RESTful produces binary file

I'm new using CXF and Spring to make RESTful webservices.

This is my problem: I want to create a service that produces "any" kind of file(can be image,document,txt or even pdf), and also a XML. So far I got this code:

@Path("/download/")
@GET
@Produces({"application/*"})
public CustomXML getFile() throws Exception; 

I don't know exactly where to begin so please be patient.

EDIT:

Complete code of Bryant Luk(thanks!)

@Path("/download/")
@GET
public javax.ws.rs.core.Response getFile() throws Exception {
    if (/* want the pdf file */) {
        File file = new File("...");
        return Response.ok(file, MediaType.APP开发者_StackOverflow社区LICATION_OCTET_STREAM)
            .header("content-disposition", "attachment; filename =" + file.getName())
            .build(); 
    }

    /* default to xml file */
    return Response.ok(new FileInputStream("custom.xml")).type("application/xml").build();
}

If it will return any file, you might want to make your method more "generic" and return a javax.ws.rs.core.Response which you can set the Content-Type header programmatically:

@Path("/download/")
@GET
public javax.ws.rs.core.Response getFile() throws Exception {
    if (/* want the pdf file */) {
        return Response.ok(new File(/*...*/)).type("application/pdf").build(); 
    }

    /* default to xml file */
    return Response.ok(new FileInputStream("custom.xml")).type("application/xml").build();
}

We also use CXF and Spring, and this is my preferable API.

import javax.ws.rs.core.Context;

@Path("/")
public interface ContentService
{
    @GET
    @Path("/download/")
    @Produces(MediaType.WILDCARD)
    InputStream getFile() throws Exception;
}

@Component
public class ContentServiceImpl implements ContentService
{
    @Context
    private MessageContext context;

    @Override
    public InputStream getFile() throws Exception
    {
        File f;
        String contentType;
        if (/* want the pdf file */) {
            f = new File("...pdf");
            contentType = MediaType.APPLICATION_PDF_VALUE;
        } else { /* default to xml file */
            f = new File("custom.xml");
            contentType = MediaType.APPLICATION_XML_VALUE;
        }
        context.getHttpServletResponse().setContentType(contentType);
        context.getHttpServletResponse().setHeader("Content-Disposition", "attachment; filename=" + f.getName());
        return new FileInputStream(f);
    }
}