1=new Pdfdemos();
        String xx=pal1.generate_pdf();
        return "redirect:/";
    }
}

Check this solution: https://stackoverflow.com/questions/17955777/redirect-to-an-external-url-from-controller-action-in-spring-mvc — Ilya Lysenko, Feb 25 '20 at 16:50
I am able to redirect but not download and redirect at the sae time.. — sanjeet pal, Feb 25 '20 at 16:56
You can redirect from a web page with using Java Script after downloading a PDF. — Ilya Lysenko, Feb 25 '20 at 17:02

Ilya Lysenko · Answer 1 · 2020-02-25T18:07:33.947

Simplified version of creating and downloading a PDF:

@Service
public class PdfService {

    public InputStream createPdf() throws Exception {
        ByteArrayOutputStream out = new ByteArrayOutputStream();

        Document document = new Document(PageSize.A4, 50, 50, 50, 50);
        PdfWriter writer = PdfWriter.getInstance(document, out);

        writer.setEncryption("user_password".getBytes(), "owner_password".getBytes(),
                    PdfWriter.ALLOW_PRINTING |
                    PdfWriter.ALLOW_ASSEMBLY |
                    PdfWriter.ALLOW_COPY |
                    PdfWriter.ALLOW_DEGRADED_PRINTING |
                    PdfWriter.ALLOW_FILL_IN |
                    PdfWriter.ALLOW_MODIFY_ANNOTATIONS |
                    PdfWriter.ALLOW_MODIFY_CONTENTS |
                    PdfWriter.ALLOW_SCREENREADERS |
                    PdfWriter.ALLOW_ASSEMBLY |
                    PdfWriter.ENCRYPTION_AES_128, 0);

        document.open();

        document.add(new Paragraph("My example PDF document"));
        // some logic here

        document.close();

        return new ByteArrayInputStream(out.toByteArray());
    }
}


@Controller
@RequestMapping("/admin/generate_pdf")
public class PdfController {

    @Autowired
    private PdfService pdfService;

    @GetMapping("/online")
    public void generatePdf(HttpServletResponse response) throws Exception {
        response.setContentType("application/pdf");
        response.setHeader("Content-Disposition", "attachment; filename=\"mydocument.pdf\"");

        InputStream pdf = pdfService.createPdf();
        org.apache.commons.io.IOUtils.copy(pdf, response.getOutputStream());
        response.flushBuffer();
    }
}

What about redirecting, as I said in comments, you can do it with using JS at the frontend (after calling the /admin/generate_pdf/online url). You can't download file and make refresh/redirect at the same time.

xerx593 · Accepted Answer · 2020-02-25T19:46:11.757

Just to get the pdf (download into browser from local file system), this code is sufficient:

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("/admin/generate_pdf")
public class PdfController {

    @GetMapping(value = "/online", /*this is "nice to have" ->*/ produces = MediaType.APPLICATION_PDF_VALUE)
    @ResponseBody // this is important, as the return type byte[]
    public byte[] generating_pdf() throws IOException {//exception handling...
        System.out.println("hello");//logging
        // re-generate new file if needed (thread-safety!)...
        // ..and dump the content as byte[] response body:
        return Files.readAllBytes(Paths.get("d:\\sanjeet7.pdf"));
    }
}

... if you need "a refresh", you can "rewrite" the file/re-call your service, but still maybe not the "thread-safest" solution.

Edit: With no further configuration (port/context root/...), You should reach this at: http://localhost:8080/admin/generate_pdf/online

If you want to "operate closer to the bytes" and with void return type/no @ResponseBody and want an additional redirect (to be tested), I think this should still work:

@Controller
public class ... {

   @GetMapping(value = ..., produces ...)
   //no request body, void return type, response will be autowired and can be handled
   public void generatePdf(javax.servlet.http.HttpServletResponse response) throws ... {
      java.io.OutputStream outStr = response.getOutputStream();
      // dump from "somewhere" into outStr, "finally" close.
      outStr.close();
      //TO BE TESTED:
      response.sendRedirect("/");
   }
}

..or even (return a "view name" + operate on outputStream):

   @GetMapping(value = ..., produces = "application/pdf")
   //return a "view name" (!), and you can inject (only) the outputstream (without enclosing response) 
   public String generatePdf(java.io.OutputStream outputstream) throws... {          
      // ... do your things on outputstream, IOUtils is good...
      // close the stream(?)
      // ..and
      return "redirect:/"; // to a redirect or a view name.
      // .... (in a "spring way", which could also save you some "context path problems"
   } ...

Thank for solution it really work.please consider about the second problem when I uncomment the pdf password instructions it show me 404 page not found.. — sanjeet pal, Feb 25 '20 at 17:45
#second_problem: check/test my edit, @sanjeetpal ...and at the frontend, you might have either some options. — xerx593, Feb 25 '20 at 17:58
the 404 might also be a "missing error page" (for another error code/problem) — xerx593, Feb 25 '20 at 18:02
response.sendRedirect("/admin"); redirect me to localhost:8080/admin instead of local host:8080/project_name/admin — sanjeet pal, Feb 25 '20 at 18:08
..then, you need additionally (to add to method signature) `HttpServletRequest request`, and use `request.getContextPath()` (=`/project_name`) (or obtain it from "somewhere else") — xerx593, Feb 25 '20 at 18:16
Adding project_name in request.getContextpath()(=/project_name) doesn't make it deployment friendly everyone I have to change on deploying on different platform....Sorry for irritating you ...I am just asking for community help.. — sanjeet pal, Feb 25 '20 at 18:26
nono, `request.getContextPath()` is environment safe/works everywhere/comes from browser (plz dont nail me to load balancing&proxy cases)...but still *reconsider* to complete this request with a redirect. (you deliver a "redirect code", but content ... this is not consistent with the purpose of redirect) ..maybe a "new tab" is good enough ...with all browsers — xerx593, Feb 25 '20 at 19:04
the use of `"Content-Disposition"`(filename, size, ... see ilia's reply) header might also have some effects on some browsers (IE!?)! — xerx593, Feb 25 '20 at 19:55

How to download pdf file and redirect to home page in Spring mvc

2 Answers2