如何检查字节数组是否为空？

Question

我使用以下代码来获取上传文件。

 @POST
    @Path("update")
    @Consumes(MediaType.WILDCARD)
    public boolean updateWorkBookMaster(MultipartFormDataInput input) {
        try {
            //get form data
            Map<String, List<InputPart>> uploadForm = input.getFormDataMap();

            //get uploaded file
            List<InputPart> inputParts = uploadForm.get("workBookFile");
            MultivaluedMap<String, String> header = inputParts.get(0).getHeaders();
            InputStream inputStream = inputParts.get(0).getBody(InputStream.class, null);
            byte[] bytes = IOUtils.toByteArray(inputStream);

现在我想检查这个byte[]是否为空， 在调试时，如果我没有上传任何文件，则显示其长度为9，为什么9不是0。

Answer 1

您可以通过以下方式对文件执行空检查：

import org.glassfish.jersey.media.multipart.ContentDisposition;
import org.glassfish.jersey.media.multipart.FormDataBodyPart;
import org.glassfish.jersey.media.multipart.FormDataMultiPart;

@POST
@Path("update")
@Consumes(MediaType.WILDCARD)
public boolean updateWorkBookMaster(FormDataMultiPart multiPartData) {
    try {
        final FormDataBodyPart workBookFilePart = multiPartData.getField("workBookFile");
        final ContentDisposition workBookFileDetails = workBookFilePart.getContentDisposition();
        final InputStream workBookFileDocument = workBookFilePart.getValueAs(InputStream.class);

        if (workBookFileDetails.getFileName() != null || 
            workBookFileDetails.getFileName().trim().length() > 0 ) {
            // file is present
        } else {
            // file is not uploadded
        }
    } ... // other code
}