Getting a file from an http request in java

Question

I am wondering if there are any compiler flags you can set to pick up this case. Say I have the following files:

a.h

class a
{
    public:
    int lala(void);
    int lala2(void);
};

a.cpp

#include "a.h"

int a::lala(void)
{
    return 5;
}

main.cpp

#include <iostream>
#include "a.h"

int main()
{
    a thi;
    std::cout << thi.lala() << std::endl;
    return 0;
}

The problem here is that the function lala2 is not implemented and although its not used not even a warning is issued.

So i don't know how it led to this but basically in a large portion of code there was an un-implemented function. I am just wondering if there are any compiler flags that will allow us to pick this up? Using g++ -pedantic -Wall was not enough.

Solution 1

public byte[] download(URL url) throws IOException {
    URLConnection uc = url.openConnection();
    int len = uc.getContentLength();
    InputStream is = new BufferedInputStream(uc.getInputStream());
    try {
        byte[] data = new byte[len];
        int offset = 0;
        while (offset < len) {
            int read = is.read(data, offset, data.length - offset);
            if (read < 0) {
                break;
            }
          offset += read;
        }
        if (offset < len) {
            throw new IOException(
                String.format("Read %d bytes; expected %d", offset, len));
        }
        return data;
    } finally {
        is.close();
    }
}

Edit: Cleaned up the code.

Solution 2

Check out the URL and URLConnection classes. Here's some documentation: http://www.exampledepot.com/egs/java.net/Post.html

Solution 3

If the intention is to run another resource while your servlet is executing with out transferring control to the other resource you can try using include(request, response).

RequestDispatcher dispatcher =
   getServletContext().getRequestDispatcher("/url of other resource");
if (dispatcher != null)
   dispatcher.include(request, response);
} 

You may put this on a servlet and the result of the other resource is included on your servlet.

EDIT: Since you are looking to get a file back then this solution works for that too.

Comments

[rhughes]

If you tried to use this method you would probably get a linker error.

[Fantastic Mr Fox]

@rhughes, Correct but I would like to get a compiler warning so that I can pick up this function.

[Klaus]

The compiler can't see that the function is not needed and not defined. This can only be done in link stage.

[RodeoClown]

Thanks Vincent. It doesn't look like that will quite meet what I am looking for - I'm not looking to include anything in the response. There is no response in this instance (it is a scheduled task that runs purely server-side).