Add HEADER in HTTP Request in Java

Question

I'm using this following code to send simple HTTP Request :

try
{
    Socket  s = new Socket ();
    s.bind    (new InetSocketAddress (ipFrom, 0));
    s.connect (new InetSocketAddress (ipTo,   80), 1000);

    PrintWriter     writer = new PrintWriter    (s.getOutputStream ());
    BufferedReader  reader = new BufferedReader (new InputStreamReader (s.getInputStream ()));

    writer.print ("GET " + szUrl + " HTTP/1.0\r\n\r\n"); 
    writer.flush ();

    s     .close ();
    reader.close ();
    writer.close ();
}

However, as you can see, I don't send a custom HEADER. What should I add to send a custom HEADER ?

Bozho · Accepted Answer · 2010-02-06 18:59:44Z

6

Don't try to implement the HTTP protocol yourself.

Use HttpComponents by Apache.

(or its older and a little easier to use version - HttpClient)

answered Feb 6, 2010 at 18:59

Bozho

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1 Comment

bill0ute Over a year ago

Hi. Thanks for this advice. It seems to be very simple and powerful !

Tano · Accepted Answer · 2010-02-06 19:11:08Z

5

When you write

writer.print ("GET " + szUrl + " HTTP/1.0\r\n\r\n");

The \r\n\r\n bit is sending a line-feed/carriage-return to end the line and then another one to indicate that there are no more headers. This is a standard in both HTTP and email formats, i.e. a blank line indicates the end of headers. In order to add additional headers you just need to not send that sequence until you're done. You can do the following instead

writer.print ("GET " + szUrl + " HTTP/1.0\r\n"); 
writer.print ("header1: value1\r\n"); 
writer.print ("header2: value2\r\n"); 
writer.print ("header3: value3\r\n"); 
// end the header section
writer.print ("\r\n");

answered Feb 6, 2010 at 19:11

Tano

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Comments

Malax · Accepted Answer · 2010-02-06 19:03:08Z

1

Even if I suggest to try HttpComponents as mentioned by Bozho instead of implementing HTTP by yourself, this is would be the way to add a custom header:

 writer.print ("GET " + szUrl + " HTTP/1.0\r\n"); 
 writer.print ("X-MyOwnHeader: SomeValue\r\n");

answered Feb 6, 2010 at 19:03

Malax

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2 Comments

Tano Over a year ago

Specifically, the end of the header section is denoted by "\r\n\r\n", so whatever the last header line is should end in that, or should be followed by another line saying writer.print("\r\n");

x4u Over a year ago

Almost right, you just need another writer.print("\r\n"); at the end to finish the header part.

Jack · Accepted Answer · 2010-02-06 19:03:14Z

1

You should use classes already prepared to be used for http connections, like HTTPUrlConnection that is a childreon of UrlConnection and has this method

void setRequestProperty(String key, String value)

that should be used to set parameters of the request (like HEADER field).. check here for reference

answered Feb 6, 2010 at 19:03

Jack

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1 Comment

Brad Ellis Over a year ago

Not if your intent is to learn a lower level abstraction of computer science.

fospathi · Accepted Answer · 2020-06-03 00:57:10Z

1

You can also see URLConnection.

https://docs.oracle.com/javase/1.5.0/docs/api/java/net/URLConnection.html

edited Jun 3, 2020 at 0:57

fospathi

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answered Feb 6, 2010 at 19:03

oneat

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2 Comments

bill0ute Over a year ago

Hi, I can't really use URLConnection because I need to bind to a local IP. My server have 5 ips, and I need to send my Request from on of this.

Stephen C Over a year ago

@billOute - what? A URLConnection is perfectly capable of dealing with that. You just need to use different IP addresses in the URLs!!

Chandra Sekar · Accepted Answer · 2010-02-06 19:01:42Z

0

If you absolutely have to do it yourself by hand it must follow this format with each header on its own line.

name: value

Look into the header format in HTTP spec.

http://www.w3.org/Protocols/HTTP/1.0/draft-ietf-http-spec.html#Message-Headers

answered Feb 6, 2010 at 19:01

Chandra Sekar

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