[JAVA] GCM Sender and Library

import java.io.IOException; 
  
import com.google.android.gcm.server.Constants; 
import com.google.android.gcm.server.Message; 
import com.google.android.gcm.server.Result; 
import com.google.android.gcm.server.Sender; 
  
public class MD_gcmManager { 
    public static final String TAG = "MD_gcmManager"; 
    String key = "123"; 
  
    public static final String APT_KEY = "-"; 
  
    public void sendPush(String regId, String contents) { 
        Sender sender = new Sender(APT_KEY); 
        Message msg = new Message.Builder().addData(key, contents).build(); 
        Result result; 
        try { 
            result = sender.send(msg, regId, 5); 
            if (result.getMessageId() != null) { 
                // 푸쉬 전송 성공 
                System.out.println("푸쉬 전송 성공"); 
            } else { 
                String error = result.getErrorCodeName(); 
                if (Constants.ERROR_INTERNAL_SERVER_ERROR.equals(error)) { 
                    // 구글 푸시 서버 에러 
                    System.out.println("구글 푸시 서버 에러"); 
                } 
            } 
        } catch (IOException e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
            System.out.println("e:" + e.toString()); 
        } 
    } 
}

gcm-server.jarjson-simple-1.1.1.jar