文件是否附加在文件字段中？

Question

我有以下代码:

if (formItems != null && formItems.size() > 0) {
    // iterates over form's fields
    for (FileItem item : formItems) {
        // processes only fields that are not form fields
        if (!item.isFormField()) {
            String fileName = new File(item.getName()).getName();
            String filePath = uploadPath + File.separator + fileName;
            File storeFile = new File(filePath);

            // saves the file on disk
            item.write(storeFile);
            session.setAttribute("image", fileName);
        }
        // processes only form fields
        else {
            String fieldname = item.getFieldName();
            String fieldvalue = item.getString();
            session.setAttribute(fieldname, fieldvalue);
        }
    }
}

我想首先检查文件是否附加.如果已连接,则仅上载文件.我试过这个:

if(item==null)

但这不起作用.如何检查文件是否附加？我有一个文件字段:

<input type="file" name="image"/>

Answer 1

该item是永远null.

只需检查FileItem#getName()(文件名)是否为空和/或FileItem#getSize()(文件大小)是否等于0.

在你的特殊情况下,有一个<input type="file" name="image"/>,那将是:

if (!item.isFormField()) {
    if ("image".equals(item.getFieldName())) {
        if (item.getName() == null || item.getName().isEmpty()) {
            // No file was been selected.
        }

        if (item.getSize() == 0) {
            // No file was been selected, or it was an empty file.
        }
    }
}