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Android™

Send a 4-byte Length Prefix over a Socket

See more Socket/SSL/TLS Examples

Demonstrates Socket.SendCount, which sends a four-byte length prefix in network byte order. This is typically used to tell the peer how many bytes follow.

Background. A length-prefixed framing scheme sends the byte count of a message before the message body, so the receiver knows exactly how many bytes to read with a counted receive.

Chilkat Android™ Downloads

Android™
// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    CkSocket socket = new CkSocket();

    //  Connect to the server using TLS.
    boolean bTls = true;
    int maxWaitMs = 5000;
    success = socket.Connect("example.com",5000,bTls,maxWaitMs);
    if (success == false) {
        Log.i(TAG, socket.lastErrorText());
        return;
        }

    //  Send a four-byte length prefix in network byte order.  A common framing pattern is to send the
    //  number of bytes in a message before the message itself, so the peer knows exactly how many bytes
    //  to read.
    int messageLength = 512;
    success = socket.SendCount(messageLength);
    if (success == false) {
        Log.i(TAG, socket.lastErrorText());
        return;
        }

    Log.i(TAG, "Length prefix sent.");

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}