Question

I’m getting IndexOutOfBoundsException while uploading a zip file. What could be the reason? How can I solve it?

Code:-

    String sf="";
    String contentType = req.getContentType();
    DataInputStream in = new DataInputStream(req.getInputStream());
    int formDataLength = req.getContentLength();
    byte dataBytes[] = new byte[formDataLength];
    int byteRead = 0;
    int totalBytesRead = 0;
    while (totalBytesRead < formDataLength) {
        byteRead = in.read(dataBytes, totalBytesRead, formDataLength);
        totalBytesRead += byteRead;
    }
    String file = new String(dataBytes);
    String saveFile = file.substring(file.indexOf("filename=\"") + 10);
    saveFile = saveFile.substring(0, saveFile.indexOf("\n"));
    saveFile = saveFile.substring(saveFile.lastIndexOf("\\") + 1,saveFile.indexOf("\""));
    int lastIndex = contentType.lastIndexOf("=");
    String boundary = contentType.substring(lastIndex + 1,contentType.length());
    int pos;
    pos = file.indexOf("filename=\"");
    pos = file.indexOf("\n", pos) + 1;
    pos = file.indexOf("\n", pos) + 1;
    pos = file.indexOf("\n", pos) + 1;
    int boundaryLocation = file.indexOf(boundary, pos) - 4;
    int startPos = ((file.substring(0, pos)).getBytes()).length;
    int endPos = ((file.substring(0, boundaryLocation)).getBytes()).length;
    sf = "../" + File.separator + saveFile;
    FileOutputStream fileOut = new FileOutputStream(sf);
    fileOut.write(dataBytes, startPos, (endPos - startPos));  //----- Exception occurs on this line.
    fileOut.flush();
    fileOut.close();

Stacktrace:-

java.lang.IndexOutOfBoundsException
at java.io.FileOutputStream.writeBytes(Native Method)
at java.io.FileOutputStream.write(FileOutputStream.java:297)
at com.apprika.servlets.UpgradePatchServlet.uploadFile(UpgradePatchServlet.java:77)
at com.apprika.servlets.UpgradePatchServlet.upgradeServer(UpgradePatchServlet.java:40)
at com.apprika.servlets.UpgradePatchServlet.doPost(UpgradePatchServlet.java:30)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:636)

Server is running on Linux and uploading file from Windows.

---

I’ve tried apache commons file upload but still not getting any success.

    try {
                 DiskFileItemFactory factory = new DiskFileItemFactory();
                 ServletFileUpload upload = new ServletFileUpload(factory);
                 List<FileItem> items = upload.parseRequest(req);
                 for (FileItem item : items) {
                    if (!item.isFormField()) {
                        InputStream is = item.getInputStream();
                        FileOutputStream os = new FileOutputStream("/up/" + item.getName());
                        byte[] b = new byte[4096];
                        int bytesRead = 0;
                        while ((bytesRead = is.read(b)) != -1) {
                            os.write(b, 0, bytesRead);
                        }
                        os.flush();
                        os.close();
                        is.close();
                    }
                 }
            }catch (Exception e) {
                e.printStackTrace();
            }

Now it gives error java.io.FileNotFoundException: /up (Is a directory)
`

Answer 1

You are converting the uploaded bytes into a string without specifying the encoding. The default encoding on the server is not necessary the same as the one used for the upload.
Therefore the strings length is not guaranteed to be the same as the byte arrays length, so computing the offsets into this array based on the string could lead to all sorts of problems.

I would recommend using something like Apache Commons Fileupload instead of trying to do all the parsing yourself as getting all the details right is not easy.
A good starting point would be this answer: How to upload files to server using JSP/Servlet?