如何在REST响应[重复]后删除文件

Question

在文件作为REST请求的响应返回后，处理删除文件的最佳方法是什么？

我有一个endpoint，可以根据请求创建一个文件，并在响应中返回它。一旦发送了响应，该文件就不再需要，可以/应该删除。

@Path("file")
@GET
@Produces({MediaType.APPLICATION_OCTET_STREAM})
@Override
public Response getFile() {

        // Create the file
        ...

        // Get the file as a steam for the entity
        File file = new File("the_new_file");

        ResponseBuilder response = Response.ok((Object) file);
        response.header("Content-Disposition", "attachment; filename=\"the_new_file\"");
        return response.build();

        // Obviously I can't do this but at this point I need to delete the file!

}

我想我可以创建一个tmp文件，但我认为有一个更优雅的机制来实现这一点。该文件可能相当大，因此我无法将其加载到内存中。

Answer 1

我最近用泽西做了类似的事

@GET
@Produces("application/zip")
@Path("/export")
public Response exportRuleSet(@QueryParam("ids") final List<String> ids) {

    try {
        final File exportFile = serviceClass.method(ruleSetIds);

        final InputStream responseStream = new FileInputStream(exportFile);


        StreamingOutput output = new StreamingOutput() {
            @Override
            public void write(OutputStream out) throws IOException, WebApplicationException {  
                int length;
                byte[] buffer = new byte[1024];
                while((length = responseStream.read(buffer)) != -1) {
                    out.write(buffer, 0, length);
                }
                out.flush();
                responseStream.close();
               boolean isDeleted = exportFile.delete();
                log.info(exportFile.getCanonicalPath()+":File is deleted:"+ isDeleted);                 
            }   
        };
        return Response.ok(output).header("Content-Disposition", "attachment; filename=rulset-" + exportFile.getName()).build();
    }

Answer 2

有一个更优雅的解决方案，不写文件，直接写入Response实例中包含的输出流。

Answer 3

将StreamingOutput用作实体：

final Path path;
...
return Response.ok().entity(new StreamingOutput() {
    @Override
    public void write(final OutputStream output) throws IOException, WebApplicationException {
        try {
            Files.copy(path, output);
        } finally {
            Files.delete(path);
        }
    }
}