Deep analysis of webwork file uploading mechanism in Java

After clicking the Upload button, the WebWork program flow is as follows:

Step 1) into the Servletdispatcher.service

public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException {
........
request = wrapRequest(request);
.........
}

STEP2) into the Servletdispatcher.wraprequest

protected HttpServletRequest wrapRequest(HttpServletRequest request)
throws IOException {
........................
if (MultiPartRequest.isMultiPart(request)) {
request = new MultiPartRequestWrapper(request, getSaveDir(), getMaxSize());
}
return request;
}

STEP3) Construction method of entering Multipartrequestwrapper

public Multipartrequestwrapper (httpservletrequest request, String savedir, int maxSize)
throws IOException {
.......... .... ...
//step3.1) Gets the webwork.preperties configured parser
String parser = "";
Parser = configuration.getstring ("Webwork.multipart.parser");
//If it isn't set, use Pell
If (Parser.equals ("")) {
Log.warn ("Property Webwork.multipart.parser not set." +
Using com.opensymphony.webwork.dispatcher.multipart.PellMultiPartRequest);
Parser = "Com.opensymphony.webwork.dispatcher.multipart.PellMultiPartRequest";
}
//Legacy support for Old style property values
Else if (parser.equals ("Pell")) {
Parser = "Com.opensym Phony.webwork.dispatcher.multipart.PellMultiPartRequest ";
} else if (parser.equals ("cos")) {
Parser = " Com.opensymphony.webwork.dispatcher.multipart.CosMultiPartRequest ";
} else if (Parser.equals ("Jakarta")) {
Parser = " Com.opensymphony.webwork.dispatcher.multipart.JakartaMultiPartRequest ";

//step3.2) instantiating parser
try {
Class Baseclazz =
after fetching Com.opensymphony.webwork.dispatcher.multipart.MultiPartRequest.class;
Class clazz = class.forname (parser);
//Make sure it extends Multipartrequest
if (!baseclazz.isassignablefrom (Clazz)) {
Adderror ("Class" + Parse R + "' does not extend Multipartrequest");
return;
}
//Get the constructor
constructor ctor = Clazz.getdeclaredconstructor (New class[]{
Class.forName ("Jav Ax.servlet.http.HttpServletRequest "),
Java.lang.String.class, Int.class
});
//Build the parameter list
object[] parms = new object[]{
Request, Savedir, new Integer (maxSize)
;
Instantiate it
Multi = (multipartrequest) ctor.newinstance (parms);
.................................................
}