Get POST Data from HttpExchange

Question

Get POST Data from HttpExchange

11.2k Views Asked by AaronF At 06 May 2017 at 15:35

This seems like such a common use case that there ought to be a simple solution, yet everywhere I look is filled with extremely bloated examples.

Let's say I have a form that looks like:

<form action="http://localhost/endpoint" method="POST" enctype="multipart/form-data">
    <input type="text" name="value" />
    <input type="submit" value="Submit"/>
</form>

I submit it and on the server want to get the input value:

On the server I set up an HttpServer with a single endpoint, that in this case just sends the body data straight back:

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

import java.io.*;
import java.net.InetSocketAddress;
import java.util.function.Consumer;

public class Main {
    public static void main(String[] args) {
        try {
            HttpServer server = HttpServer.create(new InetSocketAddress(80), 10);
            server.setExecutor(null);
            server.createContext(
                    "/endpoint",
                    (HttpExchange httpExchange) -> {

                            InputStream input = httpExchange.getRequestBody();
                            StringBuilder stringBuilder = new StringBuilder();

                            new BufferedReader(new InputStreamReader(input))
                                .lines()
                                .forEach( (String s) -> stringBuilder.append(s + "\n") );

                            httpExchange.sendResponseHeaders(200, stringBuilder.length());

                            OutputStream output = httpExchange.getResponseBody();
                            output.write(stringBuilder.toString().getBytes());

                            httpExchange.close();
                    }
            );

            server.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Now, if submitting the form with the input "hi", returns

------WebKitFormBoundaryVs2BrJjCaLCWNF9o
Content-Disposition: form-data; name="value"

hi
------WebKitFormBoundaryVs2BrJjCaLCWNF9o--

This tells me that there should be a way to get the string values, but the only way I can see to do it is to manually parse it.

(Also, I'm trying to get a little dirty, implementing this server only with the libraries that come with the JDK. I've used Apache server quite a bit at work, but that isn't what I'm trying to do here.)

Original Q&A

There are 1 best solutions below

**U1t84p0we85** · Answer 1 · 2019-09-26T20:44:46.173000

public Server() throws IOException {
    HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
    server.createContext("/", new HttpHandler() {
        @Override
        public void handle(HttpExchange t) throws IOException {
            StringBuilder sb = new StringBuilder();
            InputStream ios = t.getRequestBody();
            int i;
            while ((i = ios.read()) != -1) {
                sb.append((char) i);
            }
            System.out.println("hm: " + sb.toString());

            String response = " <html>\n"
                    + "<body>\n"
                    + "\n"
                    + "<form action=\"http://localhost:8000\" method=\"post\">\n"
                    + "input: <input type=\"text\" name=\"input\"><br>\n"
                    + "input2: <input type=\"text\" name=\"input2\"><br>\n"
                    + "<input type=\"submit\">\n"
                    + "</form>\n"
                    + "\n"
                    + "</body>\n"
                    + "</html> ";
            t.sendResponseHeaders(200, response.length());
            OutputStream os = t.getResponseBody();
            os.write(response.getBytes());
            os.close();

        }
    });
    server.setExecutor(null);
    server.start();
}

not sure if you wanted this or what but this returns string of all posts page did with names and values

like that

input=value&input2=value2&......

Get POST Data from HttpExchange

There are 1 best solutions below

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