Read HTTP Parameters on TCP port using Java ServerSocket

Question

How would I read the HTTP Request parameters if I send an HTTP Request from a Java Servlet and receive it on a TCP port using ServerSocket. Can anyone please help me on this?

Following is my design

Servlet

GET/POST using HttpURLConnection

    URL url = new URL("http://localhost:2309/");
    HttpURLConnection connection = (HttpURLConnection)url.openConnection();
    connection.setRequestProperty("Content-Type", "application/text");
    connection.setRequestProperty("Accept", "application/text");
    connection.setRequestMethod("POST");        
    connection.setRequestProperty("header1", "value1");

at localhost : 2309 I have a ServerSocket up and listening for a request from above servlet. I am trying to read the request but I only read the HTTP Headers, but I do not see the request parameters (I know in above example I am not sending any parameters, I had tried this by getting Output stream of the connection and writing to it).

this is how I tried sending request parameters to my ServerSocket program.

byte[] parameters = someString.getBytes();
        OutputStream outStream = connection.getOutputStream();
        outStream.write(parameters);

Following is my ServerSocket program.

public static void main(String... args) {
    int port = 2309;
    ServerSocket sSocket = new sSocket(port);
    System.out.println("### SERVER IS UP AND RUNNING, WAITING FOR A CLIENT TO CONNECT ON " + port + " ###");
    Socket cSocket = sSocket.accept();
    System.out.println("### CONNECTION WITH THE CLIENT CREATED ###");
    BufferedReader readRequest = new BufferedReader(new InputStreamReader(cSocket.getInputStream()));
    PrintWriter writeResponse = new PrintWriter(cSocket.getOutputStream());
    String line = "";
    while (readRequest != null  && (line = readRequest.readLine()) != null) {
        if (line.length() == 0)
            break;
        System.out.println(line);
    }
    writeResponse.write("HTTP/1.0 200 OK\r\n");
    writeResponse.write("Date: Fri, 31 Dec 1999 23:59:59 GMT\r\n");
    writeResponse.write("Server: Apache/0.8.4\r\n");
    writeResponse.write("Content-Type: text/html\r\n");
    writeResponse.write("Content-Length: 59\r\n");
    writeResponse.write("Expires: Sat, 01 Jan 2000 00:59:59 GMT\r\n");
    writeResponse.write("Last-modified: Fri, 09 Aug 1996 14:21:40 GMT\r\n");
    writeResponse.write("\r\n");
    writeResponse.write("<TITLE>Example</TITLE>");
    writeResponse.write("<P>This is an example</P>");
}

Following is what I see on my ServerSocket program OUTPUT.

### SERVER IS UP AND RUNNING, WAITING FOR A CLIENT TO CONNECT ON 2309 ###
### CONNECTION WITH THE CLIENT CREATED ###
POST / HTTP/1.1
Content-Type: application/text
Accept: application/text
header1: value1
Cache-Control: no-cache
Pragma: no-cache
User-Agent: Java/1.7.0_75
Host: localhost:2309
Connection: keep-alive
### CONNECTION WITH THE CLIENT TERMINATED ###

Can anyone suggest me

1. how do I read the Request Parameters

2. Writing to output stream on connection object, will it get me the request parameters right at the place?

3. Is this a good approach, when I just want to keep an standalone server up, which will be just listening to the requests coming on to single port and serving it [OR] there is any better way through which I can perform this?

Answer 1

I was not able to get the body from HTTP Payload. And probable reason was below line.

BufferedReader readRequest = new BufferedReader(new InputStreamReader(cSocket.getInputStream()));

I changed it to

    public static void main(String... args) {
    int port = 2309;
    sSocket sSocket = new sSocket(port);
    System.out.println("### SERVER IS UP AND RUNNING, WAITING FOR A CLIENT TO CONNECT ON " + port + " ###");
    Socket cSocket = sSocket.accept();
    System.out.println("### CONNECTION WITH THE CLIENT CREATED ###");
    InputStream readRequest = cSocket.getInputStream();
    PrintWriter writeResponse = new PrintWriter(cSocket.getOutputStream());
    byte[] buf = new byte[4096];
    readRequest.read(buf);
    String httpPayload = new String(buf, "UTF-8");
    HttpPayload httpPayloadObject = new HttpPayload(httpPayload);
    Map<String, Object> httpParameters = httpPayloadObject.getHttpPayloadBodyMap();
    PushNotificationEvent event = new PushNotificationEvent(httpParameters);
    event.processEvent();
    writeResponse.write("HTTP/1.0 200 OK\r\n");
    writeResponse.write("Date: Fri, 31 Dec 1999 23:59:59 GMT\r\n");
    writeResponse.write("Server: Apache/0.8.4\r\n");
    writeResponse.write("Content-Type: text/html\r\n");
    writeResponse.write("Content-Length: 59\r\n");
    writeResponse.write("Expires: Sat, 01 Jan 2000 00:59:59 GMT\r\n");
    writeResponse.write("Last-modified: Fri, 09 Aug 1996 14:21:40 GMT\r\n");
    writeResponse.write("\r\n");
    writeResponse.write("<TITLE>Example</TITLE>");
    writeResponse.write("<P>This is an example</P>");
}

the Buffered input stream omitted the body part. Now I get the output as desired

POST / HTTP/1.1
Host: 127.0.0.1:2309
Connection: keep-alive
Content-Length: 63
Origin: chrome-extension://hgmloofddffdnphfgcellkdfbfbjeloo
header1: value1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW6**strong text**4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.111 Safari/537.36
Content-Type: application/json
Accept: */*
Accept-Encoding: gzip, deflate
    en-US,en;q=0.8

{jsondata : {key1:value1_getting_bigger_content,  key2:value2}}

the part which was not showing up in the payload previously is

{jsondata : {key1:value1_getting_bigger_content,  key2:value2}}

I am still not sure why BufferedReader or BufferedInputStream omits the body

Answer 2

You're ignoring the content-length provided and trying to read until end of stream, which will never arrive because the client hasn't closed the connection, because he's trying to read the response. You need to stop reading when you've read content-length bytes after the headers, if that header is present.

NB If you're using a Reader you should build it with the same CharSet that was sent in the headers.