Reading POST data from html form sent to serversocket
i try to write simplest possible server app in Java, displaying html form with textarea input, which after submitting gives me possibility to parse xml typed in that textarea. For now i build simple serversocket based server like that:
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class WebServer {
protected void start() {
ServerSocket s;
String gets = "";
System.out.println("Start on port 80");
try {
// create the main server socket
s = new ServerSocket(80);
} catch (Exception e) {
System.out.println("Error: " + e);
return;
}
System.out.println("Waiting for connection");
for (;;) {
try {
// wait for a connection
Socket remote = s.accept();
// remote is now the connected socket
System.out.println("Connection, sending data.");
BufferedReader in = new BufferedReader(new InputStreamReader(
remote.getInputStream()));
PrintWriter out = new PrintWriter(remote.getOutputStream());
String str = ".";
while (!str.equals("")) {
str = in.readLine();
if (str.contains("GET")){
gets = str;
break;
}
}
out.println("HTTP/1.0 200 OK");
out.println("Content-Type: text/html");
out.println("");
// Send the HTML page
String method = "get";
out.print("<html><form method="+method+">");
out.print("<textarea name=we></textarea></br>");
out.print("<input type=text name=a><input type=submit></form></html>");
out.println(gets);
out.flush();
remote.close();
} catch (Exception e) {
System.out.println("Error: " + e);
}
}
}
public static void main(String args[]) {
WebServer ws = new WebServer();
ws.start();
}
}
After form (textarea with xml and one additional text input) is submitted in 'gets' String-type variable I have Urlencoded values of my variables (also displayed on the screen, it looks like that:
gets = GET /?we=%3Cnetwork+ip_addr%3D%2210.0.0.0%2F8%22+save_ip%3D%22true%22%3E%0D%0A%3Csubnet+interf_used%3D%22200%22+name%3D%22lan1%22+%2F%3E%0D%0A%3Csubnet+interf_used%3D%22254%22+name%3D%22lan2%22+%2F%3E%0D%0A%3C%2Fnetwork%3E&a=fooBar HTTP/1.1
What can i do to change GET to POST method (if i simply change it in form and than put " if (str.contains("POST")){" it gives me string like
gets = POST / HTTP/1.1
with no variables. And after that, how i can use xml from my textarea field (called 'we')?
Answer
As there is a blank line following the headers, here is my relatively simple way of getting the post payload data, after having read the header information using the readLine() method of BufferedReader.
//socket is an instance of Socket
InputStream is = socket.getInputStream();
InputStreamReader isReader = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isReader);
//code to read and print headers
String headerLine = null;
while((headerLine = br.readLine()).length() != 0){
System.out.println(headerLine);
}
//code to read the post payload data
StringBuilder payload = new StringBuilder();
while(br.ready()){
payload.append((char) br.read());
}
System.out.println("Payload data is: "+payload.toString())