在java中将blob转换为pdf

Question

我无法将我的blob数据转换为原始的pdf文件。说文件损坏无法读取。 我的代码片段如下：

w_ItemCode =w_rs.getString(1) ;
w_FileName = w_rs.getString(2);
Blob w_Blob = w_rs.getBlob(3);
w_TOdate = w_rs.getString(4);
w_File = new File(w_Directory +"/"+ w_ItemCode+"_"+ w_FileName);
if(!w_File.exists())
    w_File.createNewFile();
if(w_Blob != null && w_Blob.length() > 0) {
    InputStream w_BLOBStream = w_Blob.getBinaryStream();
    PdfReader reader = new PdfReader(w_BLOBStream);
}