Download file, filename doesn't work in portlet

Question

I set filename in the HttpServletResponse header but when I download it has not this filename

FileInputStream fis = new FileInputStream(fileDocument         


        

Answer 1

You should not use the HttpServletResponse. Instead you should create a custom Resource and ResourceHandler:

CustomResourceHandler.java:

public final class CustomResourceHandler extends ResourceHandlerWrapper {

    // Public Constants
    public static final String LIBRARY_NAME = "exampleLib";
    public static final String RESOURCE_NAME = "exampleName";

    // Private Data Members
    private ResourceHandler wrappedResourceHandler;

    public CustomResourceHandler(ResourceHandler resourceHandler) {
        this.wrappedResourceHandler = resourceHandler;
    }

    @Override
    public Resource createResource(String resourceName, String libraryName) {

        if (LIBRARY_NAME.equals(libraryName)) {

            if (RESOURCE_NAME.equals(resourceName)) {
                return new CustomResource(libraryName, resourceName,
                    "exampleFileName.txt", "Example Content");
            }
            else {
                return super.createResource(resourceName, libraryName);
            }
        }
        else {
            return super.createResource(resourceName, libraryName);
        }
    }

    @Override
    public ResourceHandler getWrapped() {
        return wrappedResourceHandler;
    }

    @Override
    public boolean libraryExists(String libraryName) {

        if (LIBRARY_NAME.equals(libraryName)) {
            return true;
        }
        else {
            return super.libraryExists(libraryName);
        }
    }

    /* package-private */ static final class CustomResource extends Resource {

        private final String content;
        private final Map responseHeaders;
        private final String requestPath;
        private final URL url;

        public CustomResource(String libraryName, String resourceName,
            String fileName, String content) {

            super.setLibraryName(libraryName);
            super.setResourceName(resourceName);
            super.setContentType("text/plain");

            Map responseHeaders = new HashMap();
            responseHeaders.put("Content-Disposition",
                "attachment; filename=" + fileName + ";");

            this.responseHeaders = Collections.unmodifiableMap(responseHeaders);

            StringBuilder sb = new StringBuilder();
            sb.append(ResourceHandler.RESOURCE_IDENTIFIER);
            sb.append("/");
            sb.append(super.getResourceName());
            sb.append("?ln=");
            sb.append(super.getLibraryName());
            this.requestPath = sb.toString();

            URL url;

            try {

                FacesContext facesContext = FacesContext.getCurrentInstance();
                ExternalContext externalContext = facesContext.getExternalContext();
                url = new URL(externalContext.encodeResourceURL(this.requestPath));
            }
            catch (MalformedURLException e) {
                url = null;
            }

            this.url = url;
            this.content = content;
        }

        @Override
        public InputStream getInputStream() throws IOException {
            return new ByteArrayInputStream(
                content.getBytes(StandardCharsets.UTF_8));
        }

        @Override
        public String getRequestPath() {
            return requestPath;
        }

        @Override
        public Map getResponseHeaders() {
            return responseHeaders;
        }

        @Override
        public URL getURL() {
            return url;
        }

        @Override
        public boolean userAgentNeedsUpdate(FacesContext facesContext) {

            // Return false if the content cannot change dynamically.
            return true;
        }
    }
}

WEB-INF/faces-config.xml:

    
        
        custom.resource.handler.CustomResourceHandler
    

Here's some example code for downloading the resource:

---

public String getDownloadURL(FacesContext facesContext) {

    return facesContext.getApplication().getResourceHandler()
            .createResource(CustomResourceHandler.RESOURCE_NAME,
                CustomResourceHandler.LIBRARY_NAME)
            .getURL().toString();
}

You can also look at the Liferay Faces JSF Export PDF for a full portlet example to download/export a file.